SPC AC 251934
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0234 PM CDT MON MAY 25 2009
VALID 252000Z - 261200Z
...NO SVR TSTM AREAS FORECAST...
...20Z UPDATE...
ONLY MINOR CHANGES TO THE CATEGORICAL AND PROBABILISTIC OUTLOOKS
HAVE BEEN MADE IN AN ATTEMPT TO PERHAPS BETTER REFLECT ONGOING
CONVECTIVE TRENDS.
...FLORIDA...
SOME CONSIDERATION WAS GIVEN TO UPGRADE SEVERE PROBABILITIES ACROSS
THE INTERIOR PENINSULA. STRONG CONVECTIVE DEVELOPMENT IS NOW WELL
UNDERWAY ALONG THE EAST AND WEST COAST SEA BREEZES...AND STORM
COVERAGE PROBABLY WILL BECOME INCREASINGLY WIDESPREAD AS THE SEA
BREEZES CONVERGE OVER THE INTERIOR PENINSULA LATE THIS AFTERNOON AND
EARLY EVENING. DELAYED INITIATION OF STORMS HAS ALLOWED BOUNDARY
LAYER HEATING TO CONTRIBUTE TO MIXED LAYER CAPE IN EXCESS OF 2000
J/KG...PARTICULARLY ACROSS THE CENTRAL AND SOUTHERN PENINSULA. THIS
WILL SUPPORT VIGOROUS UPDRAFTS IN THE PRESENCE OF A MARGINALLY
FAVORABLE THERMODYNAMIC ENVIRONMENT FOR LARGE HAIL. SIZABLE
LOWER/MID TROPOSPHERIC TEMPERATURE/DEW POINTS SPREADS WILL
CONTRIBUTE TO THE RISK FOR DAMAGING DOWNBURSTS...WHICH IS THE
PRIMARY SEVERE CONCERN. IF THE BOUNDARY LAYER WAS A BIT MORE
MOIST...PERHAPS MORE STRONGLY HEATED /WITH STEEPER LOW-LEVEL LAPSE
RATES/...IT WOULD SEEM A MORE SUBSTANTIAL/WIDESPREAD DAMAGING WIND
THREAT WOULD EXIST WITH DOWNBURSTS AND SURGING OUTFLOWS. BUT...AS
IT IS...IT STILL SEEMS PROBABLE THAT ANY DAMAGING WIND THREAT WILL
REMAIN LOCALIZED IN NATURE.
..KERR.. 05/25/2009
.PREV DISCUSSION... /ISSUED 1054 AM CDT MON MAY 25 2009/
WIDESPREAD LOW LEVEL MOISTURE...MODERATE INSTABILITY...AND WEAK FLOW
WILL ONCE AGAIN PREVAIL ACROSS THE NATION TODAY. THIS WILL LEAD TO
NUMEROUS THUNDERSTORMS OVER MOST OF THE COUNTRY...BUT ONLY LOCALIZED
THREATS OF STRONG/SEVERE STORMS.
...FL...
SIMILAR TO YESTERDAY...FULL MORNING SUNSHINE AND AMPLE MOISTURE WILL
COMBINE WITH RELATIVELY COOL MID LEVEL TEMPERATURES TO YIELD A
MODERATELY UNSTABLE AIRMASS. WEAK FLOW WILL ALLOW EAST AND WEST
COAST SEABREEZES TO MOVE INLAND AND BE THE FOCUS FOR NUMEROUS
THUNDERSTORMS THIS AFTERNOON. ISOLATED SEVERE STORMS CAPABLE OF
HAIL AND GUSTY WINDS ARE POSSIBLE THROUGH EARLY EVENING UNTIL
INSTABILITY IS DISSIPATED.
...NEB/KS AND OK/TX PANHANDLES...
MORNING WATER VAPOR IMAGERY SHOWS A MID LEVEL SHEAR AXIS MOVING
SLOWLY EASTWARD ACROSS CO AND NORTHEAST NM. THIS FEATURE WILL
SPREAD INTO THE HIGH PLAINS OF NEB/KS AND THE OK/TX PANHANDLES LATER
THIS AFTERNOON AND PROMOTE SCATTERED TO WIDESPREAD THUNDERSTORM
DEVELOPMENT. VERTICAL SHEAR IS WEAK...SUGGESTING MULTICELL STORMS
ARE MOST LIKELY. STEEP LOW LEVEL LAPSE RATES AND SUFFICIENT CAPE
WILL POSE A RISK OF GUSTY WINDS AND HAIL IN STRONGER CELLS.
...TX...
FARTHER SOUTH...SLIGHTLY STRONGER WESTERLY FLOW ALOFT WILL SPREAD
ACROSS NORTHERN MEXICO INTO CENTRAL AND SOUTH TX. THIS MAY HELP TO
ORGANIZE SCATTERED THUNDERSTORMS THAT DEVELOP IN THIS REGION.
SIMILAR TO YESTERDAY...A FEW OF THESE STORMS MAY BECOME SEVERE.
HOWEVER...A FOCUSED SEVERE EVENT IS NOT CURRENTLY ANTICIPATED.
...NORTHERN PLAINS...
STORMS ARE LIKELY TO DEVELOP THIS AFTERNOON ALONG A WEAK SURFACE
BOUNDARY FROM EASTERN ND INTO CENTRAL NEB. LOW LEVEL MOISTURE IS
INCREASING AHEAD OF THE BOUNDARY WHILE DAYTIME HEATING OCCURS. A
FEW STORMS ALONG THIS AXIS MAY BECOME SEVERE WITH DAMAGING WINDS AND
HAIL. HOWEVER...AREAL COVERAGE OF SEVERE STORMS SHOULD REMAIN
RATHER LOW.
...MO...
REMNANT DEEP CIRCULATION CONTINUES TO TRACK NORTHEASTWARD ACROSS
NORTHERN AR INTO SOUTHERN MO. A PLUME OF TROPICAL MOISTURE IN THE
EASTERN HALF OF THE SYSTEM WILL SPREAD NORTHWARD INTO PARTS OF
CENTRAL/SOUTHERN MO TODAY WITH DEWPOINTS IN THE LOWER 70S. DEEP
LAYER VERTICAL SHEAR IS WEAK IN THIS AREA...BUT THERE MAY BE
SUFFICIENT NEAR-SURFACE SHEAR FOR A BRIEF TORNADO THIS AFTERNOON.
THIS REGIME HAS RESULTED IN AT LEAST AN ISOLATED TORNADO OR TWO THE
LAST COUPLE OF DAYS OVER TN/AL.
...DELMARVA...
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG
A SLOWLY RETREATING SURFACE BOUNDARY EXTENDING FROM DE INTO CENTRAL
WV. VERTICAL SHEAR IS WEAK...BUT COVERAGE OF STORMS AND AMPLE
MOISTURE/INSTABILITY MAY BE SUFFICIENT FOR LOCALLY GUSTY/DAMAGING
WINDS IN STRONGEST CORES.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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