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000
FXUS63 KSGF 051930
AFDSGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
130 PM CST WED NOV 5 2008
...MESOSCALE CONVECTIVE DISCUSSION...
.UPDATE...
CONDITIONS COMING TOGETHER TO SUPPORT RAPID THUNDERSTORM
DEVELOPMENT DURING THE MID/LATE AFTERNOON HOURS.
AT 100 PM...SFC ANALYSIS INDICATES A STRONG AREA OF LOW PRESSURE
OVER SOUTHEASTERN SOUTH DAKOTA. A COLD FRONT EXTENDS SOUTHWARD
FROM THIS LOW THROUGH EASTERN NEB...CENTRAL KS AND INTO THE
PANHANDLES OF OK AND TX. A DRYLINE IS LOCATED ROUGHLY FROM
CENTRAL KS SOUTHWARD INTO WESTERN OK. A BROAD AREA OF PRESSURE
FALLS IS LOCATED AHEAD OF THE SFC FRONTS. THE TIGHTENING PRESSURE
GRADIENT HAS KEPT WINDS QUITE GUSTY...WITH SUSTAINED WINDS AROUND
25 MPH OR SO AND GUSTS NEAR 40 MPH.
STRONG LOW LEVEL WINDS...AROUND 40KT AT 925MB AND 40KT TO 50KT
AT 850MB...HAVE AIDED IN CONTINUED MOISTURE ADVECTION AHEAD OF
THE DRYLINE AND COLD FRONT. SFC DEWPOINTS ARE IN THE UPPER 50S TO
AROUND 60F...AND LITTLE CHANGE IN VALUES ARE EXPECTED AHEAD OF THE
FRONT. OVER THE OZARKS...THERE HAS BEEN A DECENT MOISTURE GRADIENT
FROM WEST TO EAST. UPPER 50S DEWPOINTS ARE MAKING THEIR WAY INTO
AREAS NEAR THE MO/KS STATE LINE...BUT VALUES ARE STILL ONLY AROUND
50F OVER THE EASTERN OZARKS. STRONG FLOW JUST OFF THE SFC AND A
MORE SOUTHERLY OR JUST SOUTH OF WEST COMPONENT TO THE SFC WILL
WILL RESULT IN A SLOW...BUT STEADY INCREASE IN DEWPOINT ACROSS THE
REST OF THE AREA THIS AFTERNOON.
ALOFT...THERE ARE A FEW FEATURES OF INTEREST TO NOTE. FIRST...A
100KT JET STREAK LOCATED ON THE EASTERN PERIPHERY OF THE DEEP
TROUGH OVER THE ROCKIES HAS RESULTED IN BROAD SCALE LIFT. THIS IS
HIGHLIGHTED IN WAT VAP IMAGERY BY A PLUME OF MOISTURE FROM THE TX
PANHANDLE THROUGH WESTERN AND CENTRAL PORTIONS OF OK/KS. ANOTHER
120KT JET STREAK IS GEARING UP ON THE WESTERN PERIPHERY OF THE
TROUGH AND THERE ARE INCREASING INDICATIONS OF LIFT OVER NEW
MEXICO IN THE WAT VAP IMAGERY. LOOKING AT 18Z RAOBS AT KTOP AND
KOUN...IT IS CLEAR THAT THE BROAD SCALE LIFT AHEAD OF THE TROUGH
HAS BEEN ENOUGH TO SUBSTANTIALLY WEAKEN A RATHER STAUNCH CAP THAT
WAS OBSERVED WITH THE 12Z RAOBS.
OVER THE NEXT FEW HOURS...THROUGH APPROXIMATELY 430 PM...
CONDITIONS WILL REMAIN QUIET OVER EXTREME SE KS AND THE MO
OZARKS...SANS A FEW WAA SHRA OVER WESTERN ZONES. ALL EYES WILL BE
FOCUSED ON A DEVELOPING PREFRONTAL TROUGH OVER SE KS AND NE OK AS
BROAD SCALE LIFT FINALLY ZAPS THE REMAINING CAP AND DISCRETE
SUPERCELLS ERUPT. AFTER 430 PM...STORMS THAT HAVE DEVELOPED OVER
SE KS AND NE OK WILL QUICKLY SPREAD TO THE NORTHEAST AND IMPINGE
ON OUR EXTREME SE KS AND FAR WESTERN MO COUNTIES.
