000
FXUS63 KLOT 200524
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1224 AM CDT SAT SEP 20 2008

.DISCUSSION...
240 PM CDT

ONCE AGAIN...ONLY SOME MINOR ADJUSTMENT NECESSARY FOR THE
AFTERNOON FORECAST UPDATE.

FOR THE NEAR TERM...THE PRIMARY CONCERN IS CLOUD COVER SPREADING
NORTH OF THE UPPER LOW OVER THE LOWER MISSISSIPPI VALLEY TRACKING
NWD. PER LATEST SATELLITE OBS AND VISUAL INSPECTION OF CLOUD
COVER...HAVE INCREASED CLOUD COVER FOR THE REMAINDER OF THE
AFTERNOON AND THROUGH THE OVERNIGHT HOURS. WHILE THE CLOUD COVER
IS GENERALLY CIRRUS...IT HAS BECOME SUFFICIENTLY THICK ENOUGH TO
BE OPAQUE OVER A SIGNIFICANT PORTION OF THE SKY. THE EVOLUTION OF
THIS FEATURE WILL ALSO HAVE SOME IMPACT ON THE FORECAST OF THE
LOCAL AREA INTO THE SHORT TERM FORECAST PERIOD...PARTICULARLY THE
TEMPERATURE FORECAST. THE SHORT TERM MODELS ARE TRENDING TOWARD A
MORE AMPLIFIED PATTERN OVER THE CENTRAL CONUS...PUMPING UP A
STRONGER BENT-BACK RIDGE OVER THE NORTHERN PLAINS OVER THE
WEEKEND...WHILE DIGGING A DEEPER BROAD SCALE TROUGH OVER ERN
CANADA AND THE NERN CONUS. THE UPPER LOW MOVING UP THE MISSISSIPPI
VALLEY APPEARS TO BE CREATING A WEAKNESS IN THE UPPER LEVEL
PATTERN...ALLOWING THE BROAD ERN TROUGH TO DIG FARTHER SOUTH. THE
EFFECT AT THE SURFACE IS TO BUILD HIGH PRESSURE SWWD OVER THE
GREAT LAKES AND INTO NRN IL/IN. THIS WILL IN EFFECT...ALLOW A BACK
DOOR COLD FRONT TO PUSH OVER THE AREA...DRIVING TEMPERATURES OVER
THE REGION A BIT LOWER FOR SUNDAY AND MONDAY. STILL FEEL THAT
SATURDAY WILL BE RATHER WARM AS THE UPPER LOW TO THE SOUTH WILL
NOT YET BE CLOSE ENOUGH TO SIGNIFICANTLY AFFECT THE LOCAL WEATHER
PICTURE...WITH THE EXCEPTION OF KEEPING A CANOPY OF CIRRUS IN
PLACE.

TRANSITIONING INTO THE LONGER TERM...BY SUNDAY AND MONDAY...THE
MODELS ARE MAINTAINING SIMILAR TRENDS OVER RECENT RUNS. THE
NAM/ECMWF ARE TRENDING SLOWER THAN THE GFS WITH THE PROGRESSION
OF THE NEXT UPSTREAM TROUGH MOVING INTO PACIFIC NORTHWEST AND
LIFTING OUT THE MISSISSIPPI VALLEY UPPER LOW. STILL FEEL THAT THE
SLOWER SOLUTION IS THE WAY TO GO BASED ON RECENT TRENDS...SO THIS
SOLUTION HAS GENERALLY BEEN FOLLOWED AGAIN TODAY. THE MAIN
ADJUSTMENT TO THE NAM GUIDANCE FOR THE SHORTER TERM HAS BEEN TO
LOWER TEMPERATURES HIGH TEMPS ON SUNDAY AND MONDAY TO EMPHASIZE
THE IMPACT OF THE BACK DOOR COLD FRONT AND THE RESULTANT LONG
PERIOD OF ELY FLOW OFF OF LAKE MICHIGAN. HAVE ALSO INTRODUCED
SLIGHT CHANCE POPS TO THE SWRN PORTION OF THE CWA AS THE UPPER LOW
BRINGS SOME FORCING AND INSTABILITY TO THE REGION.

LOOKING FARTHER INTO THE LONG TERM...HAVE MADE LITTLE CHANGE AS
THE ECMWF...BOTH LAST NIGHT`S 00Z RUN AND THE NEW 12Z RUN BOTH
MAINTAIN VERY GOOD CONTINUITY WITH THE PROGRESSION OF THE UPSTREAM
TROUGH. GIVEN THIS GOOD RUN TO RUN CONTINUITY...AS WELL AS GOOD
CONTINUITY WITH THE 12Z NAM...HAVE LARGELY DISCOUNTED THE FASTER
GFS AND WILL CONTINUE TO KEEP POPS OUT OF THE LOCAL AREA UNTIL
LATE WEDNESDAY NIGHT AND THURSDAY.

OVERALL...EXPECT A GENERALLY DRY PERIOD FOR NRN IL/NWRN INDIANA.
EVEN WITH TEMPERATURES EXPECTED TO BE A LITTLE LOWER THAN
PREVIOUSLY FORECAST FOR SUNDAY AND MONDAY...THE GENERAL TREND FOR
TEMPERATURES WILL BE TO BE ABOVE NORMAL FOR THE PERIOD.

KREIN

&&

.AVIATION...

06Z TAFS...GRADIENT WEAKENING EARLY THIS MORNING WITH LIGHT
SOUTHERLY WINDS BECOMING LIGHT AND VRB WITH MANY LOCATIONS SOUTH
OF THE TERMINALS ALREADY CALM. VISIBILITIES BEGINNING TO DIP TO
6-8SM AT SOME LOCATIONS. EXPECT MVFR VIS TO BE COMMON BY DAY BREAK
AND WILL TAKE RFD/DPA TO 3SM. CLOSER TO ORD/MDW WHERE TEMPS WILL
STAY A FEW DEGREES WARMER...THINK 5-6SM OR BETTER SHOULD HANDLE
TONIGHT. WILL NEED TO WATCH TRENDS OVERNIGHT WITH PATCHY OR
SHALLOW DENSE GROUND FOG POSSIBLE.

GRADIENT REMAINS LIGHT INTO THIS AFTERNOON WITH WINDS GENERALLY
LIGHT WESTERLY. THOUGH LIGHT GRADIENT SHOULD ALLOW A LAKE BREEZE
TO FORM...PRIOR TO COLD FRONT ARRIVING. HAVE MAINTAINED CURRENT
TIMING OF 20Z AT ORD/MDW. COLD FRONT PUSHES SOUTH ACROSS LAKE
MICHIGAN...REACHING NORTHEAST IL DURING THE EVENING BUT SPEEDS
SHOULD BE BELOW 10KTS. WINDS TURN NORTHEAST WITH FROPA AND REMAIN
NORTHEAST INTO SUNDAY.

WITH LOW LEVEL MOISTURE INCREASING ALONG/AHEAD OF THE FRONT...
EXPECT A FEW ISOLATED SHOWERS BUT THESE SHOULD REMAIN NORTH OF
TERMINALS THRU EARLY EVENING AND DISSIPATE WITH SUNSET. ALSO
COULD BE A FEW SHOWERS/TS WITH UPPER LOW OVER SOUTHERN IL. CMS

&&

.MARINE...
133 PM CDT

THE HIGH OVER THE NORTHEAST COAST AND THE LOW OVER HUDSON BAY WILL
KEEP THE PRESSURE GRADIENT OVER NORTHERN LAKE MICHIGAN LARGE THIS
AFTERNOON. WE WILL KEEP THE GALE WARNING FOR THE GUSTS OF WIND
INTO THE 34 TO 38 KNOT RANGE. AS THE LOW MOVES EAST...A HIGH IS
FORECAST TO MOVE INTO ONTARIO BY SATURDAY EVENING. THE WIND WILL
DIMINISH LATE TONIGHT AND BY SATURDAY MORNING IS EXPECTED TO
BECOME MORE NORTHERLY.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 200442
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1142 PM CDT FRI SEP 19 2008

.DISCUSSION...
ISSUED 842 PM CDT FRI SEP 19 2008

WEAK UPPER LEVEL LOW IS CENTERED OVER MISSOURI...WITH MAINLY
DIURNALLY INDUCED SHOWERS/STORMS ROTATING AROUND THE SOUTH AND
EAST SIDE OF THE SYSTEM. 00Z ILX AND FORECAST SOUNDINGS SUGGEST
AIRMASS OVER CENTRAL AND SOUTHEAST ILLINOIS IS STILL FAIRLY DRY.
HOWEVER...LAPSE RATES ARE ON THE STEEP SIDE.

UPPER LOW IS EXPECTED TO DRIFT TOWARD THE FORECAST AREA OVERNIGHT...
BUT IS SHOULD NOT REALLY IMPACT US UNTIL SATURDAY. THE FORCING
WITH THE WEAK LOW IS NOT VERY GOOD...WITH DIURNAL HEATING
COMBINING WITH STEEP LAPSE RATES TO PRODUCE PRECIPITATION.
RADAR/SATELLITE TRENDS HAVE BEEN ON THE WAY DOWN SINCE SUNSET AND
EXPECT THIS TREND TO CONTINUE WITH LOSS OF DIURNAL INSTABILITY.

GOING FORECAST IS IN PRETTY GOOD SHAPE. ONLY EXPECT MINOR TWEAKS
TO THE GRIDS FOR THE LATEST TRENDS...SO NO ZONE UPDATE IS NEEDED
AT THIS TIME. WILL KEEP AN EYE ON THE PRECIPITATION TRENDS...BUT
THINK MAJORITY OF THE PRECIPITATION SHOULD MISS US AND/OR
DISSIPATE BEFORE IT GETS HERE.

BAK
&&

.AVIATION...
ISSUED 1142 PM CDT FRI SEP 19 2008

QUIET/VFR CONDITIONS EXPECTED TO PERSIST FOR MAJORITY OF 06Z TAF
PERIOD. A WEAK UPPER LEVEL LOW OVER MISSOURI WILL SLOWLY DRIFT
NORTHEAST INTO ILLINOIS BY SATURDAY AFTERNOON. A CIRRUS CLOUD
SHIELD WILL REMAIN ACROSS THE AREA IN ADVANCE OF THE
CIRCULATION...WHILE VFR CU/TCU/CB CEILINGS WILL DEVELOP WITH
AFTERNOON HEATING SATURDAY AS THE SYSTEM DRAWS CLOSER. SCATTERED
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE DURING THE AFTERNOON AS
WELL...BUT THE EXPECTED COVERAGE IS NOT HIGH ENOUGH TO CARRY MORE
THAN A VICINITY MENTION AT ANY ONE TERMINAL. THE COOLEST
TEMPERATURES ALOFT AND ASSOCIATED BEST CHANCE FOR THUNDER WILL
OCCUR OVER THE KSPI/KDEC TERMINALS. THE LOWER CLOUD AND
PRECIPITATION RISK WILL DIMINISH AGAIN AFTER SUNSET. WINDS SHOULD
REMAIN LIGHT/VARIABLE THROUGHOUT AWAY FROM ANY CONVECTION.

BAK
&&

.PREV DISCUSSION...
ISSUED 145 PM CDT FRI SEP 19 2008

FORECAST CONCERN THIS PERIOD WILL REVOLVE AROUND WEAK UPPER LOW
ACRS THE SRN PLAINS AND ITS AFFECT ON OUR WEATHER THIS WEEKEND.
SURFACE HIGH PRESSURE ACRS ERN OHIO WILL CONTINUE TO SLOWLY MOVE
AWAY FROM THE REGION OVR THE NEXT 24 HOURS. WEAK SOUTHERLY FLOW
HAS HELPED BRING SFC DEW POINTS INTO THE UPPER 50S TO LOWER 60S
THIS AFTN. MEANWHILE...SATELLITE AND PROFILER DATA INDICATES 2
DISTINCT UPPER WAVES ACRS THE SRN PLAINS. THE FIRST WAVE WAS
LOCATED OVR ERN COLORADO AND WRN KS WITH THE SECOND UPPER LEVEL
FEATURE OVR ERN OK INTO WRN ARK. A LARGE AREA OF HIGH LEVEL
MOISTURE HAS WORKED ITS WAY NWD INTO THE MIDWEST THIS AFTN AND
WDLY SCATTERED SHOWERS AND THUNDERSTORMS WERE OCCURRING TO THE
EAST OF THE UPPER LEVEL FEATURES ACRS ARKANSAS INTO SRN MO.

SHORT TERM...TONIGHT THROUGH MONDAY
NO REAL MODEL DIFFERENCES SEEN THIS PERIOD AS THE MAIN WEATHER
FEATURE WILL BE WITH THE UPPER LEVEL WAVE ACRS THE SRN PLAINS.
CLOUDS AND RAIN CHANCES WILL BE INCREASED AHEAD OF THE DISTURBANCE
ON SATURDAY AND LINGER INTO SUNDAY. COOL MID LEVEL TEMPERATURES
AND AN INCREASE IN LOW LVL MOISTURE WILL PRODUCE SOME WEAK
INSTABILITY DURING THE AFTN AND EVENING HOURS SAT AND SUN. THIS
WL LEAD TO AT BEST...ISOLATED TO WDLY SCATTERED SHOWERS AND
T-STORMS. CAN`T REALLY SEE GOING ANY HIGHER THAN 20 TO 30 PERCENT
ON POPS WITH LACK OF ANY SIGNIFICANT LOW LVL FORCING. FORECAST
SOUNDINGS SUGGEST THE BETTER MOISTURE PROFILES WOULD BE WHEN THE
UPPER LEVEL WAVE WOULD BE RIGHT OVR CNTRL IL...SUNDAY AFTN AND
EVENING. WITH THE INCREASE IN CLOUD COVER...TEMPS WERE HELD AT OR
BELOW GUID VALUES FOR BOTH SATURDAY AND SUNDAY...WHICH WOULD PUT
HIGHS IN THE UPPER 70S TO LOWER 80S.

MODELS ALL AGREE THAT BY MONDAY THE WEAK UPPER LEVEL SYSTEM WL
TRACK EAST OF THE AREA WHILE UPPER LEVEL RIDGING BUILDS ACRS
THE MIDWEST AHEAD OF A FAIRLY STRONG TROF OVER THE WRN U.S.

LONG TERM...TUESDAY THROUGH FRIDAY
A FAIRLY STRONG NORTHERN STREAM SHORTWAVE IS EXPECTED TO PUSH ACRS
THE PLAINS LATER TUESDAY INTO WEDNESDAY. MODELS CONTINUE TO SUGGEST
THE MAIN UPPER WAVE AND BEST FORCING ASSOCIATED WITH THE TROF WL
PASS WELL NORTHWEST OF OUR AREA LATE WED INTO THURSDAY. A WEAKENING
COLD FRONT WL STRUGGLE TO MAKE IT THIS FAR EAST WED NIGHT INTO
THU WITH ITS ASSOCIATED LOW PRECIP CHANCES. ALL MEDIUM RANGE MODELS
CONTINUE TO INDICATE THE LOW LEVEL FLOW AHEAD OF THE FRONT DOES NOT
SUGGEST A REAL SIGNIFICANT RAIN THREAT WITH WHAT IS LEFT OF THE
FRONT ON THURSDAY ACRS OUR AREA. TEMPERATURES DURING THIS PERIOD
WL AVERAGE A FEW DEGREES ABOVE NORMAL WITH DAYTIME HIGHS IN THE
UPPER 70S TO LOWER 80S WHILE OVERNIGHT LOWS DROP INTO THE UPPER
50S TO LOWER 60S.

SMITH


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 200142
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
842 PM CDT FRI SEP 19 2008

.DISCUSSION...
ISSUED 842 PM CDT FRI SEP 19 2008

WEAK UPPER LEVEL LOW IS CENTERED OVER MISSOURI...WITH MAINLY
DIURNALLY INDUCED SHOWERS/STORMS ROTATING AROUND THE SOUTH AND
EAST SIDE OF THE SYSTEM. 00Z ILX AND FORECAST SOUNDINGS SUGGEST
AIRMASS OVER CENTRAL AND SOUTHEAST ILLINOIS IS STILL FAIRLY DRY.
HOWEVER...LAPSE RATES ARE ON THE STEEP SIDE.

UPPER LOW IS EXPECTED TO DRIFT TOWARD THE FORECAST AREA OVERNIGHT...
BUT IS SHOULD NOT REALLY IMPACT US UNTIL SATURDAY. THE FORCING
WITH THE WEAK LOW IS NOT VERY GOOD...WITH DIURNAL HEATING
COMBINING WITH STEEP LAPSE RATES TO PRODUCE PRECIPITATION.
RADAR/SATELLITE TRENDS HAVE BEEN ON THE WAY DOWN SINCE SUNSET AND
EXPECT THIS TREND TO CONTINUE WITH LOSS OF DIURNAL INSTABILITY.

GOING FORECAST IS IN PRETTY GOOD SHAPE. ONLY EXPECT MINOR TWEAKS
TO THE GRIDS FOR THE LATEST TRENDS...SO NO ZONE UPDATE IS NEEDED
AT THIS TIME. WILL KEEP AN EYE ON THE PRECIPITATION TRENDS...BUT
THINK MAJORITY OF THE PRECIPITATION SHOULD MISS US AND/OR
DISSIPATE BEFORE IT GETS HERE.

BAK
&&

.AVIATION...
ISSUED 625 PM CDT FRI SEP 19 2008

QUIET/VFR CONDITIONS EXPECTED TO PERSIST FOR MAJORITY OF 00Z TAF
PERIOD. A WEAK UPPER LEVEL LOW OVER MISSOURI WILL SLOWLY DRIFT
NORTHEAST INTO ILLINOIS BY SATURDAY AFTERNOON. A CIRRUS CLOUD
SHIELD WILL REMAIN ACROSS THE AREA IN ADVANCE OF THE
CIRCULATION...WHILE VFR CU/TCU/CB CEILINGS WILL DEVELOP WITH
AFTERNOON HEATING SATURDAY AS THE SYSTEM DRAWS CLOSER. SCATTERED
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE DURING THE AFTERNOON
AS WELL...BUT THE EXPECTED COVERAGE IS NOT HIGH ENOUGH TO CARRY
MORE THAN A VICINITY MENTION AT ANY ONE TERMINAL. THE COOLEST
TEMPERATURES ALOFT AND ASSOCIATED BEST CHANCE FOR THUNDER WILL
OCCUR OVER THE KSPI/KDEC TERMINALS. WINDS SHOULD REMAIN
LIGHT/VARIABLE THROUGHOUT AWAY FROM ANY CONVECTION.

BAK
&&

.PREV DISCUSSION...
ISSUED 145 PM CDT FRI SEP 19 2008

FORECAST CONCERN THIS PERIOD WILL REVOLVE AROUND WEAK UPPER LOW
ACRS THE SRN PLAINS AND ITS AFFECT ON OUR WEATHER THIS WEEKEND.
SURFACE HIGH PRESSURE ACRS ERN OHIO WILL CONTINUE TO SLOWLY MOVE
AWAY FROM THE REGION OVR THE NEXT 24 HOURS. WEAK SOUTHERLY FLOW
HAS HELPED BRING SFC DEW POINTS INTO THE UPPER 50S TO LOWER 60S
THIS AFTN. MEANWHILE...SATELLITE AND PROFILER DATA INDICATES 2
DISTINCT UPPER WAVES ACRS THE SRN PLAINS. THE FIRST WAVE WAS
LOCATED OVR ERN COLORADO AND WRN KS WITH THE SECOND UPPER LEVEL
FEATURE OVR ERN OK INTO WRN ARK. A LARGE AREA OF HIGH LEVEL
MOISTURE HAS WORKED ITS WAY NWD INTO THE MIDWEST THIS AFTN AND
WDLY SCATTERED SHOWERS AND THUNDERSTORMS WERE OCCURRING TO THE
EAST OF THE UPPER LEVEL FEATURES ACRS ARKANSAS INTO SRN MO.

SHORT TERM...TONIGHT THROUGH MONDAY
NO REAL MODEL DIFFERENCES SEEN THIS PERIOD AS THE MAIN WEATHER
FEATURE WILL BE WITH THE UPPER LEVEL WAVE ACRS THE SRN PLAINS.
CLOUDS AND RAIN CHANCES WILL BE INCREASED AHEAD OF THE DISTURBANCE
ON SATURDAY AND LINGER INTO SUNDAY. COOL MID LEVEL TEMPERATURES
AND AN INCREASE IN LOW LVL MOISTURE WILL PRODUCE SOME WEAK
INSTABILITY DURING THE AFTN AND EVENING HOURS SAT AND SUN. THIS
WL LEAD TO AT BEST...ISOLATED TO WDLY SCATTERED SHOWERS AND
T-STORMS. CAN`T REALLY SEE GOING ANY HIGHER THAN 20 TO 30 PERCENT
ON POPS WITH LACK OF ANY SIGNIFICANT LOW LVL FORCING. FORECAST
SOUNDINGS SUGGEST THE BETTER MOISTURE PROFILES WOULD BE WHEN THE
UPPER LEVEL WAVE WOULD BE RIGHT OVR CNTRL IL...SUNDAY AFTN AND
EVENING. WITH THE INCREASE IN CLOUD COVER...TEMPS WERE HELD AT OR
BELOW GUID VALUES FOR BOTH SATURDAY AND SUNDAY...WHICH WOULD PUT
HIGHS IN THE UPPER 70S TO LOWER 80S.

MODELS ALL AGREE THAT BY MONDAY THE WEAK UPPER LEVEL SYSTEM WL
TRACK EAST OF THE AREA WHILE UPPER LEVEL RIDGING BUILDS ACRS
THE MIDWEST AHEAD OF A FAIRLY STRONG TROF OVER THE WRN U.S.

LONG TERM...TUESDAY THROUGH FRIDAY
A FAIRLY STRONG NORTHERN STREAM SHORTWAVE IS EXPECTED TO PUSH ACRS
THE PLAINS LATER TUESDAY INTO WEDNESDAY. MODELS CONTINUE TO SUGGEST
THE MAIN UPPER WAVE AND BEST FORCING ASSOCIATED WITH THE TROF WL
PASS WELL NORTHWEST OF OUR AREA LATE WED INTO THURSDAY. A WEAKENING
COLD FRONT WL STRUGGLE TO MAKE IT THIS FAR EAST WED NIGHT INTO
THU WITH ITS ASSOCIATED LOW PRECIP CHANCES. ALL MEDIUM RANGE MODELS
CONTINUE TO INDICATE THE LOW LEVEL FLOW AHEAD OF THE FRONT DOES NOT
SUGGEST A REAL SIGNIFICANT RAIN THREAT WITH WHAT IS LEFT OF THE
FRONT ON THURSDAY ACRS OUR AREA. TEMPERATURES DURING THIS PERIOD
WL AVERAGE A FEW DEGREES ABOVE NORMAL WITH DAYTIME HIGHS IN THE
UPPER 70S TO LOWER 80S WHILE OVERNIGHT LOWS DROP INTO THE UPPER
50S TO LOWER 60S.

SMITH

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 200012
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
712 PM CDT FRI SEP 19 2008

.DISCUSSION...
240 PM CDT

ONCE AGAIN...ONLY SOME MINOR ADJUSTMENT NECESSARY FOR THE
AFTERNOON FORECAST UPDATE.

