Wednesday, June 23, 2010

Area Forecast Discussion - South Central/Southwest Missouri

FXUS63 KSGF 240447
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
1147 PM CDT WED JUN 23 2010

..UPDATE TO AVIATION...

UPDATE...

CONVECTION CONTINUES TO WANE ACROSS THE NORTH THIS EVENING. THE
CONVECTIVE OUTFLOW HAS FAILED TO PUSH UP ANY NEW UPDRAFTS ACROSS
THE LAKES REGION OF CENTRAL MISSOURI FOR THE PAST FEW HOURS. WITH
THIS BOUNDARY PUSHING INTO AN INCREASINGLY DRY AND CAPPED
ATMOSPHERE...CHANCES FOR CONVECTION HAVE DECREASED. STILL CANNOT
RULE OUT AN ELEVATED STORM OVERNIGHT AS AN ELEVATED FRONT BEGINS
TO PUSH INTO CENTRAL MISSOURI. HAVE GENERALLY GONE WITH SLIGHT
CHANCE POPS FOR THE REMAINDER OF TONIGHT. AS FOR SEVERE
THREAT...ANY STORMS THAT CAN MANAGE TO DEVELOP SHOULD BE SUB SEVERE
WITH A BRIEF HEAVY RAINFALL THREAT. ON THAT NOTE...SEVERE
THUNDERSTORM WATCH 397 WILL BE ALLOWED TO EXPIRE AT THE TOP OF THE
HOUR. UPDATED PRODUCTS FORTHCOMING.

SCHAUMANN

&&

SHORT TERM (TONIGHT THRU SATURDAY MORNING)...

NUMEROUS FORECAST ISSUES FOR THE SHORT TERM TODAY...INCLUDING
FRONTAL PASSAGE AND ASSOCIATED POPS...WX...TEMPS....AND SEVERE
WEATHER POTENTIAL TONIGHT...AND FRONTAL PLACEMENT AND POPS THURSDAY
AND FRIDAY.

COLD FRONT IS CURRENTLY IN THE VICINITY OF DES MOINES WEST TO AROUND
TOPEKA EARLY THIS AFTERNOON...WITH A STRONG SHORTWAVE TRAVERSING THE
WESTERN GREAT LAKES. THIS BOUNDARY SHOULD CONTINUE TO DROP SOUTH
THIS EVENING...EVENTUALLY STALLING OUT NEAR THE MISSOURI/ARKANSAS
STATE LINE BY THURSDAY MORNING.

SOME CONTINUING CONCERN ABOUT JUST HOW MUCH CONVECTION IS GOING TO
BE ABLE TO GET GOING ALONG THE FRONT TONIGHT AS IT MOVES INTO THE
SGF CWA AFTER 00Z...WITH MORNING SOUNDINGS SHOWING A VERY CAPPED
ATMOSPHERE IN PLACE. WITH CINH BEING AS STRONG AS IT IS...SUSPECT
THAT CONVECTION THAT DOES DEVELOP WILL BE JUST ALONG THE FRONT WHERE
THE FRONTAL CIRCULATION IS STRONG ENOUGH TO OVERCOME INHIBITION.
STRONG TO SEVERE STORMS WILL BE POSSIBLE ALONG THE FRONT THIS
EVENING...WITH 2000-2500 JOULES OF MLCAPE AND 20-25 KT OF BULK SHEAR
AVAILABLE. 00Z SGF SOUNDING WILL LIKELY TELL THE STORY AS FAR AS
PARTICULAR CONVECTIVE RISKS...BUT 12Z RAOB DOES SUGGEST THAT STRONG
WIND GUSTS WILL IN ALL LIKELIHOOD BE THE BIGGEST THREAT WITH THE
STRONGEST AND MOST ORGANIZED CONVECTION...CONSIDERING AMPLE DRY AIR
IN THE LOW TO MID LEVELS AND ANTICIPATED STEEP LOW LEVEL LAPSE RATES.

HIGHEST THREAT LEVEL FOR SEVERE WEATHER IS ANTICIPATED TO BE NORTH
OF I-44...WHERE UPPER LEVEL SUPPORT...WHILE STILL NOT
IMPRESSIVE...WILL BE THE GREATEST. INTERESTINGLY...NUMBER OF HI-RES
4KM WRF RUNS...INCLUDING OUTPUT FROM SPC/NSSL MODELS...LOCAL WFO
MODEL...AND MODELS FROM SURROUNDING OFFICES ARE SHOWING CONVECTION
ALL BUT DYING OUT AS IT REACHES I-44. THIS ISN'T A TOTALLY
UNBELIEVABLE SCENARIO...WITH CONVERGENCE ALONG THE FRONT DECREASING
AS IT MOVES SOUTH...AND INSTABILITY DECREASING AS THE NIGHT GOES ON.
I'M NOT QUITE READY TO BUY INTO THE IDEA OF THINGS BEING COMPLETELY
DRY OF THE I-44 CORRIDOR...BUT HAVE INDICATED SOMEWHAT LOWER POPS
ACROSS THAT AREA THIS EVENING.

