000
FXUS63 KEAX 201723
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1123 AM CST TUE JAN 20 2009

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

FORECAST DILEMMAS THIS MORNING ARE FOCUSED MAINLY ON TEMPERATURES
OVER THE NEXT FEW DAYS. STRONG NORTHERLY WINDS WITHIN THE AMPLIFIED
PATTERN ACROSS THE CONUS HAS BROUGHT SOME ABUNDANT CLOUD COVER TO
THE REGION OVERNIGHT BEHIND A SHORTWAVE THAT MOVED SOUTH THROUGH THE
REGION YESTERDAY. COLD AIR ADVECTION WITHIN THE CLOUD LAYER HAS
MANAGED TO SQUEEZE SOME FLURRIES OUT ACROSS THE REGION DURING THE
EARLY MORNING HOURS...WITH SOME FREEZING DRIZZLE ALSO MIXED IN WHERE
THE MOISTURE WAS SALLOW ENOUGH TO NOT REACH THE PREFERRED DENDRITIC
GROWTH ZONE.

FOR TODAY...A COLD NORTH TO NORTHWEST WIND WILL PREVAIL THROUGH THE
FIRST HALF OF THE DAY WITH THE CLOUD COVER HANGING TOUGH. EXPECT
SOME SCATTERED FLURRIES TO PERSIST THROUGH THE MID MORNING HOURS AS
THE COLD AIR ADVECTION /CAA/ KEEPS GOING. HOWEVER...MODEL SOUNDINGS
INDICATE THAT THE CAA SHOULD STOP AROUND 14Z TO 15Z AS THE SURFACE
RIDGE TO OUR NORTH SLIDES SOUTH INTO THE CWA...BRINGING AN END TO
THE FLURRIES. WITH THE CENTER OF THE SURFACE RIDGE PASSING THROUGH
THIS AFTERNOON...WESTERLY WINDS WILL SPREAD ACROSS THE REGION AS
WARM AIR BEGINS TO SLOSH BACK TO THE EAST. THIS SHOULD SHOVE WHAT
CLOUD COVER IS OUT THERE EAST. WITH SOME SUNSHINE EXPECTED ACROSS
THE WESTERN REACHES OF THE FORECAST AREA...HAVE ADJUST THE GOING
TEMPERATURES FOR TODAY TO BE A BLEND OF THE WARMER MAV AND COOLER
MET NUMBERS...ESPECIALLY ACROSS THE WESTERN REACHES WHERE THERE
SHOULD BE LOTS OF SUNSHINE BY MID AFTERNOON.

FOR WEDNESDAY AND THURSDAY...A GENERAL BROADENING OF THE RIDGE...AS
IT BEGINS TO BREAK DOWN...WILL ALLOW A LOT OF WARM AIR TO SPREAD
EAST. SURFACE WINDS FROM THE SOUTHWEST...AND A DRY NORTHWEST TO WEST
FLOW ALOFT...WILL ALLOW FOR ABUNDANT SUNSHINE. AS A RESULT...
EXPECTATIONS ARE THAT HIGH TEMPERATURES SHOULD BE AT LEAST AS WARM
/IF NOT WARMER/ THAN THE GOING WARM MAV GUIDANCE NUMBERS IN MOST
AREAS. HAVE ADJUSTED GOING HIGH TEMPERATURES ACCORDINGLY.
OTHERWISE...LITTLE ELSE WAS CHANGED IN THE FORECAST.

CUTTER

&&

.AVIATION...

AREA OF STRATUS IS BEGINNING TO SHRINK...ALTHOUGH SOME COLD AIR CU
IS STARTING TO DEVELOP OVER TAF SITES. OCCASIONAL FLURRIES ARE NOT
OUT OF THE QUESTION THIS AFTERNOON...HOWEVER CHANCES DO NOT SEEM
WORTHY OF INCLUDING AT THIS POINT...AS THE AFFECTS OF THE SHORTWAVE
ALOFT CONTINUES TO MOVE SOUTHEAST. SKIES ARE EXPECTED TO CLEAR BY
EARLY EVENING. LIGHT NORTHERLY WINDS WILL GRADUALLY TURN WESTERLY
THEN SOUTHWESTERLY BY MIDNIGHT.

NRR

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 201137
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
537 AM CST TUE JAN 20 2009

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

FORECAST DILEMMAS THIS MORNING ARE FOCUSED MAINLY ON TEMPERATURES
OVER THE NEXT FEW DAYS. STRONG NORTHERLY WINDS WITHIN THE AMPLIFIED
PATTERN ACROSS THE CONUS HAS BROUGHT SOME ABUNDANT CLOUD COVER TO
THE REGION OVERNIGHT BEHIND A SHORTWAVE THAT MOVED SOUTH THROUGH THE
REGION YESTERDAY. COLD AIR ADVECTION WITHIN THE CLOUD LAYER HAS
MANAGED TO SQUEEZE SOME FLURRIES OUT ACROSS THE REGION DURING THE
EARLY MORNING HOURS...WITH SOME FREEZING DRIZZLE ALSO MIXED IN WHERE
THE MOISTURE WAS SALLOW ENOUGH TO NOT REACH THE PREFERRED DENDRITIC
GROWTH ZONE.

FOR TODAY...A COLD NORTH TO NORTH NORTHWEST WIND WILL PREVAIL
THROUGH THE FIRST HALF OF THE DAY WITH THE CLOUD COVER HANGING
TOUGH. EXPECT SOME SCATTERED FLURRIES TO PERSIST THROUGH THE MID
MORNING HOURS AS THE COLD AIR ADVECTION /CAA/ KEEPS GOING.
HOWEVER...MODEL SOUNDINGS INDICATE THAT THE CAA SHOULD STOP AROUND
14Z TO 15Z AS THE SURFACE RIDGE TO OUR NORTH SLIDES SOUTH INTO THE
CWA...BRINGING AN END TO THE FLURRIES. WITH THE CENTER OF THE
SURFACE RIDGE PASSING THROUGH THIS AFTERNOON...WESTERLY WINDS WILL
SPREAD ACROSS THE REGION AS WARM AIR BEGINS TO SLOSH BACK TO THE
EAST. THIS SHOULD SHOVE WHAT CLOUD COVER IS OUT THERE EAST. WITH
SOME SUNSHINE EXPECTED ACROSS THE WESTERN REACHES OF THE FORECAST
AREA...HAVE ADJUST THE GOING TEMPERATURES FOR TODAY TO BE A BLEND OF
THE WARMER MAV AND COOLER MET NUMBERS...ESPECIALLY ACROSS THE
WESTERN REACHES WHERE THERE SHOULD BE LOTS OF SUNSHINE BY MID
AFTERNOON.

FOR WEDNESDAY AND THURSDAY...A GENERAL BROADENING OF THE RIDGE...AS
IT BEGINS TO BREAK DOWN...WILL ALLOW A LOT OF WARM AIR TO SPREAD
EAST. SURFACE WINDS FROM THE SOUTHWEST...AND A DRY NORTHWEST TO WEST
FLOW ALOFT...WILL ALLOW FOR ABUNDANT SUNSHINE. AS A RESULT...
EXPECTATIONS ARE THAT HIGH TEMPERATURES SHOULD BE AT LEAST AS WARM
/IF NOT WARMER/ THAN THE GOING WARM MAV GUIDANCE NUMBERS IN MOST
AREAS. HAVE ADJUSTED GOING HIGH TEMPERATURES ACCORDINGLY.
OTHERWISE...LITTLE ELSE WAS CHANGED IN THE FORECAST.

CUTTER

&&

.AVIATION...

SHALLOW MVFR STRATUS CONTINUES STREAM SOUTHWARD ALONG THE MISSOURI
RIVER AND OVER THE TERMINALS THIS MORNING. RUC SOUNDINGS SHOW
CONTINUED LOW LEVEL INSTABILITY...WHICH HAS SUPPORTED PERSISTENT
LIGHT RADAR ECHOES ALL NIGHT. CLOUD TEMPERATURES REMAIN RIGHT ON THE
CUSP OF CONTAINING ICE NUCLEI...WHICH HAS RESULTED IN PERIODS OF
LIGHT SNOW GRAINS AND OCCASIONAL LIGHT FREEZING DRIZZLE. EXPECT THIS
TREND TO CONTINUE THROUGH THE MORNING...WITH CEILINGS OCCASIONALLY
DROPPING BELOW 2KFT. NO SIGNIFICANT ICING ISSUES ARE EXPECTED DUE TO
THE VERY LIGHT PRECIPITATION AND LARGE DEWPOINT DEPRESSIONS AT THE
SURFACE WHICH SHOULD LEND TO THE SUBLIMATION/EVAPORATION OF MOST
PRECIP.

OTHERWISE...WINDS WILL GRADUALLY DIMINISH THIS MORNING...AND THEN
SLOWLY BACK TOWARD THE WEST BY LATE IN THE DAY. THIS BACKING WILL
PROMOTE A MORE DOWNSLOPE FLOW...ALLOWING SKIES TO CLEAR BY 00Z.
CLEAR SKIES WILL CONTINUE OVERNIGHT...WITH WINDS STEADILY BACKING
INTO THE SOUTH AND RESUMING AN 8-10 KNOT SPEED AFTER 06Z.

BOOKBINDER

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 200935
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
335 AM CST TUE JAN 20 2009


.DISCUSSION...

FORECAST DILEMMAS THIS MORNING ARE FOCUSED MAINLY ON TEMPERATURES
OVER THE NEXT FEW DAYS. STRONG NORTHERLY WINDS WITHIN THE AMPLIFIED
PATTERN ACROSS THE CONUS HAS BROUGHT SOME ABUNDANT CLOUD COVER TO
THE REGION OVERNIGHT BEHIND A SHORTWAVE THAT MOVED SOUTH THROUGH THE
REGION YESTERDAY. COLD AIR ADVECTION WITHIN THE CLOUD LAYER HAS
MANAGED TO SQUEEZE SOME FLURRIES OUT ACROSS THE REGION DURING THE
EARLY MORNING HOURS...WITH SOME FREEZING DRIZZLE ALSO MIXED IN WHERE
THE MOISTURE WAS SALLOW ENOUGH TO NOT REACH THE PREFERRED DENDRITIC
GROWTH ZONE.

FOR TODAY...A COLD NORTH TO NORTH NORTHWEST WIND WILL PREVAIL
THROUGH THE FIRST HALF OF THE DAY WITH THE CLOUD COVER HANGING
TOUGH. EXPECT SOME SCATTERED FLURRIES TO PERSIST THROUGH THE MID
MORNING HOURS AS THE COLD AIR ADVECTION /CAA/ KEEPS GOING.
HOWEVER...MODEL SOUNDINGS INDICATE THAT THE CAA SHOULD STOP AROUND
14Z TO 15Z AS THE SURFACE RIDGE TO OUR NORTH SLIDES SOUTH INTO THE
CWA...BRINGING AN END TO THE FLURRIES. WITH THE CENTER OF THE
SURFACE RIDGE PASSING THROUGH THIS AFTERNOON...WESTERLY WINDS WILL
SPREAD ACROSS THE REGION AS WARM AIR BEGINS TO SLOSH BACK TO THE
EAST. THIS SHOULD SHOVE WHAT CLOUD COVER IS OUT THERE EAST. WITH
SOME SUNSHINE EXPECTED ACROSS THE WESTERN REACHES OF THE FORECAST
AREA...HAVE ADJUST THE GOING TEMPERATURES FOR TODAY TO BE A BLEND OF
THE WARMER MAV AND COOLER MET NUMBERS...ESPECIALLY ACROSS THE
WESTERN REACHES WHERE THERE SHOULD BE LOTS OF SUNSHINE BY MID
AFTERNOON.

FOR WEDNESDAY AND THURSDAY...A GENERAL BROADENING OF THE RIDGE...AS
IT BEGINS TO BREAK DOWN...WILL ALLOW A LOT OF WARM AIR TO SPREAD
EAST. SURFACE WINDS FROM THE SOUTHWEST...AND A DRY NORTHWEST TO WEST
FLOW ALOFT...WILL ALLOW FOR ABUNDANT SUNSHINE. AS A RESULT...
EXPECTATIONS ARE THAT HIGH TEMPERATURES SHOULD BE AT LEAST AS WARM
/IF NOT WARMER/ THAN THE GOING WARM MAV GUIDANCE NUMBERS IN MOST
AREAS. HAVE ADJUSTED GOING HIGH TEMPERATURES ACCORDINGLY.
OTHERWISE...LITTLE ELSE WAS CHANGED IN THE FORECAST.

CUTTER

&&

.AVIATION...

FOR THE 06Z TAFS...AREA OF LIGHT FREEZING DRIZZLE HAS EXPANDED IN
COVERAGE JUST EAST AND SOUTH OF KMCI/KMKC SINCE 04Z. CLOUD
TEMPERATURES HAVE NOT COOLED AS FAST AS EARLIER THOUGHT AND AS SUCH
THEY SUPPORT FREEZING DRIZZLE UNTIL AROUND 09Z. FORTUNATELY THE
PRECIPITATION IS VERY LIGHT AND EXPECT IT TO REMAIN OUT OF THE
TERMINALS. COULD SEE SCATTERED FLURRIES DURING THE PRE-DAWN HOURS.

OTHERWISE...MVFR CEILINGS THROUGH MID MORNING. BY THAT TIME THE
LARGE AREA OF CLEARING OVER EASTERN IA SHOULD BEGIN TO ERODE THE
STRATUS DECK OVER WESTERN MO. THE STIFF NORTHERLY WINDS WILL REMAIN
GUSTY UNTIL JUST BEFORE SUNRISE. WINDS WILL BACK TO THE WEST THEN
SOUTHWEST DURING THE MID TO LATE AFTERNOON HOURS WITH VFR CONDITIONS
FROM 18Z THROUGH THE REST OF THE FORECAST.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 200610
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1210 AM CST TUE JAN 20 2009

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

HAVE MADE A NUMBER OF CHANGES TO THE FORECAST WITH THE MOST NOTABLE
BEING CLOUD COVER. SATELLITE IMAGERY SHOWS EXTENSIVE LOW LEVEL
CLOUDINESS EXTENDING THROUGH MN/IA. 00Z NAM CONDENSATION PRESSURE
DEFICIT PROGS AS WELL AS PROGGED SOUNDINGS INDICATE THE STRATUS WILL
BE WITH US THROUGH THE NIGHT AND FOR MOST IF NOT ALL OF TUESDAY
MORNING. MODERATELY STRONG COLD AIR ADVECTION WILL COMBINE WITH THE
CLOUD COVER TO LIMIT/SLOW DOWN THE WARMING ON TUESDAY. THUS HAVE
LOWERED MAX TEMPERATURES BY SEVERAL DEGREES. IF WE DO NOT START THE
CLEARING IN THE WESTERN CWA BY 00Z IT WILL BE TOUGH TO EVEN REACH
THE UPDATED LOWER MAX TEMPERATURES. INSPECTION OF PROGGED SOUNDINGS
AND UPSTREAM OBSERVATIONS ALSO SUPPORT INCLUDING FLURRIES THROUGH
THE NIGHT.

MJ

&&

.PREV DISCUSSION...
/256 PM CST MON JAN 19 2009/
THE LAST IN THE SERIES OF COLD FRONTS WAS QUICKLY DRIVING SOUTH INTO
XTRM NERN NEB/NWRN IA. A PREFRONTAL TROUGH WAS NOTED AHEAD OF THE
BOUNDARY IN SE NEBRASKA. THIS PREFRONTAL TROUGH MARKS THE LEADING
EDGE OF STRONG NW WINDS. GUSTS TO 30 TO 35 MPH HAVE BEEN RECORDED
BEHIND THE TROUGH AS DEEP MIXING OCCURRING THROUGH ABOUT 800MB. THIS
DEEP MIXED LAYER WILL MOVE INTO NWRN MO EARLY THIS EVE...THEN
PROGRESS RAPIDLY SE THROUGH THE NIGHT. HAVE ONLY MADE MINOR CHANGES
TO WIND GRIDS FOR TNGT. WEAK INSTABILITY THROUGH ABOUT 800 MB IN
COMBINATION WITH WEAK FORCING ASSOCIATED WITH A SHORTWAVE TROUGH IN
IA...SHOULD BE SUFFICIENT TO PRODUCE SCT FLURRIES/SNOW SHOWERS
ACROSS MUCH OF THE CWA TNGT. BEST COVERAGE TO BE IN ERN GRIDS...IN
AN AREA OF DEEPER MOISTURE AND SLIGHTLY BETTER UVV.

COLD AIR MASS IN THE ERN DAKOTAS AND MUCH OF MINNESOTA SIMILAR TO
YESTERDAY WITH FCST LOWS TNGT CLOSELY MATCHING THIS MORNINGS TEMPS.
EARLY MORNING STRATUS/STRATOCU TO QUICKLY DISSIPATE FM WEST TO EAST
AS A SFC RIDGE BUILDS INTO MISSOURI. DEEP SUBSIDENCE WILL ALSO AID IN
THE CLEARING PROCESS.

THE SPEED OF THE EROSION OF CLOUD COVER ALONG WITH THE SPEED OF THE
SFC RIDGE IS ONCE AGAIN CRITICAL FOR AFTN TEMPS ON TUESDAY. GFS IS
FASTER WITH DEVELOPING THE DOWNSLOPE FLOW ACROSS THE NWRN ONE HALF OF
THE CWA. WILL COMPROMISE WITH THE SLOWER NAM. THIS SCENARIO FITS WELL
WITH CURRENT FCST TEMPS WITH ONLY MINOR CHANGES. IF DOWNSLOPE DOES
DEVELOP AS FAST AS THE GFS DEPICTS...TEMPS FOR THE NWRN ONE THIRD OF
THE CWA WILL LIKELY NEED TO BE BUMPED...CLOSER TO THE MAV GUIDANCE.

TOUGH TO DETERMINE HOW MUCH OF A TEMP FALL WILL OCCUR TUESDAY NIGHT.
EVENING DECOUPLING MAY OCCUR BEFORE WINDS INCREASE TOWARD MIDNIGHT.
IN ADDITION...THE SPEED OF A SFC TROUGH ALSO VARIES BETWEEN THE NAM
AND GFS WHICH WILL HAVE A MAJOR ROLE IN TEMPS.

WAS TEMPTED TO GO FOR WARMER TEMPS ON WEDNESDAY...BUT MIXING IS
RATHER WEAK...WHICH WILL MAKE IT DIFFICULT TO REALIZE THE FULL
POTENTIAL OF STG WARMING ABOVE THE BOUNDARY LAYER.

DB

MEDIUM RANGE (THURSDAY-MONDAY)...

