Thursday, April 29, 2010

Area Forecast Discussion - South Central/Southwest Missouri

FXUS63 KSGF 291707
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
1207 PM CDT THU APR 29 2010

..UPDATE TO AVIATION...

DISCUSSION...

AN ACTIVE STRETCH OF WEATHER IS ON THE HORIZON AS A SOUTHWEST FLOW
ALOFT DEVELOPS ACROSS THE CENTRAL UNITED STATES. THE FIRST
FORECAST CONCERN WAS WINDS TODAY WITH A WIND ADVISORY IN EFFECT
ALONG AND WEST OF THE HIGHWAY 65 CORRIDOR. ATTENTION THEN TURNS TO
WHAT WILL BE A COMPLEX CONVECTIVE SCENARIO INTO AT LEAST THE FIRST
HALF OF THE WEEKEND.

THE UPPER LEVEL RIDGE WHICH WAS RESPONSIBLE FOR A DRY AND MILD
WEDNESDAY HAS NOW SHIFTED OFF TO THE EAST OF THE REGION. IN ITS
WAKE...A LARGE AREA OF HEIGHT FALLS ARE SPREADING EAST INTO THE
PLAINS AND OZARKS REGION. THE LOW LEVELS HAVE RESPONDED NICELY
WITH A STRONG PRESSURE GRADIENT FROM THE HIGH PLAINS TO THE
MISSISSIPPI RIVER. THIS PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN
TODAY AS A SURFACE LOW SWINGS EAST ACROSS NEBRASKA. CURRENT WIND
ADVISORY LOOKS GOOD AS SOUTHEAST KANSAS/WESTERN MISSOURI SHOULD
HAVE NO PROBLEM HITTING 30 MPH SUSTAINED CRITERIA. GUSTS TO 45
STILL LOOK REASONABLE WITH DECENT MIXING EXPECTED. ONE MINOR
CONCERN IS HOW QUICKLY WE WILL DECOUPLE TONIGHT. THERE IS A
POSSIBILITY THAT GUST POTENTIAL COULD INCREASE OUT WEST THIS
EVENING AS A LOW LEVEL JET STRENGTHENS...IF WE ARE SLOW TO
DECOUPLE. IF THIS HAPPENS...THE WIND ADVISORY MAY NEED TO BE
EXTENDED. AS FOR TEMPERATURES...HIGHS IN THE UPPER 70S TO LOWER
80S ARE STILL ON TRACK FOR TODAY...WITH MOST AREAS IN THE 60S
TONIGHT.

MEANWHILE...A COLD FRONT WILL BEGIN TO MAKE SLOW PROGRESS TO THE
SOUTHEAST ACROSS THE CENTRAL PLAINS TONIGHT AS SHORT WAVE ENERGY
ROUNDS THE BASE OF A DEEP WESTERN UNITED STATES TROUGH. AM STILL
EXPECTING MOST IF NOT ALL OF THE CONVECTION TO REMAIN WEST OF THE
AREA TONIGHT...BUT KEPT LOW CHANCES GOING IN CASE SOMETHING CAN
SNEAK IN HERE LATE. CONFIDENCE REMAINS LOW REGARDING THE
CONVECTIVE SCENARIO FOR FRIDAY. MODELS CONTINUE TO BREAK OUT QUITE
A BIT OF QPF WELL AHEAD OF THE FRONT. INVESTIGATION OF MODEL
SOUNDINGS REVEALS THAT MODELS ARE VERY QUICK TO ERODE WHAT WILL BE
A STRONG ELEVATED MIXED LAYER. INITIALLY...THE MORE LIKELY
SCENARIO MAY BE WEAK SHOWERS ROOTED BELOW THE EML WITH A QUICK
RETURN OF LOW LEVEL MOISTURE. WE MAY THEN SEE ELEVATED CONVECTION
DEVELOP FRIDAY MORNING ALONG AND EAST OF THE HIGHWAY 65 CORRIDOR
ON THE NOSE OF A VEERING AND WEAKENING LOW LEVEL JET. IF THIS
OCCURS...THIS ACTIVITY SHOULD SHIFT EAST THROUGHOUT THE DAY.