FOR THE NEAR TERM...THE PRIMARY CONCERN IS CLOUD COVER SPREADING
NORTH OF THE UPPER LOW OVER THE LOWER MISSISSIPPI VALLEY TRACKING
NWD. PER LATEST SATELLITE OBS AND VISUAL INSPECTION OF CLOUD
COVER...HAVE INCREASED CLOUD COVER FOR THE REMAINDER OF THE
AFTERNOON AND THROUGH THE OVERNIGHT HOURS. WHILE THE CLOUD COVER
IS GENERALLY CIRRUS...IT HAS BECOME SUFFICIENTLY THICK ENOUGH TO
BE OPAQUE OVER A SIGNIFICANT PORTION OF THE SKY. THE EVOLUTION OF
THIS FEATURE WILL ALSO HAVE SOME IMPACT ON THE FORECAST OF THE
LOCAL AREA INTO THE SHORT TERM FORECAST PERIOD...PARTICULARLY THE
TEMPERATURE FORECAST. THE SHORT TERM MODELS ARE TRENDING TOWARD A
MORE AMPLIFIED PATTERN OVER THE CENTRAL CONUS...PUMPING UP A
STRONGER BENT-BACK RIDGE OVER THE NORTHERN PLAINS OVER THE
WEEKEND...WHILE DIGGING A DEEPER BROAD SCALE TROUGH OVER ERN
CANADA AND THE NERN CONUS. THE UPPER LOW MOVING UP THE MISSISSIPPI
VALLEY APPEARS TO BE CREATING A WEAKNESS IN THE UPPER LEVEL
PATTERN...ALLOWING THE BROAD ERN TROUGH TO DIG FARTHER SOUTH. THE
EFFECT AT THE SURFACE IS TO BUILD HIGH PRESSURE SWWD OVER THE
GREAT LAKES AND INTO NRN IL/IN. THIS WILL IN EFFECT...ALLOW A BACK
DOOR COLD FRONT TO PUSH OVER THE AREA...DRIVING TEMPERATURES OVER
THE REGION A BIT LOWER FOR SUNDAY AND MONDAY. STILL FEEL THAT
SATURDAY WILL BE RATHER WARM AS THE UPPER LOW TO THE SOUTH WILL
NOT YET BE CLOSE ENOUGH TO SIGNIFICANTLY AFFECT THE LOCAL WEATHER
PICTURE...WITH THE EXCEPTION OF KEEPING A CANOPY OF CIRRUS IN
PLACE.

TRANSITIONING INTO THE LONGER TERM...BY SUNDAY AND MONDAY...THE
MODELS ARE MAINTAINING SIMILAR TRENDS OVER RECENT RUNS. THE
NAM/ECMWF ARE TRENDING SLOWER THAN THE GFS WITH THE PROGRESSION
OF THE NEXT UPSTREAM TROUGH MOVING INTO PACIFIC NORTHWEST AND
LIFTING OUT THE MISSISSIPPI VALLEY UPPER LOW. STILL FEEL THAT THE
SLOWER SOLUTION IS THE WAY TO GO BASED ON RECENT TRENDS...SO THIS
SOLUTION HAS GENERALLY BEEN FOLLOWED AGAIN TODAY. THE MAIN
ADJUSTMENT TO THE NAM GUIDANCE FOR THE SHORTER TERM HAS BEEN TO
LOWER TEMPERATURES HIGH TEMPS ON SUNDAY AND MONDAY TO EMPHASIZE
THE IMPACT OF THE BACK DOOR COLD FRONT AND THE RESULTANT LONG
PERIOD OF ELY FLOW OFF OF LAKE MICHIGAN. HAVE ALSO INTRODUCED
SLIGHT CHANCE POPS TO THE SWRN PORTION OF THE CWA AS THE UPPER LOW
BRINGS SOME FORCING AND INSTABILITY TO THE REGION.

LOOKING FARTHER INTO THE LONG TERM...HAVE MADE LITTLE CHANGE AS
THE ECMWF...BOTH LAST NIGHT`S 00Z RUN AND THE NEW 12Z RUN BOTH
MAINTAIN VERY GOOD CONTINUITY WITH THE PROGRESSION OF THE UPSTREAM
TROUGH. GIVEN THIS GOOD RUN TO RUN CONTINUITY...AS WELL AS GOOD
CONTINUITY WITH THE 12Z NAM...HAVE LARGELY DISCOUNTED THE FASTER
GFS AND WILL CONTINUE TO KEEP POPS OUT OF THE LOCAL AREA UNTIL
LATE WEDNESDAY NIGHT AND THURSDAY.

OVERALL...EXPECT A GENERALLY DRY PERIOD FOR NRN IL/NWRN INDIANA.
EVEN WITH TEMPERATURES EXPECTED TO BE A LITTLE LOWER THAN
PREVIOUSLY FORECAST FOR SUNDAY AND MONDAY...THE GENERAL TREND FOR
TEMPERATURES WILL BE TO BE ABOVE NORMAL FOR THE PERIOD.

KREIN

&&

.AVIATION...
710 PM CDT

00Z TAFORS...CDFNT EXTENDING SWWRD FM LO PRES OVR SRN HUDSON BAY
BACK ACROSS MN AND ERN SD. WITH WESTERLIES ACROSS CANADA LITTLE
SWRD PUSH TO THIS PORTION OF CDFNT WITH PRES RISE CNTR CONFINED TO
MANITOBA AND WRN ONTARIO AT ERLY EVE. CDFNT TO EVENTUALLY SINK
ACRS THE SRN GRTLKS SAT AFTN BUT SFC WND TO TO OFF LK MI DUE TO LK
BRZ UNDER WK PRES GRAD BEFORE SYNOPTIC GO TO NERLY TOWARD 00Z SUN.

FEW SHRA AND TS CURRENTLY ALONG/AHEAD OF CDFNT IN MN WHERE DWPTS
POOLING IN UPR 50S AND LWR 60S. WEAKENING BOUNDARY AND OR LK BRZ
COULD PROVIDE FOCUS FOR ISOLD TS LATER SAT AFTN BUT APPEARS BETTER
CHC WILL BE FM MN-IA BORDER E ACRS SRN WI...POST WSHFT...WHERE MID
AND UPR LVL TEMPS COOL A BIT AND STEEPEN LAPSE RATES AS UPPER TROF
DIGS ESE ACRS ONTARIO.

EXPECT JUST AREAS OF CI AT THE TERMINALS THRU PD...ASSOCIATED WITH
CUT OFF UPR LO DRIFTING NEWRD FM SRN MO. DWPTS ALSO IN UPR 50S AND
LWR 60S ACROSS LOCAL AREA BUR DENSE UPR CLOUD COVER TO INHIBIT
RADIATIONAL COOLING AND FG FORMATION SO JUST SOME PRE SUNRISE
MVFR VSBY DUE BR/HZ HANGING AROUND FAVORED LOCATIONS OF RFD AND
DPA TIL HEATING ALLOWS BL MIXING.

TRS

&&

.MARINE...
133 PM CDT

THE HIGH OVER THE NORTHEAST COAST AND THE LOW OVER HUDSON BAY WILL
KEEP THE PRESSURE GRADIENT OVER NORTHERN LAKE MICHIGAN LARGE THIS
AFTERNOON. WE WILL KEEP THE GALE WARNING FOR THE GUSTS OF WIND
INTO THE 34 TO 38 KNOT RANGE. AS THE LOW MOVES EAST...A HIGH IS
FORECAST TO MOVE INTO ONTARIO BY SATURDAY EVENING. THE WIND WILL
DIMINISH LATE TONIGHT AND BY SATURDAY MORNING IS EXPECTED TO
BECOME MORE NORTHERLY.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL
     10 PM FRIDAY.

&&

$$

000
FXUS63 KILX 192325
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
625 PM CDT FRI SEP 19 2008

.DISCUSSION...
ISSUED 145 PM CDT FRI SEP 19 2008

FORECAST CONCERN THIS PERIOD WILL REVOLVE AROUND WEAK UPPER LOW
ACRS THE SRN PLAINS AND ITS AFFECT ON OUR WEATHER THIS WEEKEND.
SURFACE HIGH PRESSURE ACRS ERN OHIO WILL CONTINUE TO SLOWLY MOVE
AWAY FROM THE REGION OVR THE NEXT 24 HOURS. WEAK SOUTHERLY FLOW
HAS HELPED BRING SFC DEW POINTS INTO THE UPPER 50S TO LOWER 60S
THIS AFTN. MEANWHILE...SATELLITE AND PROFILER DATA INDICATES 2
DISTINCT UPPER WAVES ACRS THE SRN PLAINS. THE FIRST WAVE WAS
LOCATED OVR ERN COLORADO AND WRN KS WITH THE SECOND UPPER LEVEL
FEATURE OVR ERN OK INTO WRN ARK. A LARGE AREA OF HIGH LEVEL
MOISTURE HAS WORKED ITS WAY NWD INTO THE MIDWEST THIS AFTN AND
WDLY SCATTERED SHOWERS AND THUNDERSTORMS WERE OCCURRING TO THE
EAST OF THE UPPER LEVEL FEATURES ACRS ARKANSAS INTO SRN MO.

SHORT TERM...TONIGHT THROUGH MONDAY
NO REAL MODEL DIFFERENCES SEEN THIS PERIOD AS THE MAIN WEATHER
FEATURE WILL BE WITH THE UPPER LEVEL WAVE ACRS THE SRN PLAINS.
CLOUDS AND RAIN CHANCES WILL BE INCREASED AHEAD OF THE DISTURBANCE
ON SATURDAY AND LINGER INTO SUNDAY. COOL MID LEVEL TEMPERATURES
AND AN INCREASE IN LOW LVL MOISTURE WILL PRODUCE SOME WEAK
INSTABILITY DURING THE AFTN AND EVENING HOURS SAT AND SUN. THIS
WL LEAD TO AT BEST...ISOLATED TO WDLY SCATTERED SHOWERS AND
T-STORMS. CAN`T REALLY SEE GOING ANY HIGHER THAN 20 TO 30 PERCENT
ON POPS WITH LACK OF ANY SIGNIFICANT LOW LVL FORCING. FORECAST
SOUNDINGS SUGGEST THE BETTER MOISTURE PROFILES WOULD BE WHEN THE
UPPER LEVEL WAVE WOULD BE RIGHT OVR CNTRL IL...SUNDAY AFTN AND
EVENING. WITH THE INCREASE IN CLOUD COVER...TEMPS WERE HELD AT OR
BELOW GUID VALUES FOR BOTH SATURDAY AND SUNDAY...WHICH WOULD PUT
HIGHS IN THE UPPER 70S TO LOWER 80S.

MODELS ALL AGREE THAT BY MONDAY THE WEAK UPPER LEVEL SYSTEM WL
TRACK EAST OF THE AREA WHILE UPPER LEVEL RIDGING BUILDS ACRS
THE MIDWEST AHEAD OF A FAIRLY STRONG TROF OVER THE WRN U.S.

LONG TERM...TUESDAY THROUGH FRIDAY
A FAIRLY STRONG NORTHERN STREAM SHORTWAVE IS EXPECTED TO PUSH ACRS
THE PLAINS LATER TUESDAY INTO WEDNESDAY. MODELS CONTINUE TO SUGGEST
THE MAIN UPPER WAVE AND BEST FORCING ASSOCIATED WITH THE TROF WL
PASS WELL NORTHWEST OF OUR AREA LATE WED INTO THURSDAY. A WEAKENING
COLD FRONT WL STRUGGLE TO MAKE IT THIS FAR EAST WED NIGHT INTO
THU WITH ITS ASSOCIATED LOW PRECIP CHANCES. ALL MEDIUM RANGE MODELS
CONTINUE TO INDICATE THE LOW LEVEL FLOW AHEAD OF THE FRONT DOES NOT
SUGGEST A REAL SIGNIFICANT RAIN THREAT WITH WHAT IS LEFT OF THE
FRONT ON THURSDAY ACRS OUR AREA. TEMPERATURES DURING THIS PERIOD
WL AVERAGE A FEW DEGREES ABOVE NORMAL WITH DAYTIME HIGHS IN THE
UPPER 70S TO LOWER 80S WHILE OVERNIGHT LOWS DROP INTO THE UPPER
50S TO LOWER 60S.

SMITH
&&

.AVIATION...
ISSUED 625 PM CDT FRI SEP 19 2008

QUIET/VFR CONDITIONS EXPECTED TO PERSIST FOR MAJORITY OF 00Z TAF
PERIOD. A WEAK UPPER LEVEL LOW OVER MISSOURI WILL SLOWLY DRIFT
NORTHEAST INTO ILLINOIS BY SATURDAY AFTERNOON. A CIRRUS CLOUD
SHIELD WILL REMAIN ACROSS THE AREA IN ADVANCE OF THE
CIRCULATION...WHILE VFR CU/TCU/CB CEILINGS WILL DEVELOP WITH
AFTERNOON HEATING SATURDAY AS THE SYSTEM DRAWS CLOSER. SCATTERED
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE DURING THE AFTERNOON
AS WELL...BUT THE EXPECTED COVERAGE IS NOT HIGH ENOUGH TO CARRY
MORE THAN A VICINITY MENTION AT ANY ONE TERMINAL. THE COOLEST
TEMPERATURES ALOFT AND ASSOCIATED BEST CHANCE FOR THUNDER WILL
OCCUR OVER THE KSPI/KDEC TERMINALS. WINDS SHOULD REMAIN
LIGHT/VARIABLE THROUGHOUT AWAY FROM ANY CONVECTION.

BAK
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 191941
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
241 PM CDT FRI SEP 19 2008

.DISCUSSION...
240 PM CDT

ONCE AGAIN...ONLY SOME MINOR ADJUSTMENT NECESSARY FOR THE
AFTERNOON FORECAST UPDATE.

FOR THE NEAR TERM...THE PRIMARY CONCERN IS CLOUD COVER SPREADING
NORTH OF THE UPPER LOW OVER THE LOWER MISSISSIPPI VALLEY TRACKING
NWD. PER LATEST SATELLITE OBS AND VISUAL INSPECTION OF CLOUD
COVER...HAVE INCREASED CLOUD COVER FOR THE REMAINDER OF THE
AFTERNOON AND THROUGH THE OVERNIGHT HOURS. WHILE THE CLOUD COVER
IS GENERALLY CIRRUS...IT HAS BECOME SUFFICIENTLY THICK ENOUGH TO
BE OPAQUE OVER A SIGNIFICANT PORTION OF THE SKY. THE EVOLUTION OF
THIS FEATURE WILL ALSO HAVE SOME IMPACT ON THE FORECAST OF THE
LOCAL AREA INTO THE SHORT TERM FORECAST PERIOD...PARTICULARLY THE
TEMPERATURE FORECAST. THE SHORT TERM MODELS ARE TRENDING TOWARD A
MORE AMPLIFIED PATTERN OVER THE CENTRAL CONUS...PUMPING UP A
STRONGER BENT-BACK RIDGE OVER THE NORTHERN PLAINS OVER THE
WEEKEND...WHILE DIGGING A DEEPER BROAD SCALE TROUGH OVER ERN
CANADA AND THE NERN CONUS. THE UPPER LOW MOVING UP THE MISSISSIPPI
VALLEY APPEARS TO BE CREATING A WEAKNESS IN THE UPPER LEVEL
PATTERN...ALLOWING THE BROAD ERN TROUGH TO DIG FARTHER SOUTH. THE
EFFECT AT THE SURFACE IS TO BUILD HIGH PRESSURE SWWD OVER THE
GREAT LAKES AND INTO NRN IL/IN. THIS WILL IN EFFECT...ALLOW A BACK
DOOR COLD FRONT TO PUSH OVER THE AREA...DRIVING TEMPERATURES OVER
THE REGION A BIT LOWER FOR SUNDAY AND MONDAY. STILL FEEL THAT
SATURDAY WILL BE RATHER WARM AS THE UPPER LOW TO THE SOUTH WILL
NOT YET BE CLOSE ENOUGH TO SIGNIFICANTLY AFFECT THE LOCAL WEATHER
PICTURE...WITH THE EXCEPTION OF KEEPING A CANOPY OF CIRRUS IN
PLACE.

TRANSITIONING INTO THE LONGER TERM...BY SUNDAY AND MONDAY...THE
MODELS ARE MAINTAINING SIMILAR TRENDS OVER RECENT RUNS. THE
NAM/ECMWF ARE TRENDING SLOWER THAN THE GFS WITH THE PROGRESSION
OF THE NEXT UPSTREAM TROUGH MOVING INTO PACIFIC NORTHWEST AND
LIFTING OUT THE MISSISSIPPI VALLEY UPPER LOW. STILL FEEL THAT THE
SLOWER SOLUTION IS THE WAY TO GO BASED ON RECENT TRENDS...SO THIS
SOLUTION HAS GENERALLY BEEN FOLLOWED AGAIN TODAY. THE MAIN
ADJUSTMENT TO THE NAM GUIDANCE FOR THE SHORTER TERM HAS BEEN TO
LOWER TEMPERATURES HIGH TEMPS ON SUNDAY AND MONDAY TO EMPHASIZE
THE IMPACT OF THE BACK DOOR COLD FRONT AND THE RESULTANT LONG
PERIOD OF ELY FLOW OFF OF LAKE MICHIGAN. HAVE ALSO INTRODUCED
SLIGHT CHANCE POPS TO THE SWRN PORTION OF THE CWA AS THE UPPER LOW
BRINGS SOME FORCING AND INSTABILITY TO THE REGION.

LOOKING FARTHER INTO THE LONG TERM...HAVE MADE LITTLE CHANGE AS
THE ECMWF...BOTH LAST NIGHT`S 00Z RUN AND THE NEW 12Z RUN BOTH
MAINTAIN VERY GOOD CONTINUITY WITH THE PROGRESSION OF THE UPSTREAM
TROUGH. GIVEN THIS GOOD RUN TO RUN CONTINUITY...AS WELL AS GOOD
CONTINUITY WITH THE 12Z NAM...HAVE LARGELY DISCOUNTED THE FASTER
GFS AND WILL CONTINUE TO KEEP POPS OUT OF THE LOCAL AREA UNTIL
LATE WEDNESDAY NIGHT AND THURSDAY.

OVERALL...EXPECT A GENERALLY DRY PERIOD FOR NRN IL/NWRN INDIANA.
EVEN WITH TEMPERATURES EXPECTED TO BE A LITTLE LOWER THAN
PREVIOUSLY FORECAST FOR SUNDAY AND MONDAY...THE GENERAL TREND FOR
TEMPERATURES WILL BE TO BE ABOVE NORMAL FOR THE PERIOD.

KREIN

&&

.AVIATION...

1800 UTC TAFS...

WE EXPECT THE WIND TO BE AROUND 8 TO 12 KNOTS THOROUGH THE REST
OF THE DAY. THE FRONT OVER MINNESOTA AND NORTH DAKOTA IS NOT
FORECAST TO MOVE INTO ILLINOIS UNTIL SATURDAY MORNING. BY THEN...
WE EXPECT THE FRONT TO BE VERY WEAK. SO WE EXPECT NO
PRECIPITATION...JUST A WIND SHIFT TO THE WEST. THE WIND WILL BE
VERY LIGHT TONIGHT...SO THERE MAY BE SOME GROUND FOG IN ROCKFORD
AND DUPAGE AIRPORT LATE TONIGHT.

&&

.MARINE...
133 PM CDT

THE HIGH OVER THE NORTHEAST COAST AND THE LOW OVER HUDSON BAY WILL
KEEP THE PRESSURE GRADIENT OVER NORTHERN LAKE MICHIGAN LARGE THIS
AFTENROON. WE WILL KEEP THE GALE WARNING FOR THE GUSTS OF WIND
INTO THE 34 TO 38 KNOT RANGE. AS THE LOW MOVES EAST...A HIGH IS
FORECAST TO MOVE INTO ONTARIO BY SATURDAY EVENING. THE WIND WILL
DIMINISH LATE TONIGHT AND BY SATURDAY MORNING IS EXPECTED TO
BECOME MORE NORTHERLY.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL
     10 PM FRIDAY.

&&

$$

000
FXUS63 KILX 191903
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
203 PM CDT FRI SEP 19 2008

.DISCUSSION...
ISSUED 145 PM CDT FRI SEP 19 2008

FORECAST CONCERN THIS PERIOD WILL REVOLVE AROUND WEAK UPPER LOW
ACRS THE SRN PLAINS AND ITS AFFECT ON OUR WEATHER THIS WEEKEND.
SURFACE HIGH PRESSURE ACRS ERN OHIO WILL CONTINUE TO SLOWLY MOVE
AWAY FROM THE REGION OVR THE NEXT 24 HOURS. WEAK SOUTHERLY FLOW
HAS HELPED BRING SFC DEW POINTS INTO THE UPPER 50S TO LOWER 60S
THIS AFTN. MEANWHILE...SATELLITE AND PROFILER DATA INDICATES 2
DISTINCT UPPER WAVES ACRS THE SRN PLAINS. THE FIRST WAVE WAS
LOCATED OVR ERN COLORADO AND WRN KS WITH THE SECOND UPPER LEVEL
FEATURE OVR ERN OK INTO WRN ARK. A LARGE AREA OF HIGH LEVEL
MOISTURE HAS WORKED ITS WAY NWD INTO THE MIDWEST THIS AFTN AND
WDLY SCATTERED SHOWERS AND THUNDERSTORMS WERE OCCURRING TO THE
EAST OF THE UPPER LEVEL FEATURES ACRS ARKANSAS INTO SRN MO.

SHORT TERM...TONIGHT THROUGH MONDAY
NO REAL MODEL DIFFERENCES SEEN THIS PERIOD AS THE MAIN WEATHER
FEATURE WILL BE WITH THE UPPER LEVEL WAVE ACRS THE SRN PLAINS.
CLOUDS AND RAIN CHANCES WILL BE INCREASED AHEAD OF THE DISTURBANCE
ON SATURDAY AND LINGER INTO SUNDAY. COOL MID LEVEL TEMPERATURES
AND AN INCREASE IN LOW LVL MOISTURE WILL PRODUCE SOME WEAK
INSTABILITY DURING THE AFTN AND EVENING HOURS SAT AND SUN. THIS
WL LEAD TO AT BEST...ISOLATED TO WDLY SCATTERED SHOWERS AND
T-STORMS. CAN`T REALLY SEE GOING ANY HIGHER THAN 20 TO 30 PERCENT
ON POPS WITH LACK OF ANY SIGNIFICANT LOW LVL FORCING. FORECAST
SOUNDINGS SUGGEST THE BETTER MOISTURE PROFILES WOULD BE WHEN THE
UPPER LEVEL WAVE WOULD BE RIGHT OVR CNTRL IL...SUNDAY AFTN AND
EVENING. WITH THE INCREASE IN CLOUD COVER...TEMPS WERE HELD AT OR
BELOW GUID VALUES FOR BOTH SATURDAY AND SUNDAY...WHICH WOULD PUT
HIGHS IN THE UPPER 70S TO LOWER 80S.

MODELS ALL AGREE THAT BY MONDAY THE WEAK UPPER LEVEL SYSTEM WL
TRACK EAST OF THE AREA WHILE UPPER LEVEL RIDGING BUILDS ACRS
THE MIDWEST AHEAD OF A FAIRLY STRONG TROF OVER THE WRN U.S.

LONG TERM...TUESDAY THROUGH FRIDAY
A FAIRLY STRONG NORTHERN STREAM SHORTWAVE IS EXPECTED TO PUSH ACRS
THE PLAINS LATER TUESDAY INTO WEDNESDAY. MODELS CONTINUE TO SUGGEST
THE MAIN UPPER WAVE AND BEST FORCING ASSOCIATED WITH THE TROF WL
PASS WELL NORTHWEST OF OUR AREA LATE WED INTO THURSDAY. A WEAKENING
COLD FRONT WL STRUGGLE TO MAKE IT THIS FAR EAST WED NIGHT INTO
THU WITH ITS ASSOCIATED LOW PRECIP CHANCES. ALL MEDIUM RANGE MODELS
CONTINUE TO INDICATE THE LOW LEVEL FLOW AHEAD OF THE FRONT DOES NOT
SUGGEST A REAL SIGNIFICANT RAIN THREAT WITH WHAT IS LEFT OF THE
FRONT ON THURSDAY ACRS OUR AREA. TEMPERATURES DURING THIS PERIOD
WL AVERAGE A FEW DEGREES ABOVE NORMAL WITH DAYTIME HIGHS IN THE
UPPER 70S TO LOWER 80S WHILE OVERNIGHT LOWS DROP INTO THE UPPER
50S TO LOWER 60S.