MEDIUM RANGE MODELS CONTINUE TO HAVE DIFFICULTY RESOLVING THE
PATTERN EVOLUTION OVER THE EAST PACIFIC BASIN AND WRN CONUS THROUGH
THE PERIOD. PARADE OF ENERGETIC WAVES AND STRONG JET STREAM ACROSS
THE CNTRL PACIFIC ARE ALREADY BEGINNING TO INFLUENCE THE PINCHING OF
THE HIGH AMPLITUDE WRN CONUS RIDGE. EVENTUAL RETROGRESSION OF THE
RIDGING TOWARDS 140W-150W WITH THE MAINTENANCE OF NEGATIVE HEIGHT
ANOMALIES OVER HUDSON BAY TELECONNECTS WELL WITH ENERGY DIVING SOUTH
OFF THE CALIFORNIA COAST...AND BECOMING DISCONNECTED FROM THE NRN
STREAM FLOW. ALL MEDIUM RANGE MODELS INDICATE THIS TYPE OF
PATTERN...HOWEVER DISPLAY SIGNIFICANT DISAGREEMENT ON WHETHER THE
CUTOFF TROUGH RETROGRADES SWWD UNDER THE EAST PACIFIC RIDGE...OR IN
PART GETS PICKED UP BY ENERGY DIVING SOUTH FROM BRITISH COLUMBIA
OVER THE WEEKEND. OPERATIONAL MODELS AND ENSEMBLES ARE ESSENTIALLY
SPLIT ON THE POSSIBLE ARRAY OF SOLUTIONS...WITH THE 12Z GFS AND 00Z
ECMWF IN GENERAL AGREEMENT THAT THE BRITISH COLUMBIA WAVE WILL
LARGELY BYPASS CALIFORNIA CUTOFF (OR AT LEAST PICK UP AND SHEAR ONLY
PART OF THE ENERGY INTO THE JET ALOFT). CAN ENVISION EITHER OF THESE
TWO SCENARIOS OCCURRING...BUT WILL HEDGE TOWARDS A BLEND OF THE 00Z
ECMWF AND 12Z GEFS AS A COMPROMISE...THUS KEEPING SOME MEASURE OF
FORECAST CONTINUITY.

EARLY IN THE PERIOD...MODELS HAVE COME INTO AGREEMENT THAT PRIMARY
FRONTAL BOUNDARY WILL BE DELAYED UNTIL THURSDAY EVENING...ALLOWING
ONE MORE DAY OF EARLY SPRINGLIKE TEMPERATURES...AND HAVE PUSHED HIGH
TEMPS TOWARDS THE UPPER END OF ENSEMBLE GUIDANCE. IT STILL APPEARS
THAT THE MAJORITY OF POST FRONTAL CAA WILL LAG THE WIND SHIFT...WITH
TRAJECTORIES ACTUALLY TAKING THE CORE OF THE COLDEST LOW LEVEL
AIRMASS INTO THE UPPER MIDWEST AND GREAT LAKES. HOWEVER...MEX
GUIDANCE APPEARED A BIT TOO WARM INITIALLY...AND TOOK A BLEND
TOWARDS THE LOWER END OF ENSEMBLE GUIDANCE FRIDAY...GRADUALLY MOVING
TOWARDS AN ENSEMBLE MEAN ON SUNDAY...RESULTING IN A FORECAST OF NEAR
TO JUST BELOW AVERAGE TEMPERATURES FOR FRIDAY THROUGH SUNDAY.

SAW NO JUSTIFIABLE REASON TO INTRODUCE POPS FOR ANY PARTICULAR TIME
PERIOD GIVEN THE OVERALL PATTERN UNCERTAINTY. THERE DOES APPEAR TO
BE SOME SMALL SUPPORT FOR FLURRY ACTIVITY SOMETIME IN THE POST
FRONTAL REGIME FRIDAY OR SATURDAY...THOUGH AGAIN PINPOINTING AN
EXACT TIME FOR AN ESSENTIALLY NON-MEASURABLE EVENT IS FRUITLESS AT
THIS TIME. OVERALL PATTERN LOOKS QUITE FAVORABLE FOR AN UPSLOPE HIGH
PLAINS/EAST SLOPES OF THE ROCKIES EVENT...AND THINK THE 12Z
OPERATIONAL GFS IS FAR TOO AGGRESSIVE IN BRINGING HIGHER QPF EWD
AWAY FROM THE ARCING BAROCLINIC ZONE THROUGH THE WEEKEND.
CERTAINLY...AS SOME MEASURE OF ENERGY EJECTS ACROSS THE SRN HIGH
PLAINS BY EARLY NEXT WEEK...SOME AREA OF WAA LIGHT WINTER WEATHER
COULD BE EXPECTED...THOUGH TIMING AND POSITIONING UNCERTAINTY
PRECLUDES ANY WEATHER MENTION AS OF YET. IT SHOULD BE NOTED THAT THE
LATEST 12Z ECMWF DOES DEPICT A REALISTIC VERSION OF BOTH THE UPPER
AIR FEATURES AND LOW LEVEL BAROCLINIC ZONE MONDAY...PLACING THE AREA
IN A ZONE OF FZRA/SN TRANSITION. STILL PLENTY OF TIME TO FINE TUNE
DETAILS...THOUGH BASIC PATTERN RECOGNITION SUGGESTS HIGHER POPS WILL
BE NEEDED IN FUTURE FORECASTS.

21

&&

.AVIATION...

FOR THE 06Z TAFS...AREA OF LIGHT FREEZING DRIZZLE HAS EXPANDED IN
COVERAGE JUST EAST AND SOUTH OF KMCI/KMKC SINCE 04Z. CLOUD
TEMPERATURES HAVE NOT COOLED AS FAST AS EARLIER THOUGHT AND AS SUCH
THEY SUPPORT FREEZING DRIZZLE UNTIL AROUND 09Z. FORTUNATELY THE
PRECIPITATION IS VERY LIGHT AND EXPECT IT TO REMAIN OUT OF THE
TERMINALS. COULD SEE SCATTERED FLURRIES DURING THE PRE-DAWN HOURS.

OTHERWISE...MVFR CEILINGS THROUGH MID MORNING. BY THAT TIME THE
LARGE AREA OF CLEARING OVER EASTERN IA SHOULD BEGIN TO ERODE THE
STRATUS DECK OVER WESTERN MO. THE STIFF NORTHERLY WINDS WILL REMAIN
GUSTY UNTIL JUST BEFORE SUNRISE. WINDS WILL BACK TO THE WEST THEN
SOUTHWEST DURING THE MID TO LATE AFTERNOON HOURS WITH VFR CONDITIONS
FROM 18Z THROUGH THE REST OF THE FORECAST.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 200239
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
839 PM CST MON JAN 19 2009

.DISCUSSION...

HAVE MADE A NUMBER OF CHANGES TO THE FORECAST WITH THE MOST NOTABLE
BEING CLOUD COVER. SATELLITE IMAGERY SHOWS EXTENSIVE LOW LEVEL
CLOUDINESS EXTENDING THROUGH MN/IA. 00Z NAM CONDENSATION PRESSURE
DEFICIT PROGS AS WELL AS PROGGED SOUNDINGS INDICATE THE STRATUS WILL
BE WITH US THROUGH THE NIGHT AND FOR MOST IF NOT ALL OF TUESDAY
MORNING. MODERATELY STRONG COLD AIR ADVECTION WILL COMBINE WITH THE
CLOUD COVER TO LIMIT/SLOW DOWN THE WARMING ON TUESDAY. THUS HAVE
LOWERED MAX TEMPERATURES BY SEVERAL DEGREES. IF WE DO NOT START THE
CLEARING IN THE WESTERN CWA BY 00Z IT WILL BE TOUGH TO EVEN REACH
THE UPDATED LOWER MAX TEMPERATURES. INSPECTION OF PROGGED SOUNDINGS
AND UPSTREAM OBSERVATIONS ALSO SUPPORT INCLUDING FLURRIES THROUGH
THE NIGHT.

MJ

&&

.PREV DISCUSSION...
/256 PM CST MON JAN 19 2009/
THE LAST IN THE SERIES OF COLD FRONTS WAS QUICKLY DRIVING SOUTH INTO
XTRM NERN NEB/NWRN IA. A PREFRONTAL TROUGH WAS NOTED AHEAD OF THE
BOUNDARY IN SE NEBRASKA. THIS PREFRONTAL TROUGH MARKS THE LEADING
EDGE OF STRONG NW WINDS. GUSTS TO 30 TO 35 MPH HAVE BEEN RECORDED
BEHIND THE TROUGH AS DEEP MIXING OCCURRING THROUGH ABOUT 800MB. THIS
DEEP MIXED LAYER WILL MOVE INTO NWRN MO EARLY THIS EVE...THEN
PROGRESS RAPIDLY SE THROUGH THE NIGHT. HAVE ONLY MADE MINOR CHANGES
TO WIND GRIDS FOR TNGT. WEAK INSTABILITY THROUGH ABOUT 800 MB IN
COMBINATION WITH WEAK FORCING ASSOCIATED WITH A SHORTWAVE TROUGH IN
IA...SHOULD BE SUFFICIENT TO PRODUCE SCT FLURRIES/SNOW SHOWERS
ACROSS MUCH OF THE CWA TNGT. BEST COVERAGE TO BE IN ERN GRIDS...IN
AN AREA OF DEEPER MOISTURE AND SLIGHTLY BETTER UVV.

COLD AIR MASS IN THE ERN DAKOTAS AND MUCH OF MINNESOTA SIMILAR TO
YESTERDAY WITH FCST LOWS TNGT CLOSELY MATCHING THIS MORNINGS TEMPS.
EARLY MORNING STRATUS/STRATOCU TO QUICKLY DISSIPATE FM WEST TO EAST
AS A SFC RIDGE BUILDS INTO MISSOURI. DEEP SUBSIDENCE WILL ALSO AID IN
THE CLEARING PROCESS.

THE SPEED OF THE EROSION OF CLOUD COVER ALONG WITH THE SPEED OF THE
SFC RIDGE IS ONCE AGAIN CRITICAL FOR AFTN TEMPS ON TUESDAY. GFS IS
FASTER WITH DEVELOPING THE DOWNSLOPE FLOW ACROSS THE NWRN ONE HALF OF
THE CWA. WILL COMPROMISE WITH THE SLOWER NAM. THIS SCENARIO FITS WELL
WITH CURRENT FCST TEMPS WITH ONLY MINOR CHANGES. IF DOWNSLOPE DOES
DEVELOP AS FAST AS THE GFS DEPICTS...TEMPS FOR THE NWRN ONE THIRD OF
THE CWA WILL LIKELY NEED TO BE BUMPED...CLOSER TO THE MAV GUIDANCE.

TOUGH TO DETERMINE HOW MUCH OF A TEMP FALL WILL OCCUR TUESDAY NIGHT.
EVENING DECOUPLING MAY OCCUR BEFORE WINDS INCREASE TOWARD MIDNIGHT.
IN ADDITION...THE SPEED OF A SFC TROUGH ALSO VARIES BETWEEN THE NAM
AND GFS WHICH WILL HAVE A MAJOR ROLE IN TEMPS.

WAS TEMPTED TO GO FOR WARMER TEMPS ON WEDNESDAY...BUT MIXING IS
RATHER WEAK...WHICH WILL MAKE IT DIFFICULT TO REALIZE THE FULL
POTENTIAL OF STG WARMING ABOVE THE BOUNDARY LAYER.

DB

MEDIUM RANGE (THURSDAY-MONDAY)...

MEDIUM RANGE MODELS CONTINUE TO HAVE DIFFICULTY RESOLVING THE
PATTERN EVOLUTION OVER THE EAST PACIFIC BASIN AND WRN CONUS THROUGH
THE PERIOD. PARADE OF ENERGETIC WAVES AND STRONG JET STREAM ACROSS
THE CNTRL PACIFIC ARE ALREADY BEGINNING TO INFLUENCE THE PINCHING OF
THE HIGH AMPLITUDE WRN CONUS RIDGE. EVENTUAL RETROGRESSION OF THE
RIDGING TOWARDS 140W-150W WITH THE MAINTENANCE OF NEGATIVE HEIGHT
ANOMALIES OVER HUDSON BAY TELECONNECTS WELL WITH ENERGY DIVING SOUTH
OFF THE CALIFORNIA COAST...AND BECOMING DISCONNECTED FROM THE NRN
STREAM FLOW. ALL MEDIUM RANGE MODELS INDICATE THIS TYPE OF
PATTERN...HOWEVER DISPLAY SIGNIFICANT DISAGREEMENT ON WHETHER THE
CUTOFF TROUGH RETROGRADES SWWD UNDER THE EAST PACIFIC RIDGE...OR IN
PART GETS PICKED UP BY ENERGY DIVING SOUTH FROM BRITISH COLUMBIA
OVER THE WEEKEND. OPERATIONAL MODELS AND ENSEMBLES ARE ESSENTIALLY
SPLIT ON THE POSSIBLE ARRAY OF SOLUTIONS...WITH THE 12Z GFS AND 00Z
ECMWF IN GENERAL AGREEMENT THAT THE BRITISH COLUMBIA WAVE WILL
LARGELY BYPASS CALIFORNIA CUTOFF (OR AT LEAST PICK UP AND SHEAR ONLY
PART OF THE ENERGY INTO THE JET ALOFT). CAN ENVISION EITHER OF THESE
TWO SCENARIOS OCCURRING...BUT WILL HEDGE TOWARDS A BLEND OF THE 00Z
ECMWF AND 12Z GEFS AS A COMPROMISE...THUS KEEPING SOME MEASURE OF
FORECAST CONTINUITY.

EARLY IN THE PERIOD...MODELS HAVE COME INTO AGREEMENT THAT PRIMARY
FRONTAL BOUNDARY WILL BE DELAYED UNTIL THURSDAY EVENING...ALLOWING
ONE MORE DAY OF EARLY SPRINGLIKE TEMPERATURES...AND HAVE PUSHED HIGH
TEMPS TOWARDS THE UPPER END OF ENSEMBLE GUIDANCE. IT STILL APPEARS
THAT THE MAJORITY OF POST FRONTAL CAA WILL LAG THE WIND SHIFT...WITH
TRAJECTORIES ACTUALLY TAKING THE CORE OF THE COLDEST LOW LEVEL
AIRMASS INTO THE UPPER MIDWEST AND GREAT LAKES. HOWEVER...MEX
GUIDANCE APPEARED A BIT TOO WARM INITIALLY...AND TOOK A BLEND
TOWARDS THE LOWER END OF ENSEMBLE GUIDANCE FRIDAY...GRADUALLY MOVING
TOWARDS AN ENSEMBLE MEAN ON SUNDAY...RESULTING IN A FORECAST OF NEAR
TO JUST BELOW AVERAGE TEMPERATURES FOR FRIDAY THROUGH SUNDAY.

SAW NO JUSTIFIABLE REASON TO INTRODUCE POPS FOR ANY PARTICULAR TIME
PERIOD GIVEN THE OVERALL PATTERN UNCERTAINTY. THERE DOES APPEAR TO
BE SOME SMALL SUPPORT FOR FLURRY ACTIVITY SOMETIME IN THE POST
FRONTAL REGIME FRIDAY OR SATURDAY...THOUGH AGAIN PINPOINTING AN
EXACT TIME FOR AN ESSENTIALLY NON-MEASURABLE EVENT IS FRUITLESS AT
THIS TIME. OVERALL PATTERN LOOKS QUITE FAVORABLE FOR AN UPSLOPE HIGH
PLAINS/EAST SLOPES OF THE ROCKIES EVENT...AND THINK THE 12Z
OPERATIONAL GFS IS FAR TOO AGGRESSIVE IN BRINGING HIGHER QPF EWD
AWAY FROM THE ARCING BAROCLINIC ZONE THROUGH THE WEEKEND.
CERTAINLY...AS SOME MEASURE OF ENERGY EJECTS ACROSS THE SRN HIGH
PLAINS BY EARLY NEXT WEEK...SOME AREA OF WAA LIGHT WINTER WEATHER
COULD BE EXPECTED...THOUGH TIMING AND POSITIONING UNCERTAINTY
PRECLUDES ANY WEATHER MENTION AS OF YET. IT SHOULD BE NOTED THAT THE
LATEST 12Z ECMWF DOES DEPICT A REALISTIC VERSION OF BOTH THE UPPER
AIR FEATURES AND LOW LEVEL BAROCLINIC ZONE MONDAY...PLACING THE AREA
IN A ZONE OF FZRA/SN TRANSITION. STILL PLENTY OF TIME TO FINE TUNE
DETAILS...THOUGH BASIC PATTERN RECOGNITION SUGGESTS HIGHER POPS WILL
BE NEEDED IN FUTURE FORECASTS.

21

&&

.AVIATION...

FOR THE 00Z TAFS...MVFR CEILINGS HAVE RETURNED TO THE TERMINALS AND
WILL REMAIN THROUGH THE NIGHT AND INTO TUESDAY MORNING. NOTICED A
BAND OF IFR CEILINGS WITH VISIBILITIES AROUND 3SM OVER PARTS OF SW
AND WEST CENTRAL IA WITH SPOTTY REPORTS OF -FZDZ. WILL BE KEEPING A
CLOSE EYE ON NW MO EARLY THIS EVENING TO SEE IF THIS WEATHER
TRANSFERS SOUTHWARD AS THE TRAJECTORIES SUGGEST. CONFIDENCE
CURRENTLY LACKING TO INCLUDE IFR CEILINGS BUT CANNOT RULE OUT THAT
AMENDMENTS MAY BE NEEDED LATER THIS EVENING. THIS WEATHER OCCURRING
ON THE MESOSCALE AND AS SUCH THE 12Z/18Z MODELS WERE NOT ABLE TO
MODEL THIS. WILL BE WATCHING TO SEE IF THE 00Z RUNS PICK UP ON THIS.

OTHERWISE...TIGHTENING SURFACE PRESSURE GRADIENT OVER NE WILL PUSH
SOUTHEAST THIS EVENING WITH STRONG/GUSTY NORTHERLY WINDS FOR THE
BETTER PART OF THIS EVENING BUT NOT ARRIVING UNTIL 02Z/03Z. WINDS
WILL DIMINISH SIGNIFICANTLY AROUND SUNRISE. WILL LIKELY SEE MVFR
CEILINGS UNTIL MID AFTERNOON WHEN WINDS VEER TO THE WEST AND ENTRAIN
DRIER AIR INTO THE SUB CLOUD LAYER WHICH WILL THEN SCOUR OUT THE
STRATUS.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 192348
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
547 PM CST MON JAN 19 2009

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...
/256 PM CST MON JAN 19 2009/
THE LAST IN THE SERIES OF COLD FRONTS WAS QUICKLY DRIVING SOUTH INTO
XTRM NERN NEB/NWRN IA. A PREFRONTAL TROUGH WAS NOTED AHEAD OF THE
BOUNDARY IN SE NEBRASKA. THIS PREFRONTAL TROUGH MARKS THE LEADING
EDGE OF STRONG NW WINDS. GUSTS TO 30 TO 35 MPH HAVE BEEN RECORDED
BEHIND THE TROUGH AS DEEP MIXING OCCURRING THROUGH ABOUT 800MB. THIS
DEEP MIXED LAYER WILL MOVE INTO NWRN MO EARLY THIS EVE...THEN
PROGRESS RAPIDLY SE THROUGH THE NIGHT. HAVE ONLY MADE MINOR CHANGES
TO WIND GRIDS FOR TNGT. WEAK INSTABILITY THROUGH ABOUT 800 MB IN
COMBINATION WITH WEAK FORCING ASSOCIATED WITH A SHORTWAVE TROUGH IN
IA...SHOULD BE SUFFICIENT TO PRODUCE SCT FLURRIES/SNOW SHOWERS
ACROSS MUCH OF THE CWA TNGT. BEST COVERAGE TO BE IN ERN GRIDS...IN
AN AREA OF DEEPER MOISTURE AND SLIGHTLY BETTER UVV.

