SPC AC 051246
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0746 AM CDT WED SEP 05 2007
VALID 051300Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS TODAY FOR CENTRAL/NE UT...ERN
ID...WRN WY...AND NW CO...
...THERE IS A SLGT RISK OF SVR TSTMS TODAY FOR NE TX...
...UT/ERN ID/WRN WY/NW CO TODAY...
THE MID LEVEL TROUGH OVER SRN ID AND NV THIS MORNING WILL PROGRESS
EWD OVER UT AND WRN WY/CO BY TONIGHT. RESIDUAL MONSOONAL MOISTURE
AND ASCENT DOWNSTREAM FROM THE TROUGH ARE SUPPORTING WIDELY
SCATTERED THUNDERSTORMS THIS MORNING OVER CENTRAL UT. EXPECT
ADDITIONAL THUNDERSTORM DEVELOPMENT AS DAYTIME HEATING...BOUNDARY
LAYER DEWPOINTS IN THE LOW-MID 50S...AND CONDITIONALLY UNSTABLE MID
LEVEL LAPSE RATES COMBINE TO SUPPORT MLCAPE VALUES OF 500-1000 J/KG
THIS AFTERNOON. IN ADDITION TO THIS INSTABILITY...VERTICAL SHEAR
PROFILES WILL BE FAVORABLE FOR BOTH SUPERCELLS AND BOWING LINE
SEGMENTS...WITH AN ATTENDANT THREAT FOR DAMAGING WINDS AND LARGE
HAIL.
...NE TX AREA TODAY...
A MID LEVEL TROUGH OVER OK/N CENTRAL TX WILL EJECT ENEWD TO MO AND
WRN AR IN RESPONSE TO HEIGHT FALLS OVER THE ROCKIES WITH THE NRN
GREAT BASIN TROUGH. A DEEP SWATH OF TROPICAL MOISTURE ACCOMPANIES
THIS EJECTING WAVE FROM ERN OK/TX INTO LA/AR...WHERE SCATTERED
THUNDERSTORMS WILL OCCUR AGAIN TODAY. SOMEWHAT ENHANCED LOW-MID
LEVEL WIND PROFILES AND VERTICAL SHEAR /PER THE PALESTINE PROFILER/
WILL SPREAD NEWD IN ADVANCE OF THE MID LEVEL WAVE FROM CENTRAL TX
TOWARD NE TX/SE OK BY THIS EVENING. THOUGH POOR LAPSE RATES AND
WIDESPREAD CLOUD COVER WILL TEND TO LIMIT INSTABILITY...THE RICH
MOISTURE AND REASONABLY STRONG L0W-LEVEL SHEAR MAY SUPPORT A TORNADO
OR TWO WITH SUPERCELLS ON THE SRN AND ERN PERIPHERY OF THE LARGER
CONVECTIVE CLUSTER.
...ND/NW MN TODAY...
A SURFACE COLD FRONT WILL DRIFT SEWD ACROSS ND INTO NW MN IN THE
WAKE OF A MID LEVEL WAVE TRAVERSING MANITOBA AND WRN ONTARIO.
BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 60S SE OF THE FRONT...ALONG
WITH DAYTIME HEATING...WILL CONTRIBUTE TO MLCAPE VALUES IN EXCESS OF
1000 J/KG. HOWEVER...A SUFFICIENTLY STRONG CAP SHOULD INHIBIT
SURFACE-BASED THUNDERSTORM DEVELOPMENT TODAY...WITH ELEVATED STORMS
MORE PROBABLE BY EARLY TONIGHT ON THE COOL SIDE OF THE BOUNDARY.
MODEST INSTABILITY AND POOR PHASING OF THE STRONGER VERTICAL SHEAR
WITH THE WARM SECTOR SUGGEST THAT THE THREAT FOR LARGE HAIL AND/OR
DAMAGING WINDS WILL BE MARGINAL AT BEST.
..THOMPSON/GRAMS.. 09/05/2007
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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