SMITH
&&


.AVIATION...
ISSUED 1251 PM CDT FRI SEP 19 2008
ADDING IN SOME CU FOR DEVELOPMENT THIS AFTERNOON UNDER A BKN
BLANKET OF CIRRUS AS THE LOW PUSHES UP FROM THE SSE. LLVL MOISTURE
INCREASING THRU TODAY...WITH MINIMAL MIXING WILL RESULT IN SOME
VSBY ISSUES FOR THE PREDAWN HOURS. DROPPING VSBYS TO 2SM TO 3SM WITH
WORST FOG TO THE WEST IN SFC POOL OF MSTR. AFTER SUNRISE...RETURN
TO VFR QUICKLY. SHOWERS EXPECTED FOR TOMORROW WILL BE OCCURRING
AFTER 18Z.

HJS
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 191834
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
134 PM CDT FRI SEP 19 2008

.DISCUSSION...
300 AM CDT

ONLY MINOR TWEAKS TO GOING FCST.  FIRST OFF...SATLT LOOPS SHOW HI
CLOUDINESS...ASSD WITH MID LVL CIRCULATION MOVG EWD FROM SRN PLAINS
INTO NWRN AR...SPREADING NWD ACROSS IL AND INTO SRN WI.
HOWEVER...WITH MID LVL RIDGING IN PLACE FROM MID MS VLY EWD ACROSS
OH VLY...MOST OF THESE CLOUDS SHOULD DSIPT WITH TIME.  IN
ADDITION...MUCH OF THIS CLOUDINESS IS JUST THIN CI WITH ONLY A FEW
BANDS LIKELY BEING OPAQUE.  THEREFORE WILL GO WITH MOSTLY SUNNY
SKIES OVR NRN PORTION OF FA FOR TDY...AND PARTLY SUNNY S AND
E...CLOSER TO UPSTREAM CLOUD SOURCE.  THIS SHOULD HAVE LTL INFLUENCE
ON AFTN MAX TEMPS...AFTER ALL CURRENT TEMPS SWD ACROSS IL HAVE SHOWN
NRLY NORMAL RESPONSE TO RADIATIONAL COOLING OVERNIGHT...SO NO REASON
TO THINK CLOUD COVER WILL INHIBIT DAYTIME HEATING EITHER.

WATER VAPOR IMAGERY ALSO SHOWS DEEP WX SYS MOVG EWD ACROSS HUDSON
BAY.  THIS WILL PUSH ITS ASSD COLD FRONT SWD TO UPR GRTLKS TNGT.
MODEST LLVL MOISTURE RETURN TAKING PLACE IN ISALLOBARIC TROF FROM
CNTRL PLAINS NNEWD ACROSS MN AND INTO WRN ONTARIO.  SOME CONVECTION
HAS DVLPD IN THIS ZONE.  HOWEVER...AS FRONT APCHS MIDWEST/SRN GRTLKS
WED AFTN...UPR SUPPORT FOR PCPN WILL ALREADY BE HEADING ACROSS ERN
CANADA.  ALTHOUGH SOME DEW POINT POOLING IS STILL FCST ALG FRONTAL
BOUNDARY...WILL KEEP FCST DRY AND JUST BRING IN SOME SCT-BKN
CLOUDINESS WITH FROPA WED EVENING.  THIS SITN LOOKS ALMOST IDENTICAL
IN NATURE AND TIMING...TO THIS PAST WED WHEN BACK DOOR FRONT SLIPPED
DOWN LK MI AND INTO NERN IL LATE IN DAY.  AS WAS THE CASE ON
WED.../WHEN HI TEMPS REACHED WELL INTO THE LWR 80S/...WEAK FORCING
AHD OF BOUNDARY AND SOME COMPRESSIONAL WARMING...SUPPORTS GOING WITH
SLGTLY WARMER GFS MOS NUMBERS ON SAT.

SAT NGT AND SUNDAY...ANOTHER LARGE SFC HI BUILDS SEWD ACROSS ERN
ONTARIO...RETURNING THE AREA TO A DRY NELY-ELY LLVL FLOW INTO
MONDAY.  AS A RESULT...WILL KEEP DRY FCST GOING INTO EXTENDED PERIOD
WITH TEMPS RMNG AT OR ABV SEASONAL NORMALS.

NEG TILTED H5 TROF FCST TO LIFT SLOWLY NEWD SUN-MON...BUT DAMPEN OUT
CONSIDERABLY BY THE TIME IT MOVS INTO MID-UPR MS VLY SUN NGT-MON AS
ZONE OF STGR LLVL MOISTURE ADVECTION GET REESTABLISHED WELL TO OUR W
AS DEEPER TROFFING EVOLVES OVR WRN CANADA.  THIS SYS IS FCST TO
EVENTUALLY PROGRESS EWD ACROSS SRN CAN/NRN PLAINS STAS AND BRING A
COLD FRONT SEWD INTO RGN WED OR WED NGT.  GIVEN FCST OF
BETTER...FURTHER SOUTH DYNAMIC FIELD ASSD WITH THIS FEATURE...AND
LIKELY INCRS IN LLVL MOISTURE BY WED...WILL HAVE LO CHC POPS IN ALL
BUT FAR SRN/ERN FA ABOUT WED NGT TIME FRAME.

MERZLOCK

&&

.AVIATION...

1800 UTC TAFS...

WE EXPECT THE WIND TO BE AROUND 8 TO 12 KNOTS THOROUGH THE REST
OF THE DAY. THE FRONT OVER MINNESOTA AND NORTH DAKOTA IS NOT
FORECAST TO MOVE INTO ILLINOIS UNTIL SATURDAY MORNING. BY THEN...
WE EXPECT THE FRONT TO BE VERY WEAK. SO WE EXPECT NO
PRECIPITATION...JUST A WIND SHIFT TO THE WEST. THE WIND WILL BE
VERY LIGHT TONIGHT...SO THERE MAY BE SOME GROUND FOG IN ROCKFORD
AND DUPAGE AIRPORT LATE TONIGHT.


&&

.MARINE...
133 PM CDT

THE HIGH OVER THE NORTHEAST COAST AND THE LOW OVER HUDSON BAY WILL
KEEP THE PRESSURE GRADIENT OVER NORTHERN LAKE MICHIGAN LARGE THIS
AFTENROON. WE WILL KEEP THE GALE WARNING FOR THE GUSTS OF WIND
INTO THE 34 TO 38 KNOT RANGE. AS THE LOW MOVES EAST...A HIGH IS
FORECAST TO MOVE INTO ONTARIO BY SATURDAY EVENING. THE WIND WILL
DIMINISH LATE TONIGHT AND BY SATURDAY MORNING IS EXPECTED TO
BECOME MORE NORTHERLY.


&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL
     10 PM FRIDAY.

&&

$$

000
FXUS63 KILX 191754
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1254 PM CDT FRI SEP 19 2008

.DISCUSSION...
ISSUED 1035 AM CDT FRI SEP 19 2008
HIGH PRESSURE SLIDING OFF OVER NEW ENGLAND...WITH THE RIDGE BACK
INTO THE SRN PLAINS. HOWEVER...AN UPPER LEVEL LOW IS MOVING OUT
OVER THE SE...AND SPREADING SOME HIGH LEVEL CLOUDS OVER THE REGION
TODAY. THIS IS EXPECTED TO CONTINUE THROUGHOUT THE DAY. MAJORITY
OF FORECAST IS RIGHT ON TRACK...ONLY SOME TWEAKS TO THE DEWPOINTS.
NO UPDATE TO THE ZONE PACKAGE NECESSARY AT THIS TIME.



&&

.AVIATION...
ISSUED 1251 PM CDT FRI SEP 19 2008
ADDING IN SOME CU FOR DEVELOPMENT THIS AFTERNOON UNDER A BKN
BLANKET OF CIRRUS AS THE LOW PUSHES UP FROM THE SSE. LLVL MOISTURE
INCREASING THRU TODAY...WITH MINIMAL MIXING WILL RESULT IN SOME
VSBY ISSUES FOR THE PREDAWN HOURS. DROPPING VSBYS TO 2SM TO 3SM WITH
WORST FOG TO THE WEST IN SFC POOL OF MSTR. AFTER SUNRISE...RETURN
TO VFR QUICKLY. SHOWERS EXPECTED FOR TOMORROW WILL BE OCCURRING
AFTER 18Z.



HJS
&&

.PREV DISCUSSION...
ISSUED 112 AM CDT FRI SEP 19 2008

QUIET FORECAST OVER THE NEXT SEVERAL DAYS...WITH ONLY POSSIBLE FLY
IN THE OINTMENT BEING A WEAK UPPER-LEVEL DISTURBANCE APPROACHING
FROM THE SOUTHWEST THIS WEEKEND.

LATEST SURFACE CHART STILL SHOWS SPRAWLING RIDGE OF HIGH PRESSURE
FROM NEW ENGLAND SOUTHWESTWARD INTO THE SOUTHERN PLAINS...KEEPING
MUCH OF THE EASTERN CONUS DRY. MEANWHILE...A WEAK FRONTAL BOUNDARY
IS SETTING OFF A FEW SHOWERS AND THUNDERSTORMS ACROSS THE DAKOTAS.
ALOFT...MAIN BELT OF THE WESTERLIES REMAINS WELL TO THE NORTH ACROSS
CANADA...WHILE WEAK UPPER LOW SPINS OVER OKLAHOMA.

SHORT TERM...TODAY THROUGH SUNDAY
UPPER FEATURE OVER THE SOUTHERN PLAINS WILL MEANDER SLOWLY
NORTHEASTWARD TODAY...PROVIDING PLENTY OF HIGH THIN CLOUDINESS
ACROSS CENTRAL ILLINOIS. DESPITE CLOUD COVER...CONDITIONS WILL
REMAIN MOSTLY SUNNY WITH HIGH TEMPS ONCE AGAIN CLIMBING INTO THE
LOWER 80S. CLOUDS WILL CONTINUE TO INCREASE TONIGHT INTO
SATURDAY...AS UPPER FEATURE SLOWLY APPROACHES FROM THE SOUTHWEST.
00Z 19 SEP NAM-WRF TENDS TO KEEP THIS SYSTEM LARGELY SOUTH OF
CENTRAL ILLINOIS THROUGH SUNDAY...THUS KEEPING MOST OF THE
ASSOCIATED PRECIP OUT OF THE AREA AS WELL. MEANWHILE...00Z
GFS/CANADIAN AND 12Z ECMWF ALL BRING FEATURE FURTHER NORTH...ALBEIT
IN A WEAKENING STATE. WILL SIDE WITH THE MODEL CONSENSUS
HERE...WHICH WILL MEAN PARTLY TO MOSTLY CLOUDY SKIES OVER THE
WEEKEND...WITH A SLIGHT CHANCE OF SHOWERS/STORMS.

SINCE SYSTEM WILL INITIALLY BE ENCOUNTERING A DRY ENVIRONMENT AS IT
TRIES TO PENETRATE NORTHWARD INTO SURFACE RIDGING...THINK PRECIP
WILL BE SLOW TO GET ORGANIZED ACROSS THE REGION. WILL THEREFORE KEEP
BULK OF KILX CWA DRY THROUGH SATURDAY. WITH WEAKENING UPPER LOW
BASICALLY LIFTING RIGHT ACROSS CENTRAL ILLINOIS AND SOMEWHAT BETTER
LOW-LEVEL MOISTURE BEING TAPPED FROM THE SOUTH...THINK A SLIGHT
CHANCE POP IS ADVISABLE DURING THE DAY SUNDAY. MITIGATING FACTORS
FOR PRECIP WILL BE WEAKENING UPPER DYNAMICS AND DRY ATMOSPHERE...BUT
THINK ENOUGH LIFT AND MOISTURE WILL BE PRESENT TO WARRANT SLIGHT
POPS. WITH ADDITIONAL CLOUDS AND PERHAPS A FEW SHOWERS
AROUND...TEMPS WILL BE A COUPLE OF DEGREES COOLER ON SUNDAY...WITH
AFTERNOON HIGHS MAINLY IN THE UPPER 70S.

LONG TERM...MONDAY THROUGH THURSDAY
ONCE WEEKEND SYSTEM DISSIPATES AND MOVES OUT OF THE AREA...ATTENTION
WILL THEN TURN TO NORTHERN STREAM SHORT-WAVE AND APPROACHING COLD
FRONT LATER IN THE WEEK. MODELS CONTINUE TO INDICATE STRONG
UPPER-LEVEL RIDGING ACROSS THE MIDWEST EARLY IN THE WEEK...IN
RESPONSE TO DIGGING TROUGH ACROSS THE NORTHERN ROCKIES.
HOWEVER...RIDGE IS NOT QUITE AS STRONG AS IN PREVIOUS RUNS AND THUS
BREAKS DOWN A BIT FASTER AS WAVE APPROACHES FROM THE WEST BY
WEDNESDAY/THURSDAY. AS A RESULT...FRONTAL BOUNDARY THAT WAS
PREVIOUSLY EXPECTED TO STALL AND WASH OUT TO THE WEST ACROSS
WISCONSIN AND IOWA MAY MAKE IT INTO CENTRAL ILLINOIS BEFORE
DISSIPATING. CURRENT GRIDS FEATURE SLIGHT CHANCE POPS ACROSS THE
W/NW CWA ON THURSDAY...AND THIS STILL LOOKS GOOD ACCORDING TO THE
LATEST SUITE OF MODEL GUIDANCE.

BARNES


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 191559
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1059 AM CDT FRI SEP 19 2008

.DISCUSSION...
ISSUED 1035 AM CDT FRI SEP 19 2008
HIGH PRESSURE SLIDING OFF OVER NEW ENGLAND...WITH THE RIDGE BACK
INTO THE SRN PLAINS. HOWEVER...AN UPPER LEVEL LOW IS MOVING OUT
OVER THE SE...AND SPREADING SOME HIGH LEVEL CLOUDS OVER THE REGION
TODAY. THIS IS EXPECTED TO CONTINUE THROUGHOUT THE DAY. MAJORITY
OF FORECAST IS RIGHT ON TRACK...ONLY SOME TWEAKS TO THE DEWPOINTS.
NO UPDATE TO THE ZONE PACKAGE NECESSARY AT THIS TIME.

HJS
&&

.AVIATION...
ISSUED 615 AM CDT FRI SEP 19 2008

SFC HIGH PRES RIDGE MI-IL-MO WILL REMAIN NEARLY STATIONARY THRU 12Z
SAT WITH LGT SELY/SLY SFC WNDS. ISOLATED VSBYS 5SM BR WILL BE PSBL
THRU 14Z TDY...BUT COVERAGE TOO SPARCE FOR MENTION IN THE TAFS.
BKN-OVC HIGH CIRRUS OVER MUCH OF THE AREA WILL CONT AS AN UPPER
LEVEL SHORTWAVE OVER AR MOVES SLOWLY NWD. SCT 5K FT STRATOCU WILL BE
POSSIBLE 19Z-23Z TODAY...SIMILAR TO OBSERVED ON THU.

04
&&

.PREV DISCUSSION...
ISSUED 112 AM CDT FRI SEP 19 2008

QUIET FORECAST OVER THE NEXT SEVERAL DAYS...WITH ONLY POSSIBLE FLY
IN THE OINTMENT BEING A WEAK UPPER-LEVEL DISTURBANCE APPROACHING
FROM THE SOUTHWEST THIS WEEKEND.

LATEST SURFACE CHART STILL SHOWS SPRAWLING RIDGE OF HIGH PRESSURE
FROM NEW ENGLAND SOUTHWESTWARD INTO THE SOUTHERN PLAINS...KEEPING
MUCH OF THE EASTERN CONUS DRY. MEANWHILE...A WEAK FRONTAL BOUNDARY
IS SETTING OFF A FEW SHOWERS AND THUNDERSTORMS ACROSS THE DAKOTAS.
ALOFT...MAIN BELT OF THE WESTERLIES REMAINS WELL TO THE NORTH ACROSS
CANADA...WHILE WEAK UPPER LOW SPINS OVER OKLAHOMA.

SHORT TERM...TODAY THROUGH SUNDAY
UPPER FEATURE OVER THE SOUTHERN PLAINS WILL MEANDER SLOWLY
NORTHEASTWARD TODAY...PROVIDING PLENTY OF HIGH THIN CLOUDINESS
ACROSS CENTRAL ILLINOIS. DESPITE CLOUD COVER...CONDITIONS WILL
REMAIN MOSTLY SUNNY WITH HIGH TEMPS ONCE AGAIN CLIMBING INTO THE
LOWER 80S. CLOUDS WILL CONTINUE TO INCREASE TONIGHT INTO
SATURDAY...AS UPPER FEATURE SLOWLY APPROACHES FROM THE SOUTHWEST.
00Z 19 SEP NAM-WRF TENDS TO KEEP THIS SYSTEM LARGELY SOUTH OF
CENTRAL ILLINOIS THROUGH SUNDAY...THUS KEEPING MOST OF THE
ASSOCIATED PRECIP OUT OF THE AREA AS WELL. MEANWHILE...00Z
GFS/CANADIAN AND 12Z ECMWF ALL BRING FEATURE FURTHER NORTH...ALBEIT
IN A WEAKENING STATE. WILL SIDE WITH THE MODEL CONSENSUS
HERE...WHICH WILL MEAN PARTLY TO MOSTLY CLOUDY SKIES OVER THE
WEEKEND...WITH A SLIGHT CHANCE OF SHOWERS/STORMS.

SINCE SYSTEM WILL INITIALLY BE ENCOUNTERING A DRY ENVIRONMENT AS IT
TRIES TO PENETRATE NORTHWARD INTO SURFACE RIDGING...THINK PRECIP
WILL BE SLOW TO GET ORGANIZED ACROSS THE REGION. WILL THEREFORE KEEP
BULK OF KILX CWA DRY THROUGH SATURDAY. WITH WEAKENING UPPER LOW
BASICALLY LIFTING RIGHT ACROSS CENTRAL ILLINOIS AND SOMEWHAT BETTER
LOW-LEVEL MOISTURE BEING TAPPED FROM THE SOUTH...THINK A SLIGHT
CHANCE POP IS ADVISABLE DURING THE DAY SUNDAY. MITIGATING FACTORS
FOR PRECIP WILL BE WEAKENING UPPER DYNAMICS AND DRY ATMOSPHERE...BUT
THINK ENOUGH LIFT AND MOISTURE WILL BE PRESENT TO WARRANT SLIGHT
POPS. WITH ADDITIONAL CLOUDS AND PERHAPS A FEW SHOWERS
AROUND...TEMPS WILL BE A COUPLE OF DEGREES COOLER ON SUNDAY...WITH
AFTERNOON HIGHS MAINLY IN THE UPPER 70S.

LONG TERM...MONDAY THROUGH THURSDAY
ONCE WEEKEND SYSTEM DISSIPATES AND MOVES OUT OF THE AREA...ATTENTION
WILL THEN TURN TO NORTHERN STREAM SHORT-WAVE AND APPROACHING COLD
FRONT LATER IN THE WEEK. MODELS CONTINUE TO INDICATE STRONG
UPPER-LEVEL RIDGING ACROSS THE MIDWEST EARLY IN THE WEEK...IN
RESPONSE TO DIGGING TROUGH ACROSS THE NORTHERN ROCKIES.
HOWEVER...RIDGE IS NOT QUITE AS STRONG AS IN PREVIOUS RUNS AND THUS
BREAKS DOWN A BIT FASTER AS WAVE APPROACHES FROM THE WEST BY
WEDNESDAY/THURSDAY. AS A RESULT...FRONTAL BOUNDARY THAT WAS
PREVIOUSLY EXPECTED TO STALL AND WASH OUT TO THE WEST ACROSS
WISCONSIN AND IOWA MAY MAKE IT INTO CENTRAL ILLINOIS BEFORE
DISSIPATING. CURRENT GRIDS FEATURE SLIGHT CHANCE POPS ACROSS THE
W/NW CWA ON THURSDAY...AND THIS STILL LOOKS GOOD ACCORDING TO THE
LATEST SUITE OF MODEL GUIDANCE.

BARNES

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 191134
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
634 AM CDT FRI SEP 19 2008

.DISCUSSION...
300 AM CDT

ONLY MINOR TWEAKS TO GOING FCST.  FIRST OFF...SATLT LOOPS SHOW HI
CLOUDINESS...ASSD WITH MID LVL CIRCULATION MOVG EWD FROM SRN PLAINS
INTO NWRN AR...SPREADING NWD ACROSS IL AND INTO SRN WI.
HOWEVER...WITH MID LVL RIDGING IN PLACE FROM MID MS VLY EWD ACROSS
OH VLY...MOST OF THESE CLOUDS SHOULD DSIPT WITH TIME.  IN
ADDITION...MUCH OF THIS CLOUDINESS IS JUST THIN CI WITH ONLY A FEW
BANDS LIKELY BEING OPAQUE.  THEREFORE WILL GO WITH MOSTLY SUNNY
SKIES OVR NRN PORTION OF FA FOR TDY...AND PARTLY SUNNY S AND
E...CLOSER TO UPSTREAM CLOUD SOURCE.  THIS SHOULD HAVE LTL INFLUENCE
ON AFTN MAX TEMPS...AFTER ALL CURRENT TEMPS SWD ACROSS IL HAVE SHOWN
NRLY NORMAL RESPONSE TO RADIATIONAL COOLING OVERNIGHT...SO NO REASON
TO THINK CLOUD COVER WILL INHIBIT DAYTIME HEATING EITHER.

WATER VAPOR IMAGERY ALSO SHOWS DEEP WX SYS MOVG EWD ACROSS HUDSON
BAY.  THIS WILL PUSH ITS ASSD COLD FRONT SWD TO UPR GRTLKS TNGT.
MODEST LLVL MOISTURE RETURN TAKING PLACE IN ISALLOBARIC TROF FROM
CNTRL PLAINS NNEWD ACROSS MN AND INTO WRN ONTARIO.  SOME CONVECTION
HAS DVLPD IN THIS ZONE.  HOWEVER...AS FRONT APCHS MIDWEST/SRN GRTLKS
WED AFTN...UPR SUPPORT FOR PCPN WILL ALREADY BE HEADING ACROSS ERN
CANADA.  ALTHOUGH SOME DEW POINT POOLING IS STILL FCST ALG FRONTAL
BOUNDARY...WILL KEEP FCST DRY AND JUST BRING IN SOME SCT-BKN
CLOUDINESS WITH FROPA WED EVENING.  THIS SITN LOOKS ALMOST IDENTICAL
IN NATURE AND TIMING...TO THIS PAST WED WHEN BACK DOOR FRONT SLIPPED
DOWN LK MI AND INTO NERN IL LATE IN DAY.  AS WAS THE CASE ON
WED.../WHEN HI TEMPS REACHED WELL INTO THE LWR 80S/...WEAK FORCING
AHD OF BOUNDARY AND SOME COMPRESSIONAL WARMING...SUPPORTS GOING WITH
SLGTLY WARMER GFS MOS NUMBERS ON SAT.