COLD AIR MASS IN THE ERN DAKOTAS AND MUCH OF MINNESOTA SIMILAR TO
YESTERDAY WITH FCST LOWS TNGT CLOSELY MATCHING THIS MORNINGS TEMPS.
EARLY MORNING STRATUS/STRATOCU TO QUICKLY DISSIPATE FM WEST TO EAST
AS A SFC RIDGE BUILDS INTO MISSOURI. DEEP SUBSIDENCE WILL ALSO AID IN
THE CLEARING PROCESS.

THE SPEED OF THE EROSION OF CLOUD COVER ALONG WITH THE SPEED OF THE
SFC RIDGE IS ONCE AGAIN CRITICAL FOR AFTN TEMPS ON TUESDAY. GFS IS
FASTER WITH DEVELOPING THE DOWNSLOPE FLOW ACROSS THE NWRN ONE HALF OF
THE CWA. WILL COMPROMISE WITH THE SLOWER NAM. THIS SCENARIO FITS WELL
WITH CURRENT FCST TEMPS WITH ONLY MINOR CHANGES. IF DOWNSLOPE DOES
DEVELOP AS FAST AS THE GFS DEPICTS...TEMPS FOR THE NWRN ONE THIRD OF
THE CWA WILL LIKELY NEED TO BE BUMPED...CLOSER TO THE MAV GUIDANCE.

TOUGH TO DETERMINE HOW MUCH OF A TEMP FALL WILL OCCUR TUESDAY NIGHT.
EVENING DECOUPLING MAY OCCUR BEFORE WINDS INCREASE TOWARD MIDNIGHT.
IN ADDITION...THE SPEED OF A SFC TROUGH ALSO VARIES BETWEEN THE NAM
AND GFS WHICH WILL HAVE A MAJOR ROLE IN TEMPS.

WAS TEMPTED TO GO FOR WARMER TEMPS ON WEDNESDAY...BUT MIXING IS
RATHER WEAK...WHICH WILL MAKE IT DIFFICULT TO REALIZE THE FULL
POTENTIAL OF STG WARMING ABOVE THE BOUNDARY LAYER.

DB

MEDIUM RANGE (THURSDAY-MONDAY)...

MEDIUM RANGE MODELS CONTINUE TO HAVE DIFFICULTY RESOLVING THE
PATTERN EVOLUTION OVER THE EAST PACIFIC BASIN AND WRN CONUS THROUGH
THE PERIOD. PARADE OF ENERGETIC WAVES AND STRONG JET STREAM ACROSS
THE CNTRL PACIFIC ARE ALREADY BEGINNING TO INFLUENCE THE PINCHING OF
THE HIGH AMPLITUDE WRN CONUS RIDGE. EVENTUAL RETROGRESSION OF THE
RIDGING TOWARDS 140W-150W WITH THE MAINTENANCE OF NEGATIVE HEIGHT
ANOMALIES OVER HUDSON BAY TELECONNECTS WELL WITH ENERGY DIVING SOUTH
OFF THE CALIFORNIA COAST...AND BECOMING DISCONNECTED FROM THE NRN
STREAM FLOW. ALL MEDIUM RANGE MODELS INDICATE THIS TYPE OF
PATTERN...HOWEVER DISPLAY SIGNIFICANT DISAGREEMENT ON WHETHER THE
CUTOFF TROUGH RETROGRADES SWWD UNDER THE EAST PACIFIC RIDGE...OR IN
PART GETS PICKED UP BY ENERGY DIVING SOUTH FROM BRITISH COLUMBIA
OVER THE WEEKEND. OPERATIONAL MODELS AND ENSEMBLES ARE ESSENTIALLY
SPLIT ON THE POSSIBLE ARRAY OF SOLUTIONS...WITH THE 12Z GFS AND 00Z
ECMWF IN GENERAL AGREEMENT THAT THE BRITISH COLUMBIA WAVE WILL
LARGELY BYPASS CALIFORNIA CUTOFF (OR AT LEAST PICK UP AND SHEAR ONLY
PART OF THE ENERGY INTO THE JET ALOFT). CAN ENVISION EITHER OF THESE
TWO SCENARIOS OCCURRING...BUT WILL HEDGE TOWARDS A BLEND OF THE 00Z
ECMWF AND 12Z GEFS AS A COMPROMISE...THUS KEEPING SOME MEASURE OF
FORECAST CONTINUITY.

EARLY IN THE PERIOD...MODELS HAVE COME INTO AGREEMENT THAT PRIMARY
FRONTAL BOUNDARY WILL BE DELAYED UNTIL THURSDAY EVENING...ALLOWING
ONE MORE DAY OF EARLY SPRINGLIKE TEMPERATURES...AND HAVE PUSHED HIGH
TEMPS TOWARDS THE UPPER END OF ENSEMBLE GUIDANCE. IT STILL APPEARS
THAT THE MAJORITY OF POST FRONTAL CAA WILL LAG THE WIND SHIFT...WITH
TRAJECTORIES ACTUALLY TAKING THE CORE OF THE COLDEST LOW LEVEL
AIRMASS INTO THE UPPER MIDWEST AND GREAT LAKES. HOWEVER...MEX
GUIDANCE APPEARED A BIT TOO WARM INITIALLY...AND TOOK A BLEND
TOWARDS THE LOWER END OF ENSEMBLE GUIDANCE FRIDAY...GRADUALLY MOVING
TOWARDS AN ENSEMBLE MEAN ON SUNDAY...RESULTING IN A FORECAST OF NEAR
TO JUST BELOW AVERAGE TEMPERATURES FOR FRIDAY THROUGH SUNDAY.

SAW NO JUSTIFIABLE REASON TO INTRODUCE POPS FOR ANY PARTICULAR TIME
PERIOD GIVEN THE OVERALL PATTERN UNCERTAINTY. THERE DOES APPEAR TO
BE SOME SMALL SUPPORT FOR FLURRY ACTIVITY SOMETIME IN THE POST
FRONTAL REGIME FRIDAY OR SATURDAY...THOUGH AGAIN PINPOINTING AN
EXACT TIME FOR AN ESSENTIALLY NON-MEASURABLE EVENT IS FRUITLESS AT
THIS TIME. OVERALL PATTERN LOOKS QUITE FAVORABLE FOR AN UPSLOPE HIGH
PLAINS/EAST SLOPES OF THE ROCKIES EVENT...AND THINK THE 12Z
OPERATIONAL GFS IS FAR TOO AGGRESSIVE IN BRINGING HIGHER QPF EWD
AWAY FROM THE ARCING BAROCLINIC ZONE THROUGH THE WEEKEND.
CERTAINLY...AS SOME MEASURE OF ENERGY EJECTS ACROSS THE SRN HIGH
PLAINS BY EARLY NEXT WEEK...SOME AREA OF WAA LIGHT WINTER WEATHER
COULD BE EXPECTED...THOUGH TIMING AND POSITIONING UNCERTAINTY
PRECLUDES ANY WEATHER MENTION AS OF YET. IT SHOULD BE NOTED THAT THE
LATEST 12Z ECMWF DOES DEPICT A REALISTIC VERSION OF BOTH THE UPPER
AIR FEATURES AND LOW LEVEL BAROCLINIC ZONE MONDAY...PLACING THE AREA
IN A ZONE OF FZRA/SN TRANSITION. STILL PLENTY OF TIME TO FINE TUNE
DETAILS...THOUGH BASIC PATTERN RECOGNITION SUGGESTS HIGHER POPS WILL
BE NEEDED IN FUTURE FORECASTS.

21

&&

.AVIATION...

FOR THE 00Z TAFS...MVFR CEILINGS HAVE RETURNED TO THE TERMINALS AND
WILL REMAIN THROUGH THE NIGHT AND INTO TUESDAY MORNING. NOTICED A
BAND OF IFR CEILINGS WITH VISIBILITIES AROUND 3SM OVER PARTS OF SW
AND WEST CENTRAL IA WITH SPOTTY REPORTS OF -FZDZ. WILL BE KEEPING A
CLOSE EYE ON NW MO EARLY THIS EVENING TO SEE IF THIS WEATHER
TRANSFERS SOUTHWARD AS THE TRAJECTORIES SUGGEST. CONFIDENCE
CURRENTLY LACKING TO INCLUDE IFR CEILINGS BUT CANNOT RULE OUT THAT
AMENDMENTS MAY BE NEEDED LATER THIS EVENING. THIS WEATHER OCCURRING
ON THE MESOSCALE AND AS SUCH THE 12Z/18Z MODELS WERE NOT ABLE TO
MODEL THIS. WILL BE WATCHING TO SEE IF THE 00Z RUNS PICK UP ON THIS.

OTHERWISE...TIGHTENING SURFACE PRESSURE GRADIENT OVER NE WILL PUSH
SOUTHEAST THIS EVENING WITH STRONG/GUSTY NORTHERLY WINDS FOR THE
BETTER PART OF THIS EVENING BUT NOT ARRIVING UNTIL 02Z/03Z. WINDS
WILL DIMINISH SIGNIFICANTLY AROUND SUNRISE. WILL LIKELY SEE MVFR
CEILINGS UNTIL MID AFTERNOON WHEN WINDS VEER TO THE WEST AND ENTRAIN
DRIER AIR INTO THE SUB CLOUD LAYER WHICH WILL THEN SCOUR OUT THE
STRATUS.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 192056
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
256 PM CST MON JAN 19 2009


.DISCUSSION...

THE LAST IN THE SERIES OF COLD FRONTS WAS QUICKLY DRIVING SOUTH INTO XTRM
NERN NEB/NWRN IA. A PREFRONTAL TROUGH WAS NOTED AHEAD OF THE BOUNDARY
IN SE NEBRASKA. THIS PREFRONTAL TROUGH MARKS THE LEADING EDGE OF
STRONG NW WINDS. GUSTS TO 30 TO 35 MPH HAVE BEEN RECORDED BEHIND THE
TROUGH AS DEEP MIXING OCCURRING THROUGH ABOUT 800MB. THIS DEEP MIXED
LAYER WILL MOVE INTO NWRN MO EARLY THIS EVE...THEN PROGRESS RAPIDLY
SE THROUGH THE NIGHT. HAVE ONLY MADE MINOR CHANGES TO WIND GRIDS FOR
TNGT. WEAK INSTABILITY THROUGH ABOUT 800 MB IN COMBINATION WITH WEAK
FORCING ASSOCIATED WITH A SHORTWAVE TROUGH IN IA...SHOULD BE
SUFFICIENT TO PRODUCE SCT FLURRIES/SNOW SHOWERS ACROSS MUCH OF THE
CWA TNGT. BEST COVERAGE TO BE IN ERN GRIDS...IN AN AREA OF DEEPER
MOISTURE AND SLIGHTLY BETTER UVV.

COLD AIR MASS IN THE ERN DAKOTAS AND MUCH OF MINNESOTA SIMILAR TO
YESTERDAY WITH FCST LOWS TNGT CLOSELY MATCHING THIS MORNINGS TEMPS.
EARLY MORNING STRATUS/STRATOCU TO QUICKLY DISSIPATE FM WEST TO EAST
AS A SFC RIDGE BUILDS INTO MISSOURI. DEEP SUBSIDENCE WILL ALSO AID IN
THE CLEARING PROCESS.

THE SPEED OF THE EROSION OF CLOUD COVER ALONG WITH THE SPEED OF THE
SFC RIDGE IS ONCE AGAIN CRITICAL FOR AFTN TEMPS ON TUESDAY. GFS IS
FASTER WITH DEVELOPING THE DOWNSLOPE FLOW ACROSS THE NWRN ONE HALF OF
THE CWA. WILL COMPROMISE WITH THE SLOWER NAM. THIS SCENARIO FITS WELL
WITH CURRENT FCST TEMPS WITH ONLY MINOR CHANGES. IF DOWNSLOPE DOES
DEVELOP AS FAST AS THE GFS DEPICTS...TEMPS FOR THE NWRN ONE THIRD OF
THE CWA WILL LIKELY NEED TO BE BUMPED...CLOSER TO THE MAV GUIDANCE.

TOUGH TO DETERMINE HOW MUCH OF A TEMP FALL WILL OCCUR TUESDAY NIGHT.
EVENING DECOUPLING MAY OCCUR BEFORE WINDS INCREASE TOWARD MIDNIGHT.
IN ADDITION...THE SPEED OF A SFC TROUGH ALSO VARIES BETWEEN THE NAM
AND GFS WHICH WILL HAVE A MAJOR ROLE IN TEMPS.

WAS TEMPTED TO GO FOR WARMER TEMPS ON WEDNESDAY...BUT MIXING IS
RATHER WEAK...WHICH WILL MAKE IT DIFFICULT TO REALIZE THE FULL
POTENTIAL OF STG WARMING ABOVE THE BOUNDARY LAYER.

DB

MEDIUM RANGE (THURSDAY-MONDAY)...

MEDIUM RANGE MODELS CONTINUE TO HAVE DIFFICULTY RESOLVING THE
PATTERN EVOLUTION OVER THE EAST PACIFIC BASIN AND WRN CONUS THROUGH
THE PERIOD. PARADE OF ENERGETIC WAVES AND STRONG JET STREAM ACROSS
THE CNTRL PACIFIC ARE ALREADY BEGINNING TO INFLUENCE THE PINCHING OF
THE HIGH AMPLITUDE WRN CONUS RIDGE. EVENTUAL RETROGRESSION OF THE
RIDGING TOWARDS 140W-150W WITH THE MAINTENANCE OF NEGATIVE HEIGHT
ANOMALIES OVER HUDSON BAY TELECONNECTS WELL WITH ENERGY DIVING SOUTH
OFF THE CALIFORNIA COAST...AND BECOMING DISCONNECTED FROM THE NRN
STREAM FLOW. ALL MEDIUM RANGE MODELS INDICATE THIS TYPE OF
PATTERN...HOWEVER DISPLAY SIGNIFICANT DISAGREEMENT ON WHETHER THE
CUTOFF TROUGH RETROGRADES SWWD UNDER THE EAST PACIFIC RIDGE...OR IN
PART GETS PICKED UP BY ENERGY DIVING SOUTH FROM BRITISH COLUMBIA
OVER THE WEEKEND. OPERATIONAL MODELS AND ENSEMBLES ARE ESSENTIALLY
SPLIT ON THE POSSIBLE ARRAY OF SOLUTIONS...WITH THE 12Z GFS AND 00Z
ECMWF IN GENERAL AGREEMENT THAT THE BRITISH COLUMBIA WAVE WILL
LARGELY BYPASS CALIFORNIA CUTOFF (OR AT LEAST PICK UP AND SHEAR ONLY
PART OF THE ENERGY INTO THE JET ALOFT). CAN ENVISION EITHER OF THESE
TWO SCENARIOS OCCURRING...BUT WILL HEDGE TOWARDS A BLEND OF THE 00Z
ECMWF AND 12Z GEFS AS A COMPROMISE...THUS KEEPING SOME MEASURE OF
FORECAST CONTINUITY.

EARLY IN THE PERIOD...MODELS HAVE COME INTO AGREEMENT THAT PRIMARY
FRONTAL BOUNDARY WILL BE DELAYED UNTIL THURSDAY EVENING...ALLOWING
ONE MORE DAY OF EARLY SPRINGLIKE TEMPERATURES...AND HAVE PUSHED HIGH
TEMPS TOWARDS THE UPPER END OF ENSEMBLE GUIDANCE. IT STILL APPEARS
THAT THE MAJORITY OF POST FRONTAL CAA WILL LAG THE WIND SHIFT...WITH
TRAJECTORIES ACTUALLY TAKING THE CORE OF THE COLDEST LOW LEVEL
AIRMASS INTO THE UPPER MIDWEST AND GREAT LAKES. HOWEVER...MEX
GUIDANCE APPEARED A BIT TOO WARM INITIALLY...AND TOOK A BLEND
TOWARDS THE LOWER END OF ENSEMBLE GUIDANCE FRIDAY...GRADUALLY MOVING
TOWARDS AN ENSEMBLE MEAN ON SUNDAY...RESULTING IN A FORECAST OF NEAR
TO JUST BELOW AVERAGE TEMPERATURES FOR FRIDAY THROUGH SUNDAY.

SAW NO JUSTIFIABLE REASON TO INTRODUCE POPS FOR ANY PARTICULAR TIME
PERIOD GIVEN THE OVERALL PATTERN UNCERTAINTY. THERE DOES APPEAR TO
BE SOME SMALL SUPPORT FOR FLURRY ACTIVITY SOMETIME IN THE POST
FRONTAL REGIME FRIDAY OR SATURDAY...THOUGH AGAIN PINPOINTING AN
EXACT TIME FOR AN ESSENTIALLY NON-MEASURABLE EVENT IS FRUITLESS AT
THIS TIME. OVERALL PATTERN LOOKS QUITE FAVORABLE FOR AN UPSLOPE HIGH
PLAINS/EAST SLOPES OF THE ROCKIES EVENT...AND THINK THE 12Z
OPERATIONAL GFS IS FAR TOO AGGRESSIVE IN BRINGING HIGHER QPF EWD
AWAY FROM THE ARCING BAROCLINIC ZONE THROUGH THE WEEKEND.
CERTAINLY...AS SOME MEASURE OF ENERGY EJECTS ACROSS THE SRN HIGH
PLAINS BY EARLY NEXT WEEK...SOME AREA OF WAA LIGHT WINTER WEATHER
COULD BE EXPECTED...THOUGH TIMING AND POSITIONING UNCERTAINTY
PRECLUDES ANY WEATHER MENTION AS OF YET. IT SHOULD BE NOTED THAT THE
LATEST 12Z ECMWF DOES DEPICT A REALISTIC VERSION OF BOTH THE UPPER
AIR FEATURES AND LOW LEVEL BAROCLINIC ZONE MONDAY...PLACING THE AREA
IN A ZONE OF FZRA/SN TRANSITION. STILL PLENTY OF TIME TO FINE TUNE
DETAILS...THOUGH BASIC PATTERN RECOGNITION SUGGESTS HIGHER POPS WILL
BE NEEDED IN FUTURE FORECASTS.

21

&&

.AVIATION...

FOR THE 18Z TAFS...SKIES HAVE CLEARED AT ALL THE TERMINALS LATE THIS
MORNING WITH A NARROWING RIBBON OF MVFR CIGS FM SERN NEB INTO NERN
KS. THIS AREA OF CLOUD CVR WILL LIKELY CONTINUE TO DISSIPATE DUE TO
INSOLATION AND DOWNSLOPE DRYING. HOWEVER...IT IS NOT OUT OF THE
QUESTION THAT THERE MAY BE AN HOUR OR TWO OF MVFR CIGS AT KSTJ THIS AFTN.