TO SAY THE LEAST...THERE IS SUBSTANTIAL DEEP LAYER AND LOW LEVEL
SHEAR. WITH DEWPOINTS SETTLING FIRMLY IN THE UPPER 50S TO AROUND
60F...MLCAPE AROUND 1000 J/KG IS EXPECTED. LARGE HAIL...DAMAGING
WIND GUSTS AND A FEW TORNADOES ARE EXPECTED. GIVEN SUCH
SUBSTANTIAL LOW LEVEL SHEAR...ANY STORMS NEAR THE HIGHEST AXIS OF
INSTABILITY WILL RUN AN INCREASED RISK FOR A FEW STRONG...LONG
LIVED TORNADOES.
DURING THE EVENING HOURS...SUPERCELLS WILL CONGEAL INTO A SQUALL
LINE AS THE COLD FRONT ACCELERATES TO THE EAST. THIS WILL
TRANSITION THE SEVERE WEATHER RISK TO DAMAGING STRAIGHT LINE WINDS
AND A FEW EMBEDDED TORNADOES FOR AREAS ALONG AND WEST OF THE
HIGHWAY 65 CORRIDOR. AS THIS LINE HEADS FURTHER INTO THE OZARKS
OVERNIGHT...A GENERAL WEAKENING TREND IS EXPECTED...THOUGH THE
RISK FOR DAMAGING WIND GUSTS WILL REMAIN.
GAGAN
&&
.DISCUSSION...
MAIN FOCUS WITH THIS PACKAGE WILL BE CENTERED ON STRONG SYNOPTIC
SCALE STORM SYSTEM TAKING AIM AT THE PLAINS AND MISSISSIPPI VALLEY
REGION OVER THE NEXT COUPLE OF DAYS.
WATER VAPOR IMAGERY SHOWS A STRONG UPPER LEVEL WAVE IN THE
NORTHERN ROCKIES WITH STRONG 120-130KT UPPER LEVEL JET STREAK
DIGGING SOUTH ON THE WESTERN SIDE OF THE TROUGH. STORM SYSTEM IS
EXPECTED TO CLOSE OFF OVER THE HIGH PLAINS LATER TODAY. FURTHER
EAST AHEAD OF THE LOW...SOUTHERLY WINDS OF 10 TO 20 KTS WAS
KEEPING TEMPERATURES IN THE MID 50S TO LOW 60S WEST OF THE PLATEAU
SO FAR TONIGHT. DEW POINTS CONTINUE TO CREEP UP...AIDED BY THE
STRONG LOW LEVEL JET OF 45 TO 60 KTS IN THE PLAINS. THIS WAS ALSO
AIDING IN SOME WARM SECTOR CONVECTION BREAKING OUT TO OUR NORTH AT
THE MOMENT.
MODELS ARE IN DECENT AGREEMENT WITH MAIN FEATURES THROUGH THE
FIRST FEW PERIODS OF THE FORECAST. AS MENTIONED ABOVE...UPPER LOW
IS EXPECTED TO CLOSE OFF IN THE HIGH PLAINS TODAY. LOW LEVEL
MOISTURE TRANSPORT WILL CONTINUE IN EARNEST TODAY WEST OF THE
PLATEAU WITH DEWPOINTS TRYING TO CREEP INTO THE UPPER 50S TO LOW
60S OVER SOUTHEAST KANSAS AND FAR SOUTHWEST MISSOURI BY 00Z.
STRONG SOUTH WINDS WILL BE THE MAIN STORY FOR TODAYS WEATHER WITH
SOME GUSTS OF 35 TO 40 KTS POSSIBLE WEST OF THE PLATEAU. SHOULD
REMAIN BELOW ADVISORY CRITERIA BUT WILL MAKE MENTION IN THE
MORNING HWO. MAY SEE SOME SCATTERED CONVECTION IN THE WARM SECTOR
OVER THE NORTHWEST 1/4 OF THE CWA DURING THE DAY AND HAVE BUMPED
UP POPS THERE SLIGHTLY. THE MAIN ACTION IS SLATED FOR TONIGHT
HOWEVER FOR CONVECTION.
STRONG UPPER JET STREAK 110-120KT WILL BE ROUNDING THE BASE OF THE
UPPER LEVEL LOW THIS EVENING WHILE LOW STARTS TO BECOME NEGATIVELY
TILTED. STRONG 850 WINDS WILL CONTINUE OUT OF THE SOUTH TO
SOUTHWEST AT 40 TO 50KTS AND WILL HAVE PLENTY OF LOW LEVEL SHEAR.