SAT NGT AND SUNDAY...ANOTHER LARGE SFC HI BUILDS SEWD ACROSS ERN
ONTARIO...RETURNING THE AREA TO A DRY NELY-ELY LLVL FLOW INTO
MONDAY.  AS A RESULT...WILL KEEP DRY FCST GOING INTO EXTENDED PERIOD
WITH TEMPS RMNG AT OR ABV SEASONAL NORMALS.

NEG TILTED H5 TROF FCST TO LIFT SLOWLY NEWD SUN-MON...BUT DAMPEN OUT
CONSIDERABLY BY THE TIME IT MOVS INTO MID-UPR MS VLY SUN NGT-MON AS
ZONE OF STGR LLVL MOISTURE ADVECTION GET REESTABLISHED WELL TO OUR W
AS DEEPER TROFFING EVOLVES OVR WRN CANADA.  THIS SYS IS FCST TO
EVENTUALLY PROGRESS EWD ACROSS SRN CAN/NRN PLAINS STAS AND BRING A
COLD FRONT SEWD INTO RGN WED OR WED NGT.  GIVEN FCST OF
BETTER...FURTHER SOUTH DYNAMIC FIELD ASSD WITH THIS FEATURE...AND
LIKELY INCRS IN LLVL MOISTURE BY WED...WILL HAVE LO CHC POPS IN ALL
BUT FAR SRN/ERN FA ABOUT WED NGT TIME FRAME.

MERZLOCK

&&

.AVIATION...

12Z TAFS...LITTLE CHANGE FROM GOING FORECAST. CIRRUS CONTINUES TO
SPREAD NORTHEAST ACROSS THE REGION THIS MORNING. RH FIELDS SUGGEST
SCT/BKN HIGH CLOUDS THRU THE PERIOD. LIGHT SSE WINDS TURN MORE SSW
LATER THIS MORNING AND INCREASE TO AROUND 10KTS. WINDS DIMINISH
THIS EVENING AND BECOME LIGHT AND VRB OVERNIGHT. AS LOW LEVEL
MOISTURE BEGINS TO INCREASE LATER TODAY AND TONIGHT...ALONG WITH
LIGHT WINDS...COULD BE SOME PATCHY FOG TOWARD THE END OF THE
PERIOD BUT HAVE NOT INCLUDED WITH THIS FORECAST. CMS

&&

.MARINE...

220 AM...OVERALL FEW CHANGES TO GOING FORECAST/GRIDS. HIGH PRESSURE
OVER NEW ENGLAND WILL CONTINUE TO MOVE NORTHEAST TODAY WHILE LOW
PRESSURE OVER NORTHERN MANITOBA DEEPENS AS IT MOVES EAST ACROSS
HUDSON BAY TODAY. PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS
INCREASES ACROSS THE NORTHERN LAKES AND GALES TO 35 KTS LOOK
REASONABLE...THUS HAVE MAINTAINED GOING GALE WARNING FOR THE
NORTHERN TWO FIFTHS OF LAKE MICHIGAN. AS THE LOW CONTINUES EAST
TONIGHT...THE GRADIENT WEAKENS AND A TRAILING COLD FRONT WILL
REACH NORTHERN LAKE MICHIGAN SATURDAY MORNING. THIS FRONT WILL
CONTINUE SOUTH ACROSS LAKE MICHIGAN REACHING THE SOUTHERN END BY
LATE AFTERNOON SATURDAY. ANOTHER HIGH MOVES ACROSS SOUTHERN ONTARIO
AND THE NORTHERN LAKES SATURDAY AND SATURDAY NIGHT... KEEPING A
TIGHTER GRADIENT ACROSS THE WESTERN LAKES AND EXPECT 15-25KTS WILL
BE POSSIBLE BEHIND THIS FRONT. THE HIGH SLOWLY MOVES EAST SUNDAY
WITH WINDS DIMINISHING THRU THE DAY. AS THE HIGH MOVES EAST SUNDAY
NIGHT...WINDS ONCE AGAIN TURN SOUTHERLY MONDAY. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 UNTIL
     10 PM FRIDAY.

&&

$$

000
FXUS63 KILX 191116 CCA
AFDILX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE LINCOLN IL
615 AM CDT FRI SEP 19 2008

CORRECTED ISSUE TIME

.DISCUSSION...
ISSUED 112 AM CDT FRI SEP 19 2008

QUIET FORECAST OVER THE NEXT SEVERAL DAYS...WITH ONLY POSSIBLE FLY
IN THE OINTMENT BEING A WEAK UPPER-LEVEL DISTURBANCE APPROACHING
FROM THE SOUTHWEST THIS WEEKEND.

LATEST SURFACE CHART STILL SHOWS SPRAWLING RIDGE OF HIGH PRESSURE
FROM NEW ENGLAND SOUTHWESTWARD INTO THE SOUTHERN PLAINS...KEEPING
MUCH OF THE EASTERN CONUS DRY. MEANWHILE...A WEAK FRONTAL BOUNDARY
IS SETTING OFF A FEW SHOWERS AND THUNDERSTORMS ACROSS THE DAKOTAS.
ALOFT...MAIN BELT OF THE WESTERLIES REMAINS WELL TO THE NORTH ACROSS
CANADA...WHILE WEAK UPPER LOW SPINS OVER OKLAHOMA.

SHORT TERM...TODAY THROUGH SUNDAY
UPPER FEATURE OVER THE SOUTHERN PLAINS WILL MEANDER SLOWLY
NORTHEASTWARD TODAY...PROVIDING PLENTY OF HIGH THIN CLOUDINESS
ACROSS CENTRAL ILLINOIS. DESPITE CLOUD COVER...CONDITIONS WILL
REMAIN MOSTLY SUNNY WITH HIGH TEMPS ONCE AGAIN CLIMBING INTO THE
LOWER 80S. CLOUDS WILL CONTINUE TO INCREASE TONIGHT INTO
SATURDAY...AS UPPER FEATURE SLOWLY APPROACHES FROM THE SOUTHWEST.
00Z 19 SEP NAM-WRF TENDS TO KEEP THIS SYSTEM LARGELY SOUTH OF
CENTRAL ILLINOIS THROUGH SUNDAY...THUS KEEPING MOST OF THE
ASSOCIATED PRECIP OUT OF THE AREA AS WELL. MEANWHILE...00Z
GFS/CANADIAN AND 12Z ECMWF ALL BRING FEATURE FURTHER NORTH...ALBEIT
IN A WEAKENING STATE. WILL SIDE WITH THE MODEL CONSENSUS
HERE...WHICH WILL MEAN PARTLY TO MOSTLY CLOUDY SKIES OVER THE
WEEKEND...WITH A SLIGHT CHANCE OF SHOWERS/STORMS.

SINCE SYSTEM WILL INITIALLY BE ENCOUNTERING A DRY ENVIRONMENT AS IT
TRIES TO PENETRATE NORTHWARD INTO SURFACE RIDGING...THINK PRECIP
WILL BE SLOW TO GET ORGANIZED ACROSS THE REGION. WILL THEREFORE KEEP
BULK OF KILX CWA DRY THROUGH SATURDAY. WITH WEAKENING UPPER LOW
BASICALLY LIFTING RIGHT ACROSS CENTRAL ILLINOIS AND SOMEWHAT BETTER
LOW-LEVEL MOISTURE BEING TAPPED FROM THE SOUTH...THINK A SLIGHT
CHANCE POP IS ADVISABLE DURING THE DAY SUNDAY. MITIGATING FACTORS
FOR PRECIP WILL BE WEAKENING UPPER DYNAMICS AND DRY ATMOSPHERE...BUT
THINK ENOUGH LIFT AND MOISTURE WILL BE PRESENT TO WARRANT SLIGHT
POPS. WITH ADDITIONAL CLOUDS AND PERHAPS A FEW SHOWERS
AROUND...TEMPS WILL BE A COUPLE OF DEGREES COOLER ON SUNDAY...WITH
AFTERNOON HIGHS MAINLY IN THE UPPER 70S.

LONG TERM...MONDAY THROUGH THURSDAY
ONCE WEEKEND SYSTEM DISSIPATES AND MOVES OUT OF THE AREA...ATTENTION
WILL THEN TURN TO NORTHERN STREAM SHORT-WAVE AND APPROACHING COLD
FRONT LATER IN THE WEEK. MODELS CONTINUE TO INDICATE STRONG
UPPER-LEVEL RIDGING ACROSS THE MIDWEST EARLY IN THE WEEK...IN
RESPONSE TO DIGGING TROUGH ACROSS THE NORTHERN ROCKIES.
HOWEVER...RIDGE IS NOT QUITE AS STRONG AS IN PREVIOUS RUNS AND THUS
BREAKS DOWN A BIT FASTER AS WAVE APPROACHES FROM THE WEST BY
WEDNESDAY/THURSDAY. AS A RESULT...FRONTAL BOUNDARY THAT WAS
PREVIOUSLY EXPECTED TO STALL AND WASH OUT TO THE WEST ACROSS
WISCONSIN AND IOWA MAY MAKE IT INTO CENTRAL ILLINOIS BEFORE
DISSIPATING. CURRENT GRIDS FEATURE SLIGHT CHANCE POPS ACROSS THE
W/NW CWA ON THURSDAY...AND THIS STILL LOOKS GOOD ACCORDING TO THE
LATEST SUITE OF MODEL GUIDANCE.

BARNES
&&

.AVIATION...
ISSUED 615 AM CDT FRI SEP 19 2008

SFC HIGH PRES RIDGE MI-IL-MO WILL REMAIN NEARLY STATIONARY THRU 12Z
SAT WITH LGT SELY/SLY SFC WNDS. ISOLATED VSBYS 5SM BR WILL BE PSBL
THRU 14Z TDY...BUT COVERAGE TOO SPARCE FOR MENTION IN THE TAFS.
BKN-OVC HIGH CIRRUS OVER MUCH OF THE AREA WILL CONT AS AN UPPER
LEVEL SHORTWAVE OVER AR MOVES SLOWLY NWD. SCT 5K FT STRATOCU WILL BE
POSSIBLE 19Z-23Z TODAY...SIMILAR TO OBSERVED ON THU.

04
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 191115
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
112 AM CDT FRI SEP 19 2008

.DISCUSSION...
ISSUED 112 AM CDT FRI SEP 19 2008

QUIET FORECAST OVER THE NEXT SEVERAL DAYS...WITH ONLY POSSIBLE FLY
IN THE OINTMENT BEING A WEAK UPPER-LEVEL DISTURBANCE APPROACHING
FROM THE SOUTHWEST THIS WEEKEND.

LATEST SURFACE CHART STILL SHOWS SPRAWLING RIDGE OF HIGH PRESSURE
FROM NEW ENGLAND SOUTHWESTWARD INTO THE SOUTHERN PLAINS...KEEPING
MUCH OF THE EASTERN CONUS DRY. MEANWHILE...A WEAK FRONTAL BOUNDARY
IS SETTING OFF A FEW SHOWERS AND THUNDERSTORMS ACROSS THE DAKOTAS.
ALOFT...MAIN BELT OF THE WESTERLIES REMAINS WELL TO THE NORTH ACROSS
CANADA...WHILE WEAK UPPER LOW SPINS OVER OKLAHOMA.

SHORT TERM...TODAY THROUGH SUNDAY
UPPER FEATURE OVER THE SOUTHERN PLAINS WILL MEANDER SLOWLY
NORTHEASTWARD TODAY...PROVIDING PLENTY OF HIGH THIN CLOUDINESS
ACROSS CENTRAL ILLINOIS. DESPITE CLOUD COVER...CONDITIONS WILL
REMAIN MOSTLY SUNNY WITH HIGH TEMPS ONCE AGAIN CLIMBING INTO THE
LOWER 80S. CLOUDS WILL CONTINUE TO INCREASE TONIGHT INTO
SATURDAY...AS UPPER FEATURE SLOWLY APPROACHES FROM THE SOUTHWEST.
00Z 19 SEP NAM-WRF TENDS TO KEEP THIS SYSTEM LARGELY SOUTH OF
CENTRAL ILLINOIS THROUGH SUNDAY...THUS KEEPING MOST OF THE
ASSOCIATED PRECIP OUT OF THE AREA AS WELL. MEANWHILE...00Z
GFS/CANADIAN AND 12Z ECMWF ALL BRING FEATURE FURTHER NORTH...ALBEIT
IN A WEAKENING STATE. WILL SIDE WITH THE MODEL CONSENSUS
HERE...WHICH WILL MEAN PARTLY TO MOSTLY CLOUDY SKIES OVER THE
WEEKEND...WITH A SLIGHT CHANCE OF SHOWERS/STORMS.

SINCE SYSTEM WILL INITIALLY BE ENCOUNTERING A DRY ENVIRONMENT AS IT
TRIES TO PENETRATE NORTHWARD INTO SURFACE RIDGING...THINK PRECIP
WILL BE SLOW TO GET ORGANIZED ACROSS THE REGION. WILL THEREFORE KEEP
BULK OF KILX CWA DRY THROUGH SATURDAY. WITH WEAKENING UPPER LOW
BASICALLY LIFTING RIGHT ACROSS CENTRAL ILLINOIS AND SOMEWHAT BETTER
LOW-LEVEL MOISTURE BEING TAPPED FROM THE SOUTH...THINK A SLIGHT
CHANCE POP IS ADVISABLE DURING THE DAY SUNDAY. MITIGATING FACTORS
FOR PRECIP WILL BE WEAKENING UPPER DYNAMICS AND DRY ATMOSPHERE...BUT
THINK ENOUGH LIFT AND MOISTURE WILL BE PRESENT TO WARRANT SLIGHT
POPS. WITH ADDITIONAL CLOUDS AND PERHAPS A FEW SHOWERS
AROUND...TEMPS WILL BE A COUPLE OF DEGREES COOLER ON SUNDAY...WITH
AFTERNOON HIGHS MAINLY IN THE UPPER 70S.

LONG TERM...MONDAY THROUGH THURSDAY
ONCE WEEKEND SYSTEM DISSIPATES AND MOVES OUT OF THE AREA...ATTENTION
WILL THEN TURN TO NORTHERN STREAM SHORT-WAVE AND APPROACHING COLD
FRONT LATER IN THE WEEK. MODELS CONTINUE TO INDICATE STRONG
UPPER-LEVEL RIDGING ACROSS THE MIDWEST EARLY IN THE WEEK...IN
RESPONSE TO DIGGING TROUGH ACROSS THE NORTHERN ROCKIES.
HOWEVER...RIDGE IS NOT QUITE AS STRONG AS IN PREVIOUS RUNS AND THUS
BREAKS DOWN A BIT FASTER AS WAVE APPROACHES FROM THE WEST BY
WEDNESDAY/THURSDAY. AS A RESULT...FRONTAL BOUNDARY THAT WAS
PREVIOUSLY EXPECTED TO STALL AND WASH OUT TO THE WEST ACROSS
WISCONSIN AND IOWA MAY MAKE IT INTO CENTRAL ILLINOIS BEFORE
DISSIPATING. CURRENT GRIDS FEATURE SLIGHT CHANCE POPS ACROSS THE
W/NW CWA ON THURSDAY...AND THIS STILL LOOKS GOOD ACCORDING TO THE
LATEST SUITE OF MODEL GUIDANCE.

BARNES
&&

.AVIATION...
ISSUED 615 AM CDT FRI SEP 19 2008

SFC HIGH PRES RIDGE MI-IL-MO WILL REMAIN NEARLY STATIONARY THRU 12Z
SAT WITH LGT SELY/SLY SFC WNDS. ISOLATED VSBYS 5SM BR WILL BE PSBL
THRU 14Z TDY...BUT COVERAGE TOO SPARCE FOR MENTION IN THE TAFS.
BKN-OVC HIGH CIRRUS OVER MUCH OF THE AREA WILL CONT AS AN UPPER
LEVEL SHORTWAVE OVER AR MOVES SLOWLY NWD. SCT 5K FT STRATOCU WILL BE
POSSIBLE 19Z-23Z TODAY...SIMILAR TO OBSERVED ON THU.

04
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 190827
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
300 AM CDT FRI SEP 19 2008

.DISCUSSION...REGARDING MORNING ZONES/GRIDS...
300 AM CDT

ONLY MINOR TWEAKS TO GOING FCST.  FIRST OFF...SATLT LOOPS SHOW HI
CLOUDINESS...ASSD WITH MID LVL CIRCULATION MOVG EWD FROM SRN PLAINS
INTO NWRN AR...SPREADING NWD ACROSS IL AND INTO SRN WI.
HOWEVER...WITH MID LVL RIDGING IN PLACE FROM MID MS VLY EWD ACROSS
OH VLY...MOST OF THESE CLOUDS SHOULD DSIPT WITH TIME.  IN
ADDITION...MUCH OF THIS CLOUDINESS IS JUST THIN CI WITH ONLY A FEW
BANDS LIKELY BEING OPAQUE.  THEREFORE WILL GO WITH MOSTLY SUNNY
SKIES OVR NRN PORTION OF FA FOR TDY...AND PARTLY SUNNY S AND
E...CLOSER TO UPSTREAM CLOUD SOURCE.  THIS SHOULD HAVE LTL INFLUENCE
ON AFTN MAX TEMPS...AFTER ALL CURRENT TEMPS SWD ACROSS IL HAVE SHOWN
NRLY NORMAL RESPONSE TO RADIATIONAL COOLING OVERNIGHT...SO NO REASON
TO THINK CLOUD COVER WILL INHIBIT DAYTIME HEATING EITHER.

WATER VAPOR IMAGERY ALSO SHOWS DEEP WX SYS MOVG EWD ACROSS HUDSON
BAY.  THIS WILL PUSH ITS ASSD COLD FRONT SWD TO UPR GRTLKS TNGT.
MODEST LLVL MOISTURE RETURN TAKING PLACE IN ISALLOBARIC TROF FROM
CNTRL PLAINS NNEWD ACROSS MN AND INTO WRN ONTARIO.  SOME CONVECTION
HAS DVLPD IN THIS ZONE.  HOWEVER...AS FRONT APCHS MIDWEST/SRN GRTLKS
WED AFTN...UPR SUPPORT FOR PCPN WILL ALREADY BE HEADING ACROSS ERN
CANADA.  ALTHOUGH SOME DEW POINT POOLING IS STILL FCST ALG FRONTAL
BOUNDARY...WILL KEEP FCST DRY AND JUST BRING IN SOME SCT-BKN
CLOUDINESS WITH FROPA WED EVENING.  THIS SITN LOOKS ALMOST IDENTICAL
IN NATURE AND TIMING...TO THIS PAST WED WHEN BACK DOOR FRONT SLIPPED
DOWN LK MI AND INTO NERN IL LATE IN DAY.  AS WAS THE CASE ON
WED.../WHEN HI TEMPS REACHED WELL INTO THE LWR 80S/...WEAK FORCING
AHD OF BOUNDARY AND SOME COMPRESSIONAL WARMING...SUPPORTS GOING WITH
SLGTLY WARMER GFS MOS NUMBERS ON SAT.

SAT NGT AND SUNDAY...ANOTHER LARGE SFC HI BUILDS SEWD ACROSS ERN
ONTARIO...RETURNING THE AREA TO A DRY NELY-ELY LLVL FLOW INTO
MONDAY.  AS A RESULT...WILL KEEP DRY FCST GOING INTO EXTENDED PERIOD
WITH TEMPS RMNG AT OR ABV SEASONAL NORMALS.

NEG TILTED H5 TROF FCST TO LIFT SLOWLY NEWD SUN-MON...BUT DAMPEN OUT
CONSIDERABLY BY THE TIME IT MOVS INTO MID-UPR MS VLY SUN NGT-MON AS
ZONE OF STGR LLVL MOISTURE ADVECTION GET REESTABLISHED WELL TO OUR W
AS DEEPER TROFFING EVOLVES OVR WRN CANADA.  THIS SYS IS FCST TO
EVENTUALLY PROGRESS EWD ACROSS SRN CAN/NRN PLAINS STAS AND BRING A
COLD FRONT SEWD INTO RGN WED OR WED NGT.  GIVEN FCST OF
BETTER...FURTHER SOUTH DYNAMIC FIELD ASSD WITH THIS FEATURE...AND
LIKELY INCRS IN LLVL MOISTURE BY WED...WILL HAVE LO CHC POPS IN ALL
BUT FAR SRN/ERN FA ABOUT WED NGT TIME FRAME.

MERZLOCK

&&

.AVIATION...

06Z TAFS...QUIET WEATHER THRU THE PERIOD. HIGH PRESSURE OVER THE
EASTERN LAKES WILL CONTINUE TO MOVE EAST OVERNIGHT. SOUTHEAST
WINDS WILL TURN SOUTHERLY BY MORNING AND INCREASE TO 10-12KTS BY
LATE MORNING AS THE GRADIENT TIGHTENS A BIT. WINDS DIMINISH WITH
SUNSET THIS EVENING. CIRRUS SPREADING NORTH AND RH FIELDS SUGGEST
A SCT/BKN HIGH DECK THRU MUCH OF THE PERIOD BUT CIRRUS SHOULD BE
RATHER THIN. CMS

&&

.MARINE...

220 AM...OVERALL FEW CHANGES TO GOING FORECAST/GRIDS. HIGH PRESSURE
OVER NEW ENGLAND WILL CONTINUE TO MOVE NORTHEAST TODAY WHILE LOW
PRESSURE OVER NORTHERN MANITOBA DEEPENS AS IT MOVES EAST ACROSS
HUDSON BAY TODAY. PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS
INCREASES ACROSS THE NORTHERN LAKES AND GALES TO 35 KTS LOOK
REASONABLE...THUS HAVE MAINTAINED GOING GALE WARNING FOR THE
NORTHERN TWO FIFTHS OF LAKE MICHIGAN. AS THE LOW CONTINUES EAST
TONIGHT...THE GRADIENT WEAKENS AND A TRAILING COLD FRONT WILL
REACH NORTHERN LAKE MICHIGAN SATURDAY MORNING. THIS FRONT WILL
CONTINUE SOUTH ACROSS LAKE MICHIGAN REACHING THE SOUTHERN END BY
LATE AFTERNOON SATURDAY. ANOTHER HIGH MOVES ACROSS SOUTHERN ONTARIO
AND THE NORTHERN LAKES SATURDAY AND SATURDAY NIGHT... KEEPING A
TIGHTER GRADIENT ACROSS THE WESTERN LAKES AND EXPECT 15-25KTS WILL
BE POSSIBLE BEHIND THIS FRONT. THE HIGH SLOWLY MOVES EAST SUNDAY
WITH WINDS DIMINISHING THRU THE DAY. AS THE HIGH MOVES EAST SUNDAY
NIGHT...WINDS ONCE AGAIN TURN SOUTHERLY MONDAY. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565...7 AM
     FRIDAY TO 10 PM FRIDAY.

&&

$$

000
FXUS63 KLOT 190720
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
220 AM CDT FRI SEP 19 2008

.DISCUSSION...
300 PM CDT

QUIET WEATHER TO CONTINUE THROUGH THE PERIOD.

FOR THE NEAR TERM...THE MAIN CONCERN WILL BE OVERNIGHT LOW
TEMPERATURES. WITH THE LARGE...SPRAWLING HIGH PRESSURE SYSTEM
SLOWLY MOVING EAST TO SERN CANADA AND A RIDGE AXIS EXTENDING BACK
OVER NRN IL/IN...MOSTLY CLEAR SKIES WILL CONTINUE THROUGH THE
OVERNIGHT HOURS. THIS WILL ALLOW WINDS TO DECREASE AND ALLOW
TEMPERATURES TO DROP TO QUITE COMFORTABLE LEVELS. PREVIOUSLY
ANTICIPATED THAT DEWPOINTS WOULD DROP INTO THE LOWER 40S PER
YESTERDAY`S NAM GUIDANCE...BUT ENHANCED SFC MOISTURE FROM RECENT
RAINS KEPT DEWPOINTS IN THE 50S...AND THIS APPEARS TO BE A
PERSISTENT LEVEL. THUS...WILL KEEP THE AMENDED TREND OF OVERNIGHT
LOWS IN THE LOW 50S TONIGHT RATHER THAN THE UPPER 40S AS
PREVIOUSLY ANTICIPATED. WITH LOW LEVEL FLOW TURNING OFF OF LAKE
MICHIGAN AND NEARSHORE LAKE WATER TEMPERATURES AROUND 70F...LAKE
FRONT LOCATIONS WILL REMAIN SOMEWHAT WARMER...PERHAPS ONLY
DROPPING DOWN TO AROUND 60F.