NEXT CONCERN IS THE NEXT COLD FRONT TO ENTER THE TERMINALS THIS
EVENING. STG AND GUSTY NORTH WINDS WILL FOLLOW THE PASSAGE OF THE
BOUNDARY WITH WINDS SLOWLY DIMINISHING THROUGH THE NIGHT. MVFR
STRATUS DECK ALREADY IN PLACE ACROSS THE ERN DAKOTAS LATE THIS
MORNING WILL INVADE THE TERMINALS TONIGHT. CURRENT CIG HEIGHTS IN
THE DAKOTAS ARE A GOOD COMPROMISE WITH GFS AND NAM GUIDANCE. CIGS TO
GRADUALLY RISE TUESDAY MORNING AS THE SFC RIDGE BUILDS INTO MO.

DB

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 191732
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1132 AM CST MON JAN 19 2009

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

/321 AM CST MON JAN 19 2009/
THE FIRST OF TWO BACKDOOR FRONTS HAS ACCELERATED INTO NORTHERN
ARKANSAS EARLY THIS MORNING...WITH GUSTY NORTH WINDS CONTINUING
ALONG THE MO/KS BORDER. TEMPERATURE FALL HAS BEEN RETARDED BY THE
EXISTING STRATUS CANOPY...BUT AS SKIES BEGIN TO CLEAR FROM THE NORTH
AFTER 10Z...A MORE PRECIPITOUS TEMPERATURE DROP IS EXPECTED ACROSS
NORTHERN MO BEFORE DAYBREAK.

LOW LEVEL WINDS HAVING FINALLY VEERED TO THE DUE NORTH...AND EVEN
NNE IN A FEW OBS...THUS CONFIRMING THAT LOW LEVEL COLD ADVECTION
WILL DOMINATE THROUGH THE NEXT 48 HOURS. IN FACT...RECENT ANALYSIS
SUGGESTS THAT THE DIURNAL EASTWARD PUSH OF CHINOOK FLOW EMANATING
FROM THE ROCKIES UPPER RIDGE WILL LIKELY ARRIVE TOO LATE AND MEET A
CONFLUENCE TOO FAR WEST TO PENETRATE INTO THE CWA TODAY. THUS KEPT
HIGHS ACROSS THE ENTIRE CWA IN THE 30S TODAY...AND IT IS POSSIBLE
THAT NE ZONES MAY NOT ESCAPE THE UPPER 20S DUE TO SNOWPACK EFFECTS.

A SECONDARY FRONTAL SURGE WILL ARRIVE THIS EVENING...ACCOMPANIED BY
LOW CLOUDS AND ANOTHER ROUND OF SNOW SHOWERS. FORCING IS A BIT MORE
ROBUST WITH THIS SHORTWAVE AND ASSOCIATED JETLET...ENOUGH TO WARRANT
30-40% CHANCES OF MEASURABLE PRECIPITATION IN THE FORM OF A DUSTING
TO A FEW TENTHS OF AN INCH. MUCH LIKE THIS PAST EVENING...THE VERY
TIGHT VORTICITY GRADIENT ALOFT WILL TRANSLATE TO A TIGHT
POST-FRONTAL SURFACE PRESSURE GRADIENT WITH WEAK STATIC STABILITY.
THIS WILL PROMOTE HIGHER THAN EXPECTED GUSTS OF 30 TO 40 MPH
ACCOMPANYING THE STRONGER SURFACE FLOW THAT WILL OVERSPREAD ERN KS
AND FAR WRN MO BETWEEN 02 AND 06Z.

925MB TEMPS WILL HOVER IN THE -6 TO -10C RANGE THROUGH THE DAY
TUESDAY AS HIGH PRESSURE BUILDS SOUTHWEST OF THE REGION. DESPITE
CLEARING SKIES...HIGHS WILL STRUGGLE TO REACH THE MID-UPPER 20S OVER
NE MO...AND THE MID 30S ALONG THE KS BORDER.

A TURN TO MORE WESTERLY SURFACE FLOW WILL OCCUR TUESDAY NIGHT AS THE
WESTERN RIDGE BEGINS ITS EXPECTED RAPID BREAKDOWN. RISING
TEMPERATURES TUESDAY NIGHT LOOK LIKELY...ALTHOUGH THE EXTENT TO
WHICH THIS WARMUP CONTINUES INTO THE DAY WEDNESDAY WILL BE LIKELY
RESTRICTED BY ONE FINAL LOW LEVEL TROUGH THAT WILL RETAIN THE MOST
AGGRESSIVE DOWNSLOPE ACROSS THE PLAINS. WILL ERR ON THE SIDE OF
OPTIMISM WITH TEMPS REACHING THE 50S OVER THE SWRN QUADRANT OF THE
FORECAST AREA.

BOOKBINDER

&&

.AVIATION...

FOR THE 18Z TAFS...SKIES HAVE CLEARED AT ALL THE TERMINALS LATE THIS
MORNING WITH A NARROWING RIBBON OF MVFR CIGS FM SERN NEB INTO NERN
KS. THIS AREA OF CLOUD CVR WILL LIKELY CONTINUE TO DISSIPATE DUE TO
INSOLATION AND DOWNSLOPE DRYING. HOWEVER...IT IS NOT OUT OF THE
QUESTION THAT THERE MAY BE AN HOUR OR TWO OF MVFR CIGS AT KSTJ THIS AFTN.

NEXT CONCERN IS THE NEXT COLD FRONT TO ENTER THE TERMINALS THIS
EVENING. STG AND GUSTY NORTH WINDS WILL FOLLOW THE PASSAGE OF THE
BOUNDARY WITH WINDS SLOWLY DIMINISHING THROUGH THE NIGHT. MVFR
STRATUS DECK ALREADY IN PLACE ACROSS THE ERN DAKOTAS LATE THIS
MORNING WILL INVADE THE TERMINALS TONIGHT. CURRENT CIG HEIGHTS IN
THE DAKOTAS ARE A GOOD COMPROMISE WITH GFS AND NAM GUIDANCE. CIGS TO
GRADUALLY RISE TUESDAY MORNING AS THE SFC RIDGE BUILDS INTO MO.

DB

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 190922
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
321 AM CST MON JAN 19 2009

.DISCUSSION...

THE FIRST OF TWO BACKDOOR FRONTS HAS ACCELERATED INTO NORTHERN
ARKANSAS EARLY THIS MORNING...WITH GUSTY NORTH WINDS CONTINUING
ALONG THE MO/KS BORDER. TEMPERATURE FALL HAS BEEN RETARDED BY THE
EXISTING STRATUS CANOPY...BUT AS SKIES BEGIN TO CLEAR FROM THE NORTH
AFTER 10Z...A MORE PRECIPITOUS TEMPERATURE DROP IS EXPECTED ACROSS
NORTHERN MO BEFORE DAYBREAK.

LOW LEVEL WINDS HAVING FINALLY VEERED TO THE DUE NORTH...AND EVEN
NNE IN A FEW OBS...THUS CONFIRMING THAT LOW LEVEL COLD ADVECTION
WILL DOMINATE THROUGH THE NEXT 48 HOURS. IN FACT...RECENT ANALYSIS
SUGGESTS THAT THE DIURNAL EASTWARD PUSH OF CHINOOK FLOW EMANATING
FROM THE ROCKIES UPPER RIDGE WILL LIKELY ARRIVE TOO LATE AND MEET A
CONFLUENCE TOO FAR WEST TO PENETRATE INTO THE CWA TODAY. THUS KEPT
HIGHS ACROSS THE ENTIRE CWA IN THE 30S TODAY...AND IT IS POSSIBLE
THAT NE ZONES MAY NOT ESCAPE THE UPPER 20S DUE TO SNOWPACK EFFECTS.

A SECONDARY FRONTAL SURGE WILL ARRIVE THIS EVENING...ACCOMPANIED BY
LOW CLOUDS AND ANOTHER ROUND OF SNOW SHOWERS. FORCING IS A BIT MORE
ROBUST WITH THIS SHORTWAVE AND ASSOCIATED JETLET...ENOUGH TO WARRANT
30-40% CHANCES OF MEASURABLE PRECIPITATION IN THE FORM OF A DUSTING
TO A FEW TENTHS OF AN INCH. MUCH LIKE THIS PAST EVENING...THE VERY
TIGHT VORTICITY GRADIENT ALOFT WILL TRANSLATE TO A TIGHT
POST-FRONTAL SURFACE PRESSURE GRADIENT WITH WEAK STATIC STABILITY.
THIS WILL PROMOTE HIGHER THAN EXPECTED GUSTS OF 30 TO 40 MPH
ACCOMPANYING THE STRONGER SURFACE FLOW THAT WILL OVERSPREAD ERN KS
AND FAR WRN MO BETWEEN 02 AND 06Z.

925MB TEMPS WILL HOVER IN THE -6 TO -10C RANGE THROUGH THE DAY
TUESDAY AS HIGH PRESSURE BUILDS SOUTHWEST OF THE REGION. DESPITE
CLEARING SKIES...HIGHS WILL STRUGGLE TO REACH THE MID-UPPER 20S OVER
NE MO...AND THE MID 30S ALONG THE KS BORDER.

A TURN TO MORE WESTERLY SURFACE FLOW WILL OCCUR TUESDAY NIGHT AS THE
WESTERN RIDGE BEGINS ITS EXPECTED RAPID BREAKDOWN. RISING
TEMPERATURES TUESDAY NIGHT LOOK LIKELY...ALTHOUGH THE EXTENT TO
WHICH THIS WARMUP CONTINUES INTO THE DAY WEDNESDAY WILL BE LIKELY
RESTRICTED BY ONE FINAL LOW LEVEL TROUGH THAT WILL RETAIN THE MOST
AGGRESSIVE DOWNSLOPE ACROSS THE PLAINS. WILL ERR ON THE SIDE OF
OPTIMISM WITH TEMPS REACHING THE 50S OVER THE SWRN QUADRANT OF THE
FORECAST AREA.

BOOKBINDER

&&

.AVIATION...

FOR THE 06Z TAFS...MVFR CEILINGS AND BRISK/GUSTY NNW WINDS WILL
CONTINUE THROUGH THE PRE-DAWN HOURS AT ALL 3 TERMINALS. TIME OF
ARRIVAL TOOL AND SATELLITE IMAGERY SUGGEST THESE CEILINGS WILL
SCATTER OUT BY 12Z WITH THE WINDS DIMINISHING TO LESS THAN 10KTS AS
WELL. THEN EXPECT VFR CONDITIONS FOR MOST OF THE DAYLIGHT HOURS.
HOWEVER...ANOTHER FAST MOVING CLIPPER TYPE SYSTEM WILL DIVE
SOUTHWARD THROUGH IA TOMORROW. AN ASSOCIATED COLD FRONT WILL
ACCOMPANY THIS FEATURE WITH ANOTHER SURGE OF MVFR CEILINGS AND GUSTY
NORTHERLY WINDS. WENT CONSERVATIVE WITH WINDS MONDAY EVENING AND
THINK THERE IS A GROWING CONCERN THAT LATER FORECASTS WILL NEED TO
BEEF UP THE SPEEDS. THERE IS ALSO THE THREAT OF SCATTERED SNOW
SHOWERS BUT COVERAGE AND CONFIDENCE IN OCCURRENCE NOT HIGH ENOUGH
YET TO INSERT IN FORECAST.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 190545
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1145 PM CST SUN JAN 18 2009

...UPDATED AVIATION DISCUSSION...

.SHORT TERM...

LITTLE HAS CHANGED THE LAST COUPLE OF DAYS WITH THE HIGHLY AMPLIFIED
RIDGE IN THE WRN CONUS. SHORTWAVES EMBEDDED IN THE MERIDIONAL
NORTHERLY FLOW ALOFT CONTINUE TO PROGRESS RAPIDLY SOUTH THROUGH THE
PLAINS AND UPR MISS VALLEY...PLAYING HAVOC ON TEMPERATURE FCST IN
THE CWA. WIND SHIFTS ACCOMPANYING EACH WAVE WILL TEMPORARILY CUTOFF
DOWNSLOPE WARMING WITH A MORE NORTHERLY TRAJECTORY OVER THE SNOW
FIELDS. MODELS HAVE RECENTLY BEEN TOO BULLISH WITH THE COOLING AFTER
EACH WIND SHIFT WITH THE PERIODS OF DOWNSLOPE WINDS PROVIDING WARMER
TEMPS FURTHER EAST THAN THE MODELS INDICATE. AS A RESULT...MODELS
HAVE BEEN DEPICTING A STRATUS AND STRATOCU FIELD CONSIDERABLY TOO
FAR WEST. OVERALL...GFS HAS BEEN SUPERIOR IN FORECASTING
TEMPERATURES THE LAST COUPLE OF DAYS...RELATIVE TO THE NAM AND FWC
GUIDANCE. HOWEVER...EVEN THE GFS HAS BEEN TOO COLD.

FIRST CONCERN...IS THE ELONGATED UPPER SHORTWAVE TROUGH IN THE WRN
GREAT LAKES AND UPR MISS VALLEY. WINDS HAVE VEERED IN THE ERN DAKOTAS
AND MINNESOTA WITH COOLER TEMPS SPREADING SOUTH TOWARD NRN IOWA AND
NERN NEB. TEMPERATURES ARE NOT ESPECIALLY COLD WITH READINGS MAINLY
IN THE 20S IN MINNESOTA. GIVEN THE INCREASE IN MID AND HIGH CLOUD
COVER TNGT...ALONG WITH AT 10 TO 15 KNOT WINDS...PREFER TO GO ABOVE
GUIDANCE FOR OVERNIGHT MINS TONIGHT.

ANOTHER PROBLEM WILL ONCE AGAIN BE THE SWWD EXTENT OF POST FRONTAL
STRATUS AND STRATOCU TNGT. MODELS ARE ALREADY TOO FAR SOUTH AND WEST
WITH THE LOW CLOUD SHIELD TO OUR NORTH. REGARDLESS...LOW CLOUD DECK
WILL LIKELY INVADE AT LEAST THE ERN CWA AFT MIDNIGHT...PSBLY
EXTENDING AS FAR WEST AS THE MO/KS STATE LINE. OTHERWISE...DEPTH OF
MOISTURE IN THE ERN GRIDS MAY BE SUFFICIENT TO TRIGGER A FEW
FLURRIES OVER THE ERN GRIDS AS THE SHORTWAVE BRUSHES ERN MO TNGT.

WINDS BEHIND TO BACK TO A LIGHT DOWNSLOPE WIND ON MONDAY...IN ADVANCE
OF THE NEXT SHORTWAVE TO TARGET NE MO MONDAY NIGHT. THIS WILL LIKELY
ERODE THE WRN EDGE OF THE LOW CLOUD DECK...FOR THE WRN CWA...BY
MONDAY AFTN. HAVE BOOSTED TEMPS FOR THE WRN CWA ON MONDAY...BUT WOULD
NOT BE SURPRISED IF THEY HAVE TO BE RAISED AGAIN.

THE TRACK OF THE SHORTWAVE TROUGH MONDAY NIGHT IS A LITTLE MORE WEST
THAN PREVIOUS MODELS...WHICH WILL PROVIDE A LITTLE BETTER
OPPORTUNITY FOR SNOW FLURRIES OR VERY LIGHT SNOW FOR THE XTRM ERN CWA
MONDAY NIGHT. HAVE RAISED POPS A LITTLE...BUT REGARDLESS ANY
ACCUMULATION WILL BE QUITE LIGHT.

THE NEXT IN THE SERIES OF WIND SHIFTS WILL ACCOMPANY THE SHORTWAVE
MONDAY NIGHT. THE LOW CLOUD DECK WILL ONCE AGAIN WORK WEST...BUT
ERODE FM THE WEST ON TUESDAY AS DOWNSLOPE WARMING WILL ONCE AGAIN
MAINLY AFFECT THE WRN GRIDS. TEMPS ARE TRICKY...BUT GIVEN RECENT
HISTORY...HAVE TO LEAN TOWARD WARMER THAN GUIDANCE TEMPS.

DB

MEDIUM RANGE (WEDNESDAY-SUNDAY)...

MEDIUM RANGE MODELS CONTINUE TO ADVERTISE THE GRADUAL BREAKDOWN OF
THE CURRENT LONGWAVE HIGH AMPLITUDE POSITIVE PNA PATTERN OVER THE
WRN HEMISPHERE...HOWEVER ALSO CONTINUE TO STRUGGLE WITH THE DETAILS
OF SMALLER SHORTWAVES IN THE PACIFIC BASIN WHICH PROGRESSIVELY
UNDERCUT THE WRN CONUS RIDGE AXIS. ANALYSIS OF NRN HEMISPHERE WV/IR
SATELLITE IMAGERY CLEARLY SHOW THE CULPRITS EXTENDING ACROSS THE ERN
HEMISPHERE...IN THE FORM OF NUMEROUS TRANSIENT SHORTER WAVELENGTH
FEATURES ALONG WITH SEVERAL POLEWARD ORIENTED SUBTROPICAL FEEDS INTO
THE MIDLATITUDE JET STREAM. REGARDLESS...ALL MEDIUM RANGE MODELS
SUITES INDICATE DESTRUCTIVE INTERFERENCE OF THE WRN RIDGE...WITH THE
TYPICAL NWWD RETROGRESSION OF THE RIDGE PEAK...AND A DAMPENED SELY
PROPAGATION TO THE RIDGE BASE WITH WEAK ENERGY PACKETS LOWERING
HEIGHTS IN BETWEEN. RECENT OPERATIONAL GFS RUNS HAVE ACTUALLY
DISPLAYED SOME CONSISTENCY...AND HAVE BOTH SUPPORT FROM ENSEMBLE
GUIDANCE...AS WELL AS CONCEPTUAL MODELS SUGGESTING REESTABLISHMENT
OF RIDGING NEAR 140W-150W WITH MAINTENANCE OF LOWER HEIGHTS OVER
HUDSON BAY...AND POSITIVELY TILTED TYPE TROUGHING FROM THE NRN
PLAINS TO THE SWRN CONUS. THIS PATTERN CONFIGURATION WOULD LEAD TO
INCREASED SFC PRESSURE RISES OVER NRN CANADA AND THE NRN ROCKIES
FORCING FRONTAL BOUNDARIES SOUTH OF THE CWA...WITH WEAK SHORTWAVES
QUICKLY TRAVERSING SOUTH OF THE REGION IN MORE OF A SPLIT FLOW
PATTERN.

MOST FAVORABLE PERIOD OF DOWNSLOPE PREFRONTAL WARMING LOOKS TO OCCUR
ON WEDNESDAY WITH LOW LEVEL BOUNDARY ESSENTIALLY WASHING OUT OVER
MISSOURI. WITH MIDLEVEL HEIGHTS JUST BEGINNING TO RAPIDLY
INCREASE...FAIRLY STEEP THICKNESS (AND HENCE TEMPERATURE) GRADIENT
SHOULD EXIST...LEADING TO LARGER UNCERTAINTY IN HIGH TEMPERATURE
FORECASTS. HAVE PUSHED SLIGHTLY ABOVE MEX GUIDANCE...BUT NOT QUITE
AS WARM AS THE HIGHEST ENSEMBLE GUIDANCE...THOUGH CERTAINLY WRN
LOCATIONS COULD EXPERIENCE HIGHS ABOVE ALL ENSEMBLE GUIDANCE. A MORE
DEFINED FRONTAL BOUNDARY WILL PUSH THROUGH THE AREA THURSDAY
AFTERNOON...THOUGH TRAILING CAA APPEARS TO LAG THE FRONT
SIGNIFICANTLY...ALLOWING MODEST WARMING EVEN WITH NLY WINDS. THE
REMAINDER OF THE MEDIUM RANGE WILL BE CHARACTERIZED BY DOMINATING
CANADIAN SFC HIGH PRESSURE...WITH LOW LEVEL THICKNESSES INDICATING
TEMPERATURES AT OR SLIGHTLY BELOW AVERAGE. PUSHED FORECAST TOWARDS
THE LOWER END OF ENSEMBLE GUIDANCE IN THIS RESPECT.

