SPC AC 241241
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0741 AM CDT THU MAR 24 2011
VALID 241300Z - 251200Z
...NO SVR TSTM AREAS FORECAST...
...W TX THIS AFTERNOON/EVENING...
LOW-LEVEL MOISTURE WILL SPREAD NWWD FROM S TX INTO W TX TODAY AS A
LEE TROUGH/DRYLINE SHARPENS ACROSS W TX. SURFACE HEATING ON THE NW
EDGE OF THE RETURNING MOISTURE...ALONG WITH LOW-LEVEL ASCENT ALONG
THE DEVELOPING DRYLINE...COULD OVERCOME CONVECTIVE INHIBITION AND
SUPPORT ISOLATED THUNDERSTORM DEVELOPMENT THIS AFTERNOON. THOUGH
INSTABILITY WILL REMAIN RATHER MODEST /MLCAPE LESS THAN 1000 J PER
KG/...SUBSTANTIAL DEEP-LAYER SHEAR AND STEEP LAPSE RATES COULD
SUPPORT MARGINALLY SEVERE HAIL AND STRONG OUTFLOW WINDS FOR A FEW
HOURS LATE THIS AFTERNOON/EVENING BEFORE THE CAP STRENGTHENS.
...CENTRAL/NE OK AREA TONIGHT...
A SHORTWAVE TROUGH OVER UT/AZ THIS MORNING WILL MOVE ENEWD TOWARD
THE CENTRAL PLAINS BY TONIGHT. THE APPROACH OF THIS WAVE WILL
INDUCE WEAK LEE CYCLOGENESIS...THE REMNANTS OF WHICH WILL MOVE EWD
INTO SW OK/NW TX BY THE END OF THE PERIOD. A STRENGTHENING SLY/SWLY
LLJ IS EXPECTED TONIGHT OVER OK ALONG WITH RETURNING MOISTURE ABOVE
THE BOUNDARY LAYER. THE NET RESULT WILL BE A STRONG WAA REGIME WITH
INCREASING MOISTURE AND CAPE BASED IN THE 850-700 MB LAYER. MUCAPE
IN EXCESS OF 1000 J/KG...EFFECTIVE BULK SHEAR AOA 40-50 KT...AND
COOL MIDLEVEL TEMPERATURES COULD SUPPORT MARGINALLY SEVERE HAIL WITH
ELEVATED CONVECTION OVERNIGHT IN THE WAA REGIME.
...NRN CA COAST AND SACRAMENTO VALLEY TODAY...
A STRONG MIDLEVEL SHORTWAVE TROUGH WILL PROGRESS ESEWD AND INLAND
OVER NRN CA TODAY INTO EARLY TONIGHT. THE THERMODYNAMIC ENVIRONMENT
WILL NOT BE PARTICULARLY FAVORABLE FOR THUNDERSTORMS AS A RESULT OF
WIDESPREAD CLOUDS/RAIN AND COOL SURFACE TEMPERATURES TODAY.
HOWEVER...COLD MIDLEVEL TEMPERATURES /NEAR -30 C AT 500 MB/ WILL
SUPPORT SUFFICIENTLY STEEP LAPSE RATES FOR MARGINAL BUOYANCY /MUCAPE
AOB 200 J PER KG/ NEAR THE COAST AND IN THE SACRAMENTO VALLEY LATER
THIS AFTERNOON. CLOCKWISE TURNING HODOGRAPHS AND ASCENT WITHIN THE
LEFT EXIT REGION OF THE MID-UPPER JET...IN COMBINATION WITH WEAK
SURFACE-BASED INSTABILITY...COULD SUPPORT ISOLATED STRONG CONVECTIVE
GUSTS AND POSSIBLY A WEAK TORNADO IN THE SACRAMENTO VALLEY.
..THOMPSON/GRAMS.. 03/24/2011
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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