THROUGH THE REMAINDER OF THE SHORT TERM FORECAST PERIOD...THE DRY
WEATHER IS EXPECTED TO CONTINUE. THE SHORT RANGE MODELS ARE IN
RELATIVELY GOOD AGREEMENT ON THE PATTERN...SO HAVE GENERALLY
TRENDED CLOSE TO THE NAM12 FOR THE SYNOPTIC SCALE PATTERN. HAVE
MADE SOME ADJUSTMENT TO THE MAX AND MIN TEMPERATURES DUE TO A
PERCEPTION THAT THE NAM IS OVER FORECASTING DEWPOINTS AGAIN. HAVE
NOT MADE QUITE THE ADJUSTMENTS MADE YESTERDAY...BUT WILL MAINTAIN
DEWPOINTS IN THE LOWER TO MIDDLE 50S AS THE CONTINENTAL POLAR
AIRMASS IS CUT OFF FROM A SIGNIFICANT INFLUX OF MOISTURE DUE TO
THE POSITION OF THE RIDGE AXIS. SO...HAVE TEMPERED MAX AND MIN
TEMPS EXTREMES BY A FEW DEGREES TO LOWER THE FORECAST MAXS AND
RAISE THE FORECAST MINS A FEW DEGREES FROM GUIDANCE.

LOOKING INTO THE LONGER TERM...THE GFS AND ECMWF BOTH ARE TRENDING
SLOWER WITH THE APPROACH OF THE NEXT UPSTREAM TROUGH. THE MODELS
ARE...ONCE AGAIN...TRENDING SLOWER WITH THE PROGRESSION OF THIS
SYSTEM...NOT MOVING IT ONSHORE INTO THE PACIFIC NORTHWEST UNTIL
LATE FRIDAY NIGHT...ABOUT 12-24 HOURS SLOWER THAN YESTERAY`S MODEL
RUNS. THIS TREND CONTINUES LATER INTO THE FORECAST PERIOD WITH THE
LEE SFC TROUGH NOT DEVELOPING OVER THE CNTRL PLAINS UNTIL TUESDAY.
THE GUIDANCE IS TEMPORALLY CONSISTENT ON THE PATTERN...BUT IS JUST
TRENDING SLOWER. SO...WILL CONTINUE THIS TREND AND HOLD OFF ON
INTRODUCING ANY PCPN INTO THE FORECAST FOR THE WRN SXNS OF THE
FORECAST AREA.

THUS...FOR THE NEXT SEVEN DAYS...EXPECT DRY WEATHER TO
CONTINUE...WITH SEASONABLE OR SLIGHTLY ABOVE NORMAL TEMPERATURES.

KREIN

&&

.AVIATION...

06Z TAFS...QUIET WEATHER THRU THE PERIOD. HIGH PRESSURE OVER THE
EASTERN LAKES WILL CONTINUE TO MOVE EAST OVERNIGHT. SOUTHEAST
WINDS WILL TURN SOUTHERLY BY MORNING AND INCREASE TO 10-12KTS BY
LATE MORNING AS THE GRADIENT TIGHTENS A BIT. WINDS DIMINISH WITH
SUNSET THIS EVENING. CIRRUS SPREADING NORTH AND RH FIELDS SUGGEST
A SCT/BKN HIGH DECK THRU MUCH OF THE PERIOD BUT CIRRUS SHOULD BE
RATHER THIN. CMS

&&

.MARINE...

220 AM...OVERALL FEW CHANGES TO GOING FORECAST/GRIDS. HIGH PRESSURE
OVER NEW ENGLAND WILL CONTINUE TO MOVE NORTHEAST TODAY WHILE LOW
PRESSURE OVER NORTHERN MANITOBA DEEPENS AS IT MOVES EAST ACROSS
HUDSON BAY TODAY. PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS
INCREASES ACROSS THE NORTHERN LAKES AND GALES TO 35 KTS LOOK
REASONABLE...THUS HAVE MAINTAINED GOING GALE WARNING FOR THE
NORTHERN TWO FIFTHS OF LAKE MICHIGAN. AS THE LOW CONTINUES EAST
TONIGHT...THE GRADIENT WEAKENS AND A TRAILING COLD FRONT WILL
REACH NORTHERN LAKE MICHIGAN SATURDAY MORNING. THIS FRONT WILL
CONTINUE SOUTH ACROSS LAKE MICHIGAN REACHING THE SOUTHERN END BY
LATE AFTERNOON SATURDAY. ANOTHER HIGH MOVES ACROSS SOUTHERN ONTARIO
AND THE NORTHERN LAKES SATURDAY AND SATURDAY NIGHT... KEEPING A
TIGHTER GRADIENT ACROSS THE WESTERN LAKES AND EXPECT 15-25KTS WILL
BE POSSIBLE BEHIND THIS FRONT. THE HIGH SLOWLY MOVES EAST SUNDAY
WITH WINDS DIMINISHING THRU THE DAY. AS THE HIGH MOVES EAST SUNDAY
NIGHT...WINDS ONCE AGAIN TURN SOUTHERLY MONDAY. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565...7 AM
     FRIDAY TO 10 PM FRIDAY.

&&

$$

000
FXUS63 KILX 190612
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
112 AM CDT FRI SEP 19 2008

.DISCUSSION...
ISSUED 112 AM CDT FRI SEP 19 2008

QUIET FORECAST OVER THE NEXT SEVERAL DAYS...WITH ONLY POSSIBLE
FLY IN THE OINTMENT BEING A WEAK UPPER-LEVEL DISTURBANCE
APPROACHING FROM THE SOUTHWEST THIS WEEKEND.

LATEST SURFACE CHART STILL SHOWS SPRAWLING RIDGE OF HIGH PRESSURE
FROM NEW ENGLAND SOUTHWESTWARD INTO THE SOUTHERN PLAINS...KEEPING
MUCH OF THE EASTERN CONUS DRY. MEANWHILE...A WEAK FRONTAL BOUNDARY
IS SETTING OFF A FEW SHOWERS AND THUNDERSTORMS ACROSS THE DAKOTAS.
ALOFT...MAIN BELT OF THE WESTERLIES REMAINS WELL TO THE NORTH
ACROSS CANADA...WHILE WEAK UPPER LOW SPINS OVER OKLAHOMA.

SHORT TERM...TODAY THROUGH SUNDAY

UPPER FEATURE OVER THE SOUTHERN PLAINS WILL MEANDER SLOWLY
NORTHEASTWARD TODAY...PROVIDING PLENTY OF HIGH THIN CLOUDINESS
ACROSS CENTRAL ILLINOIS. DESPITE CLOUD COVER...CONDITIONS WILL
REMAIN MOSTLY SUNNY WITH HIGH TEMPS ONCE AGAIN CLIMBING INTO THE
LOWER 80S. CLOUDS WILL CONTINUE TO INCREASE TONIGHT INTO
SATURDAY...AS UPPER FEATURE SLOWLY APPROACHES FROM THE SOUTHWEST.
00Z 19 SEP NAM-WRF TENDS TO KEEP THIS SYSTEM LARGELY SOUTH OF
CENTRAL ILLINOIS THROUGH SUNDAY...THUS KEEPING MOST OF THE
ASSOCIATED PRECIP OUT OF THE AREA AS WELL. MEANWHILE...00Z
GFS/CANADIAN AND 12Z ECMWF ALL BRING FEATURE FURTHER
NORTH...ALBEIT IN A WEAKENING STATE. WILL SIDE WITH THE MODEL
CONSENSUS HERE...WHICH WILL MEAN PARTLY TO MOSTLY CLOUDY SKIES
OVER THE WEEKEND...WITH A SLIGHT CHANCE OF SHOWERS/STORMS.

SINCE SYSTEM WILL INITIALLY BE ENCOUNTERING A DRY ENVIRONMENT
AS IT TRIES TO PENETRATE NORTHWARD INTO SURFACE RIDGING...THINK
PRECIP WILL BE SLOW TO GET ORGANIZED ACROSS THE REGION. WILL
THEREFORE KEEP BULK OF KILX CWA DRY THROUGH SATURDAY. WITH
WEAKENING UPPER LOW BASICALLY LIFTING RIGHT ACROSS CENTRAL
ILLINOIS AND SOMEWHAT BETTER LOW-LEVEL MOISTURE BEING TAPPED FROM
THE SOUTH...THINK A SLIGHT CHANCE POP IS ADVISABLE DURING THE DAY
SUNDAY. MITIGATING FACTORS FOR PRECIP WILL BE WEAKENING UPPER
DYNAMICS AND DRY ATMOSPHERE...BUT THINK ENOUGH LIFT AND MOISTURE
WILL BE PRESENT TO WARRANT SLIGHT POPS. WITH ADDITIONAL CLOUDS AND
PERHAPS A FEW SHOWERS AROUND...TEMPS WILL BE A COUPLE OF DEGREES
COOLER ON SUNDAY...WITH AFTERNOON HIGHS MAINLY IN THE UPPER 70S.

LONG TERM...MONDAY THROUGH THURSDAY

ONCE WEEKEND SYSTEM DISSIPATES AND MOVES OUT OF THE
AREA...ATTENTION WILL THEN TURN TO NORTHERN STREAM SHORT-WAVE AND
APPROACHING COLD FRONT LATER IN THE WEEK. MODELS CONTINUE TO
INDICATE STRONG UPPER-LEVEL RIDGING ACROSS THE MIDWEST EARLY IN
THE WEEK...IN RESPONSE TO DIGGING TROUGH ACROSS THE NORTHERN
ROCKIES. HOWEVER...RIDGE IS NOT QUITE AS STRONG AS IN PREVIOUS RUNS
AND THUS BREAKS DOWN A BIT FASTER AS WAVE APPROACHES FROM THE WEST
BY WEDNESDAY/THURSDAY. AS A RESULT...FRONTAL BOUNDARY THAT WAS
PREVIOUSLY EXPECTED TO STALL AND WASH OUT TO THE WEST ACROSS
WISCONSIN AND IOWA MAY MAKE IT INTO CENTRAL ILLINOIS BEFORE
DISSIPATING. CURRENT GRIDS FEATURE SLIGHT CHANCE POPS ACROSS THE
W/NW CWA ON THURSDAY...AND THIS STILL LOOKS GOOD ACCORDING TO THE
LATEST SUITE OF MODEL GUIDANCE.

BARNES
&&

.AVIATION...
ISSUED 1134 PM CDT THU SEP 18 2008

A RIDGE OF HIGH PRESSURE WILL REMAIN IN PLACE ACROSS THE CENTRAL
ILLINOIS TERMINALS THROUGH THE 06Z TAF PERIOD. THIS WILL ALLOW VFR
CONDITIONS TO PERSIST. PATCHY GROUND FOG MAY DEVELOP TOWARD
MORNING...BUT IT SHOULD NOT BE VERY WIDESPREAD OR DENSE. WINDS
WILL BE LIGHT THROUGHOUT.

BAK
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 190527
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1227 AM CDT FRI SEP 19 2008

.DISCUSSION...
300 PM CDT

QUIET WEATHER TO CONTINUE THROUGH THE PERIOD.

FOR THE NEAR TERM...THE MAIN CONCERN WILL BE OVERNIGHT LOW
TEMPERATURES. WITH THE LARGE...SPRAWLING HIGH PRESSURE SYSTEM
SLOWLY MOVING EAST TO SERN CANADA AND A RIDGE AXIS EXTENDING BACK
OVER NRN IL/IN...MOSTLY CLEAR SKIES WILL CONTINUE THROUGH THE
OVERNIGHT HOURS. THIS WILL ALLOW WINDS TO DECREASE AND ALLOW
TEMPERATURES TO DROP TO QUITE COMFORTABLE LEVELS. PREVIOUSLY
ANTICIPATED THAT DEWPOINTS WOULD DROP INTO THE LOWER 40S PER
YESTERDAY`S NAM GUIDANCE...BUT ENHANCED SFC MOISTURE FROM RECENT
RAINS KEPT DEWPOINTS IN THE 50S...AND THIS APPEARS TO BE A
PERSISTENT LEVEL. THUS...WILL KEEP THE AMENDED TREND OF OVERNIGHT
LOWS IN THE LOW 50S TONIGHT RATHER THAN THE UPPER 40S AS
PREVIOUSLY ANTICIPATED. WITH LOW LEVEL FLOW TURNING OFF OF LAKE
MICHIGAN AND NEARSHORE LAKE WATER TEMPERATURES AROUND 70F...LAKE
FRONT LOCATIONS WILL REMAIN SOMEWHAT WARMER...PERHAPS ONLY
DROPPING DOWN TO AROUND 60F.

THROUGH THE REMAINDER OF THE SHORT TERM FORECAST PERIOD...THE DRY
WEATHER IS EXPECTED TO CONTINUE. THE SHORT RANGE MODELS ARE IN
RELATIVELY GOOD AGREEMENT ON THE PATTERN...SO HAVE GENERALLY
TRENDED CLOSE TO THE NAM12 FOR THE SYNOPTIC SCALE PATTERN. HAVE
MADE SOME ADJUSTMENT TO THE MAX AND MIN TEMPERATURES DUE TO A
PERCEPTION THAT THE NAM IS OVER FORECASTING DEWPOINTS AGAIN. HAVE
NOT MADE QUITE THE ADJUSTMENTS MADE YESTERDAY...BUT WILL MAINTAIN
DEWPOINTS IN THE LOWER TO MIDDLE 50S AS THE CONTINENTAL POLAR
AIRMASS IS CUT OFF FROM A SIGNIFICANT INFLUX OF MOISTURE DUE TO
THE POSITION OF THE RIDGE AXIS. SO...HAVE TEMPERED MAX AND MIN
TEMPS EXTREMES BY A FEW DEGREES TO LOWER THE FORECAST MAXS AND
RAISE THE FORECAST MINS A FEW DEGREES FROM GUIDANCE.

LOOKING INTO THE LONGER TERM...THE GFS AND ECMWF BOTH ARE TRENDING
SLOWER WITH THE APPROACH OF THE NEXT UPSTREAM TROUGH. THE MODELS
ARE...ONCE AGAIN...TRENDING SLOWER WITH THE PROGRESSION OF THIS
SYSTEM...NOT MOVING IT ONSHORE INTO THE PACIFIC NORTHWEST UNTIL
LATE FRIDAY NIGHT...ABOUT 12-24 HOURS SLOWER THAN YESTERAY`S MODEL
RUNS. THIS TREND CONTINUES LATER INTO THE FORECAST PERIOD WITH THE
LEE SFC TROUGH NOT DEVELOPING OVER THE CNTRL PLAINS UNTIL TUESDAY.
THE GUIDANCE IS TEMPORALLY CONSISTENT ON THE PATTERN...BUT IS JUST
TRENDING SLOWER. SO...WILL CONTINUE THIS TREND AND HOLD OFF ON
INTRODUCING ANY PCPN INTO THE FORECAST FOR THE WRN SXNS OF THE
FORECAST AREA.

THUS...FOR THE NEXT SEVEN DAYS...EXPECT DRY WEATHER TO
CONTINUE...WITH SEASONABLE OR SLIGHTLY ABOVE NORMAL TEMPERATURES.

KREIN

&&

.AVIATION...

06Z TAFS...QUIET WEATHER THRU THE PERIOD. HIGH PRESSURE OVER THE
EASTERN LAKES WILL CONTINUE TO MOVE EAST OVERNIGHT. SOUTHEAST
WINDS WILL TURN SOUTHERLY BY MORNING AND INCREASE TO 10-12KTS BY
LATE MORNING AS THE GRADIENT TIGHTENS A BIT. WINDS DIMINISH WITH
SUNSET THIS EVENING. CIRRUS SPREADING NORTH AND RH FIELDS SUGGEST
A SCT/BKN HIGH DECK THRU MUCH OF THE PERIOD BUT CIRRUS SHOULD BE
RATHER THIN. CMS

&&

.MARINE...

226 PM CDT

HIGH PRESSURE OVER SOUTHERN ONTARIO MOVING OFF TO THE EAST
TONIGHT AND WILL BE OVER NEW ENGLAND AND NOVA SCOTIA BY LATE
FRIDAY. FARTHER NORTH...LOW PRESSURE OVER NORTHERN SASKATCHEWAN
WILL DEEPEN AS IT MOVES EAST TO HUDSON BAY THROUGH FRIDAY. AS THE
LOW DEEPENS...THIS WILL RESULT IN A TIGHTENING SURFACE PRESSURE
GRADIENT OVER NORTHERN LAKE MICHIGAN LATER TONIGHT THROUGH MUCH OF
FRIDAY WITH SOUTH WINDS INCREASING TO MARGINAL 35 KNOT GALES
FRIDAY MORNING. THE GRADIENT WILL BEGIN TO RELAX A BIT BY FRIDAY
EVENING ALLOWING WINDS TO EASE...BEFORE A COLD FRONT TRAILING FROM
THE CANADIAN LOW PUSHES SOUTH ACROSS LAKE MICHIGAN LATE FRIDAY
NIGHT AND SATURDAY. THE FRONT WILL CONTINUE TO MOVE SOUTH OF THE
LAKES FRIDAY NIGHT AS HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE
NORTHERN LAKES. THE HIGH WILL THEN DRIFT EAST LATE IN THE
WEEKEND...ALLOWING WINDS TO ONCE AGAIN SHIFT TO THE SOUTHEAST BY
MONDAY.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565...7 AM
     FRIDAY TO 10 PM FRIDAY.

&&

$$

000
FXUS63 KILX 190434
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1134 PM CDT THU SEP 18 2008

.DISCUSSION...
ISSUED 858 PM CDT THU SEP 18 2008

A RIDGE OF HIGH PRESSURE HAS REESTABLISHED ITSELF ACROSS CENTRAL
AND SOUTHEAST ILLINOIS...PROVIDING QUIET AND SEASONABLE CONDITIONS.
STILL EXPECT SOME PATCHY...MAINLY SHALLOW...FOG TOWARD MORNING DUE
TO THE RECENT RAINS...MOSTLY CLEAR SKIES AND LIGHT WINDS.

GOING FORECAST IS IN GOOD SHAPE AND ONLY MINOR TWEAKS ARE NEEDED
TO GRIDS FOR THE LATEST TRENDS.

BAK
&&

.AVIATION...
ISSUED 1134 PM CDT THU SEP 18 2008

A RIDGE OF HIGH PRESSURE WILL REMAIN IN PLACE ACROSS THE CENTRAL
ILLINOIS TERMINALS THROUGH THE 06Z TAF PERIOD. THIS WILL ALLOW VFR
CONDITIONS TO PERSIST. PATCHY GROUND FOG MAY DEVELOP TOWARD
MORNING...BUT IT SHOULD NOT BE VERY WIDESPREAD OR DENSE. WINDS
WILL BE LIGHT THROUGHOUT.

BAK
&&

.PREV DISCUSSION...
ISSUED 200 PM CDT THU SEP 18 2008

HIGH PRESSURE CENTERED NORTH OF LAKE SUPERIOR WILL CONTINUE TO
DOMINATE THE WEATHER ACRS THE FORECAST AREA THRU FRIDAY NIGHT.
THE WEAK COOL FRONT/WIND SHIFT WHICH PUSHED ACRS THE AREA LATE
LAST NIGHT HAS ALL BUT WASHED OUT EARLY THIS AFTERNOON TO OUR
SOUTH. THE STRONGER FLOW REMAINS WELL TO OUR NORTH ACRS CNTRL
CANADA...WHILE THE WATER VAPOR LOOP DEPICTS A RATHER VIGOROUS
UPPER WAVE OVR SE COLORADO THAT MAY BRING SHOWER CHANCES A BIT
FURTHER NORTH INTO OUR AREA THAN PREVIOUSLY THOUGHT FOR THE
WEEKEND.

SHORT TERM...TONIGHT THROUGH SUNDAY
MODELS IN GOOD AGREEMENT THRU EARLY SATURDAY AS HIGH PRESSURE
HOLDS NE OF THE GREAT LAKES BRINGING PLEASANTLY WARM DAYS AND
COMFORTABLY COOL NIGHTS. 850 TEMPERATURES SUPPORT DAYTIME HIGHS
IN THE 80 TO 83 DEGREE RANGE FRIDAY AND SATURDAY WITH EARLY
MORNING LOWS DROPPING INTO THE LOWER TO MIDDLE 50S. THE UPPER
LEVEL WAVE CURRENTLY OVER THE SOUTHERN PLAINS IS FORECAST TO
SLOWLY PUSH EAST DURING THE NEXT SEVERAL DAYS AND BE POSITIONED
OVR SRN MO BY SUNDAY. THE SURFACE RIDGE AXIS BY THAT TIME WILL
BE ORIENTATED EAST-WEST ACRS CNTRL IL WHILE THE BETTER UPPER
LEVEL SUPPORT ASSOCIATED WITH THE SRN PLAINS WAVE IS FORECAST
TO TRACK SLOWLY ACRS SRN MO AND IL SATURDAY AND SUNDAY.

FORECAST SOUNDINGS...EXCPT ALONG THE I-70 CORRIDOR...NOT SHOWING
MUCH IF ANY SUPPORT FOR SHOWERS AS THE DRY LOW LEVEL EASTERLY FLOW
PREVAILS FROM THE DEPARTING HIGH. HOWEVER...MODELS CONTINUE TO
INDICATE SFC BASED CAPES IN THE 1000 J/KG RANGE BOTH SAT AND
SUNDAY AFTERNOON. THE 00Z AND NOW THE LATEST ECMWF SUGGESTS SOME
LIGHT QPF ACRS THE PARTS OF ENTIRE FCST AREA SATURDAY AND SUNDAY
AND BASED ON ITS PERFORMANCE THIS SUMMER...WL BE HARD TO IGNORE.
FOR NOW...WL INCORPORATE SOME LOW CHANCE (NOT MENTIONABLE IN THE
ZFP) POPS IN THE GRIDS BUT IF THESE TRENDS CONTINUE...WL NEED TO
RAISE POPS FOR THE WEEKEND.

LONG TERM...MONDAY THROUGH THURSDAY
THE MISSOURI SHORTWAVE IS FORECAST TO EDGE SLOWLY AWAY FROM THE
MIDWEST ON MONDAY AS UPPER LEVEL RIDGING BUILDS IN RESPONSE TO A
TROF PUSHING ACRS THE PACIFIC NW EARLY NEXT WEEK. THE NEXT SIG
SHORTWAVE TROF IS EXPECTED TO PUSH ACRS THE PLAINS AND EVENTUALLY
INTO THE MIDWEST LATE WED INTO THURSDAY BRINGING THE CHANCE FOR
SHOWERS BACK INTO THE REGION. WITH A TROF TO OUR WEST AND RIDGING
IN PLACE OVR THE MIDWEST...TEMPERATURES DURING THIS PERIOD ARE
EXPECTED TO AVERAGE ABOVE NORMAL WITH HIGHS IN THE UPPER 70S TO
LOWER 80S AND LOWS IN THE 55 TO 60 DEGREE RANGE.