HAVE NOT INTRODUCED ANY PRECIPITATION MENTION THROUGH THE MEDIUM
RANGE PERIOD...AS MODEL DISPARITY PRECLUDES ATTEMPTING TO TIME ANY
WEAK WAVE AND DEEPER ATMOSPHERIC SATURATION. IN FACT...AT SOME POINT
IN THE POST FRONTAL REGIME BETWEEN FRIDAY AND SUNDAY...FLURRIES OR
VERY LIGHT SNOW WOULD NOT BE UNEXPECTED...THOUGH PINPOINTING EXACTLY
WHEN THIS WOULD OCCUR IS ESSENTIALLY FRUITLESS AT THIS POINT.

21

&&

.AVIATION...

FOR THE 06Z TAFS...MVFR CEILINGS AND BRISK/GUSTY NNW WINDS WILL
CONTINUE THROUGH THE PRE-DAWN HOURS AT ALL 3 TERMINALS. TIME OF
ARRIVAL TOOL AND SATELLITE IMAGERY SUGGEST THESE CEILINGS WILL
SCATTER OUT BY 12Z WITH THE WINDS DIMINISHING TO LESS THAN 10KTS AS
WELL. THEN EXPECT VFR CONDITIONS FOR MOST OF THE DAYLIGHT HOURS.
HOWEVER...ANOTHER FAST MOVING CLIPPER TYPE SYSTEM WILL DIVE
SOUTHWARD THROUGH IA TOMORROW. AN ASSOCIATED COLD FRONT WILL
ACCOMPANY THIS FEATURE WITH ANOTHER SURGE OF MVFR CEILINGS AND GUSTY
NORTHERLY WINDS. WENT CONSERVATIVE WITH WINDS MONDAY EVENING AND
THINK THERE IS A GROWING CONCERN THAT LATER FORECASTS WILL NEED TO
BEEF UP THE SPEEDS. THERE IS ALSO THE THREAT OF SCATTERED SNOW
SHOWERS BUT COVERAGE AND CONFIDENCE IN OCCURRENCE NOT HIGH ENOUGH
YET TO INSERT IN FORECAST.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 182342
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
542 PM CST SUN JAN 18 2009

...UPDATED AVIATION DISCUSSION...

.SHORT TERM...

LITTLE HAS CHANGED THE LAST COUPLE OF DAYS WITH THE HIGHLY AMPLIFIED
RIDGE IN THE WRN CONUS. SHORTWAVES EMBEDDED IN THE MERIDIONAL
NORTHERLY FLOW ALOFT CONTINUE TO PROGRESS RAPIDLY SOUTH THROUGH THE
PLAINS AND UPR MISS VALLEY...PLAYING HAVOC ON TEMPERATURE FCST IN
THE CWA. WIND SHIFTS ACCOMPANYING EACH WAVE WILL TEMPORARILY CUTOFF
DOWNSLOPE WARMING WITH A MORE NORTHERLY TRAJECTORY OVER THE SNOW
FIELDS. MODELS HAVE RECENTLY BEEN TOO BULLISH WITH THE COOLING AFTER
EACH WIND SHIFT WITH THE PERIODS OF DOWNSLOPE WINDS PROVIDING WARMER
TEMPS FURTHER EAST THAN THE MODELS INDICATE. AS A RESULT...MODELS
HAVE BEEN DEPICTING A STRATUS AND STRATOCU FIELD CONSIDERABLY TOO
FAR WEST. OVERALL...GFS HAS BEEN SUPERIOR IN FORECASTING
TEMPERATURES THE LAST COUPLE OF DAYS...RELATIVE TO THE NAM AND FWC
GUIDANCE. HOWEVER...EVEN THE GFS HAS BEEN TOO COLD.

FIRST CONCERN...IS THE ELONGATED UPPER SHORTWAVE TROUGH IN THE WRN
GREAT LAKES AND UPR MISS VALLEY. WINDS HAVE VEERED IN THE ERN DAKOTAS
AND MINNESOTA WITH COOLER TEMPS SPREADING SOUTH TOWARD NRN IOWA AND
NERN NEB. TEMPERATURES ARE NOT ESPECIALLY COLD WITH READINGS MAINLY
IN THE 20S IN MINNESOTA. GIVEN THE INCREASE IN MID AND HIGH CLOUD
COVER TNGT...ALONG WITH AT 10 TO 15 KNOT WINDS...PREFER TO GO ABOVE
GUIDANCE FOR OVERNIGHT MINS TONIGHT.

ANOTHER PROBLEM WILL ONCE AGAIN BE THE SWWD EXTENT OF POST FRONTAL
STRATUS AND STRATOCU TNGT. MODELS ARE ALREADY TOO FAR SOUTH AND WEST
WITH THE LOW CLOUD SHIELD TO OUR NORTH. REGARDLESS...LOW CLOUD DECK
WILL LIKELY INVADE AT LEAST THE ERN CWA AFT MIDNIGHT...PSBLY
EXTENDING AS FAR WEST AS THE MO/KS STATE LINE. OTHERWISE...DEPTH OF
MOISTURE IN THE ERN GRIDS MAY BE SUFFICIENT TO TRIGGER A FEW
FLURRIES OVER THE ERN GRIDS AS THE SHORTWAVE BRUSHES ERN MO TNGT.

WINDS BEHIND TO BACK TO A LIGHT DOWNSLOPE WIND ON MONDAY...IN ADVANCE
OF THE NEXT SHORTWAVE TO TARGET NE MO MONDAY NIGHT. THIS WILL LIKELY
ERODE THE WRN EDGE OF THE LOW CLOUD DECK...FOR THE WRN CWA...BY
MONDAY AFTN. HAVE BOOSTED TEMPS FOR THE WRN CWA ON MONDAY...BUT WOULD
NOT BE SURPRISED IF THEY HAVE TO BE RAISED AGAIN.

THE TRACK OF THE SHORTWAVE TROUGH MONDAY NIGHT IS A LITTLE MORE WEST
THAN PREVIOUS MODELS...WHICH WILL PROVIDE A LITTLE BETTER
OPPORTUNITY FOR SNOW FLURRIES OR VERY LIGHT SNOW FOR THE XTRM ERN CWA
MONDAY NIGHT. HAVE RAISED POPS A LITTLE...BUT REGARDLESS ANY
ACCUMULATION WILL BE QUITE LIGHT.

THE NEXT IN THE SERIES OF WIND SHIFTS WILL ACCOMPANY THE SHORTWAVE
MONDAY NIGHT. THE LOW CLOUD DECK WILL ONCE AGAIN WORK WEST...BUT
ERODE FM THE WEST ON TUESDAY AS DOWNSLOPE WARMING WILL ONCE AGAIN
MAINLY AFFECT THE WRN GRIDS. TEMPS ARE TRICKY...BUT GIVEN RECENT
HISTORY...HAVE TO LEAN TOWARD WARMER THAN GUIDANCE TEMPS.

DB

MEDIUM RANGE (WEDNESDAY-SUNDAY)...

MEDIUM RANGE MODELS CONTINUE TO ADVERTISE THE GRADUAL BREAKDOWN OF
THE CURRENT LONGWAVE HIGH AMPLITUDE POSITIVE PNA PATTERN OVER THE
WRN HEMISPHERE...HOWEVER ALSO CONTINUE TO STRUGGLE WITH THE DETAILS
OF SMALLER SHORTWAVES IN THE PACIFIC BASIN WHICH PROGRESSIVELY
UNDERCUT THE WRN CONUS RIDGE AXIS. ANALYSIS OF NRN HEMISPHERE WV/IR
SATELLITE IMAGERY CLEARLY SHOW THE CULPRITS EXTENDING ACROSS THE ERN
HEMISPHERE...IN THE FORM OF NUMEROUS TRANSIENT SHORTER WAVELENGTH
FEATURES ALONG WITH SEVERAL POLEWARD ORIENTED SUBTROPICAL FEEDS INTO
THE MIDLATITUDE JET STREAM. REGARDLESS...ALL MEDIUM RANGE MODELS
SUITES INDICATE DESTRUCTIVE INTERFERENCE OF THE WRN RIDGE...WITH THE
TYPICAL NWWD RETROGRESSION OF THE RIDGE PEAK...AND A DAMPENED SELY
PROPAGATION TO THE RIDGE BASE WITH WEAK ENERGY PACKETS LOWERING
HEIGHTS IN BETWEEN. RECENT OPERATIONAL GFS RUNS HAVE ACTUALLY
DISPLAYED SOME CONSISTENCY...AND HAVE BOTH SUPPORT FROM ENSEMBLE
GUIDANCE...AS WELL AS CONCEPTUAL MODELS SUGGESTING REESTABLISHMENT
OF RIDGING NEAR 140W-150W WITH MAINTENANCE OF LOWER HEIGHTS OVER
HUDSON BAY...AND POSITIVELY TILTED TYPE TROUGHING FROM THE NRN
PLAINS TO THE SWRN CONUS. THIS PATTERN CONFIGURATION WOULD LEAD TO
INCREASED SFC PRESSURE RISES OVER NRN CANADA AND THE NRN ROCKIES
FORCING FRONTAL BOUNDARIES SOUTH OF THE CWA...WITH WEAK SHORTWAVES
QUICKLY TRAVERSING SOUTH OF THE REGION IN MORE OF A SPLIT FLOW
PATTERN.

MOST FAVORABLE PERIOD OF DOWNSLOPE PREFRONTAL WARMING LOOKS TO OCCUR
ON WEDNESDAY WITH LOW LEVEL BOUNDARY ESSENTIALLY WASHING OUT OVER
MISSOURI. WITH MIDLEVEL HEIGHTS JUST BEGINNING TO RAPIDLY
INCREASE...FAIRLY STEEP THICKNESS (AND HENCE TEMPERATURE) GRADIENT
SHOULD EXIST...LEADING TO LARGER UNCERTAINTY IN HIGH TEMPERATURE
FORECASTS. HAVE PUSHED SLIGHTLY ABOVE MEX GUIDANCE...BUT NOT QUITE
AS WARM AS THE HIGHEST ENSEMBLE GUIDANCE...THOUGH CERTAINLY WRN
LOCATIONS COULD EXPERIENCE HIGHS ABOVE ALL ENSEMBLE GUIDANCE. A MORE
DEFINED FRONTAL BOUNDARY WILL PUSH THROUGH THE AREA THURSDAY
AFTERNOON...THOUGH TRAILING CAA APPEARS TO LAG THE FRONT
SIGNIFICANTLY...ALLOWING MODEST WARMING EVEN WITH NLY WINDS. THE
REMAINDER OF THE MEDIUM RANGE WILL BE CHARACTERIZED BY DOMINATING
CANADIAN SFC HIGH PRESSURE...WITH LOW LEVEL THICKNESSES INDICATING
TEMPERATURES AT OR SLIGHTLY BELOW AVERAGE. PUSHED FORECAST TOWARDS
THE LOWER END OF ENSEMBLE GUIDANCE IN THIS RESPECT.

HAVE NOT INTRODUCED ANY PRECIPITATION MENTION THROUGH THE MEDIUM
RANGE PERIOD...AS MODEL DISPARITY PRECLUDES ATTEMPTING TO TIME ANY
WEAK WAVE AND DEEPER ATMOSPHERIC SATURATION. IN FACT...AT SOME POINT
IN THE POST FRONTAL REGIME BETWEEN FRIDAY AND SUNDAY...FLURRIES OR
VERY LIGHT SNOW WOULD NOT BE UNEXPECTED...THOUGH PINPOINTING EXACTLY
WHEN THIS WOULD OCCUR IS ESSENTIALLY FRUITLESS AT THIS POINT.

21

&&

.AVIATION...

FOR THE 00Z TAFS...WINDSHIFT LINE/SURFACE TROUGH PUSHING THROUGH
NORTHWEST MO ATTM. WINDS WILL VEER TO THE NNW WITH SUSTAINED SPEEDS
IN THE MID TEENS AND GUSTS INTO THE LOW 20S. THIS WILL LAST INTO THE
PRE-DAWN HOURS OF MONDAY MORNING. OTHER CONCERN IS WHETHER OR NOT
MVFR CEILINGS WILL FINALLY MAKE IT INTO THE TERMINALS. FOR THE PAST
SEVERAL DAYS MODELS HAVE BEEN TOO FAR WEST WITH THIS CLOUDINESS.
HOWEVER...UPSTREAM SURFACE OBS SHOW MVFR CEILINGS ABOUT 100 MILES
FURTHER WEST THAN LAST 2 NIGHTS SO GIVEN CURRENT LOW LEVEL
TRAJECTORIES THINK THE NAM/RUC SOLUTIONS LOOK REASONABLE AND WILL
KEEP THE MVFR CEILINGS IN STARTING AROUND MIDNIGHT. DO THINK THIS
CEILING WILL NOT HOLD FOR LONG AND LOOK FOR THEM TO SCATTER OUT
TOWARDS SUNRISE.

LATER MONDAY CONFIDENCE LACKING ON WHETHER LOW CLOUDS WILL RETURN SO
WILL LEAVE THEM OUT FOR NOW AND GO WITH VFR CONDITIONS ALL DAY
MONDAY.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 182109
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
309 PM CST SUN JAN 18 2009

.SHORT TERM...

LITTLE HAS CHANGED THE LAST COUPLE OF DAYS WITH THE HIGHLY AMPLIFIED RIDGE
IN THE WRN CONUS. SHORTWAVES EMBEDDED IN THE MERIDIONAL NORTHERLY
FLOW ALOFT CONTINUE TO PROGRESS RAPIDLY SOUTH THROUGH THE PLAINS AND UPR
MISS VALLEY...PLAYING HAVOC ON TEMPERATURE FCST IN THE CWA. WIND
SHIFTS ACCOMPANYING EACH WAVE WILL TEMPORARILY CUTOFF DOWNSLOPE
WARMING WITH A MORE NORTHERLY TRAJECTORY OVER THE SNOW FIELDS. MODELS
HAVE RECENTLY BEEN TOO BULLISH WITH THE COOLING AFTER EACH WIND SHIFT
WITH THE PERIODS OF DOWNSLOPE WINDS PROVIDING WARMER TEMPS FURTHER
EAST THAN THE MODELS INDICATE. AS A RESULT...MODELS HAVE BEEN
DEPICTING A STRATUS AND STRATOCU FIELD CONSIDERABLY TOO FAR WEST. OVERALL...GFS
HAS BEEN SUPERIOR IN FORECASTING TEMPERATURES THE LAST COUPLE OF
DAYS...RELATIVE TO THE NAM AND FWC GUIDANCE. HOWEVER...EVEN THE GFS
HAS BEEN TOO COLD.

FIRST CONCERN...IS THE ELONGATED UPPER SHORTWAVE TROUGH IN THE WRN
GREAT LAKES AND UPR MISS VALLEY. WINDS HAVE VEERED IN THE ERN DAKOTAS
AND MINNESOTA WITH COOLER TEMPS SPREADING SOUTH TOWARD NRN IOWA AND
NERN NEB. TEMPERATURES ARE NOT ESPECIALLY COLD WITH READINGS MAINLY
IN THE 20S IN MINNESOTA. GIVEN THE INCREASE IN MID AND HIGH CLOUD
COVER TNGT...ALONG WITH AT 10 TO 15 KNOT WINDS...PREFER TO GO ABOVE
GUIDANCE FOR OVERNIGHT MINS TONIGHT.

ANOTHER PROBLEM WILL ONCE AGAIN BE THE SWWD EXTENT OF POST FRONTAL
STRATUS AND STRATOCU TNGT. MODELS ARE ALREADY TOO FAR SOUTH AND WEST
WITH THE LOW CLOUD SHIELD TO OUR NORTH. REGARDLESS...LOW CLOUD DECK WILL LIKELY
INVADE AT LEAST THE ERN CWA AFT MIDNIGHT...PSBLY EXTENDING AS FAR
WEST AS THE MO/KS STATE LINE. OTHERWISE...DEPTH OF MOISTURE IN THE
ERN GRIDS MAY BE SUFFICIENT TO TRIGGER A FEW FLURRIES OVER THE ERN
GRIDS AS THE SHORTWAVE BRUSHES ERN MO TNGT.

WINDS BEHIND TO BACK TO A LIGHT DOWNSLOPE WIND ON MONDAY...IN ADVANCE
OF THE NEXT SHORTWAVE TO TARGET NE MO MONDAY NIGHT. THIS WILL LIKELY
ERODE THE WRN EDGE OF THE LOW CLOUD DECK...FOR THE WRN CWA...BY
MONDAY AFTN. HAVE BOOSTED TEMPS FOR THE WRN CWA ON MONDAY...BUT WOULD
NOT BE SURPRISED IF THEY HAVE TO BE RAISED AGAIN.

THE TRACK OF THE SHORTWAVE TROUGH MONDAY NIGHT IS A LITTLE MORE WEST
THAN PREVIOUS MODELS...WHICH WILL PROVIDE A LITTLE BETTER
OPPORTUNITY FOR SNOW FLURRIES OR VERY LIGHT SNOW FOR THE XTRM ERN CWA
MONDAY NIGHT. HAVE RAISED POPS A LITTLE...BUT REGARDLESS ANY
ACCUMULATION WILL BE QUITE LIGHT.

THE NEXT IN THE SERIES OF WIND SHIFTS WILL ACCOMPANY THE SHORTWAVE
MONDAY NIGHT. THE LOW CLOUD DECK WILL ONCE AGAIN WORK WEST...BUT
ERODE FM THE WEST ON TUESDAY AS DOWNSLOPE WARMING WILL ONCE AGAIN
MAINLY AFFECT THE WRN GRIDS. TEMPS ARE TRICKY...BUT GIVEN RECENT
HISTORY...HAVE TO LEAN TOWARD WARMER THAN GUIDANCE TEMPS.

DB

MEDIUM RANGE (WEDNESDAY-SUNDAY)...