ANOTHER AREA OF CONCERN MAY THEN BE THAT SURFACE FRONT AND A
TRAILING DRY LINE COMING INTO SOUTHEAST KANSAS AND WESTERN
MISSOURI EITHER LATE FRIDAY OR FRIDAY EVENING. BESIDES THE
MOISTURE CONVERGENCE ALONG THESE LOW LEVEL FEATURES...ADDITIONAL
TRIGGERING MECHANISMS REMAIN IN QUESTION. IF STORMS CAN DEVELOP IN
THIS CORRIDOR...THEY MAY HAVE A BETTER CHANCE AT BEING SURFACE
BASED. GIVEN THE STRONG DEEP LAYER SHEAR EXPECTED...SEVERE STORMS
REMAIN A CONCERN ACROSS THE ENTIRE FORECAST AREA...ESPECIALLY IN
THOSE AREAS THAT MANAGE TO DESTABILIZE. IT IS JUST TOO EARLY TO
TELL WHERE THAT MAY OCCUR AS THIS WILL BE A SHORT TERM FORECAST
ISSUE. SATURDAY IS NO EASIER AS THE POSITION OF THAT FRONT WILL
PLAY A HUGE ROLE IN SEVERE POTENTIAL. FROM A SYNOPTIC
STANDPOINT...THE NAM SEEMS MORE REASONABLE KEEPING THE FRONT
ACROSS SOUTHEAST KANSAS OR WESTERN MISSOURI EARLY IN THE DAY.
HOWEVER...IT IS QUITE POSSIBLE THAT CONVECTIVE OUTFLOWS MAY AID
THE FRONT IN ITS PROGRESS TO THE SOUTHEAST. AGAIN...ANOTHER SHORT
TERM FORECAST ISSUE. WILL SIDE WITH THE NAM FOR NOW AND INCLUDE A
STRONG TO SEVERE THREAT FOR MUCH OF THE FORECAST AREA ON SATURDAY.
WILL ALSO CONTINUE TO MENTION A LIMITED THREAT FOR FLOODING WITH
MULTIPLE ROUNDS OF CONVECTION POSSIBLE.

CURRENT THINKING IS THAT STRONGER SHORT WAVE ENERGY AND CONVECTION
ON SATURDAY MAY BE ENOUGH TO PUSH THE FRONT EAST OF THE AREA. HAVE
THEREFORE LOWERED POPS SOME ON SUNDAY. STILL NOT OUT OF THE WOODS
COMPLETELY AS WE WILL REMAIN IN A SOUTHWEST FLOW ALOFT. MEDIUM
RANGE MODELS THEN BRING ANOTHER STRONGER WAVE THROUGH THE REGION
LATER MONDAY AND MONDAY NIGHT. KEPT CHANCE POPS GOING FOR THIS
PERIOD. HAVE LOWERED TEMPERATURES FOR THE SUNDAY AND EARLY NEXT
WEEK PERIOD WITH CONFIDENCE A LITTLE HIGHER THAT THE FRONT WILL
CLEAR THE AREA.

SCHAUMANN

&&

AVIATION...

FOR THE 18Z TAFS...WINDS WILL BE THE MAIN CONCERN THROUGH THE
PERIOD. STRONG STORM SYSTEM TO THE WEST WILL PROVIDE STRONG
SOUTHERLY SURFACE WINDS TO THE AREA. IN ADDITION...LOW LEVEL WIND
SHEAR OF 40 TO 55 KTS WILL REMAIN POSSIBLE THROUGH MUCH OF THE
FORECAST PERIOD. SOME CONVECTION MAY DEVLEOP OUT AHEAD OF THE
FRONT BY FRIDAY MORNING AND HAVE ALSO BROUGHT CEILINGS DOWN TO
AROUND 2500 FEET AFTER 14-15Z FRIDAY.

LINDENBERG

&&

SGF WATCHES/WARNINGS/ADVISORIES...
MO...WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MOZ055-066>068-
077>079-088>090-093>095-101>104.

KS...WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR KSZ073-097-101.

&&

$$


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