SMITH


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 190159
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
859 PM CDT THU SEP 18 2008

.DISCUSSION...
ISSUED 858 PM CDT THU SEP 18 2008

A RIDGE OF HIGH PRESSURE HAS REESTABLISHED ITSELF ACROSS CENTRAL
AND SOUTHEAST ILLINOIS...PROVIDING QUIET AND SEASONABLE CONDITIONS.
STILL EXPECT SOME PATCHY...MAINLY SHALLOW...FOG TOWARD MORNING DUE
TO THE RECENT RAINS...MOSTLY CLEAR SKIES AND LIGHT WINDS.

GOING FORECAST IS IN GOOD SHAPE AND ONLY MINOR TWEAKS ARE NEEDED
TO GRIDS FOR THE LATEST TRENDS.

BAK &&

.AVIATION...
ISSUED 700 PM CDT THU SEP 18 2008

A RIDGE OF HIGH PRESSURE WILL REMAIN IN PLACE ACROSS THE CENTRAL
ILLINOIS TERMINALS THROUGH THE 00Z TAF PERIOD. THIS WILL ALLOW VFR
CONDITIONS TO PERSIST. PATCHY GROUND FOG MAY DEVELOP TOWARD
MORNING...BUT IT SHOULD NOT BE VERY WIDESPREAD OR DENSE. WINDS
WILL BE LIGHT THROUGHOUT.

BAK
&&

.PREV DISCUSSION...
ISSUED 200 PM CDT THU SEP 18 2008

HIGH PRESSURE CENTERED NORTH OF LAKE SUPERIOR WILL CONTINUE TO
DOMINATE THE WEATHER ACRS THE FORECAST AREA THRU FRIDAY NIGHT.
THE WEAK COOL FRONT/WIND SHIFT WHICH PUSHED ACRS THE AREA LATE
LAST NIGHT HAS ALL BUT WASHED OUT EARLY THIS AFTERNOON TO OUR
SOUTH. THE STRONGER FLOW REMAINS WELL TO OUR NORTH ACRS CNTRL
CANADA...WHILE THE WATER VAPOR LOOP DEPICTS A RATHER VIGOROUS
UPPER WAVE OVR SE COLORADO THAT MAY BRING SHOWER CHANCES A BIT
FURTHER NORTH INTO OUR AREA THAN PREVIOUSLY THOUGHT FOR THE
WEEKEND.

SHORT TERM...TONIGHT THROUGH SUNDAY
MODELS IN GOOD AGREEMENT THRU EARLY SATURDAY AS HIGH PRESSURE
HOLDS NE OF THE GREAT LAKES BRINGING PLEASANTLY WARM DAYS AND
COMFORTABLY COOL NIGHTS. 850 TEMPERATURES SUPPORT DAYTIME HIGHS
IN THE 80 TO 83 DEGREE RANGE FRIDAY AND SATURDAY WITH EARLY
MORNING LOWS DROPPING INTO THE LOWER TO MIDDLE 50S. THE UPPER
LEVEL WAVE CURRENTLY OVER THE SOUTHERN PLAINS IS FORECAST TO
SLOWLY PUSH EAST DURING THE NEXT SEVERAL DAYS AND BE POSITIONED
OVR SRN MO BY SUNDAY. THE SURFACE RIDGE AXIS BY THAT TIME WILL
BE ORIENTATED EAST-WEST ACRS CNTRL IL WHILE THE BETTER UPPER
LEVEL SUPPORT ASSOCIATED WITH THE SRN PLAINS WAVE IS FORECAST
TO TRACK SLOWLY ACRS SRN MO AND IL SATURDAY AND SUNDAY.

FORECAST SOUNDINGS...EXCPT ALONG THE I-70 CORRIDOR...NOT SHOWING
MUCH IF ANY SUPPORT FOR SHOWERS AS THE DRY LOW LEVEL EASTERLY FLOW
PREVAILS FROM THE DEPARTING HIGH. HOWEVER...MODELS CONTINUE TO
INDICATE SFC BASED CAPES IN THE 1000 J/KG RANGE BOTH SAT AND
SUNDAY AFTERNOON. THE 00Z AND NOW THE LATEST ECMWF SUGGESTS SOME
LIGHT QPF ACRS THE PARTS OF ENTIRE FCST AREA SATURDAY AND SUNDAY
AND BASED ON ITS PERFORMANCE THIS SUMMER...WL BE HARD TO IGNORE.
FOR NOW...WL INCORPORATE SOME LOW CHANCE (NOT MENTIONABLE IN THE
ZFP) POPS IN THE GRIDS BUT IF THESE TRENDS CONTINUE...WL NEED TO
RAISE POPS FOR THE WEEKEND.

LONG TERM...MONDAY THROUGH THURSDAY
THE MISSOURI SHORTWAVE IS FORECAST TO EDGE SLOWLY AWAY FROM THE
MIDWEST ON MONDAY AS UPPER LEVEL RIDGING BUILDS IN RESPONSE TO A
TROF PUSHING ACRS THE PACIFIC NW EARLY NEXT WEEK. THE NEXT SIG
SHORTWAVE TROF IS EXPECTED TO PUSH ACRS THE PLAINS AND EVENTUALLY
INTO THE MIDWEST LATE WED INTO THURSDAY BRINGING THE CHANCE FOR
SHOWERS BACK INTO THE REGION. WITH A TROF TO OUR WEST AND RIDGING
IN PLACE OVR THE MIDWEST...TEMPERATURES DURING THIS PERIOD ARE
EXPECTED TO AVERAGE ABOVE NORMAL WITH HIGHS IN THE UPPER 70S TO
LOWER 80S AND LOWS IN THE 55 TO 60 DEGREE RANGE.

SMITH

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 190000
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
700 PM CDT THU SEP 18 2008

.DISCUSSION...
ISSUED 200 PM CDT THU SEP 18 2008

HIGH PRESSURE CENTERED NORTH OF LAKE SUPERIOR WILL CONTINUE TO
DOMINATE THE WEATHER ACRS THE FORECAST AREA THRU FRIDAY NIGHT.
THE WEAK COOL FRONT/WIND SHIFT WHICH PUSHED ACRS THE AREA LATE
LAST NIGHT HAS ALL BUT WASHED OUT EARLY THIS AFTERNOON TO OUR
SOUTH. THE STRONGER FLOW REMAINS WELL TO OUR NORTH ACRS CNTRL
CANADA...WHILE THE WATER VAPOR LOOP DEPICTS A RATHER VIGOROUS
UPPER WAVE OVR SE COLORADO THAT MAY BRING SHOWER CHANCES A BIT
FURTHER NORTH INTO OUR AREA THAN PREVIOUSLY THOUGHT FOR THE
WEEKEND.

SHORT TERM...TONIGHT THROUGH SUNDAY
MODELS IN GOOD AGREEMENT THRU EARLY SATURDAY AS HIGH PRESSURE
HOLDS NE OF THE GREAT LAKES BRINGING PLEASANTLY WARM DAYS AND
COMFORTABLY COOL NIGHTS. 850 TEMPERATURES SUPPORT DAYTIME HIGHS
IN THE 80 TO 83 DEGREE RANGE FRIDAY AND SATURDAY WITH EARLY
MORNING LOWS DROPPING INTO THE LOWER TO MIDDLE 50S. THE UPPER
LEVEL WAVE CURRENTLY OVER THE SOUTHERN PLAINS IS FORECAST TO
SLOWLY PUSH EAST DURING THE NEXT SEVERAL DAYS AND BE POSITIONED
OVR SRN MO BY SUNDAY. THE SURFACE RIDGE AXIS BY THAT TIME WILL
BE ORIENTATED EAST-WEST ACRS CNTRL IL WHILE THE BETTER UPPER
LEVEL SUPPORT ASSOCIATED WITH THE SRN PLAINS WAVE IS FORECAST
TO TRACK SLOWLY ACRS SRN MO AND IL SATURDAY AND SUNDAY.

FORECAST SOUNDINGS...EXCPT ALONG THE I-70 CORRIDOR...NOT SHOWING
MUCH IF ANY SUPPORT FOR SHOWERS AS THE DRY LOW LEVEL EASTERLY FLOW
PREVAILS FROM THE DEPARTING HIGH. HOWEVER...MODELS CONTINUE TO
INDICATE SFC BASED CAPES IN THE 1000 J/KG RANGE BOTH SAT AND
SUNDAY AFTERNOON. THE 00Z AND NOW THE LATEST ECMWF SUGGESTS SOME
LIGHT QPF ACRS THE PARTS OF ENTIRE FCST AREA SATURDAY AND SUNDAY
AND BASED ON ITS PERFORMANCE THIS SUMMER...WL BE HARD TO IGNORE.
FOR NOW...WL INCORPORATE SOME LOW CHANCE (NOT MENTIONABLE IN THE
ZFP) POPS IN THE GRIDS BUT IF THESE TRENDS CONTINUE...WL NEED TO
RAISE POPS FOR THE WEEKEND.

LONG TERM...MONDAY THROUGH THURSDAY
THE MISSOURI SHORTWAVE IS FORECAST TO EDGE SLOWLY AWAY FROM THE
MIDWEST ON MONDAY AS UPPER LEVEL RIDGING BUILDS IN RESPONSE TO A
TROF PUSHING ACRS THE PACIFIC NW EARLY NEXT WEEK. THE NEXT SIG
SHORTWAVE TROF IS EXPECTED TO PUSH ACRS THE PLAINS AND EVENTUALLY
INTO THE MIDWEST LATE WED INTO THURSDAY BRINGING THE CHANCE FOR
SHOWERS BACK INTO THE REGION. WITH A TROF TO OUR WEST AND RIDGING
IN PLACE OVR THE MIDWEST...TEMPERATURES DURING THIS PERIOD ARE
EXPECTED TO AVERAGE ABOVE NORMAL WITH HIGHS IN THE UPPER 70S TO
LOWER 80S AND LOWS IN THE 55 TO 60 DEGREE RANGE.

SMITH
&&

.AVIATION...
ISSUED 700 PM CDT THU SEP 18 2008

A RIDGE OF HIGH PRESSURE WILL REMAIN IN PLACE ACROSS THE CENTRAL
ILLINOIS TERMINALS THROUGH THE 00Z TAF PERIOD. THIS WILL ALLOW VFR
CONDITIONS TO PERSIST. PATCHY GROUND FOG MAY DEVELOP TOWARD
MORNING...BUT IT SHOULD NOT BE VERY WIDESPREAD OR DENSE. WINDS
WILL BE LIGHT THROUGHOUT.

BAK
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 182350
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
650 PM CDT THU SEP 18 2008

.DISCUSSION...
300 PM CDT

QUIET WEATHER TO CONTINUE THROUGH THE PERIOD.

FOR THE NEAR TERM...THE MAIN CONCERN WILL BE OVERNIGHT LOW
TEMPERATURES. WITH THE LARGE...SPRAWLING HIGH PRESSURE SYSTEM
SLOWLY MOVING EAST TO SERN CANADA AND A RIDGE AXIS EXTENDING BACK
OVER NRN IL/IN...MOSTLY CLEAR SKIES WILL CONTINUE THROUGH THE
OVERNIGHT HOURS. THIS WILL ALLOW WINDS TO DECREASE AND ALLOW
TEMPERATURES TO DROP TO QUITE COMFORTABLE LEVELS. PREVIOUSLY
ANTICIPATED THAT DEWPOINTS WOULD DROP INTO THE LOWER 40S PER
YESTERDAY`S NAM GUIDANCE...BUT ENHANCED SFC MOISTURE FROM RECENT
RAINS KEPT DEWPOINTS IN THE 50S...AND THIS APPEARS TO BE A
PERSISTENT LEVEL. THUS...WILL KEEP THE AMENDED TREND OF OVERNIGHT
LOWS IN THE LOW 50S TONIGHT RATHER THAN THE UPPER 40S AS
PREVIOUSLY ANTICIPATED. WITH LOW LEVEL FLOW TURNING OFF OF LAKE
MICHIGAN AND NEARSHORE LAKE WATER TEMPERATURES AROUND 70F...LAKE
FRONT LOCATIONS WILL REMAIN SOMEWHAT WARMER...PERHAPS ONLY
DROPPING DOWN TO AROUND 60F.

THROUGH THE REMAINDER OF THE SHORT TERM FORECAST PERIOD...THE DRY
WEATHER IS EXPECTED TO CONTINUE. THE SHORT RANGE MODELS ARE IN
RELATIVELY GOOD AGREEMENT ON THE PATTERN...SO HAVE GENERALLY
TRENDED CLOSE TO THE NAM12 FOR THE SYNOPTIC SCALE PATTERN. HAVE
MADE SOME ADJUSTMENT TO THE MAX AND MIN TEMPERATURES DUE TO A
PERCEPTION THAT THE NAM IS OVER FORECASTING DEWPOINTS AGAIN. HAVE
NOT MADE QUITE THE ADJUSTMENTS MADE YESTERDAY...BUT WILL MAINTAIN
DEWPOINTS IN THE LOWER TO MIDDLE 50S AS THE CONTINENTAL POLAR
AIRMASS IS CUT OFF FROM A SIGNIFICANT INFLUX OF MOISTURE DUE TO
THE POSITION OF THE RIDGE AXIS. SO...HAVE TEMPERED MAX AND MIN
TEMPS EXTREMES BY A FEW DEGREES TO LOWER THE FORECAST MAXS AND
RAISE THE FORECAST MINS A FEW DEGREES FROM GUIDANCE.

LOOKING INTO THE LONGER TERM...THE GFS AND ECMWF BOTH ARE TRENDING
SLOWER WITH THE APPROACH OF THE NEXT UPSTREAM TROUGH. THE MODELS
ARE...ONCE AGAIN...TRENDING SLOWER WITH THE PROGRESSION OF THIS
SYSTEM...NOT MOVING IT ONSHORE INTO THE PACIFIC NORTHWEST UNTIL
LATE FRIDAY NIGHT...ABOUT 12-24 HOURS SLOWER THAN YESTERAY`S MODEL
RUNS. THIS TREND CONTINUES LATER INTO THE FORECAST PERIOD WITH THE
LEE SFC TROUGH NOT DEVELOPING OVER THE CNTRL PLAINS UNTIL TUESDAY.
THE GUIDANCE IS TEMPORALLY CONSISTENT ON THE PATTERN...BUT IS JUST
TRENDING SLOWER. SO...WILL CONTINUE THIS TREND AND HOLD OFF ON
INTRODUCING ANY PCPN INTO THE FORECAST FOR THE WRN SXNS OF THE
FORECAST AREA.

THUS...FOR THE NEXT SEVEN DAYS...EXPECT DRY WEATHER TO
CONTINUE...WITH SEASONABLE OR SLIGHTLY ABOVE NORMAL TEMPERATURES.

KREIN

&&

.AVIATION...
648 PM CDT

0000 UTC TAFS...QUIET WEATHER WILL PERSIST ACROSS TERMINALS OVER
THE NEXT 24 HOURS. EASTERLY WINDS ON THE SOUTHWEST PERIPHERY OF
THE BROAD ANTICYCLONE MOVING ACROSS THE EASTERN GREAT LAKES WILL
GRADUALLY VEER TO THE SOUTHEAST THIS EVENING IN RESPONSE TO
PRESSURE FALLS ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. LOW
PRESSURE ACROSS MANITOBA WILL STRENGTHEN TONIGHT AND THEN MOVE
ACROSS SOUTHERN HUDSON BAY TOMORROW AFTERNOON. THE STRONGEST
SOUTH AND SOUTHWEST WINDS WITH THIS SYSTEM WILL BE CONFINED WELL
TO THE NORTH OF THE TERMINALS INTO THE UPPER GREAT LAKES. FOR THE
TERMINALS...WILL CONTINUE IDEA OF PREVIOUS FORECAST WITH SOUTHEAST
WINDS OVERNIGHT BECOMING SOUTH SOUTHWEST IN ADVANCE OF THE SFC
TROUGH TOMORROW MORNING. COLD FRONTAL BOUNDARY ASSOCIATED WITH
THIS SYSTEM WILL BE FAIRLY SLOW INTO THE AREA...NOT LIKELY UNTIL
SATURDAY AFTERNOON...SO SOUTH SOUTHWEST WINDS AROUND 10 KNOTS WILL
CONTINUE THROUGH THE DAY ACROSS THE TERMINALS. IN TERMS OF SKY
COVER...ONLY SOME BKN HIGH CIRRUS THIS EVENING WILL BEGIN TO
THIN...BUT SHOULD THICKEN AGAIN ON FRIDAY AS SOUTHERN STREAM
SYSTEM BEGINS TO MOVE INTO MID MS RIVER VALLEY SATURDAY MORNING.

MARSILI

&&

.MARINE...

226 PM CDT

HIGH PRESSURE OVER SOUTHERN ONTARIO MOVING OFF TO THE EAST
TONIGHT AND WILL BE OVER NEW ENGLAND AND NOVA SCOTIA BY LATE
FRIDAY. FARTHER NORTH...LOW PRESSURE OVER NORTHERN SASKATCHEWAN
WILL DEEPEN AS IT MOVES EAST TO HUDSON BAY THROUGH FRIDAY. AS THE
LOW DEEPENS...THIS WILL RESULT IN A TIGHTENING SURFACE PRESSURE
GRADIENT OVER NORTHERN LAKE MICHIGAN LATER TONIGHT THROUGH MUCH OF
FRIDAY WITH SOUTH WINDS INCREASING TO MARGINAL 35 KNOT GALES
FRIDAY MORNING. THE GRADIENT WILL BEGIN TO RELAX A BIT BY FRIDAY
EVENING ALLOWING WINDS TO EASE...BEFORE A COLD FRONT TRAILING FROM
THE CANADIAN LOW PUSHES SOUTH ACROSS LAKE MICHIGAN LATE FRIDAY
NIGHT AND SATURDAY. THE FRONT WILL CONTINUE TO MOVE SOUTH OF THE
LAKES FRIDAY NIGHT AS HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE
NORTHERN LAKES. THE HIGH WILL THEN DRIFT EAST LATE IN THE
WEEKEND...ALLOWING WINDS TO ONCE AGAIN SHIFT TO THE SOUTHEAST BY
MONDAY.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565...7 AM
     FRIDAY TO 10 PM FRIDAY.

&&

$$

000
FXUS63 KLOT 182000
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
300 PM CDT THU SEP 18 2008

.DISCUSSION...
300 PM CDT

QUIET WEATHER TO CONTINUE THROUGH THE PERIOD.

FOR THE NEAR TERM...THE MAIN CONCERN WILL BE OVERNIGHT LOW
TEMPERATURES. WITH THE LARGE...SPRAWLING HIGH PRESSURE SYSTEM
SLOWLY MOVING EAST TO SERN CANADA AND A RIDGE AXIS EXTENDING BACK
OVER NRN IL/IN...MOSTLY CLEAR SKIES WILL CONTINUE THROUGH THE
OVERNIGHT HOURS. THIS WILL ALLOW WINDS TO DECREASE AND ALLOW
TEMPERATURES TO DROP TO QUITE COMFORTABLE LEVELS. PREVIOUSLY
ANTICIPATED THAT DEWPOINTS WOULD DROP INTO THE LOWER 40S PER
YESTERDAY`S NAM GUIDANCE...BUT ENHANCED SFC MOISTURE FROM RECENT
RAINS KEPT DEWPOINTS IN THE 50S...AND THIS APPEARS TO BE A
PERSISTENT LEVEL. THUS...WILL KEEP THE AMENDED TREND OF OVERNIGHT
LOWS IN THE LOW 50S TONIGHT RATHER THAN THE UPPER 40S AS
PREVIOUSLY ANTICIPATED. WITH LOW LEVEL FLOW TURNING OFF OF LAKE
MICHIGAN AND NEARSHORE LAKE WATER TEMPERATURES AROUND 70F...LAKE
FRONT LOCATIONS WILL REMAIN SOMEWHAT WARMER...PERHAPS ONLY
DROPPING DOWN TO AROUND 60F.

THROUGH THE REMAINDER OF THE SHORT TERM FORECAST PERIOD...THE DRY
WEATHER IS EXPECTED TO CONTINUE. THE SHORT RANGE MODELS ARE IN
RELATIVELY GOOD AGREEMENT ON THE PATTERN...SO HAVE GENERALLY
TRENDED CLOSE TO THE NAM12 FOR THE SYNOPTIC SCALE PATTERN. HAVE
MADE SOME ADJUSTMENT TO THE MAX AND MIN TEMPERATURES DUE TO A
PERCEPTION THAT THE NAM IS OVER FORECASTING DEWPOINTS AGAIN. HAVE
NOT MADE QUITE THE ADJUSTMENTS MADE YESTERDAY...BUT WILL MAINTAIN
DEWPOINTS IN THE LOWER TO MIDDLE 50S AS THE CONTINENTAL POLAR
AIRMASS IS CUT OFF FROM A SIGNIFICANT INFLUX OF MOISTURE DUE TO
THE POSITION OF THE RIDGE AXIS. SO...HAVE TEMPERED MAX AND MIN
TEMPS EXTREMES BY A FEW DEGREES TO LOWER THE FORECAST MAXS AND
RAISE THE FORECAST MINS A FEW DEGREES FROM GUIDANCE.

LOOKING INTO THE LONGER TERM...THE GFS AND ECMWF BOTH ARE TRENDING
SLOWER WITH THE APPROACH OF THE NEXT UPSTREAM TROUGH. THE MODELS
ARE...ONCE AGAIN...TRENDING SLOWER WITH THE PROGRESSION OF THIS
SYSTEM...NOT MOVING IT ONSHORE INTO THE PACIFIC NORTHWEST UNTIL
LATE FRIDAY NIGHT...ABOUT 12-24 HOURS SLOWER THAN YESTERAY`S MODEL
RUNS. THIS TREND CONTINUES LATER INTO THE FORECAST PERIOD WITH THE
LEE SFC TROUGH NOT DEVELOPING OVER THE CNTRL PLAINS UNTIL TUESDAY.
THE GUIDANCE IS TEMPORALLY CONSISTENT ON THE PATTERN...BUT IS JUST
TRENDING SLOWER. SO...WILL CONTINUE THIS TREND AND HOLD OFF ON
INTRODUCING ANY PCPN INTO THE FORECAST FOR THE WRN SXNS OF THE
FORECAST AREA.

THUS...FOR THE NEXT SEVEN DAYS...EXPECT DRY WEATHER TO
CONTINUE...WITH SEASONABLE OR SLIGHTLY ABOVE NORMAL TEMPERATURES.

KREIN

&&

.AVIATION...

1238 PM CDT

FOR THE 18Z TAFS...VERY QUIET VFR AVIATION WEATHER CONDITIONS TO
CONTINUE. SURFACE HIGH PRESSURE CENTERED OVER SOUTHERN ONTARIO
EARLY THIS AFTERNOON WITH LIGHT EAST GRADIENT WINDS ACROSS
FORECAST AREA. MORNING RAOB ANALYSIS INDICATES MIN/UPPER LEVEL
RIDGE OVERHEAD AS WELL...RESULTING IN SUBSIDENCE AND GENERALLY
CLEAR SKIES ACROSS TERMINALS.

AS SURFACE HIGH GRADUALLY MOVES OFF TO THE EAST OVER THE NEXT 24
HOURS...WINDS GENERALLY 10 KNOTS OR LESS WILL SHIFT TO THE
SOUTHEAST TONIGHT AND TO THE SOUTH ON FRIDAY. ANY LAKE BREEZE
EXPECTED TO REMAIN EAST OF KORD/KMDW THROUGH 18Z FRIDAY. OTHER
THAN SCATTERED HIGH CIRRUS...LITTLE CLOUD COVER EXPECTED WITH VFR
CONDITIONS THROUGH THE PERIOD.

