SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0723 AM CDT SUN APR 29 2012 VALID 291300Z - 301200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CENTRAL/SOUTHERN HIGH PLAINS...AND ALONG A CORRIDOR FROM OK INTO IL/IND.... A LARGE UPPER LOW IS CENTERED OVER WESTERN ND THIS MORNING...WITH A BROAD REGION OF CYCLONIC FLOW ALOFT OVER MUCH OF THE WESTERN STATES AND NORTHERN/CENTRAL PLAINS. MEANWHILE...A WEAK SURFACE BOUNDARY EXTENDS FROM WEST TX ACROSS CENTRAL OK...THEN INTO PARTS OF MO/IL. THIS BOUNDARY WILL BE THE FOCUS OF SCATTERED STRONG/SEVERE THUNDERSTORMS TODAY. ...OK INTO SOUTHERN IL/IN... CONVECTION HAS BEEN OCCURRING OVERNIGHT ALONG AND NORTH OF THE SURFACE BOUNDARY...REINFORCING IT AND SUPPRESSING ITS NORTHWARD MOVEMENT. A COMBINATION OF AMPLE LOW LEVEL MOISTURE AND SUBSTANTIAL DAYTIME HEATING WILL HELP TO DESTABILIZE THE AIR MASS ALONG AND SOUTH OF THE BOUNDARY BY MID AFTERNOON...WITH MLCAPE VALUES OF AROUND 1500 J/KG AND ONLY WEAK CAPPING. THIS WILL LIKELY RESULT IN THE DEVELOPMENT OF SCATTERED THUNDERSTORMS ALONG AND NORTH OF THE BOUNDARY. LOW LEVEL VERTICAL SHEAR WILL BE RATHER WEAK...BUT DEEP LAYER EFFECTIVE SHEAR WILL BE SUFFICIENT FOR MULTICELL OR OCCASIONAL SUPERCELL STORM STRUCTURES CAPABLE OF HAIL AND GUSTY WINDS. ...CENTRAL/SOUTHERN HIGH PLAINS... MORNING WATER VAPOR IMAGERY SHOWS A COMPACT UPPER VORT MAX OVER UT. THIS FEATURE WILL TRACK EASTWARD BY LATE THIS AFTERNOON AND AFFECT PORTIONS OF CO/NM AND EVENTUALLY KS/TX. MOST MODEL SOLUTIONS AGREE WITH DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS OF SOUTHERN CO/NORTHERN NM. THIS ACTIVITY WILL TRACK EASTWARD INTO A PROGRESSIVELY MORE UNSTABLE AIR MASS OVER SOUTHEAST CO/NORTHEAST NM. SIMILAR TO AREA FARTHER EAST...LOW LEVEL WINDS WILL BE RATHER WEAK THOUGH THE AFTERNOON AND EARLY EVENING WHICH SHOULD LIMIT THE TORNADO POTENTIAL. HOWEVER...FAVORABLE DEEP LAYER EFFECTIVE SHEAR WILL PROMOTE SUPERCELL STRUCTURES CAPABLE OF LARGE HAIL /SOME VERY LARGE/ AND DAMAGING WINDS. AFTER DARK...MODELS SUGGEST THE SOUTHERLY LOW LEVEL JET WILL STRENGTHEN AND MAY YIELD A SOMEWHAT GREATER CHANCE OF A TORNADO OR TWO ACROSS PORTIONS OF THE TX PANHANDLE INTO SOUTHEAST CO. ..HART/SMITH.. 04/29/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1300.html
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