FRONTAL BOUNDARY ANTICIPATED TO BE STALLED OUT ACROSS EXTREME
NORTHERN ARKANSAS ON THURSDAY THROUGH MUCH OF THE DAY. A FEW
THUNDERSTORMS WILL BE POSSIBLE NEAR AND ALONG THE BOUNDARY...THOUGH
REALLY THINK THAT BEST CHANCES WILL BE SOUTH OF THE SGF CWA.
PERHAPS THE BIGGEST CHANGE ON THURSDAY FROM THE PREVIOUS DAYS WILL
BE MUCH-WELCOMED RELIEF FROM THE HEAT. STILL SOME QUESTION AS TO
JUST HOW COOL WE'LL GET TOMORROW...BUT UPPER 80S TO PERHAPS NEAR 90
ARE EXPECTED ACROSS AREAS SOUTH OF A JOPLIN TO SPRINGFIELD TO ROLLA
LINE...WITH MID 80S NORTH.

UNFORTUNATELY COOLER TEMPERATURES LOOK TO BE SHORT-LIVED...AS THE
FRONT WILL MIX BACK NORTH AS A WARM FRONT ON FRIDAY. THIS SHOULD
PUT US RIGHT BACK INTO THE SUMMER HEAT JUST IN TIME FOR THE
WEEKEND.

BOXELL

&&

LONG TERM (SATURDAY THROUGH WEDNESDAY)...

MED RANGE MODELS CONTINUE TO SHOW AGREEMENT WITH THE OVERALL UPPER
LEVEL PATTERN EVOLUTION. A FAST...NEARLY ZONAL...FLOW WILL GIVE WAY
TO AMPLIFICATION AND THE DEVELOPMENT OF AN OMEGA PATTERN OVER NORTH
AMERICA HEADING INTO NEXT WEEK. THIS AMPLIFICATION WILL SEND A COLD
FRONT THROUGH THE REGION IN THE SUNDAY/MONDAY TIME FRAME...WITH SOME
SPREAD AMONGST MODEL SOLUTIONS AS TO EXACT TIMING. NEXT WEEK...THE
OMEGA PATTERN TAKES SHAPE WITH A DEEP TROUGH OVER THE EASTERN CONUS
AND RIDGING NOW FOCUSED TO OUR WEST OVER THE ROCKIES AND HIGH
PLAINS. THE PROGGED ORIENTATION OF THESE TROUGH/RIDGE FEATURES
SUGGESTS A SLIGHTLY COOLER AND DRIER REGIME ACROSS OUR NECK OF THE
WOODS. THE KEY WILL ULTIMATELY BE JUST WHERE THE UPPER RIDGE AXIS
SETS UP...BUT CURRENT INDICATIONS ARE THAT OUR LOW LEVEL FLOW WILL
BE DOMINATED BY AN EASTERLY/DRY FLOW...LEADING TO THE INFLUX OF A
MORE PLEASANT AIRMASS NEXT WEEK. BEFORE THEN...MORE HEAT/HUMIDITY IS
EXPECTED THIS WEEKEND. WILL ONCE AGAIN NEED TO WATCH HEAT INDEX
LEVELS AS HIGHS WARM INTO THE LOW/MID 90S. RAIN CHANCES LOOK BEST
WITH THE FRONTAL PASSAGE IN THE SUNDAY/MONDAY TIME FRAME.

GAGAN

&&

AVIATION...

A COLD FRONT WILL SLOWLY PUSH SOUTH ACROSS SOUTHWEST MISSOURI LATE
TONIGHT. A FEW THUNDERSTORMS WILL REMAIN POSSIBLE NEAR THE
FRONT...BUT COVERAGE IS EXPECTED TO BE ISOLATED IN NATURE.
THEREFORE KEPT PREVAILING CB GROUP BUT REMOVED VCSH MENTION. LIGHT
AND VARIABLE WINDS WILL SHIFT TO LIGHT NORTHERLY BEHIND THE FRONT.
THIS FRONT IS THEN EXPECTED TO STALL ACROSS NORTHERN ARKANSAS ON
THURSDAY. ADDITIONAL THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE
NEAR THE FRONT. THINK MOST IF NOT ALL ACTIVITY WILL BE IN NORTHERN
ARKANSAS...BUT KEPT CB GROUP IN AT KBBG GIVEN RELATIVELY CLOSE
PROXIMITY.

SCHAUMANN

&&

SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$


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