RATZER

&&

.MARINE...

226 PM CDT

HIGH PRESSURE OVER SOUTHERN ONTARIO MOVING OFF TO THE EAST
TONIGHT AND WILL BE OVER NEW ENGLAND AND NOVA SCOTIA BY LATE
FRIDAY. FARTHER NORTH...LOW PRESSURE OVER NORTHERN SASKATCHEWAN
WILL DEEPEN AS IT MOVES EAST TO HUDSON BAY THROUGH FRIDAY. AS THE
LOW DEEPENS...THIS WILL RESULT IN A TIGHTENING SURFACE PRESSURE
GRADIENT OVER NORTHERN LAKE MICHIGAN LATER TONIGHT THROUGH MUCH OF
FRIDAY WITH SOUTH WINDS INCREASING TO MARGINAL 35 KNOT GALES
FRIDAY MORNING. THE GRADIENT WILL BEGIN TO RELAX A BIT BY FRIDAY
EVENING ALLOWING WINDS TO EASE...BEFORE A COLD FRONT TRAILING FROM
THE CANADIAN LOW PUSHES SOUTH ACROSS LAKE MICHIGAN LATE FRIDAY
NIGHT AND SATURDAY. THE FRONT WILL CONTINUE TO MOVE SOUTH OF THE
LAKES FRIDAY NIGHT AS HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE
NORTHERN LAKES. THE HIGH WILL THEN DRIFT EAST LATE IN THE
WEEKEND...ALLOWING WINDS TO ONCE AGAIN SHIFT TO THE SOUTHEAST BY
MONDAY.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565...7 AM
     FRIDAY TO 10 PM FRIDAY.

&&

$$

000
FXUS63 KLOT 181927
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
227 PM CDT THU SEP 18 2008

.DISCUSSION...
226 AM CDT

TODAYS WEATHER CAN BE SUMMED UP IN 4 WORDS...BIG BUBBLE NO TROUBLE.

EXPANSIVE RIDGE OF HIGH PRESSURE HAS PRETTY MUCH TAKEN OVER THE
ENTIRE EASTERN PORTION OF THE US WITH THE CORE SITTING OVER LAKE
SUPERIOR. THIS RIDGE WILL TRACK EAST TOWARD NEW ENGLAND TODAY
WHICH WILL EVENTUALLY CAUSE OUR WINDS TO SHIFT TO BEING MORE
SOUTHWESTERLY BY EARLY FRIDAY. WITH 850MB TEMPS NOT DROPPING OFF
TOO MUCH AFTER YESTERDAYS COLD FRONT...PLENTIFUL SUNSHINE...AND A
FAIRLY DRY AIR MASS...THINK THAT MID 70S APPEAR REASONABLE FOR
HIGH TEMPS TODAY EVEN WITH A LIGHT WIND OFF OF THE LAKE.

TEMPS SHOULD CLIMB HIGHER ON FRIDAY WITH THE MORE FAVORABLE
SOUTHWESTERLIES IN PLACE AND 850MB TEMPS ON THE INCREASE. NEXT
FEATURE OF NOTE IS A COLD FRONT PROGGED TO DROP DOWN INTO THE
REGION ON SATURDAY. STILL NOT A WHOLE LOT OF MOISTURE OUT THERE
WITH THE GULF BEING CLOSED...BUT WITH COLDER MID-LEVEL AIR
ADVECTING INTO THE REGION THERE APPEARS TO BE A DECENT AMOUNT OF
UNSTABLE AIR ALOFT WITH THE GFS ACTUALLY PUTTING OUT 1500J/KG OF
ELEVATED CAPE. THIS NUMBER IS PROBABLY EXAGGERATED A BIT DUE TO THE
SFC DEW POINT LIKELY BEING TOO HIGH IN THE FORECAST SOUNDING.
THERE ALSO DOES APPEAR TO BE A LOW LEVEL CAP IN PLACE THAT THE
LIFT FROM THE COLD FRONT WILL NEED TO OVERCOME IF THE ATMOSPHERE
WANTS TO TAP INTO THE ELEVATED UNSTABLE AIR. THIS SITUATION IS
NOT LOOKING LIKELY THOUGH AS THE BEST UPPER LEVEL FORCING REMAINS
WELL TO THE NORTH NEAR THE POLAR VORTEX. AT THIS POINT...WITH
FORCING AND MOISTURE BEING RATHER LIMITED...WILL HOLD OFF ON ANY
MENTION OF PRECIP WITH FROPA SATURDAY AFTERNOON.

ANOTHER RIDGE BUILDS IN ACROSS THE GREAT LAKES FOR SUNDAY INTO
MONDAY WITH ODDLY ENOUGH SEEMS TO ALMOST BE A CARBON COPY OF THE
WEATHER PATTERN FOR TODAY INTO FRIDAY.

HALBACH

&&

.AVIATION...

1238 PM CDT

FOR THE 18Z TAFS...VERY QUIET VFR AVIATION WEATHER CONDITIONS TO
CONTINUE. SURFACE HIGH PRESSURE CENTERED OVER SOUTHERN ONTARIO
EARLY THIS AFTERNOON WITH LIGHT EAST GRADIENT WINDS ACROSS
FORECAST AREA. MORNING RAOB ANALYSIS INDICATES MIN/UPPER LEVEL
RIDGE OVERHEAD AS WELL...RESULTING IN SUBSIDENCE AND GENERALLY
CLEAR SKIES ACROSS TERMINALS.

AS SURFACE HIGH GRADUALLY MOVES OFF TO THE EAST OVER THE NEXT 24
HOURS...WINDS GENERALLY 10 KNOTS OR LESS WILL SHIFT TO THE
SOUTHEAST TONIGHT AND TO THE SOUTH ON FRIDAY. ANY LAKE BREEZE
EXPECTED TO REMAIN EAST OF KORD/KMDW THROUGH 18Z FRIDAY. OTHER
THAN SCATTERED HIGH CIRRUS...LITTLE CLOUD COVER EXPECTED WITH VFR
CONDITIONS THROUGH THE PERIOD.

RATZER

&&

.MARINE...

226 PM CDT

HIGH PRESSURE OVER SOUTHERN ONTARIO MOVING OFF TO THE EAST
TONIGHT AND WILL BE OVER NEW ENGLAND AND NOVA SCOTIA BY LATE
FRIDAY. FARTHER NORTH...LOW PRESSURE OVER NORTHERN SASKATCHEWAN
WILL DEEPEN AS IT MOVES EAST TO HUDSON BAY THROUGH FRIDAY. AS THE
LOW DEEPENS...THIS WILL RESULT IN A TIGHTENING SURFACE PRESSURE
GRADIENT OVER NORTHERN LAKE MICHIGAN LATER TONIGHT THROUGH MUCH OF
FRIDAY WITH SOUTH WINDS INCREASING TO MARGINAL 35 KNOT GALES
FRIDAY MORNING. THE GRADIENT WILL BEGIN TO RELAX A BIT BY FRIDAY
EVENING ALLOWING WINDS TO EASE...BEFORE A COLD FRONT TRAILING FROM
THE CANADIAN LOW PUSHES SOUTH ACROSS LAKE MICHIGAN LATE FRIDAY
NIGHT AND SATURDAY. THE FRONT WILL CONTINUE TO MOVE SOUTH OF THE
LAKES FRIDAY NIGHT AS HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE
NORTHERN LAKES. THE HIGH WILL THEN DRIFT EAST LATE IN THE
WEEKEND...ALLOWING WINDS TO ONCE AGAIN SHIFT TO THE SOUTHEAST BY
MONDAY.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565...7 AM
     FRIDAY TO 10 PM FRIDAY.

&&

$$

000
FXUS63 KILX 181925
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
225 PM CDT THU SEP 18 2008

.DISCUSSION...
ISSUED 200 PM CDT THU SEP 18 2008

HIGH PRESSURE CENTERED NORTH OF LAKE SUPERIOR WILL CONTINUE TO
DOMINATE THE WEATHER ACRS THE FORECAST AREA THRU FRIDAY NIGHT.
THE WEAK COOL FRONT/WIND SHIFT WHICH PUSHED ACRS THE AREA LATE
LAST NIGHT HAS ALL BUT WASHED OUT EARLY THIS AFTERNOON TO OUR
SOUTH. THE STRONGER FLOW REMAINS WELL TO OUR NORTH ACRS CNTRL
CANADA...WHILE THE WATER VAPOR LOOP DEPICTS A RATHER VIGOROUS
UPPER WAVE OVR SE COLORADO THAT MAY BRING SHOWER CHANCES A BIT
FURTHER NORTH INTO OUR AREA THAN PREVIOUSLY THOUGHT FOR THE
WEEKEND.

SHORT TERM...TONIGHT THROUGH SUNDAY
MODELS IN GOOD AGREEMENT THRU EARLY SATURDAY AS HIGH PRESSURE
HOLDS NE OF THE GREAT LAKES BRINGING PLEASANTLY WARM DAYS AND
COMFORTABLY COOL NIGHTS. 850 TEMPERATURES SUPPORT DAYTIME HIGHS
IN THE 80 TO 83 DEGREE RANGE FRIDAY AND SATURDAY WITH EARLY
MORNING LOWS DROPPING INTO THE LOWER TO MIDDLE 50S. THE UPPER
LEVEL WAVE CURRENTLY OVER THE SOUTHERN PLAINS IS FORECAST TO
SLOWLY PUSH EAST DURING THE NEXT SEVERAL DAYS AND BE POSITIONED
OVR SRN MO BY SUNDAY. THE SURFACE RIDGE AXIS BY THAT TIME WILL
BE ORIENTATED EAST-WEST ACRS CNTRL IL WHILE THE BETTER UPPER
LEVEL SUPPORT ASSOCIATED WITH THE SRN PLAINS WAVE IS FORECAST
TO TRACK SLOWLY ACRS SRN MO AND IL SATURDAY AND SUNDAY.

FORECAST SOUNDINGS...EXCPT ALONG THE I-70 CORRIDOR...NOT SHOWING
MUCH IF ANY SUPPORT FOR SHOWERS AS THE DRY LOW LEVEL EASTERLY FLOW
PREVAILS FROM THE DEPARTING HIGH. HOWEVER...MODELS CONTINUE TO
INDICATE SFC BASED CAPES IN THE 1000 J/KG RANGE BOTH SAT AND
SUNDAY AFTERNOON. THE 00Z AND NOW THE LATEST ECMWF SUGGESTS SOME
LIGHT QPF ACRS THE PARTS OF ENTIRE FCST AREA SATURDAY AND SUNDAY
AND BASED ON ITS PERFORMANCE THIS SUMMER...WL BE HARD TO IGNORE.
FOR NOW...WL INCORPORATE SOME LOW CHANCE (NOT MENTIONABLE IN THE
ZFP) POPS IN THE GRIDS BUT IF THESE TRENDS CONTINUE...WL NEED TO
RAISE POPS FOR THE WEEKEND.

LONG TERM...MONDAY THROUGH THURSDAY
THE MISSOURI SHORTWAVE IS FORECAST TO EDGE SLOWLY AWAY FROM THE
MIDWEST ON MONDAY AS UPPER LEVEL RIDGING BUILDS IN RESPONSE TO A
TROF PUSHING ACRS THE PACIFIC NW EARLY NEXT WEEK. THE NEXT SIG
SHORTWAVE TROF IS EXPECTED TO PUSH ACRS THE PLAINS AND EVENTUALLY
INTO THE MIDWEST LATE WED INTO THURSDAY BRINGING THE CHANCE FOR
SHOWERS BACK INTO THE REGION. WITH A TROF TO OUR WEST AND RIDGING
IN PLACE OVR THE MIDWEST...TEMPERATURES DURING THIS PERIOD ARE
EXPECTED TO AVERAGE ABOVE NORMAL WITH HIGHS IN THE UPPER 70S TO
LOWER 80S AND LOWS IN THE 55 TO 60 DEGREE RANGE.

SMITH
&&

.AVIATION...
ISSUED 118 PM CDT THU SEP 18 2008
HIGH PRESSURE REMAINS THE MAIN STORY...BUT SLIDING OFF TO THE
EAST. FEW CU FOR THE AFTERNOON...THEN SCT CIRRUS AT MOST IN THE
OVERNIGHT. VFR CIGS AND E/SERLY FLOW EXPECTED THROUGH THE
OVERNIGHT. PRE DAWN VISBY DROPS SHOULD REMAIN IN MVFR
CATEGORY...AND ONLY BRIEFLY BEFORE THE SUNRISE. WINDS MORE
SOUTHERLY TOMORROW MORNING AND MINIMAL...IF ANY...CLOUDS.

HJS
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 181823
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
123 PM CDT THU SEP 18 2008

.DISCUSSION...
ISSUED 1052 AM CDT THU SEP 18 2008
HIGH PRESSURE RIDGE OVER IL THIS MORNING. PLENTY OF SUN PULLING
TEMPS UP INTO THE LOWER 70S EARLY. FORECAST FOR SUNNY SKIES MAY
ACTUALLY HAVE A LITTLE BIT OF A PROBLEM AS THE LLVL MOISTURE
PROFILE HAS CHANGED SINCE THE OVERNIGHT MODEL RUNS. THIS
MORNING...NAM/GFS/NGM/RUC CU RULES ALL HAVE SIGNIFICANT CU THIS
AFTERNOON. HAVE UPDATED MAINLY FOR WRN HALF OF CWA...WEST OF RIDGE
AXIS...BUT ONLY IN MODERATION FOR NOW. BOOSTED TEMPS ONLY
SLIGHTLY AS 850MB TEMPS THIS MORNING UP A DEGREE FROM YESTERDAYS
SOUNDING AT 12Z...JUST A TOUCH OVER YESTERDAYS. ALL FORECAST
CHANGES ARE SO SUBTLE THAT NO ZONE UPDATES ARE ANTICIPATED AT THIS
TIME.



&&

.AVIATION...
ISSUED 118 PM CDT THU SEP 18 2008
HIGH PRESSURE REMAINS THE MAIN STORY...BUT SLIDING OFF TO THE
EAST. FEW CU FOR THE AFTERNOON...THEN SCT CIRRUS AT MOST IN THE
OVERNIGHT. VFR CIGS AND E/SERLY FLOW EXPECTED THROUGH THE
OVERNIGHT. PRE DAWN VISBY DROPS SHOULD REMAIN IN MVFR
CATEGORY...AND ONLY BRIEFLY BEFORE THE SUNRISE. WINDS MORE
SOUTHERLY TOMORROW MORNING AND MINIMAL...IF ANY...CLOUDS.


HJS
&&

.PREV DISCUSSION...
ISSUED 139 AM CDT THU SEP 18 2008

DRY AND PLEASANT LATE SUMMER WEATHER EXPECTED THROUGH THE ENTIRE
FORECAST PERIOD.

06Z SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED OVER LAKE
SUPERIOR...WITH WEAK FRONTAL BOUNDARY SLOWLY SINKING SOUTHWARD
INTO NORTH-CENTRAL ILLINOIS. ALOFT...MAIN STORM TRACK REMAINS WELL TO
THE NORTH ACROSS CANADA...WHILE VERY WEAK FLOW DOMINATES ACROSS
MUCH OF THE CONUS.

SHORT TERM...TODAY THROUGH SATURDAY

WEAK FRONT WILL CONTINUE TO DROP SOUTHWARD TODAY...EVENTUALLY
STALLING AND WASHING OUT ACROSS CENTRAL ILLINOIS. BOUNDARY WILL BE
COMPLETELY MOISTURE-STARVED...SO NOT EXPECTING MUCH IN THE WAY OF
CLOUD COVER WITH IT. CU-RULE INDICATES FEW-SCT CU ALONG AND AHEAD
OF THE FRONT...MAINLY ACROSS IOWA INTO THE NORTHWEST KILX CWA.
BOTTOM LINE WILL BE SUNNY SKIES ACROSS THE BOARD...WITH LIGHT E/NE
WINDS. VERY LITTLE IN THE WAY OF CAA BEHIND FRONT...SO HIGH TEMPS
WILL BE QUITE SIMILAR TO YESTERDAY...PERHAPS A DEGREE OR TWO
COOLER...WITH READINGS REACHING THE UPPER 70S TO AROUND 80 DEGREES.

WEAK UPPER LOW CURRENTLY ACROSS THE SOUTHERN ROCKIES WILL SLOWLY
TRACK EASTWARD INTO THE LOWER MISSISSIPPI RIVER VALLEY FRIDAY AND
SATURDAY. BOTH THE NAM-WRF AND GFS ARE TRYING TO GENERATE SOME
PRECIP WITH THIS SYSTEM ACROSS PARTS OF MISSOURI AND SOUTHERN
ILLINOIS...HOWEVER WITH DRY ATMOSPHERE FIRMLY IN PLACE...THINK
THIS MAY BE A BIT OVERDONE. MEANWHILE...A WAVE TRACKING ACROSS
SOUTHERN CANADA WILL PUSH A COLD FRONT SOUTHWARD INTO THE GREAT
LAKES. CENTRAL ILLINOIS WILL REMAIN BETWEEN THESE TWO
SYSTEMS...WITH THE END RESULT BEING A CONTINUATION OF MOSTLY SUNNY
AND WARM CONDITIONS WITH AFTERNOON HIGHS AROUND 80 DEGREES FOR
BOTH FRIDAY AND SATURDAY.

LONG TERM...SUNDAY THROUGH WEDNESDAY

ONCE UPPER LOW WEAKENS AND MOVES AWAY...RIDGE WILL BEGIN TO BUILD
IN EARNEST ACROSS THE MIDWEST EARLY NEXT WEEK. RIDGE WILL BE
FURTHER AMPLIFIED AS A RESULT OF NORTHERN STREAM TROUGH DIGGING
INTO THE NORTHERN ROCKIES. MODELS CONTINUE TO KEEP CENTRAL
ILLINOIS DRY THROUGH AT LEAST THE MIDDLE OF THE WEEK...AND LIKELY
ALL THE WAY THROUGH NEXT WEEKEND. HAVE THEREFORE MADE VERY FEW
CHANGES TO THE EXTENDED AT THIS TIME.

BARNES


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 181738
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1238 PM CDT THU SEP 18 2008

.DISCUSSION...
226 AM CDT

TODAYS WEATHER CAN BE SUMMED UP IN 4 WORDS...BIG BUBBLE NO TROUBLE.

EXPANSIVE RIDGE OF HIGH PRESSURE HAS PRETTY MUCH TAKEN OVER THE
ENTIRE EASTERN PORTION OF THE US WITH THE CORE SITTING OVER LAKE
SUPERIOR. THIS RIDGE WILL TRACK EAST TOWARD NEW ENGLAND TODAY
WHICH WILL EVENTUALLY CAUSE OUR WINDS TO SHIFT TO BEING MORE
SOUTHWESTERLY BY EARLY FRIDAY. WITH 850MB TEMPS NOT DROPPING OFF
TOO MUCH AFTER YESTERDAYS COLD FRONT...PLENTIFUL SUNSHINE...AND A
FAIRLY DRY AIR MASS...THINK THAT MID 70S APPEAR REASONABLE FOR
HIGH TEMPS TODAY EVEN WITH A LIGHT WIND OFF OF THE LAKE.

TEMPS SHOULD CLIMB HIGHER ON FRIDAY WITH THE MORE FAVORABLE
SOUTHWESTERLIES IN PLACE AND 850MB TEMPS ON THE INCREASE. NEXT
FEATURE OF NOTE IS A COLD FRONT PROGGED TO DROP DOWN INTO THE
REGION ON SATURDAY. STILL NOT A WHOLE LOT OF MOISTURE OUT THERE
WITH THE GULF BEING CLOSED...BUT WITH COLDER MID-LEVEL AIR
ADVECTING INTO THE REGION THERE APPEARS TO BE A DECENT AMOUNT OF
UNSTABLE AIR ALOFT WITH THE GFS ACTUALLY PUTTING OUT 1500J/KG OF
ELEVATED CAPE. THIS NUMBER IS PROBABLY EXAGGERATED A BIT DUE TO THE
SFC DEW POINT LIKELY BEING TOO HIGH IN THE FORECAST SOUNDING.
THERE ALSO DOES APPEAR TO BE A LOW LEVEL CAP IN PLACE THAT THE
LIFT FROM THE COLD FRONT WILL NEED TO OVERCOME IF THE ATMOSPHERE
WANTS TO TAP INTO THE ELEVATED UNSTABLE AIR. THIS SITUATION IS
NOT LOOKING LIKELY THOUGH AS THE BEST UPPER LEVEL FORCING REMAINS
WELL TO THE NORTH NEAR THE POLAR VORTEX. AT THIS POINT...WITH
FORCING AND MOISTURE BEING RATHER LIMITED...WILL HOLD OFF ON ANY
MENTION OF PRECIP WITH FROPA SATURDAY AFTERNOON.

ANOTHER RIDGE BUILDS IN ACROSS THE GREAT LAKES FOR SUNDAY INTO
MONDAY WITH ODDLY ENOUGH SEEMS TO ALMOST BE A CARBON COPY OF THE
WEATHER PATTERN FOR TODAY INTO FRIDAY.

HALBACH

&&

.AVIATION...

1238 PM CDT

FOR THE 18Z TAFS...VERY QUIET VFR AVIATION WEATHER CONDITIONS TO
CONTINUE. SURFACE HIGH PRESSURE CENTERED OVER SOUTHERN ONTARIO
EARLY THIS AFTERNOON WITH LIGHT EAST GRADIENT WINDS ACROSS
FORECAST AREA. MORNING RAOB ANALYSIS INDICATES MIN/UPPER LEVEL
RIDGE OVERHEAD AS WELL...RESULTING IN SUBSIDENCE AND GENERALLY
CLEAR SKIES ACROSS TERMINALS.

AS SURFACE HIGH GRADUALLY MOVES OFF TO THE EAST OVER THE NEXT 24
HOURS...WINDS GENERALLY 10 KNOTS OR LESS WILL SHIFT TO THE
SOUTHEAST TONIGHT AND TO THE SOUTH ON FRIDAY. ANY LAKE BREEZE
EXPECTED TO REMAIN EAST OF KORD/KMDW THROUGH 18Z FRIDAY. OTHER
THAN SCATTERED HIGH CIRRUS...LITTLE CLOUD COVER EXPECTED WITH VFR
CONDITIONS THROUGH THE PERIOD.

RATZER

&&

.MARINE...
1244 AM

SURFACE RIDGE AXIS SHOULD MOVE EAST OF THE LAKES TONIGHT INTO
FRIDAY AS DEEP LOW PRESSURE TRACKS EASTWARD ACROSS CENTRAL CANADA.
SET-UP FRIDAY LOOKS PRETTY SIMILAR TO TUESDAY WITH STRONG
SOUTHERLY WINDS SETTING UP OVER NORTHERN PORTIONS OF THE LAKE.
ONCE AGAIN IT APPEARS AS THOUGH WINDS WILL BE FLIRTING WITH GALES
OVER FAR NORTHERN PORTIONS OF LAKE FRIDAY AFTERNOON...AND WILL
STRONGLY CONSIDER A GALE WATCH FOR FAR NORTHERN LM WITH THIS
MORNINGS GLF ISSUANCE.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ563...10 AM FRIDAY TO 9 PM
     FRIDAY.

