SPC AC 251226
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0726 AM CDT WED APR 25 2007
VALID 251300Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN PARTS OF THE SRN
PLAINS THROUGH LOWER AND MID MS VALLEY TO TN/LOWER OH VALLEYS...
...SYNOPSIS...
LARGE UPPER LOW CENTERED NWRN OK/KS BORDER WILL CONTINUE EWD TO SWRN
MO BY THU AM. SURFACE LOW NCENTRAL OK WITH COLD FRONT EXTENDING SWD
TO NCENTRAL TX THEN SWWD TO VICINITY DRT. ACTIVE PRE-FRONTAL
CONVECTION TUESDAY HAS SHIFTED EWD ACROSS MID MS VALLEY SWWD TO TX
COAST WELL AHEAD OF FRONT. THE POTENT WARM SECTOR TUESDAY OVER THE
SRN PLAINS HAS BEEN SUBSTANTIALLY STABILIZED BY THE WIDESPREAD
CONVECTION. ADDITIONALLY INFLUX OF GULF AIRMASS HAS LESSENED AS LOW
LEVEL FLOW HAS WEAKENED AND VEERED.
FRONTAL BAND EXTENDS EWD ACROSS OH VALLEY TO OFFSHORE DELMARVA.
MARGINALLY UNSTABLE AIRMASS DEVELOPS THIS AFTERNOON ALONG AND S OF
FRONTAL ZONE PROVIDING SUPPORT FOR THUNDERSTORMS.
..LOWER MO VALLEY/ERN PORTION OF SRN PLAINS...
DAYTIME HEATING WILL AID IN DESTABILIZING AIRMASS AHEAD OF
SURFACE/UPPER LOW FROM SERN KS/NERN OK EWD INTO MO/AR. LOW/MID 70S
TEMPERATURES WILL LEAD TO MLCAPE ABOVE 1000 J/KG. MID LEVEL COLD
ADVECTION AND LARGE SCALE ASCENT AHEAD OF SURFACE/UPPER LOW WILL
LEAD TO SURFACE BASED THUNDERSTORM DEVELOPMENT BY EARLY AFTERNOON.
THE COLD CYCLONIC FLOW OF UPPER LOW WILL SUPPORT POTENTIAL FOR LOW
TOPPED SUPERCELLS INCLUDING LARGE HAIL AND POSSIBLE TORNADOES.
ACTIVITY WILL SPREAD EWD ACROSS SRN MO/NRN AR PRIOR TO WEAKENING
THIS EVENING WITH LOSS OF DAYTIME HEATING.
...MID AND LOWER MS VALLEY...
CLOUD COVER OF WEAKENING MCS ERN TX INTO LA WILL RESULT IN ONLY SLOW
DESTABILIZATION OF THE WARM SECTOR TODAY ACROSS MS VALLEY GIVEN THE
WEAKENING OF THE GULF MOISTURE INFLOW. HOWEVER AS BAND OF STRONG
MID/UPPER WINDS ROTATE EWD ACROSS SRN PLAINS/GULF STATES AND TN
VALLEY SHEAR WILL SUPPORT ORGANIZED THUNDERSTORM REDEVELOPMENT ALONG
AND AHEAD OF COLD FRONT BY LATER THIS AFTERNOON. WITH MLCAPES
GENERALLY NO GREATER THAN 1000 J/KG AND LAPSE RATES LESS THAN
7C/KM...PRIMARY SEVERE THREAT WILL BE WIND DAMAGE WITH STORMS THAT
DEVELOP LINE SEGMENTS/BOWS ALONG WITH HAIL. ISOLATED TORNADOES
POSSIBLE PARTICULARLY IF SUPERCELLS CAN DEVELOP.
...OH VALLEY EWD TO DELMARVA...
WHILE INSTABILITY EXPECTED TO BE LIMITED WITH LAPSE RATES AROUND
6C/KM AND MLCAPES LESS THAN 800 J/KG...40-50KT OF DEEP LAYER SHEAR
SUGGESTS ISOLATED SEVERE WIND EVENTS WILL BE POSSIBLE THIS
AFTERNOON. THREAT AREA WOULD EXTEND ALONG AND JUST S OF FRONTAL
ZONE EWD ACROSS OH VALLEY TO DELMARVA.
..HALES/GUYER.. 04/25/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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