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000 FXUS63 KSGF 052122 AFDSGF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 322 PM CST WED NOV 5 2008 .DISCUSSION... MAIN FORECAST FOCUS WILL BE THE THREAT FOR SEVERE THUNDERSTORMS OVER THE NEXT 12 TO 18 HOURS AS A STRONG STORM SYSTEM CROSSES THE CENTRAL UNITED STATES. MUCH COOLER WEATHER IS THEN EXPECTED FROM THE UPCOMING WEEKEND INTO NEXT WEEK. ANOTHER STORM SYSTEM IS EXPECTED TO IMPACT THE AREA SOMETIME IN THE MONDAY TO WEDNESDAY TIME FRAME. TONIGHT...STRONG UPPER LEVEL LOW PRESSURE WILL SLOWLY PUSH EAST ACROSS THE CORN BELT. AT THE SURFACE...A COLD FRONT WILL PUSH INTO SOUTHEAST KANSAS AND WESTERN MISSOURI LATE TONIGHT...MAKING IT TO THE HIGHWAY 65 CORRIDOR BY SUNRISE. STRONG TO SEVERE STORMS ARE EXPECTED ALONG THIS FRONT...AS WELL AS ALONG A PRE FRONTAL TROUGH THIS EVENING AND OVERNIGHT. PLEASE REFER TO THE MESOSCALE CONVECTIVE DISCUSSION BELOW FOR GREATER DETAIL ON THE SEVERE WEATHER THREAT. BRISK SOUTH TO SOUTHEAST WINDS AHEAD OF THE FRONT WILL SHIFT TO THE WEST. SPEAKING OF WINDS...WE HAVE NOT MET WIND ADVISORY CRITERIA UP TO THIS POINT. WILL LIKELY BE CANCELLING THE WIND ADVISORY BY 4 PM. THURSDAY...THAT FRONT WILL QUICKLY PUSH EAST OUT OF CENTRAL AND SOUTH CENTRAL MISSOURI IN THE MORNING. THE THREAT FOR THUNDERSTORMS WILL END ONCE THE FRONT EXITS THE AREA. WE MAY ACTUALLY SEE A BRIEF PERIOD OF CLEARING AS A DRY SLOT WORKS INTO THE AREA. WRAP AROUND MOISTURE MAY THEN BRING MORE CLOUDINESS INTO THE AREA BY THE AFTERNOON...ESPECIALLY OVER CENTRAL MISSOURI. TEMPERATURES ARE A TOUGH CALL GIVEN THE INCREASING CLOUD COVER AND COOLING LOW LEVELS. GENERALLY SPLIT THE DIFFERENCE BETWEEN THE MAV AND MET. THURSDAY WILL AGAIN BE WINDY AS LOW LEVEL PRESSURE GRADIENTS REMAIN RATHER TIGHT. WINDS WILL ALSO BECOME GUSTY BY THE AFTERNOON AS THE LOW LEVELS OF THE ATMOSPHERE EFFICIENTLY MIX OUT. THURSDAY NIGHT THROUGH FRIDAY NIGHT...THAT UPPER LEVEL LOW PRESSURE WILL FINALLY BEGIN TO PUSH EAST INTO THE GREAT LAKES. ONE MORE UPPER LEVEL WAVE WILL COME AROUND THE SOUTHERN FLANK OF THE LOW AND DRIVE A WEAK SURFACE TROUGH ACROSS THE AREA. NOT OUT OF THE QUESTION WE COULD SEE A LIGHT SHOWER OR TWO UP ACROSS CENTRAL MISSOURI ON FRIDAY. TEMPERATURES WILL BE ON THE COOL SIDE AS 850 MB TEMPERATURES HOVER AT OR BELOW ZERO DEGREES CELSIUS. UPCOMING WEEKEND...THE AREA WILL REMAIN UNDER A CYCLONIC NORTHWEST FLOW ALOFT. MOISTURE LOOKS PRETTY LIMITED SO AM NOT EXPECTING ANY PRECIPITATION. THE COOL TEMPERATURES WILL CONTINUE WITH HIGHS STRUGGLING TO GET INTO THE UPPER 40S AND LOWER 50S OVER MOST AREAS. EARLY NEXT WEEK...LONG WAVE CHARTS CONTINUE TO FAVOR DIGGING OF ENERGY OUT OF THE PACIFIC NORTHWEST. MEDIUM RANGE MODELS CONTINUE TO INDICATE ENERGY DIVING INTO THE FOUR CORNERS REGION AND EVENTUALLY EJECTING OUT TOWARDS THE OZARKS. STILL NOT A REAL GOOD SIGNAL FOR TIMING...BUT FEEL THAT SLIGHT TO LOW END CHANCE POPS ARE WARRANTED STARTING SUNDAY NIGHT AND MONDAY. DO NOT SEE ANY BIG WARM UPS AS LOW LEVEL TRAJECTORIES WILL LIKELY REMAIN OUT OF THE EAST AND NORTHEAST. SCHAUMANN && .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 && .PREV DISCUSSION... /ISSUED 130 PM CST WED NOV 5 2008/ ...MESOSCALE CONVECTIVE DISCUSSION... 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 && .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. && $$