&&

$$

000
FXUS63 KILX 181557
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1057 AM CDT THU SEP 18 2008

.DISCUSSION...
ISSUED 1052 AM CDT THU SEP 18 2008
HIGH PRESSURE RIDGE OVER IL THIS MORNING. PLENTY OF SUN PULLING
TEMPS UP INTO THE LOWER 70S EARLY. FORECAST FOR SUNNY SKIES MAY
ACTUALLY HAVE A LITTLE BIT OF A PROBLEM AS THE LLVL MOISTURE
PROFILE HAS CHANGED SINCE THE OVERNIGHT MODEL RUNS. THIS
MORNING...NAM/GFS/NGM/RUC CU RULES ALL HAVE SIGNIFICANT CU THIS
AFTERNOON. HAVE UPDATED MAINLY FOR WRN HALF OF CWA...WEST OF RIDGE
AXIS...BUT ONLY IN MODERATION FOR NOW. BOOSTED TEMPS ONLY
SLIGHTLY AS 850MB TEMPS THIS MORNING UP A DEGREE FROM YESTERDAYS
SOUNDING AT 12Z...JUST A TOUCH OVER YESTERDAYS. ALL FORECAST
CHANGES ARE SO SUBTLE THAT NO ZONE UPDATES ARE ANTICIPATED AT THIS
TIME.

HJS
&&

.AVIATION...
ISSUED 635 AM CDT THU SEP 18 2008...FOR THE 12Z TAFS

SOME PATCHY FOG IS FLOATING AROUND CENTRAL ILLINOIS THIS
MORNING...AS DEWPOINTS ARE SLIGHTLY HIGHER THAN THEY WERE
YESTERDAY MORNING. ONLY SPI HAS BEEN AFFECTED WITH A SHORT PERIOD
OF 1/2SM FG EARLIER THIS MORNING...BUT HAS COME BACK UP AGAIN.
WILL KEEP A TEMPO FOR IFR VIS THERE FOR A COUPLE HOURS...AND
TEMPOS FOR MVFR VIS AT THE OTHER SITES. FOG SHOULD BE SHORT
LIVED...WITH PLENTY OF SUNSHINE THE REST OF THE DAY.

SOME LIGHT FOG WITH MVFR VIS STILL POSSIBLE AGAIN FRIDAY
MORNING...BUT NOT ENOUGH TO WARRANT A MENTION IN THE TAFS THIS FAR
AHEAD.

SHIMON
&&

.PREV DISCUSSION...
ISSUED 139 AM CDT THU SEP 18 2008

DRY AND PLEASANT LATE SUMMER WEATHER EXPECTED THROUGH THE ENTIRE
FORECAST PERIOD.

06Z SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED OVER LAKE
SUPERIOR...WITH WEAK FRONTAL BOUNDARY SLOWLY SINKING SOUTHWARD
INTO NORTH-CENTRAL ILLINOIS. ALOFT...MAIN STORM TRACK REMAINS WELL TO
THE NORTH ACROSS CANADA...WHILE VERY WEAK FLOW DOMINATES ACROSS
MUCH OF THE CONUS.

SHORT TERM...TODAY THROUGH SATURDAY

WEAK FRONT WILL CONTINUE TO DROP SOUTHWARD TODAY...EVENTUALLY
STALLING AND WASHING OUT ACROSS CENTRAL ILLINOIS. BOUNDARY WILL BE
COMPLETELY MOISTURE-STARVED...SO NOT EXPECTING MUCH IN THE WAY OF
CLOUD COVER WITH IT. CU-RULE INDICATES FEW-SCT CU ALONG AND AHEAD
OF THE FRONT...MAINLY ACROSS IOWA INTO THE NORTHWEST KILX CWA.
BOTTOM LINE WILL BE SUNNY SKIES ACROSS THE BOARD...WITH LIGHT E/NE
WINDS. VERY LITTLE IN THE WAY OF CAA BEHIND FRONT...SO HIGH TEMPS
WILL BE QUITE SIMILAR TO YESTERDAY...PERHAPS A DEGREE OR TWO
COOLER...WITH READINGS REACHING THE UPPER 70S TO AROUND 80 DEGREES.

WEAK UPPER LOW CURRENTLY ACROSS THE SOUTHERN ROCKIES WILL SLOWLY
TRACK EASTWARD INTO THE LOWER MISSISSIPPI RIVER VALLEY FRIDAY AND
SATURDAY. BOTH THE NAM-WRF AND GFS ARE TRYING TO GENERATE SOME
PRECIP WITH THIS SYSTEM ACROSS PARTS OF MISSOURI AND SOUTHERN
ILLINOIS...HOWEVER WITH DRY ATMOSPHERE FIRMLY IN PLACE...THINK
THIS MAY BE A BIT OVERDONE. MEANWHILE...A WAVE TRACKING ACROSS
SOUTHERN CANADA WILL PUSH A COLD FRONT SOUTHWARD INTO THE GREAT
LAKES. CENTRAL ILLINOIS WILL REMAIN BETWEEN THESE TWO
SYSTEMS...WITH THE END RESULT BEING A CONTINUATION OF MOSTLY SUNNY
AND WARM CONDITIONS WITH AFTERNOON HIGHS AROUND 80 DEGREES FOR
BOTH FRIDAY AND SATURDAY.

LONG TERM...SUNDAY THROUGH WEDNESDAY

ONCE UPPER LOW WEAKENS AND MOVES AWAY...RIDGE WILL BEGIN TO BUILD
IN EARNEST ACROSS THE MIDWEST EARLY NEXT WEEK. RIDGE WILL BE
FURTHER AMPLIFIED AS A RESULT OF NORTHERN STREAM TROUGH DIGGING
INTO THE NORTHERN ROCKIES. MODELS CONTINUE TO KEEP CENTRAL
ILLINOIS DRY THROUGH AT LEAST THE MIDDLE OF THE WEEK...AND LIKELY
ALL THE WAY THROUGH NEXT WEEKEND. HAVE THEREFORE MADE VERY FEW
CHANGES TO THE EXTENDED AT THIS TIME.

BARNES

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KILX 181135
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
635 AM CDT THU SEP 18 2008

.DISCUSSION...
ISSUED 139 AM CDT THU SEP 18 2008

DRY AND PLEASANT LATE SUMMER WEATHER EXPECTED THROUGH THE ENTIRE
FORECAST PERIOD.

06Z SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED OVER LAKE
SUPERIOR...WITH WEAK FRONTAL BOUNDARY SLOWLY SINKING SOUTHWARD
INTO NORTH-CENTRAL ILLINOIS. ALOFT...MAIN STORM TRACK REMAINS WELL TO
THE NORTH ACROSS CANADA...WHILE VERY WEAK FLOW DOMINATES ACROSS
MUCH OF THE CONUS.

SHORT TERM...TODAY THROUGH SATURDAY

WEAK FRONT WILL CONTINUE TO DROP SOUTHWARD TODAY...EVENTUALLY
STALLING AND WASHING OUT ACROSS CENTRAL ILLINOIS. BOUNDARY WILL BE
COMPLETELY MOISTURE-STARVED...SO NOT EXPECTING MUCH IN THE WAY OF
CLOUD COVER WITH IT. CU-RULE INDICATES FEW-SCT CU ALONG AND AHEAD
OF THE FRONT...MAINLY ACROSS IOWA INTO THE NORTHWEST KILX CWA.
BOTTOM LINE WILL BE SUNNY SKIES ACROSS THE BOARD...WITH LIGHT E/NE
WINDS. VERY LITTLE IN THE WAY OF CAA BEHIND FRONT...SO HIGH TEMPS
WILL BE QUITE SIMILAR TO YESTERDAY...PERHAPS A DEGREE OR TWO
COOLER...WITH READINGS REACHING THE UPPER 70S TO AROUND 80 DEGREES.

WEAK UPPER LOW CURRENTLY ACROSS THE SOUTHERN ROCKIES WILL SLOWLY
TRACK EASTWARD INTO THE LOWER MISSISSIPPI RIVER VALLEY FRIDAY AND
SATURDAY. BOTH THE NAM-WRF AND GFS ARE TRYING TO GENERATE SOME
PRECIP WITH THIS SYSTEM ACROSS PARTS OF MISSOURI AND SOUTHERN
ILLINOIS...HOWEVER WITH DRY ATMOSPHERE FIRMLY IN PLACE...THINK
THIS MAY BE A BIT OVERDONE. MEANWHILE...A WAVE TRACKING ACROSS
SOUTHERN CANADA WILL PUSH A COLD FRONT SOUTHWARD INTO THE GREAT
LAKES. CENTRAL ILLINOIS WILL REMAIN BETWEEN THESE TWO
SYSTEMS...WITH THE END RESULT BEING A CONTINUATION OF MOSTLY SUNNY
AND WARM CONDITIONS WITH AFTERNOON HIGHS AROUND 80 DEGREES FOR
BOTH FRIDAY AND SATURDAY.

LONG TERM...SUNDAY THROUGH WEDNESDAY

ONCE UPPER LOW WEAKENS AND MOVES AWAY...RIDGE WILL BEGIN TO BUILD
IN EARNEST ACROSS THE MIDWEST EARLY NEXT WEEK. RIDGE WILL BE
FURTHER AMPLIFIED AS A RESULT OF NORTHERN STREAM TROUGH DIGGING
INTO THE NORTHERN ROCKIES. MODELS CONTINUE TO KEEP CENTRAL
ILLINOIS DRY THROUGH AT LEAST THE MIDDLE OF THE WEEK...AND LIKELY
ALL THE WAY THROUGH NEXT WEEKEND. HAVE THEREFORE MADE VERY FEW
CHANGES TO THE EXTENDED AT THIS TIME.

BARNES

&&

.AVIATION...
ISSUED 635 AM CDT THU SEP 18 2008...FOR THE 12Z TAFS

SOME PATCHY FOG IS FLOATING AROUND CENTRAL ILLINOIS THIS
MORNING...AS DEWPOINTS ARE SLIGHTLY HIGHER THAN THEY WERE
YESTERDAY MORNING. ONLY SPI HAS BEEN AFFECTED WITH A SHORT PERIOD
OF 1/2SM FG EARLIER THIS MORNING...BUT HAS COME BACK UP AGAIN.
WILL KEEP A TEMPO FOR IFR VIS THERE FOR A COUPLE HOURS...AND
TEMPOS FOR MVFR VIS AT THE OTHER SITES. FOG SHOULD BE SHORT
LIVED...WITH PLENTY OF SUNSHINE THE REST OF THE DAY.

SOME LIGHT FOG WITH MVFR VIS STILL POSSIBLE AGAIN FRIDAY
MORNING...BUT NOT ENOUGH TO WARRANT A MENTION IN THE TAFS THIS FAR
AHEAD.

SHIMON
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

000
FXUS63 KLOT 181132
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
632 AM CDT THU SEP 18 2008

.DISCUSSION...
226 AM CDT

TODAYS WEATHER CAN BE SUMMED UP IN 4 WORDS...BIG BUBBLE NO TROUBLE.

EXPANSIVE RIDGE OF HIGH PRESSURE HAS PRETTY MUCH TAKEN OVER THE
ENTIRE EASTERN PORTION OF THE US WITH THE CORE SITTING OVER LAKE
SUPERIOR. THIS RIDGE WILL TRACK EAST TOWARD NEW ENGLAND TODAY
WHICH WILL EVENTUALLY CAUSE OUR WINDS TO SHIFT TO BEING MORE
SOUTHWESTERLY BY EARLY FRIDAY. WITH 850MB TEMPS NOT DROPPING OFF
TOO MUCH AFTER YESTERDAYS COLD FRONT...PLENTIFUL SUNSHINE...AND A
FAIRLY DRY AIR MASS...THINK THAT MID 70S APPEAR REASONABLE FOR
HIGH TEMPS TODAY EVEN WITH A LIGHT WIND OFF OF THE LAKE.

TEMPS SHOULD CLIMB HIGHER ON FRIDAY WITH THE MORE FAVORABLE
SOUTHWESTERLIES IN PLACE AND 850MB TEMPS ON THE INCREASE. NEXT
FEATURE OF NOTE IS A COLD FRONT PROGGED TO DROP DOWN INTO THE
REGION ON SATURDAY. STILL NOT A WHOLE LOT OF MOISTURE OUT THERE
WITH THE GULF BEING CLOSED...BUT WITH COLDER MID-LEVEL AIR
ADVECTING INTO THE REGION THERE APPEARS TO BE A DECENT AMOUNT OF
UNSTABLE AIR ALOFT WITH THE GFS ACTUALLY PUTTING OUT 1500J/KG OF
ELEVATED CAPE. THIS NUMBER IS PROBABLY EXAGGERATED A BIT DUE TO THE
SFC DEW POINT LIKELY BEING TOO HIGH IN THE FORECAST SOUNDING.
THERE ALSO DOES APPEAR TO BE A LOW LEVEL CAP IN PLACE THAT THE
LIFT FROM THE COLD FRONT WILL NEED TO OVERCOME IF THE ATMOSPHERE
WANTS TO TAP INTO THE ELEVATED UNSTABLE AIR. THIS SITUATION IS
NOT LOOKING LIKELY THOUGH AS THE BEST UPPER LEVEL FORCING REMAINS
WELL TO THE NORTH NEAR THE POLAR VORTEX. AT THIS POINT...WITH
FORCING AND MOISTURE BEING RATHER LIMITED...WILL HOLD OFF ON ANY
MENTION OF PRECIP WITH FROPA SATURDAY AFTERNOON.

ANOTHER RIDGE BUILDS IN ACROSS THE GREAT LAKES FOR SUNDAY INTO
MONDAY WITH ODDLY ENOUGH SEEMS TO ALMOST BE A CARBON COPY OF THE
WEATHER PATTERN FOR TODAY INTO FRIDAY.

HALBACH

&&

.AVIATION...

1200 UTC TAFS...NO WEATHER OF CONSEQUENCE EXPECTED THROUGH THIS
TAF CYCLE. SKIES WILL BE CLEAR BELOW FL250...WINDS 10KT OR
LESS...AND VSBY UNRESTRICTED.

IZZI

&&

.MARINE...
1244 AM

SURFACE RIDGE AXIS SHOULD MOVE EAST OF THE LAKES TONIGHT INTO
FRIDAY AS DEEP LOW PRESSURE TRACKS EASTWARD ACROSS CENTRAL CANADA.
SET-UP FRIDAY LOOKS PRETTY SIMILAR TO TUESDAY WITH STRONG
SOUTHERLY WINDS SETTING UP OVER NORTHERN PORTIONS OF THE LAKE.
ONCE AGAIN IT APPEARS AS THOUGH WINDS WILL BE FLIRTING WITH GALES
OVER FAR NORTHERN PORTIONS OF LAKE FRIDAY AFTERNOON...AND WILL
STRONGLY CONSIDER A GALE WATCH FOR FAR NORTHERN LM WITH THIS
MORNINGS GLF ISSUANCE.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ563...10 AM FRIDAY TO 9 PM
     FRIDAY.

&&

$$

000
FXUS63 KLOT 180727
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
226 AM CDT THU SEP 18 2008

.DISCUSSION...
226 AM CDT

TODAYS WEATHER CAN BE SUMMED UP IN 4 WORDS...BIG BUBBLE NO TROUBLE.

EXPANSIVE RIDGE OF HIGH PRESSURE HAS PRETTY MUCH TAKEN OVER THE
ENTIRE EASTERN PORTION OF THE US WITH THE CORE SITTING OVER LAKE
SUPERIOR. THIS RIDGE WILL TRACK EAST TOWARD NEW ENGLAND TODAY
WHICH WILL EVENTUALLY CAUSE OUR WINDS TO SHIFT TO BEING MORE
SOUTHWESTERLY BY EARLY FRIDAY. WITH 850MB TEMPS NOT DROPPING OFF
TOO MUCH AFTER YESTERDAYS COLD FRONT...PLENTIFUL SUNSHINE...AND A
FAIRLY DRY AIR MASS...THINK THAT MID 70S APPEAR REASONABLE FOR
HIGH TEMPS TODAY EVEN WITH A LIGHT WIND OFF OF THE LAKE.

TEMPS SHOULD CLIMB HIGHER ON FRIDAY WITH THE MORE FAVORABLE
SOUTHWESTERLIES IN PLACE AND 850MB TEMPS ON THE INCREASE. NEXT
FEATURE OF NOTE IS A COLD FRONT PROGGED TO DROP DOWN INTO THE
REGION ON SATURDAY. STILL NOT A WHOLE LOT OF MOISTURE OUT THERE
WITH THE GULF BEING CLOSED...BUT WITH COLDER MID-LEVEL AIR
ADVECTING INTO THE REGION THERE APPEARS TO BE A DECENT AMOUNT OF
UNSTABLE AIR ALOFT WITH THE GFS ACTUALLY PUTTING OUT 1500J/KG OF
ELEVATED CAPE. THIS NUMBER IS PROBABLY EXAGGERATED A BIT DUE TO THE
SFC DEW POINT LIKELY BEING TOO HIGH IN THE FORECAST SOUNDING.
THERE ALSO DOES APPEAR TO BE A LOW LEVEL CAP IN PLACE THAT THE
LIFT FROM THE COLD FRONT WILL NEED TO OVERCOME IF THE ATMOSPHERE
WANTS TO TAP INTO THE ELEVATED UNSTABLE AIR. THIS SITUATION IS
NOT LOOKING LIKELY THOUGH AS THE BEST UPPER LEVEL FORCING REMAINS
WELL TO THE NORTH NEAR THE POLAR VORTEX. AT THIS POINT...WITH
FORCING AND MOISTURE BEING RATHER LIMITED...WILL HOLD OFF ON ANY
MENTION OF PRECIP WITH FROPA SATURDAY AFTERNOON.

ANOTHER RIDGE BUILDS IN ACROSS THE GREAT LAKES FOR SUNDAY INTO
MONDAY WITH ODDLY ENOUGH SEEMS TO ALMOST BE A CARBON COPY OF THE
WEATHER PATTERN FOR TODAY INTO FRIDAY.

HALBACH

&&

.AVIATION...

0600 UTC TAFS...ANOTHER QUIET TAF CYCLE. ONLY CONCERN IS THE
POTENTIAL FOR A BRIEF PERIOD OF REDUCED VSBYS AROUND SUNRISE THIS
MORNING AS CLEAR SKIES/LIGHT WINDS/MOIST GROUND LEAVE CONDITIONS
SOMEWHAT FAVORABLE FOR SOME BR TO FORM. HAVE INTRODUCED PERIOD OF
MVFR VSBY AT DPA THIS MORNING AND STRONGLY CONSIDERED IT FOR ORD
DESPITE THE MORE URBANIZED LOCATION...BUT KEPT IT OUT OF ORD DUE
TO CLOSER PROXIMITY TO MORE URBANIZED LANDSCAPE. WILL MONITOR
TRENDS THROUGH THE EARLY MORNING AND AMEND IF NEEDED.

IZZI

&&

.MARINE...
1244 AM

SURFACE RIDGE AXIS SHOULD MOVE EAST OF THE LAKES TONIGHT INTO
FRIDAY AS DEEP LOW PRESSURE TRACKS EASTWARD ACROSS CENTRAL CANADA.
SET-UP FRIDAY LOOKS PRETTY SIMILAR TO TUESDAY WITH STRONG
SOUTHERLY WINDS SETTING UP OVER NORTHERN PORTIONS OF THE LAKE.
ONCE AGAIN IT APPEARS AS THOUGH WINDS WILL BE FLIRTING WITH GALES
OVER FAR NORTHERN PORTIONS OF LAKE FRIDAY AFTERNOON...AND WILL
STRONGLY CONSIDER A GALE WATCH FOR FAR NORTHERN LM WITH THIS
MORNINGS GLF ISSUANCE.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

000
FXUS63 KILX 180639
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
139 AM CDT THU SEP 18 2008

.DISCUSSION...
ISSUED 139 AM CDT THU SEP 18 2008

DRY AND PLEASANT LATE SUMMER WEATHER EXPECTED THROUGH THE ENTIRE
FORECAST PERIOD.

06Z SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED OVER LAKE
SUPERIOR...WITH WEAK FRONTAL BOUNDARY SLOWLY SINKING SOUTHWARD
INTO NORTH-CENTRAL ILLINOIS. ALOFT...MAIN STORM TRACK REMAINS WELL TO
THE NORTH ACROSS CANADA...WHILE VERY WEAK FLOW DOMINATES ACROSS
MUCH OF THE CONUS.

SHORT TERM...TODAY THROUGH SATURDAY

WEAK FRONT WILL CONTINUE TO DROP SOUTHWARD TODAY...EVENTUALLY
STALLING AND WASHING OUT ACROSS CENTRAL ILLINOIS. BOUNDARY WILL BE
COMPLETELY MOISTURE-STARVED...SO NOT EXPECTING MUCH IN THE WAY OF
CLOUD COVER WITH IT. CU-RULE INDICATES FEW-SCT CU ALONG AND AHEAD
OF THE FRONT...MAINLY ACROSS IOWA INTO THE NORTHWEST KILX CWA.
BOTTOM LINE WILL BE SUNNY SKIES ACROSS THE BOARD...WITH LIGHT E/NE
WINDS. VERY LITTLE IN THE WAY OF CAA BEHIND FRONT...SO HIGH TEMPS
WILL BE QUITE SIMILAR TO YESTERDAY...PERHAPS A DEGREE OR TWO
COOLER...WITH READINGS REACHING THE UPPER 70S TO AROUND 80 DEGREES.

WEAK UPPER LOW CURRENTLY ACROSS THE SOUTHERN ROCKIES WILL SLOWLY
TRACK EASTWARD INTO THE LOWER MISSISSIPPI RIVER VALLEY FRIDAY AND
SATURDAY. BOTH THE NAM-WRF AND GFS ARE TRYING TO GENERATE SOME
PRECIP WITH THIS SYSTEM ACROSS PARTS OF MISSOURI AND SOUTHERN
ILLINOIS...HOWEVER WITH DRY ATMOSPHERE FIRMLY IN PLACE...THINK
THIS MAY BE A BIT OVERDONE. MEANWHILE...A WAVE TRACKING ACROSS
SOUTHERN CANADA WILL PUSH A COLD FRONT SOUTHWARD INTO THE GREAT
LAKES. CENTRAL ILLINOIS WILL REMAIN BETWEEN THESE TWO
SYSTEMS...WITH THE END RESULT BEING A CONTINUATION OF MOSTLY SUNNY
AND WARM CONDITIONS WITH AFTERNOON HIGHS AROUND 80 DEGREES FOR
BOTH FRIDAY AND SATURDAY.

LONG TERM...SUNDAY THROUGH WEDNESDAY

ONCE UPPER LOW WEAKENS AND MOVES AWAY...RIDGE WILL BEGIN TO BUILD
IN EARNEST ACROSS THE MIDWEST EARLY NEXT WEEK. RIDGE WILL BE
FURTHER AMPLIFIED AS A RESULT OF NORTHERN STREAM TROUGH DIGGING
INTO THE NORTHERN ROCKIES. MODELS CONTINUE TO KEEP CENTRAL
ILLINOIS DRY THROUGH AT LEAST THE MIDDLE OF THE WEEK...AND LIKELY
ALL THE WAY THROUGH NEXT WEEKEND. HAVE THEREFORE MADE VERY FEW
CHANGES TO THE EXTENDED AT THIS TIME.

BARNES
&&

.AVIATION...
ISSUED 1144 PM CDT WED SEP 17 2008

A WEAK FRONTAL BOUNDARY WILL WASH OUT ACROSS THE TERMINALS TONIGHT...
WITH HIGH PRESSURE RIDGING BACK INTO THE REGION THURSDAY. THE
AIRMASS REMAINS QUITE DRY AND VFR CONDITIONS SHOULD PREVAIL
THROUGH THE 06Z TAF PERIOD. MAY SEE PATCHY GROUND FOG AGAIN
TONIGHT...BUT IT WOULD ONLY BRIEFLY DROP VSBYS TO MVFR IN A FEW
CASES.

BAK
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$