MODELS IN AGREEMENT THAT SOME DISCRETE SUPERCELLS WILL BE POSSIBLE
OVER EASTERN KANSAS SOUTHWARD INTO EASTERN OKLAHOMA LATE THIS
AFTERNOON INTO THE EVENING AND MAY CREEP INTO THE SOUTHWEST CORNER
OF THE CWA LATE THIS EVENING BEFORE FORMING INTO A SQUALL LINE
OVERNIGHT. WILL BE MENTIONING THE THREAT OF ISOLATED TORNADOES
OVER THE SOUTHWEST PORTION OF THE CWA FOR TONIGHT. MAIN HAZARD
ACROSS THE REMAINDER OF THE CWA WILL BE WITH STRAIGHT LINE WINDS
AS SQUALL LINE SHIFTS EAST OVERNIGHT INTO THURSDAY MORNING. SHEAR
STILL PRETTY STRONG OVERNIGHT WITH THE SQUALL LINE AND WOULDNT BE
SURPRISED TO SEE SOME ROTATING STORMS ALONG THE LINE. STORM EVENT
SHOULD BE FAIRLY SHORT LIVED HOWEVER WITH PRECIPITATION ENDING BY
MIDDAY OVER THE EASTERN CWA.
ATTENTION THEN TURNS TO TEMPERATURES HEADING INTO THE LATER PART
OF THE WORK WEEK. PRETTY GOOD PUNCH OF COOLER AIR WILL MOVE INTO
THE AREA WITH SEVERAL WAVES OF UPPER LEVEL ENERGY ROTATING THROUGH
THE AREA. PRECIPITATION CHANCES WITH THESE SHORTWAVES WILL BE
FAIRLY LOW...ESPECIALLY FURTHER SOUTHWEST. SHOULD BE LOOKING AT
HIGHS STRUGGLING TO REACH THE LOW 50S IN CENTRAL MO BY
FRIDAY...ESPECIALLY IF CLOUD COVER PERSISTS IN THAT REGION.
LINDENBERG
&&
.AVIATION...
FOR THE 18Z KSGF/KJLN TAFS...THERE WILL BE SEVERAL AVIATION
HAZARDS THAT ARE EXPECTED TO AFFECT THE TAF SITES THROUGH THE NEXT
24 HOURS.
GUSTY SOUTHERLY WINDS WILL CONTINUE TO AFFECT THE TAF
SITES THIS AFTERNOON INTO THE OVERNIGHT HOURS...AHEAD OF AN
APPROACHING COLD FRONT. AS THE FRONT MOVES INTO WESTERN
KANSAS...SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP AHEAD OF
THE FRONT. THE BEST CHANCES FOR THESE STORMS WILL OCCUR ACROSS
SOUTHEASTERN KANSAS AND NORTHWESTERN MISSOURI...HOWEVER A FEW OF
THESE STORMS MAY MOVE INTO EXTREME SOUTHWESTERN MISSOURI THIS
EVENING. HAVE INCLUDED CB IN THE KJLN TAF TO ACCOUNT FOR THIS...AS
CONFIDENCE IS TOO LOW TO INCLUDE A TEMPO OR PREVAIL GROUP AT THIS
TIME. THESE STORMS WILL HAVE THE POTENTIAL OF BECOMING STRONG TO
SEVERE.
AS THE FRONT PUSHES EAST A SQUALL LINE IS LIKELY TO DEVELOP NEAR
THE FRONT AND WILL PUSH THROUGH THE TAF SITES OVERNIGHT...FIRST AT
THE KJLN SITE THEN THE KSGF SITE. HEAVY RAINFALL AND GUSTY WINDS
WILL BE POSSIBLE WITH THESE STORMS. HAVE INCLUDED A TEMPO GROUP
FOR THIS ACTIVITY AS CONFIDENCE IS HIGHER IN THIS OCCURRING.
A STRONG LOW LEVEL JET WILL REMAIN ACROSS THE AREA INTO THE
OVERNIGHT HOURS...AND HAVE KEPT THE LOW LEVEL WIND SHEAR IN THE
TAFS TO ACCOUNT FOR THE WIND SHEAR.
WISE
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR MOZ066-067-077-
078-088-089-093-094-101-102.
KS...WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR KSZ073-097-101.
&&
$$
