SPC AC 101559
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1059 AM CDT TUE MAR 10 2009
VALID 101630Z - 111200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF OK/AR ACROSS
THE MID MS RIVER VALLEY...
...SRN PLAINS INTO THE LOWER GREAT LAKES...
STRONG/LOW AMPLITUDE SHORTWAVE TROUGH WILL ACCELERATE NEWD ACROSS
THE NRN PLAINS TODAY AS ASSOCIATED 100+ KT MID LEVEL JET LIFTS INTO
THE UPPER MS RIVER VALLEY. THIS WILL AID IN DEEPENING A SURFACE LOW
/LOCATED NEAR THE CENTRAL IA/MO BORDER AT 15Z/ AS IT MOVES NNEWD
ACROSS THE UPPER MS RIVER VALLEY AND INTO WI TODAY AND ACROSS THE
NRN GREAT LAKES TONIGHT. ACCOMPANYING ARCTIC COLD FRONT WILL
LIKEWISE ACCELERATE SSEWD BEHIND THE LOW AND SHOULD EXTEND FROM SWRN
OK/TX PNHDL ENEWD INTO CENTRAL MO/NWRN IL BY 21Z...AND FROM THE
LOWER GREAT LAKES/APPALACHIANS INTO THE LOWER MS RIVER
VALLEY/CENTRAL TX BY SUNRISE WEDNESDAY. AHEAD OF THE FRONT...A WARM
FRONT WILL BECOME BETTER DEFINED AND LIFT RAPIDLY NEWD ACROSS THE
GREAT LAKES REGION. THIS WILL ALLOW BROAD AREA OF SEASONABLY
WARM/MOIST BOUNDARY LAYER TO PRECEED SURFACE COLD FRONT PASSAGE WITH
DEW POINTS IN THE LOWER 50S EXTENDING AS FAR N AS LOWER MI. DESPITE
THE MOISTENING WARM SECTOR...WARM NOSE BETWEEN H85-H7 EVIDENT ON
MORNING SOUNDINGS WITHIN THE WARM SECTOR WILL LIMIT LAPSE RATES AND
OVERALL INSTABILITY FOR MUCH OF THE PERIOD. IN ADDITION...MUCH OF
THE DEEP ASCENT AND ENHANCED MID/UPPER LEVEL FLOW WILL TRAIL THE
SURFACE COLD FRONT.
EXPECT ONLY SLOW DESTABILIZATION TO OCCUR FOR MUCH OF THE EARLY TO
MID AFTERNOON WITHIN THE WARM SECTOR...ALTHOUGH MORNING VSBL IMAGERY
INDICATES HEATING WILL BE UNHINDERED FOR THE MOST PART FROM PORTIONS
OF CENTRAL OK INTO MO. THUNDERSTORM DEVELOPMENT IS EXPECTED TO
BEGIN/INCREASE OVER ERN OK/NWRN AR/SWRN-CENTRAL MO DURING THE LATE
AFTERNOON /LIKELY AROUND 20Z/ AS CAP ERODES WITH STRONG HEATING
STEEPENING LOW LEVEL LAPSE RATES AND H7 COLD FRONT OVERSPREADING
SURFACE FRONT. ALTHOUGH STRONGEST MID/UPPER LEVEL FLOW WILL TRAIL
THE SURFACE FRONT...WINDS ALOFT WILL STILL BE QUITE STRONG ACROSS
THE WARM SECTOR AND SUPPORT 40-50 KT DEEP LAYER SHEAR. THIS WILL BE
SUFFICIENT FOR SUPERCELLS AND ORGANIZED CLUSTERS/LINES OF STORMS.
ACTIVITY WILL INCREASE IN COVERAGE THROUGH THE EVENING WITH FORCED
EWD MOVEMENT AHEAD OF APPROACHING COLD FRONT OVERNIGHT. STORMS ABLE
TO PERSIST IN THE WARM SECTOR AWAY FROM SHALLOW SURFACE COLD FRONT
SHOULD SUSTAIN A RISK OF WIND DAMAGE AND ISOLATED TORNADOES.
OVERALL THREAT MAY WANE LATER THIS EVENING/OVERNIGHT AS EWD
ACCELERATION OF SURFACE FRONT BEGINS TO UNDERCUT STORMS AND WARM
SECTOR STABILIZES FROM THE SRN GREAT LAKES INTO THE OH/TN RIVER
VALLEYS AND MID SOUTH.
..EVANS/PETERS.. 03/10/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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