MEDIUM RANGE MODELS CONTINUE TO ADVERTISE THE GRADUAL BREAKDOWN OF
THE CURRENT LONGWAVE HIGH AMPLITUDE POSITIVE PNA PATTERN OVER THE
WRN HEMISPHERE...HOWEVER ALSO CONTINUE TO STRUGGLE WITH THE DETAILS
OF SMALLER SHORTWAVES IN THE PACIFIC BASIN WHICH PROGRESSIVELY
UNDERCUT THE WRN CONUS RIDGE AXIS. ANALYSIS OF NRN HEMISPHERE WV/IR
SATELLITE IMAGERY CLEARLY SHOW THE CULPRITS EXTENDING ACROSS THE ERN
HEMISPHERE...IN THE FORM OF NUMEROUS TRANSIENT SHORTER WAVELENGTH
FEATURES ALONG WITH SEVERAL POLEWARD ORIENTED SUBTROPICAL FEEDS INTO
THE MIDLATITUDE JET STREAM. REGARDLESS...ALL MEDIUM RANGE MODELS
SUITES INDICATE DESTRUCTIVE INTERFERENCE OF THE WRN RIDGE...WITH THE
TYPICAL NWWD RETROGRESSION OF THE RIDGE PEAK...AND A DAMPENED SELY
PROPAGATION TO THE RIDGE BASE WITH WEAK ENERGY PACKETS LOWERING
HEIGHTS IN BETWEEN. RECENT OPERATIONAL GFS RUNS HAVE ACTUALLY
DISPLAYED SOME CONSISTENCY...AND HAVE BOTH SUPPORT FROM ENSEMBLE
GUIDANCE...AS WELL AS CONCEPTUAL MODELS SUGGESTING REESTABLISHMENT
OF RIDGING NEAR 140W-150W WITH MAINTENANCE OF LOWER HEIGHTS OVER
HUDSON BAY...AND POSITIVELY TILTED TYPE TROUGHING FROM THE NRN
PLAINS TO THE SWRN CONUS. THIS PATTERN CONFIGURATION WOULD LEAD TO
INCREASED SFC PRESSURE RISES OVER NRN CANADA AND THE NRN ROCKIES
FORCING FRONTAL BOUNDARIES SOUTH OF THE CWA...WITH WEAK SHORTWAVES
QUICKLY TRAVERSING SOUTH OF THE REGION IN MORE OF A SPLIT FLOW
PATTERN.

MOST FAVORABLE PERIOD OF DOWNSLOPE PREFRONTAL WARMING LOOKS TO OCCUR
ON WEDNESDAY WITH LOW LEVEL BOUNDARY ESSENTIALLY WASHING OUT OVER
MISSOURI. WITH MIDLEVEL HEIGHTS JUST BEGINNING TO RAPIDLY
INCREASE...FAIRLY STEEP THICKNESS (AND HENCE TEMPERATURE) GRADIENT
SHOULD EXIST...LEADING TO LARGER UNCERTAINTY IN HIGH TEMPERATURE
FORECASTS. HAVE PUSHED SLIGHTLY ABOVE MEX GUIDANCE...BUT NOT QUITE
AS WARM AS THE HIGHEST ENSEMBLE GUIDANCE...THOUGH CERTAINLY WRN
LOCATIONS COULD EXPERIENCE HIGHS ABOVE ALL ENSEMBLE GUIDANCE. A MORE
DEFINED FRONTAL BOUNDARY WILL PUSH THROUGH THE AREA THURSDAY
AFTERNOON...THOUGH TRAILING CAA APPEARS TO LAG THE FRONT
SIGNIFICANTLY...ALLOWING MODEST WARMING EVEN WITH NLY WINDS. THE
REMAINDER OF THE MEDIUM RANGE WILL BE CHARACTERIZED BY DOMINATING
CANADIAN SFC HIGH PRESSURE...WITH LOW LEVEL THICKNESSES INDICATING
TEMPERATURES AT OR SLIGHTLY BELOW AVERAGE. PUSHED FORECAST TOWARDS
THE LOWER END OF ENSEMBLE GUIDANCE IN THIS RESPECT.

HAVE NOT INTRODUCED ANY PRECIPITATION MENTION THROUGH THE MEDIUM
RANGE PERIOD...AS MODEL DISPARITY PRECLUDES ATTEMPTING TO TIME ANY
WEAK WAVE AND DEEPER ATMOSPHERIC SATURATION. IN FACT...AT SOME POINT
IN THE POST FRONTAL REGIME BETWEEN FRIDAY AND SUNDAY...FLURRIES OR
VERY LIGHT SNOW WOULD NOT BE UNEXPECTED...THOUGH PINPOINTING EXACTLY
WHEN THIS WOULD OCCUR IS ESSENTIALLY FRUITLESS AT THIS POINT.

21

&&

.AVIATION...

FOR THE 18Z TAFS...DOWNSLOPE WARMING WILL CONTINUE TO MAINTAIN VFR
CONDITIONS THROUGH THIS EVE. MAIN CONCERN IS TOWARD MIDNIGHT WHEN A
CDFNT CURRENTLY IN XTRM NERN SD SHIFTS SOUTH INTO THE TERMINALS TNGT.
MODELS HAVE BEEN TOO PESSIMISTIC WITH THE WWD EXTENT OF THE LOW CLOUD
COVER THE LAST COUPLE OF DAYS AND APPEAR SO AGAIN TODAY. IN ADDITION...MODELS
LOOK TOO QUICK IN SHIFTING THE MVFR/VFR LOW CLOUD DECK INTO THE
TERMINALS THIS EVE... THEREFORE WILL DELAY THE ARRIVAL A FEW HOURS.
CONFIDENCE IN CLOUD DECK HEIGHT IS LACKING WITH CIGS LIKELY VARYING
BTWN 2000-3500 FEET. CLOUD DECK WILL PERSIST THROUGH THE
MORNING...BUT MAY BEGIN TO BREAK TOWARD NOON. OTHERWISE...GUSTY WINDS
THIS AFTERNOON WILL DIMINISH EARLY THIS EVENING WITH THE ONSET OF
NOCTURNAL COOLING.

DB

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 181717
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1117 AM CST SUN JAN 18 2009

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

UPPER LEVEL FLOW PATTERN WILL REACH A CLIMAX TODAY AS OPPOSING
HEIGHT ANOMALIES AMPLIFY OVER THE BITTERROOTS AND EASTERN GREAT
LAKES. AN AMAZING 700 METER 500MB HEIGHT DIFFERENTIAL BETWEEN THESE
FEATURES WILL PLAY OUT OVER THE EASTERN PLAINS AND MISSISSIPPI RIVER
VALLEY OVER THE NEXT 3 DAYS...AS THE LOWER-MID TROPOSPHERIC HEIGHT
GRADIENT TRANSLATES INTO AN EQUALLY IMPRESSIVE TEMPERATURE SPREAD
OVER THE COMING DAYS.

SHORT TERM NUMERICAL GUIDANCE CONTINUES TO SHOW THAT WARMER AIR WILL
CONTINUE TO RESIDE JUST TO OUR WEST THROUGH TUESDAY...AS A SERIES OF
IMPULSES DIVE SOUTHWARD FROM CENTRAL CANADA AND PHASE WITH THE MEAN
EASTERN TROUGH. THIS WILL PUSH A SERIES OF THREE BACKDOOR COLD
FRONTS THROUGH THE REGION OVER THE NEXT 60 HOURS...KEEPING
TEMPERATURES SEASONABLY COLD -- ESPECIALLY OVER THE ERN CWA.
PREVIOUS FORECAST ON TARGET WITH LITTLE CHANGE MADE.

AS IS THE CASE CURRENTLY...EACH OF THESE WAVES WILL LIKELY BE
ACCOMPANIED BY A PASSING BAND OF FLURRIES/LIGHT SNOW SHOWERS...BUT
GENERALLY SPEAKING THE JANUARY DROUGHT WILL PERSIST.

BOOKBINDER

&&

.AVIATION...

FOR THE 18Z TAFS...DOWNSLOPE WARMING WILL CONTINUE TO MAINTAIN VFR
CONDITIONS THROUGH THIS EVE. MAIN CONCERN IS TOWARD MIDNIGHT WHEN A
CDFNT CURRENTLY IN XTRM NERN SD SHIFTS SOUTH INTO THE TERMINALS TNGT.
MODELS HAVE BEEN TOO PESSIMISTIC WITH THE WWD EXTENT OF THE LOW CLOUD
COVER THE LAST COUPLE OF DAYS AND APPEAR SO AGAIN TODAY. IN ADDITION...MODELS
LOOK TOO QUICK IN SHIFTING THE MVFR/VFR LOW CLOUD DECK INTO THE
TERMINALS THIS EVE... THEREFORE WILL DELAY THE ARRIVAL A FEW HOURS.
CONFIDENCE IN CLOUD DECK HEIGHT IS LACKING WITH CIGS LIKELY VARYING
BTWN 2000-3500 FEET. CLOUD DECK WILL PERSIST THROUGH THE
MORNING...BUT MAY BEGIN TO BREAK TOWARD NOON. OTHERWISE...GUSTY WINDS
THIS AFTERNOON WILL DIMINISH EARLY THIS EVENING WITH THE ONSET OF
NOCTURNAL COOLING.

DB

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 181144
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
544 AM CST SUN JAN 18 2009

...UPDATED AVIATION DISCUSSION...


.DISCUSSION...

UPPER LEVEL FLOW PATTERN WILL REACH A CLIMAX TODAY AS OPPOSING
HEIGHT ANOMALIES AMPLIFY OVER THE BITTERROOTS AND EASTERN GREAT
LAKES. AN AMAZING 700 METER 500MB HEIGHT DIFFERENTIAL BETWEEN THESE
FEATURES WILL PLAY OUT OVER THE EASTERN PLAINS AND MISSISSIPPI RIVER
VALLEY OVER THE NEXT 3 DAYS...AS THE LOWER-MID TROPOSPHERIC HEIGHT
GRADIENT TRANSLATES INTO AN EQUALLY IMPRESSIVE TEMPERATURE SPREAD
OVER THE COMING DAYS.

SHORT TERM NUMERICAL GUIDANCE CONTINUES TO SHOW THAT WARMER AIR WILL
CONTINUE TO RESIDE JUST TO OUR WEST THROUGH TUESDAY...AS A SERIES OF
IMPULSES DIVE SOUTHWARD FROM CENTRAL CANADA AND PHASE WITH THE MEAN
EASTERN TROUGH. THIS WILL PUSH A SERIES OF THREE BACKDOOR COLD
FRONTS THROUGH THE REGION OVER THE NEXT 60 HOURS...KEEPING
TEMPERATURES SEASONABLY COLD -- ESPECIALLY OVER THE ERN CWA.
PREVIOUS FORECAST ON TARGET WITH LITTLE CHANGE MADE.

AS IS THE CASE CURRENTLY...EACH OF THESE WAVES WILL LIKELY BE
ACCOMPANIED BY A PASSING BAND OF FLURRIES/LIGHT SNOW SHOWERS...BUT
GENERALLY SPEAKING THE JANUARY DROUGHT WILL PERSIST.

BOOKBINDER

&&

.AVIATION...

FOR THE 12Z TAFS...CLEAR SKIES CURRENTLY DOMINATE THE TERMINALS...
BUT A MVFR DECK OF CLOUDS TO THE NORTH IS MOVING QUICKLY SOUTH. THE
CLOUDS HAVE JUST MOVED SOUTH OF THE IOWA BORDER. CURRENT
EXTRAPOLATION OF THE CLOUD MOVEMENT HAS THE DECK SKIRTING THE
TERMINALS BEGINNING BETWEEN 12Z AND 13Z. WITH THE TERMINALS RIDING
THE EDGE OF THE DECK...HAVE USED A TEMPO GROUP TO COVER THE BKN CIGS
THAT MIGHT RESULT. ONCE CLOUD COVER MOVES INTO THE TERMINALS WILL
NEED TO REASSESS THE NEED TO PUT THE BKN CIGS IN THE PREVAILING
GROUP. CLOUDS SHOULD ADVECT EAST BY THE LATE MORNING HOURS LEAVING
VFR CONDITIONS BEHIND WITH GUSTY NORTHWEST WINDS. OTHERWISE...LOOK
FOR ANOTHER MVFR DECK OF CLOUDS TO MOVE SOUTH INTO THE TERMINALS
AROUND MIDNIGHT.

CUTTER

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.

$$

000
FXUS63 KEAX 180903
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
301 AM CST SUN JAN 18 2009

.DISCUSSION...

UPPER LEVEL FLOW PATTERN WILL REACH A CLIMAX TODAY AS OPPOSING
HEIGHT ANOMALIES AMPLIFY OVER THE BITTERROOTS AND EASTERN GREAT
LAKES. AN AMAZING 700 METER 500MB HEIGHT DIFFERENTIAL BETWEEN THESE
FEATURES WILL PLAY OUT OVER THE EASTERN PLAINS AND MISSISSIPPI RIVER
VALLEY OVER THE NEXT 3 DAYS...AS THE LOWER-MID TROPOSPHERIC HEIGHT
GRADIENT TRANSLATES INTO AN EQUALLY IMPRESSIVE TEMPERATURE SPREAD
OVER THE COMING DAYS.

SHORT TERM NUMERICAL GUIDANCE CONTINUES TO SHOW THAT WARMER AIR WILL
CONTINUE TO RESIDE JUST TO OUR WEST THROUGH TUESDAY...AS A SERIES OF
IMPULSES DIVE SOUTHWARD FROM CENTRAL CANADA AND PHASE WITH THE MEAN
EASTERN TROUGH. THIS WILL PUSH A SERIES OF THREE BACKDOOR COLD
FRONTS THROUGH THE REGION OVER THE NEXT 60 HOURS...KEEPING
TEMPERATURES SEASONABLY COLD -- ESPECIALLY OVER THE ERN CWA.
PREVIOUS FORECAST ON TARGET WITH LITTLE CHANGE MADE.

AS IS THE CASE CURRENTLY...EACH OF THESE WAVES WILL LIKELY BE
ACCOMPANIED BY A PASSING BAND OF FLURRIES/LIGHT SNOW SHOWERS...BUT
GENERALLY SPEAKING THE JANUARY DROUGHT WILL PERSIST.

BOOKBINDER

&&

.AVIATION...

FOR THE 06Z TAFS...WEST EDGE OF SOME MID CLOUDS DROPPING SSE THROUGH
FAR EASTERN NE/NW MO WILL NICK THE TERMINALS BETWEEN 06Z AND 10Z BUT
VFR CONDITIONS WILL PREVAIL. THE BAND OF SNOW OVER WESTERN IA WILL
MISS ALL 3 TAF SITES OVERNIGHT. OTHERWISE...MID TO LATE MORNING
MIXING WILL ONCE AGAIN RESULT IN GUSTY NORTHWEST WINDS FROM LATE
MORNING THROUGH MID AFTERNOON...THEN DECREASE TO LESS THAN 10KTS BY
LATE AFTERNOON. A SECONDARY/BACK DOOR TYPE COLD FRONT WILL MOVE
THROUGH THE TERMINALS AFTER 00Z WITH WINDS VEERING TO THE NORTH.
COLD AIR ADVECTION LOW CLOUDS WITH MVFR CEILINGS MAY SPREAD INTO THE
TAF SITES LATE IN THE FORECAST PERIOD.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.

$$

000
FXUS63 KEAX 180538
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1138 PM CST SAT JAN 17 2009

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

TEMPERATURES CONTINUE TO DEFY GRAVITY AND HAVE GIVEN GROUND
GRUDGINGLY THIS EVENING. ALTHOUGH LOW CLOUD DECK HAS QUICKLY SHIFTED
EAST AND NOW ONLY COVERS PARTS OF THE NORTHEAST CWA THERE IS ANOTHER
BAND OF LAYERED CLOUDS OVER IA AND EXTREME EASTERN NE. THESE ARE
QUICKLY SPREADING SSE AHEAD OF A FAST MOVING VORTICITY CENTER
SHOWING UP ON WATER VAPOR IMAGERY. SO WILL RAISE TEMPERATURES ONCE
MORE BY A FEW DEGREES. REGIONAL RADAR LOOPS ALSO SHOW BANDS OF SNOW
SHOWERS ASSOCIATED WITH THIS VORTICITY MAX. 00Z GFS/RUC QPF/SNOW
ALGORITHMS DO A DECENT JOB WITH THIS SNOW AND TRACK IT ACROSS THE
NORTHEAST CWA. SO RAISED POPS CONSIDERABLY FOR A LIGHT DUSTING THIS
AREA.

MJ

&&

.PREV DISCUSSION...
/748 PM CST SAT JAN 17 2009/
OPTED TO MAKE ADJUSTMENTS TO CLOUDS/TEMPERATURES NOW FOR THE
OVERNIGHT PERIOD RATHER THAN WAIT AS TEMPERATURES UNDER THE LOW
CLOUD DECK HAVE BARELY BUDGED SINCE MID AFTERNOON AND BELIEVE THEY
WILL CONTINUE TO BE SLOW TO FALL. SO WILL RAISE MANY OVERNIGHT LOWS.
NOT OVERLY CONFIDENT ON FLURRIES OCCURRING TONIGHT AS LOW CLOUD DECK
TEMPERATURES ARE PROGGED AROUND -7C WHICH IS TYPICALLY NOT COLD
ENOUGH TO CONTAIN ICE CRYSTALS. MAY STRIP THEM OUT LATER THIS
EVENING AFTER LOOKING AT 00Z NAM.

MJ

&&

.SHORT TERM...
/239 PM CST SAT JAN 17 2009/
HIGHLY AMPLIFIED UPPER FLOW PATTERN WILL CONTINUE THROUGH TUESDAY
WITH THE WRN UPR RIDGE ONLY TO MAKE A VERY SLOW SHIFT TO THE EAST
THROUGH VERY EARLY NEXT WEEK. THE EASTWARD SHIFT OF A LARGE POSITIVE
HEIGHT ANOMALY INTO THE ROCKIES WILL YIELD A COMBINATION OF
COMPRESSIONAL AND CHINOOK WARMING ALONG THE FRONT RANGE INTO THE
CENTRAL PLAINS OF THE US AND CANADA...RESULTING IN A LARGE SCALE
RAPID SNOW MELT FOR THAT REGION. THIS WILL HAVE AN
IMPACT...ESPECIALLY FOR TEMPS IN THE BATTLE ZONE BETWEEN THE WARM
WEST AND THE SNOW COVER TO THE N AND NE.

THE STRONG NORTHERLY UPPER JET WILL DRIVE A SERIES OF FAST MOVING
SHORTWAVES THROUGH THE CWA...POSSIBLY PROVIDING FOR A FEW FLURRIES
TNGT THROUGH MONDAY UNDER A PERSISTENT STRATUS/STRATOCU
LAYER...MAINLY CONFINED TO THE ERN TWO THIRDS OF THE CWA. THE EXACT
POSITION OF THE WRN FRINGE OF THE LOW CLOUD DECK WILL BE CRITICAL IN
TEMP FCSTING THE NEXT FEW DAYS...ESPECIALLY SINCE THE CWA WILL BE IN
A SQUEEZE PLAY BETWEEN THE WARM DOWNSLOPE FLOW AND THE COOL
TRAJECTORIES OVER THE SNOW FIELDS TO THE NORTH.

NAM AND GFS CONTINUE TO PLACE MUCH OF THE CWA UNDER THE LOW CLOUD
DECK WITH THE XTRM WRN CWA IN AND OUT OF THE CLOUD DECK AS LOW LEVEL
TRAJECTORIES WAFFLE BETWEEN WEST AND NNW. PREVIOUS TEMP FCSTS HANDLED
SITUATION RATHER WELL AND SEE NO REASON TO MAKE ANY SIGNIFICANT
CHANGES.

DB

MEDIUM RANGE (TUE-SAT)...

ONLY MINOR ADJUSTMENTS MADE TO THE MEDIUM RANGE PORTIONS OF THE FCST
AS MODELS CONTINUE TO STRUGGLE IN HOW THE CURRENT +PNA PATTERN WILL
BREAKDOWN.  NEEDLESS TO SAY...INDIVIDUAL MODEL SOLNS BEYOND TUESDAY
SHOULD BE TAKEN WITH A LARGE GRAIN OF SALT. IN FACT...LATEST
ENSEMBLES ARE ALSO SHOWING HIGHER THAN NORMAL STANDARD DEVIATIONS BY
WEDNESDAY INDICATIVE OF TYPICAL STRUGGLES INVOLVING A MASSIVE
PATTERN SHIFT.

MUCH OF NEXT WEEK IS GOING TO BE CHARACTERIZED BY A SERIES OF
BATTLES BETWEEN WARM AIR UNDER UPR RIDGE TO OUR WEST...AND SERIES OF
WEAK COLD FRONTS WHICH MAY SPOIL A REALLY GOOD WARMUP FOR THE CWFA.
ON TUESDAY...DIFFERENCES BETWEEN THE GFS/ECMWF ARE EVIDENT IN THE
DEGREE OF THE WESTWARD EXTENSION OF UPR TROUGH OVER THE EASTERN US.
FEEL THAT NEXT UPR S/W WHICH ROTATES SOUTHWARD MONDAY NIGHT WILL
BRING A GOOD AMOUNT OF CLOUD COVER AND COOLER AIR FOR TUESDAY.  THUS
HAVE LOWERED TEMPS OVER THE EASTERN CWA...WHILE ALLOWING WESTERN
PORTIONS OF THE FCST AREA TO SEE A HIGHER PROBABILITY OF TAPPING
INTO A WAA REGIME WHICH SHOULD BEGIN FOR WEDNESDAY.  NEEDLESS TO
SAY...THE EVENTUAL BREAKDOWN OF THE WESTERN RIDGE SHOULD PROVIDE AT
LEAST A DAY OR TWO OF PRETTY NICE WEATHER OF THE CWA BEGINNING ON
WEDNESDAY....WITH A HIGHER LIKELIHOOD OF THE WARMEST READINGS
ARRIVING ON THURSDAY BEFORE MORE SEASONAL AIR ARRIVES ON FRIDAY.  AS
FAR AS PRECIP IS CONCERNED...DRY CONDITIONS CAN BE EXPECTED INTO THE
END OF THE WEEK.

31

&&

.AVIATION...

FOR THE 06Z TAFS...WEST EDGE OF SOME MID CLOUDS DROPPING SSE THROUGH
FAR EASTERN NE/NW MO WILL NICK THE TERMINALS BETWEEN 06Z AND 10Z BUT
VFR CONDITIONS WILL PREVAIL. THE BAND OF SNOW OVER WESTERN IA WILL
MISS ALL 3 TAF SITES OVERNIGHT. OTHERWISE...MID TO LATE MORNING
MIXING WILL ONCE AGAIN RESULT IN GUSTY NORTHWEST WINDS FROM LATE
MORNING THROUGH MID AFTERNOON...THEN DECREASE TO LESS THAN 10KTS BY
LATE AFTERNOON. A SECONDARY/BACK DOOR TYPE COLD FRONT WILL MOVE
THROUGH THE TERMINALS AFTER 00Z WITH WINDS VEERING TO THE NORTH.
COLD AIR ADVECTION LOW CLOUDS WITH MVFR CEILINGS MAY SPREAD INTO THE
TAF SITES LATE IN THE FORECAST PERIOD.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 180413
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1013 PM CST SAT JAN 17 2009

.DISCUSSION...

TEMPERATURES CONTINUE TO DEFY GRAVITY AND HAVE GIVEN GROUND
GRUDGINGLY THIS EVENING. ALTHOUGH LOW CLOUD DECK HAS QUICKLY SHIFTED
EAST AND NOW ONLY COVERS PARTS OF THE NORTHEAST CWA THERE IS ANOTHER
BAND OF LAYERED CLOUDS OVER IA AND EXTREME EASTERN NE. THESE ARE
QUICKLY SPREADING SSE AHEAD OF A FAST MOVING VORTICITY CENTER
SHOWING UP ON WATER VAPOR IMAGERY. SO WILL RAISE TEMPERATURES ONCE
MORE BY A FEW DEGREES. REGIONAL RADAR LOOPS ALSO SHOW BANDS OF SNOW
SHOWERS ASSOCIATED WITH THIS VORTICITY MAX. 00Z GFS/RUC QPF/SNOW
ALGORITHMS DO A DECENT JOB WITH THIS SNOW AND TRACK IT ACROSS THE
NORTHEAST CWA. SO RAISED POPS CONSIDERABLY FOR A LIGHT DUSTING THIS
AREA.

MJ

&&

.PREV DISCUSSION...
/748 PM CST SAT JAN 17 2009/
OPTED TO MAKE ADJUSTMENTS TO CLOUDS/TEMPERATURES NOW FOR THE
OVERNIGHT PERIOD RATHER THAN WAIT AS TEMPERATURES UNDER THE LOW
CLOUD DECK HAVE BARELY BUDGED SINCE MID AFTERNOON AND BELIEVE THEY
WILL CONTINUE TO BE SLOW TO FALL. SO WILL RAISE MANY OVERNIGHT LOWS.
NOT OVERLY CONFIDENT ON FLURRIES OCCURRING TONIGHT AS LOW CLOUD DECK
TEMPERATURES ARE PROGGED AROUND -7C WHICH IS TYPICALLY NOT COLD
ENOUGH TO CONTAIN ICE CRYSTALS. MAY STRIP THEM OUT LATER THIS
EVENING AFTER LOOKING AT 00Z NAM.

MJ

&&

.SHORT TERM...
/239 PM CST SAT JAN 17 2009/
HIGHLY AMPLIFIED UPPER FLOW PATTERN WILL CONTINUE THROUGH TUESDAY
WITH THE WRN UPR RIDGE ONLY TO MAKE A VERY SLOW SHIFT TO THE EAST
THROUGH VERY EARLY NEXT WEEK. THE EASTWARD SHIFT OF A LARGE POSITIVE
HEIGHT ANOMALY INTO THE ROCKIES WILL YIELD A COMBINATION OF
COMPRESSIONAL AND CHINOOK WARMING ALONG THE FRONT RANGE INTO THE
CENTRAL PLAINS OF THE US AND CANADA...RESULTING IN A LARGE SCALE
RAPID SNOW MELT FOR THAT REGION. THIS WILL HAVE AN
IMPACT...ESPECIALLY FOR TEMPS IN THE BATTLE ZONE BETWEEN THE WARM
WEST AND THE SNOW COVER TO THE N AND NE.

THE STRONG NORTHERLY UPPER JET WILL DRIVE A SERIES OF FAST MOVING
SHORTWAVES THROUGH THE CWA...POSSIBLY PROVIDING FOR A FEW FLURRIES
TNGT THROUGH MONDAY UNDER A PERSISTENT STRATUS/STRATOCU
LAYER...MAINLY CONFINED TO THE ERN TWO THIRDS OF THE CWA. THE EXACT
POSITION OF THE WRN FRINGE OF THE LOW CLOUD DECK WILL BE CRITICAL IN
TEMP FCSTING THE NEXT FEW DAYS...ESPECIALLY SINCE THE CWA WILL BE IN
A SQUEEZE PLAY BETWEEN THE WARM DOWNSLOPE FLOW AND THE COOL
TRAJECTORIES OVER THE SNOW FIELDS TO THE NORTH.

NAM AND GFS CONTINUE TO PLACE MUCH OF THE CWA UNDER THE LOW CLOUD
DECK WITH THE XTRM WRN CWA IN AND OUT OF THE CLOUD DECK AS LOW LEVEL
TRAJECTORIES WAFFLE BETWEEN WEST AND NNW. PREVIOUS TEMP FCSTS HANDLED
SITUATION RATHER WELL AND SEE NO REASON TO MAKE ANY SIGNIFICANT
CHANGES.

DB

MEDIUM RANGE (TUE-SAT)...

ONLY MINOR ADJUSTMENTS MADE TO THE MEDIUM RANGE PORTIONS OF THE FCST
AS MODELS CONTINUE TO STRUGGLE IN HOW THE CURRENT +PNA PATTERN WILL
BREAKDOWN.  NEEDLESS TO SAY...INDIVIDUAL MODEL SOLNS BEYOND TUESDAY
SHOULD BE TAKEN WITH A LARGE GRAIN OF SALT. IN FACT...LATEST
ENSEMBLES ARE ALSO SHOWING HIGHER THAN NORMAL STANDARD DEVIATIONS BY
WEDNESDAY INDICATIVE OF TYPICAL STRUGGLES INVOLVING A MASSIVE
PATTERN SHIFT.

MUCH OF NEXT WEEK IS GOING TO BE CHARACTERIZED BY A SERIES OF
BATTLES BETWEEN WARM AIR UNDER UPR RIDGE TO OUR WEST...AND SERIES OF
WEAK COLD FRONTS WHICH MAY SPOIL A REALLY GOOD WARMUP FOR THE CWFA.
ON TUESDAY...DIFFERENCES BETWEEN THE GFS/ECMWF ARE EVIDENT IN THE
DEGREE OF THE WESTWARD EXTENSION OF UPR TROUGH OVER THE EASTERN US.
FEEL THAT NEXT UPR S/W WHICH ROTATES SOUTHWARD MONDAY NIGHT WILL
BRING A GOOD AMOUNT OF CLOUD COVER AND COOLER AIR FOR TUESDAY.  THUS
HAVE LOWERED TEMPS OVER THE EASTERN CWA...WHILE ALLOWING WESTERN
PORTIONS OF THE FCST AREA TO SEE A HIGHER PROBABILITY OF TAPPING
INTO A WAA REGIME WHICH SHOULD BEGIN FOR WEDNESDAY.  NEEDLESS TO
SAY...THE EVENTUAL BREAKDOWN OF THE WESTERN RIDGE SHOULD PROVIDE AT
LEAST A DAY OR TWO OF PRETTY NICE WEATHER OF THE CWA BEGINNING ON
WEDNESDAY....WITH A HIGHER LIKELIHOOD OF THE WARMEST READINGS
ARRIVING ON THURSDAY BEFORE MORE SEASONAL AIR ARRIVES ON FRIDAY.  AS
FAR AS PRECIP IS CONCERNED...DRY CONDITIONS CAN BE EXPECTED INTO THE
END OF THE WEEK.

31

&&

.AVIATION...

FOR THE 00Z TAFS...GUSTY NORTHWEST WINDS WILL DIMINISH BY OR SHORTLY
AFTER 00Z AND BACK SOME TO THE WNW. THE BACKING OF THE WINDS WILL
PROVIDE JUST ENOUGH OF A DOWNSLOPE COMPONENT OF SLIGHTLY DRIER AIR
TO KEEP THE MVFR CEILINGS CURRENTLY OVER WESTERN IA/NORTHWEST MO
FROM OOZING BACK TO THE SOUTHWEST. SO VFR CONDITIONS THROUGH EARLY
SUNDAY AFTERNOON. BECAUSE OF THE PROGGED LOW LEVEL STEERING WINDS
HAVE DECIDED TO PUSH BACK THE ARRIVAL OF A MVFR CEILINGS UNTIL MID
SUNDAY AFTERNOON. EVEN THEN NOT OVERLY CONFIDENT THEY WILL REACH THE
TERMINALS UNTIL AFTER THE END OF THIS FORECAST PERIOD.

WITH CLOUD COVER LACKING TOMORROW MORNING AND THUS ALLOWING FOR
BETTER MIXING CAN SEE A RETURN TO GUSTY NORTHWEST WINDS STARTING
AROUND 16Z AND LASTING UNTIL LATE AFTERNOON.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 180148
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
748 PM CST SAT JAN 17 2009

.DISCUSSION...

OPTED TO MAKE ADJUSTMENTS TO CLOUDS/TEMPERATURES NOW FOR THE
OVERNIGHT PERIOD RATHER THAN WAIT AS TEMPERATURES UNDER THE LOW
CLOUD DECK HAVE BARELY BUDGED SINCE MID AFTERNOON AND BELIEVE THEY
WILL CONTINUE TO BE SLOW TO FALL. SO WILL RAISE MANY OVERNIGHT LOWS.
NOT OVERLY CONFIDENT ON FLURRIES OCCURRING TONIGHT AS LOW CLOUD DECK
TEMPERATURES ARE PROGGED AROUND -7C WHICH IS TYPICALLY NOT COLD
ENOUGH TO CONTAIN ICE CRYSTALS. MAY STRIP THEM OUT LATER THIS
EVENING AFTER LOOKING AT 00Z NAM.

MJ

&&

.SHORT TERM...
/239 PM CST SAT JAN 17 2009/
HIGHLY AMPLIFIED UPPER FLOW PATTERN WILL CONTINUE THROUGH TUESDAY
WITH THE WRN UPR RIDGE ONLY TO MAKE A VERY SLOW SHIFT TO THE EAST
THROUGH VERY EARLY NEXT WEEK. THE EASTWARD SHIFT OF A LARGE POSITIVE
HEIGHT ANOMALY INTO THE ROCKIES WILL YIELD A COMBINATION OF
COMPRESSIONAL AND CHINOOK WARMING ALONG THE FRONT RANGE INTO THE
CENTRAL PLAINS OF THE US AND CANADA...RESULTING IN A LARGE SCALE
RAPID SNOW MELT FOR THAT REGION. THIS WILL HAVE AN
IMPACT...ESPECIALLY FOR TEMPS IN THE BATTLE ZONE BETWEEN THE WARM
WEST AND THE SNOW COVER TO THE N AND NE.

THE STRONG NORTHERLY UPPER JET WILL DRIVE A SERIES OF FAST MOVING
SHORTWAVES THROUGH THE CWA...POSSIBLY PROVIDING FOR A FEW FLURRIES
TNGT THROUGH MONDAY UNDER A PERSISTENT STRATUS/STRATOCU
LAYER...MAINLY CONFINED TO THE ERN TWO THIRDS OF THE CWA. THE EXACT
POSITION OF THE WRN FRINGE OF THE LOW CLOUD DECK WILL BE CRITICAL IN
TEMP FCSTING THE NEXT FEW DAYS...ESPECIALLY SINCE THE CWA WILL BE IN
A SQUEEZE PLAY BETWEEN THE WARM DOWNSLOPE FLOW AND THE COOL
TRAJECTORIES OVER THE SNOW FIELDS TO THE NORTH.

NAM AND GFS CONTINUE TO PLACE MUCH OF THE CWA UNDER THE LOW CLOUD
DECK WITH THE XTRM WRN CWA IN AND OUT OF THE CLOUD DECK AS LOW LEVEL
TRAJECTORIES WAFFLE BETWEEN WEST AND NNW. PREVIOUS TEMP FCSTS HANDLED
SITUATION RATHER WELL AND SEE NO REASON TO MAKE ANY SIGNIFICANT
CHANGES.

DB

MEDIUM RANGE (TUE-SAT)...

ONLY MINOR ADJUSTMENTS MADE TO THE MEDIUM RANGE PORTIONS OF THE FCST
AS MODELS CONTINUE TO STRUGGLE IN HOW THE CURRENT +PNA PATTERN WILL
BREAKDOWN.  NEEDLESS TO SAY...INDIVIDUAL MODEL SOLNS BEYOND TUESDAY
SHOULD BE TAKEN WITH A LARGE GRAIN OF SALT. IN FACT...LATEST
ENSEMBLES ARE ALSO SHOWING HIGHER THAN NORMAL STANDARD DEVIATIONS BY
WEDNESDAY INDICATIVE OF TYPICAL STRUGGLES INVOLVING A MASSIVE
PATTERN SHIFT.

MUCH OF NEXT WEEK IS GOING TO BE CHARACTERIZED BY A SERIES OF
BATTLES BETWEEN WARM AIR UNDER UPR RIDGE TO OUR WEST...AND SERIES OF
WEAK COLD FRONTS WHICH MAY SPOIL A REALLY GOOD WARMUP FOR THE CWFA.
ON TUESDAY...DIFFERENCES BETWEEN THE GFS/ECMWF ARE EVIDENT IN THE
DEGREE OF THE WESTWARD EXTENSION OF UPR TROUGH OVER THE EASTERN US.
FEEL THAT NEXT UPR S/W WHICH ROTATES SOUTHWARD MONDAY NIGHT WILL
BRING A GOOD AMOUNT OF CLOUD COVER AND COOLER AIR FOR TUESDAY.  THUS
HAVE LOWERED TEMPS OVER THE EASTERN CWA...WHILE ALLOWING WESTERN
PORTIONS OF THE FCST AREA TO SEE A HIGHER PROBABILITY OF TAPPING
INTO A WAA REGIME WHICH SHOULD BEGIN FOR WEDNESDAY.  NEEDLESS TO
SAY...THE EVENTUAL BREAKDOWN OF THE WESTERN RIDGE SHOULD PROVIDE AT
LEAST A DAY OR TWO OF PRETTY NICE WEATHER OF THE CWA BEGINNING ON
WEDNESDAY....WITH A HIGHER LIKELIHOOD OF THE WARMEST READINGS
ARRIVING ON THURSDAY BEFORE MORE SEASONAL AIR ARRIVES ON FRIDAY.  AS
FAR AS PRECIP IS CONCERNED...DRY CONDITIONS CAN BE EXPECTED INTO THE
END OF THE WEEK.

31

&&

.AVIATION...

FOR THE 00Z TAFS...GUSTY NORTHWEST WINDS WILL DIMINISH BY OR SHORTLY
AFTER 00Z AND BACK SOME TO THE WNW. THE BACKING OF THE WINDS WILL
PROVIDE JUST ENOUGH OF A DOWNSLOPE COMPONENT OF SLIGHTLY DRIER AIR
TO KEEP THE MVFR CEILINGS CURRENTLY OVER WESTERN IA/NORTHWEST MO
FROM OOZING BACK TO THE SOUTHWEST. SO VFR CONDITIONS THROUGH EARLY
SUNDAY AFTERNOON. BECAUSE OF THE PROGGED LOW LEVEL STEERING WINDS
HAVE DECIDED TO PUSH BACK THE ARRIVAL OF A MVFR CEILINGS UNTIL MID
SUNDAY AFTERNOON. EVEN THEN NOT OVERLY CONFIDENT THEY WILL REACH THE
TERMINALS UNTIL AFTER THE END OF THIS FORECAST PERIOD.

WITH CLOUD COVER LACKING TOMORROW MORNING AND THUS ALLOWING FOR
BETTER MIXING CAN SEE A RETURN TO GUSTY NORTHWEST WINDS STARTING
AROUND 16Z AND LASTING UNTIL LATE AFTERNOON.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 172319
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
519 PM CST SAT JAN 17 2009

.SHORT TERM...
/239 PM CST SAT JAN 17 2009/
HIGHLY AMPLIFIED UPPER FLOW PATTERN WILL CONTINUE THROUGH TUESDAY
WITH THE WRN UPR RIDGE ONLY TO MAKE A VERY SLOW SHIFT TO THE EAST
THROUGH VERY EARLY NEXT WEEK. THE EASTWARD SHIFT OF A LARGE POSITIVE
HEIGHT ANOMALY INTO THE ROCKIES WILL YIELD A COMBINATION OF
COMPRESSIONAL AND CHINOOK WARMING ALONG THE FRONT RANGE INTO THE
CENTRAL PLAINS OF THE US AND CANADA...RESULTING IN A LARGE SCALE
RAPID SNOW MELT FOR THAT REGION. THIS WILL HAVE AN
IMPACT...ESPECIALLY FOR TEMPS IN THE BATTLE ZONE BETWEEN THE WARM
WEST AND THE SNOW COVER TO THE N AND NE.

THE STRONG NORTHERLY UPPER JET WILL DRIVE A SERIES OF FAST MOVING
SHORTWAVES THROUGH THE CWA...POSSIBLY PROVIDING FOR A FEW FLURRIES
TNGT THROUGH MONDAY UNDER A PERSISTENT STRATUS/STRATOCU
LAYER...MAINLY CONFINED TO THE ERN TWO THIRDS OF THE CWA. THE EXACT
POSITION OF THE WRN FRINGE OF THE LOW CLOUD DECK WILL BE CRITICAL IN
TEMP FCSTING THE NEXT FEW DAYS...ESPECIALLY SINCE THE CWA WILL BE IN
A SQUEEZE PLAY BETWEEN THE WARM DOWNSLOPE FLOW AND THE COOL
TRAJECTORIES OVER THE SNOW FIELDS TO THE NORTH.

NAM AND GFS CONTINUE TO PLACE MUCH OF THE CWA UNDER THE LOW CLOUD
DECK WITH THE XTRM WRN CWA IN AND OUT OF THE CLOUD DECK AS LOW LEVEL
TRAJECTORIES WAFFLE BETWEEN WEST AND NNW. PREVIOUS TEMP FCSTS HANDLED
SITUATION RATHER WELL AND SEE NO REASON TO MAKE ANY SIGNIFICANT
CHANGES.

DB

MEDIUM RANGE (TUE-SAT)...

ONLY MINOR ADJUSTMENTS MADE TO THE MEDIUM RANGE PORTIONS OF THE FCST
AS MODELS CONTINUE TO STRUGGLE IN HOW THE CURRENT +PNA PATTERN WILL
BREAKDOWN.  NEEDLESS TO SAY...INDIVIDUAL MODEL SOLNS BEYOND TUESDAY
SHOULD BE TAKEN WITH A LARGE GRAIN OF SALT. IN FACT...LATEST
ENSEMBLES ARE ALSO SHOWING HIGHER THAN NORMAL STANDARD DEVIATIONS BY
WEDNESDAY INDICATIVE OF TYPICAL STRUGGLES INVOLVING A MASSIVE
PATTERN SHIFT.

MUCH OF NEXT WEEK IS GOING TO BE CHARACTERIZED BY A SERIES OF
BATTLES BETWEEN WARM AIR UNDER UPR RIDGE TO OUR WEST...AND SERIES OF
WEAK COLD FRONTS WHICH MAY SPOIL A REALLY GOOD WARMUP FOR THE CWFA.
ON TUESDAY...DIFFERENCES BETWEEN THE GFS/ECMWF ARE EVIDENT IN THE
DEGREE OF THE WESTWARD EXTENSION OF UPR TROUGH OVER THE EASTERN US.
FEEL THAT NEXT UPR S/W WHICH ROTATES SOUTHWARD MONDAY NIGHT WILL
BRING A GOOD AMOUNT OF CLOUD COVER AND COOLER AIR FOR TUESDAY.  THUS
HAVE LOWERED TEMPS OVER THE EASTERN CWA...WHILE ALLOWING WESTERN
PORTIONS OF THE FCST AREA TO SEE A HIGHER PROBABILITY OF TAPPING
INTO A WAA REGIME WHICH SHOULD BEGIN FOR WEDNESDAY.  NEEDLESS TO
SAY...THE EVENTUAL BREAKDOWN OF THE WESTERN RIDGE SHOULD PROVIDE AT
LEAST A DAY OR TWO OF PRETTY NICE WEATHER OF THE CWA BEGINNING ON
WEDNESDAY....WITH A HIGHER LIKELIHOOD OF THE WARMEST READINGS
ARRIVING ON THURSDAY BEFORE MORE SEASONAL AIR ARRIVES ON FRIDAY.  AS
FAR AS PRECIP IS CONCERNED...DRY CONDITIONS CAN BE EXPECTED INTO THE
END OF THE WEEK.

31

&&

.AVIATION...

FOR THE 00Z TAFS...GUSTY NORTHWEST WINDS WILL DIMINISH BY OR SHORTLY
AFTER 00Z AND BACK SOME TO THE WNW. THE BACKING OF THE WINDS WILL
PROVIDE JUST ENOUGH OF A DOWNSLOPE COMPONENT OF SLIGHTLY DRIER AIR
TO KEEP THE MVFR CEILINGS CURRENTLY OVER WESTERN IA/NORTHWEST MO
FROM OOZING BACK TO THE SOUTHWEST. SO VFR CONDITIONS THROUGH EARLY
SUNDAY AFTERNOON. BECAUSE OF THE PROGGED LOW LEVEL STEERING WINDS
HAVE DECIDED TO PUSH BACK THE ARRIVAL OF A MVFR CEILINGS UNTIL MID
SUNDAY AFTERNOON. EVEN THEN NOT OVERLY CONFIDENT THEY WILL REACH THE
TERMINALS UNTIL AFTER THE END OF THIS FORECAST PERIOD.

WITH CLOUD COVER LACKING TOMORROW MORNING AND THUS ALLOWING FOR
BETTER MIXING CAN SEE A RETURN TO GUSTY NORTHWEST WINDS STARTING
AROUND 16Z AND LASTING UNTIL LATE AFTERNOON.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 172039
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
239 PM CST SAT JAN 17 2009

.SHORT TERM...

HIGHLY AMPLIFIED UPPER FLOW PATTERN WILL CONTINUE THROUGH TUESDAY
WITH THE WRN UPR RIDGE ONLY TO MAKE A VERY SLOW SHIFT TO THE EAST
THROUGH VERY EARLY NEXT WEEK. THE EASTWARD SHIFT OF A LARGE POSITIVE
HEIGHT ANOMALY INTO THE ROCKIES WILL YIELD A COMBINATION OF
COMPRESSIONAL AND CHINOOK WARMING ALONG THE FRONT RANGE INTO THE
CENTRAL PLAINS OF THE US AND CANADA...RESULTING IN A LARGE SCALE
RAPID SNOW MELT FOR THAT REGION. THIS WILL HAVE AN
IMPACT...ESPECIALLY FOR TEMPS IN THE BATTLE ZONE BETWEEN THE WARM
WEST AND THE SNOW COVER TO THE N AND NE.

THE STRONG NORTHERLY UPPER JET WILL DRIVE A SERIES OF FAST MOVING
SHORTWAVES THROUGH THE CWA...POSSIBLY PROVIDING FOR A FEW FLURRIES
TNGT THROUGH MONDAY UNDER A PERSISTENT STRATUS/STRATOCU
LAYER...MAINLY CONFINED TO THE ERN TWO THIRDS OF THE CWA. THE EXACT
POSITION OF THE WRN FRINGE OF THE LOW CLOUD DECK WILL BE CRITICAL IN
TEMP FCSTING THE NEXT FEW DAYS...ESPECIALLY SINCE THE CWA WILL BE IN
A SQUEEZE PLAY BETWEEN THE WARM DOWNSLOPE FLOW AND THE COOL
TRAJECTORIES OVER THE SNOW FIELDS TO THE NORTH.

NAM AND GFS CONTINUE TO PLACE MUCH OF THE CWA UNDER THE LOW CLOUD
DECK WITH THE XTRM WRN CWA IN AND OUT OF THE CLOUD DECK AS LOW LEVEL
TRAJECTORIES WAFFLE BETWEEN WEST AND NNW. PREVIOUS TEMP FCSTS HANDLED
SITUATION RATHER WELL AND SEE NO REASON TO MAKE ANY SIGNIFICANT
CHANGES.

DB

MEDIUM RANGE (TUE-SAT)...

ONLY MINOR ADJUSTMENTS MADE TO THE MEDIUM RANGE PORTIONS OF THE FCST
AS MODELS CONTINUE TO STRUGGLE IN HOW THE CURRENT +PNA PATTERN WILL
BREAKDOWN.  NEEDLESS TO SAY...INDIVIDUAL MODEL SOLNS BEYOND TUESDAY
SHOULD BE TAKEN WITH A LARGE GRAIN OF SALT. IN FACT...LATEST
ENSEMBLES ARE ALSO SHOWING HIGHER THAN NORMAL STANDARD DEVIATIONS BY
WEDNESDAY INDICATIVE OF TYPICAL STRUGGLES INVOLVING A MASSIVE PATTERN
SHIFT.

MUCH OF NEXT WEEK IS GOING TO BE CHARACTERIZED BY A SERIES OF
BATTLES BETWEEN WARM AIR UNDER UPR RIDGE TO OUR WEST...AND SERIES OF
WEAK COLD FRONTS WHICH MAY SPOIL A REALLY GOOD WARMUP FOR THE CWFA.
ON TUESDAY...DIFFERENCES BETWEEN THE GFS/ECMWF ARE EVIDENT IN THE
DEGREE OF THE WESTWARD EXTENSION OF UPR TROUGH OVER THE EASTERN US.
FEEL THAT NEXT UPR S/W WHICH ROTATES SOUTHWARD MONDAY NIGHT WILL
BRING A GOOD AMOUNT OF CLOUD COVER AND COOLER AIR FOR TUESDAY.  THUS
HAVE LOWERED TEMPS OVER THE EASTERN CWA...WHILE ALLOWING WESTERN
PORTIONS OF THE FCST AREA TO SEE A HIGHER PROBABILITY OF TAPPING
INTO A WAA REGIME WHICH SHOULD BEGIN FOR WEDNESDAY.  NEEDLESS TO
SAY...THE EVENTUAL BREAKDOWN OF THE WESTERN RIDGE SHOULD PROVIDE AT
LEAST A DAY OR TWO OF PRETTY NICE WEATHER OF THE CWA BEGINNING ON
WEDNESDAY....WITH A HIGHER LIKELIHOOD OF THE WARMEST READINGS ARRIVING ON
THURSDAY BEFORE MORE SEASONAL AIR ARRIVES ON FRIDAY.  AS FAR AS
PRECIP IS CONCERNED...DRY CONDITIONS CAN BE EXPECTED INTO THE END OF
THE WEEK.

31

&&

.AVIATION...

FOR THE 18Z TAFS...NW UPPER FLOW TO CONTINUE THROUGH SUNDAY WITH A
COUPLE OF EMBEDDED SHORTWAVE TROUGHS TO PASS THROUGH THE TERMINALS
THROUGH SUNDAY. SMALL WIND SHIFTS WITH EACH WAVE WILL HAVE AN IMPACT
ON THE PLACEMENT AND COVERAGE OF THE MVFR CLOUD COVER. LATEST STLT
DEPICTS A MVFR DECK FM XTRM NWRN MO TO NERN MO...SHIFTING SE.
HOWEVER...DOWNSLOPE FLOW AND AFTN INSOLATION HAS BEEN ERODING THE WRN
EDGE. GIVEN THAT THIS TREND WILL CONTINUE THIS AFTN...BELIEVE THE
MODELS ARE TOO FAST IN SHIFTING THE MVFR CLOUD DECK INTO THE
TERMINALS THIS AFTN. BACKING WINDS IN THE LOWER LEVELS WILL LIKELY
KEEP THE STRATUS DECK JUST TO THE EAST OF THE TERMINALS THROUGH THE
NIGHT. THE EXACT WRN EDGE OF THE STRATUS DECK IS DIFFICULT TO DEFINE
WITH CONFIDENCE ONLY MODERATE AT THIS TIME.

LOWER LEVEL WINDS WILL SHIFT MORE TOWARD THE NW/NNW SUNDAY
MORNING...AFT A WEAK LOW PRES TROUGH MOVES THROUGH THE TERMINALS.
THIS WILL LIKELY AID IN ADVANCING THE STRATUS DECK TOWARD THE
WEST...INTO THE TERMINALS. ONCE AGAIN...CONFIDENCE IS NOT HIGH.

OTHERWISE...THE GUSTY NORTHWEST WINDS WILL DIMINISH THIS EVENING WITH
WINDS BEGINNING TO INCREASE AGAIN AFT SUNRISE ON SUNDAY.

DB

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$

000
FXUS63 KEAX 172008
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
208 PM CST SAT JAN 17 2009

.SHORT TERM...

HIGHLY AMPLIFIED UPPER FLOW PATTERN WILL CONTINUE THROUGH TUESDAY
WITH THE WRN UPR RIDGE ONLY TO MAKE A VERY SLOW SHIFT TO THE EAST
THROUGH VERY EARLY NEXT WEEK. THE EASTWARD SHIFT OF A LARGE POSITIVE
HEIGHT ANOMALY INTO THE ROCKIES WILL YIELD A COMBINATION OF
COMPRESSIONAL AND CHINOOK WARMING ALONG THE FRONT RANGE INTO THE
CENTRAL PLAINS OF THE US AND CANADA...RESULTING IN A LARGE SCALE
RAPID SNOW MELT FOR THAT REGION. THIS WILL HAVE AN
IMPACT...ESPECIALLY FOR TEMPS IN THE BATTLE ZONE BETWEEN THE WARM
WEST AND THE SNOW COVER TO THE N AND NE.

THE STRONG NORTHERLY UPPER JET WILL DRIVE A SERIES OF FAST MOVING
SHORTWAVES THROUGH THE CWA...POSSIBLY PROVIDING FOR A FEW FLURRIES
TNGT THROUGH MONDAY UNDER A PERSISTENT STRATUS/STRATOCU
LAYER...MAINLY CONFINED TO THE ERN TWO THIRDS OF THE CWA. THE EXACT
POSITION OF THE WRN FRINGE OF THE LOW CLOUD DECK WILL BE CRITICAL IN
TEMP FCSTING THE NEXT FEW DAYS...ESPECIALLY SINCE THE CWA WILL BE IN
A SQUEEZE PLAY BETWEEN THE WARM DOWNSLOPE FLOW AND THE COOL
TRAJECTORIES OVER THE SNOW FIELDS TO THE NORTH.

NAM AND GFS CONTINUE TO PLACE MUCH OF THE CWA UNDER THE LOW CLOUD
DECK WITH THE XTRM WRN CWA IN AND OUT OF THE CLOUD DECK AS LOW LEVEL
TRAJECTORIES WAFFLE BETWEEN WEST AND NNW. PREVIOUS TEMP FCSTS HANDLED
SITUATION RATHER WELL AND SEE NO REASON TO CHANGE MUCH. HAVE MAINLY
JUST BUMPED OVERNIGHT MINS A FEW DEGREES TO ACCOUNT FOR THE INCREASE
IN WINDS AND THE INCREASE IN CLOUD COVER OVER THE CNTRL AND ERN CWA.

DB

MEDIUM RANGE (TUE-SAT)...

ONLY MINOR ADJUSTMENTS MADE TO THE MEDIUM RANGE PORTIONS OF THE FCST
AS MODELS CONTINUE TO STRUGGLE IN HOW THE CURRENT +PNA PATTERN WILL
BREAKDOWN.  NEEDLESS TO SAY...INDIVIDUAL MODEL SOLNS BEYOND TUESDAY
SHOULD BE TAKEN WITH A LARGE GRAIN OF SALT. IN FACT...LATEST
ENSEMBLES ARE ALSO SHOWING HIGHER THAN NORMAL STANDARD DEVIATIONS BY
WEDNESDAY INDICATIVE OF TYPICAL STRUGGLES INVOLVING A MASSIVE PATTERN
SHIFT.

MUCH OF NEXT WEEK IS GOING TO BE CHARACTERIZED BY A SERIES OF
BATTLES BETWEEN WARM AIR UNDER UPR RIDGE TO OUR WEST...AND SERIES OF
WEAK COLD FRONTS WHICH MAY SPOIL A REALLY GOOD WARMUP FOR THE CWFA.
ON TUESDAY...DIFFERENCES BETWEEN THE GFS/ECMWF ARE EVIDENT IN THE
DEGREE OF THE WESTWARD EXTENSION OF UPR TROUGH OVER THE EASTERN US.
FEEL THAT NEXT UPR S/W WHICH ROTATES SOUTHWARD MONDAY NIGHT WILL
BRING A GOOD AMOUNT OF CLOUD COVER AND COOLER AIR FOR TUESDAY.  THUS
HAVE LOWERED TEMPS OVER THE EASTERN CWA...WHILE ALLOWING WESTERN
PORTIONS OF THE FCST AREA TO SEE A HIGHER PROBABILITY OF TAPPING
INTO A WAA REGIME WHICH SHOULD BEGIN FOR WEDNESDAY.  NEEDLESS TO
SAY...THE EVENTUAL BREAKDOWN OF THE WESTERN RIDGE SHOULD PROVIDE AT
LEAST A DAY OR TWO OF PRETTY NICE WEATHER OF THE CWA BEGINNING ON
WEDNESDAY....WITH A HIGHER LIKELIHOOD OF THE WARMEST READINGS ARRIVING ON
THURSDAY BEFORE MORE SEASONAL AIR ARRIVES ON FRIDAY.  AS FAR AS
PRECIP IS CONCERNED...DRY CONDITIONS CAN BE EXPECTED INTO THE END OF
THE WEEK.

31

&&

.AVIATION...

FOR THE 18Z TAFS...NW UPPER FLOW TO CONTINUE THROUGH SUNDAY WITH A
COUPLE OF EMBEDDED SHORTWAVE TROUGHS TO PASS THROUGH THE TERMINALS
THROUGH SUNDAY. SMALL WIND SHIFTS WITH EACH WAVE WILL HAVE AN IMPACT
ON THE PLACEMENT AND COVERAGE OF THE MVFR CLOUD COVER. LATEST STLT
DEPICTS A MVFR DECK FM XTRM NWRN MO TO NERN MO...SHIFTING SE.
HOWEVER...DOWNSLOPE FLOW AND AFTN INSOLATION HAS BEEN ERODING THE WRN
EDGE. GIVEN THAT THIS TREND WILL CONTINUE THIS AFTN...BELIEVE THE
MODELS ARE TOO FAST IN SHIFTING THE MVFR CLOUD DECK INTO THE
TERMINALS THIS AFTN. BACKING WINDS IN THE LOWER LEVELS WILL LIKELY
KEEP THE STRATUS DECK JUST TO THE EAST OF THE TERMINALS THROUGH THE
NIGHT. THE EXACT WRN EDGE OF THE STRATUS DECK IS DIFFICULT TO DEFINE
WITH CONFIDENCE ONLY MODERATE AT THIS TIME.

LOWER LEVEL WINDS WILL SHIFT MORE TOWARD THE NW/NNW SUNDAY
MORNING...AFT A WEAK LOW PRES TROUGH MOVES THROUGH THE TERMINALS.
THIS WILL LIKELY AID IN ADVANCING THE STRATUS DECK TOWARD THE
WEST...INTO THE TERMINALS. ONCE AGAIN...CONFIDENCE IS NOT HIGH.

OTHERWISE...THE GUSTY NORTHWEST WINDS WILL DIMINISH THIS EVENING WITH
WINDS BEGINNING TO INCREASE AGAIN AFT SUNRISE ON SUNDAY.

DB

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$