Apr 26, 2014 1630 UTC Day 1 Convective Outlook | |||||||||
Updated: Sat Apr 26 16:30:39 UTC 2014 ( | ) | |||||||||
Probabilistic to Categorical Outlook Conversion Table |
Categorical Graphic | |||||||||
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Probabilistic Tornado Graphic | |||||||||
Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
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Probabilistic Damaging Wind Graphic | |||||||||
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
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Probabilistic Large Hail Graphic | |||||||||
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
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SPC AC 261627 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1127 AM CDT SAT APR 26 2014 VALID 261630Z - 271200Z ...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON THROUGH TONIGHT ALONG A NARROW CORRIDOR FROM W TX TO THE MID MO VALLEY... ...SUMMARY... ISOLATED SEVERE STORMS WILL BE POSSIBLE LATE THIS AFTERNOON INTO TONIGHT FROM PARTS OF WEST TEXAS NORTHWARD ACROSS OKLAHOMA AND KANSAS TO THE ADJACENT AREAS OF NEBRASKA...IOWA...AND SOUTH DAKOTA. THE PRIMARY THREATS WILL BE LARGE HAIL AND DAMAGING WIND GUSTS. ...SYNOPSIS... AN INTENSE MIDLEVEL SHORTWAVE TROUGH OVER THE LOWER CO RIVER VALLEY THIS MORNING WILL PROGRESS EWD TO THE SRN/CENTRAL HIGH PLAINS BY EARLY SUNDAY. ASSOCIATED STRONG SURFACE CYCLOGENESIS WILL OCCUR FROM NE CO THIS AFTERNOON TO SW NEB OVERNIGHT...WITH A SHARPENING LEE TROUGH/DRYLINE SWD FROM WRN KS TO NW TX. LOW-LEVEL MOISTURE WILL SPREAD NWD TODAY IN ADVANCE OF THE LEE TROUGH...WITH LOW 60S BOUNDARY LAYER DEWPOINTS REACHING CENTRAL ERN KS BY THIS EVENING...MID 60S INTO S/SW OK...AND UPPER 60S CENTRAL TX. THIS MOISTENING WILL OCCUR BENEATH STEEP MIDLEVEL LAPSE RATES OBSERVED IN REGIONAL 12Z SOUNDINGS...WITH MODERATE-STRONG BUOYANCY EXPECTED IN THE WARM SECTOR THIS AFTERNOON INTO TONIGHT. ...NW TX TO WRN OK LATE AFTERNOON THROUGH TONIGHT... DESPITE THE INCREASINGLY FAVORABLE BACKGROUND PATTERN...THERE ARE SEVERAL CONCERNS REGARDING STORM DEVELOPMENT TODAY. THE PRIMARY LIMITING FACTOR IS THE MAGNITUDE OF THE CAP VERSUS THE DEGREE OF LOW-LEVEL MOISTENING. THE EML IS RELATIVELY WARM AND AFTERNOON SURFACE CONDITIONS WITH LOW-MID 60S DEWPOINTS AND MID 80S TEMPERATURES WILL LIKELY REMAIN CAPPED...WITH DEEPER MIXING AND TEMPERATURES IN THE 90S NECESSARY TO REMOVE CONVECTIVE INHIBITION ALONG THE DRYLINE. ASSUMING THE OBSERVED THIN CIRRUS CLOUDS DO NOT HINDER SURFACE HEATING MUCH...ISOLATED HIGH-BASED STORMS MAY FORM BY 00Z ALONG THE NW TX/SW OK PORTION OF THE DRYLINE WHERE THE WARMEST SURFACE TEMPERATURES COINCIDE WITH THE W EDGE OF THE RICHER MOISTURE. IF SUCH DEVELOPMENT OCCURS...MLCAPE NEAR 3000 J/KG AND SUFFICIENT DEEP-LAYER SHEAR WILL SUPPORT A RISK FOR SUPERCELLS WITH VERY LARGE HAIL. THE LATER ARRIVAL OF THE LOW-LEVEL MOISTURE CASTS EVEN MORE DOUBT ON AFTERNOON DRYLINE STORM DEVELOPMENT FARTHER N INTO KS. THERE WILL BE A CONDITIONAL TORNADO RISK IN A NARROW WINDOW LATE THIS EVENING WHEN LOW-LEVEL MOISTURE BACKS NWWD INTO THE AFTERNOON DRYLINE POSITION/ZONE OF POTENTIAL HIGH-BASED STORM DEVELOPMENT... AND AS THE SLY LLJ STRENGTHENS. MLCAPE WILL REMAIN NEAR 3000 J/KG INTO EARLY TONIGHT AS DEWPOINTS INCREASE INTO THE MID 60S FROM NW TX INTO OK...AND EFFECTIVE SRH WILL INCREASE TO AOA 300 M2/S2. STILL...CONVECTIVE INHIBITION WILL BE RELATIVELY LARGE WITH SLOW SURFACE COOLING...AND LARGE-SCALE FORCING FOR ASCENT WILL BE WEAK UNTIL LATE TONIGHT WHEN THE SHORTWAVE TROUGH APPROACHES THE HIGH PLAINS. THUS...WILL MAINTAIN A CONDITIONAL SEVERE STORM RISK...BUT STORM COVERAGE MAY BE SPARSE. ...OK/KS TO THE MID MO VALLEY OVERNIGHT... THE ARRIVAL OF THE STRONGER HEIGHT FALLS COULD PROMOTE ELEVATED THUNDERSTORM DEVELOPMENT 06-12Z FROM WRN/CENTRAL OK INTO CENTRAL KS...WHERE LARGE HAIL AND ISOLATED DAMAGING GUSTS WILL BE THE MAIN THREATS. OTHER ELEVATED CONVECTION WITH THE RISK FOR LARGE HAIL WILL ALSO BE POSSIBLE TONIGHT IN THE ZONE OF STRONGER LOW-LEVEL WAA FROM NE NEB/SE SD INTO WRN IA. ...ERN WY/SW SD/NW NEB THIS AFTERNOON/EVENING... SOME HIGH-BASED CONVECTION COULD FORM THIS AFTERNOON IMMEDIATELY NE OF THE DEEPENING LEE CYCLONE...FROM ERN WY INTO THE NW NEB PANHANDLE. THOUGH MOISTURE WILL BE LIMITED...DEEP MIXING/STEEP LOW-LEVEL LAPSE RATES COULD SUPPORT WEAK SURFACE-BASED BUOYANCY AND SOME RISK FOR STRONG WIND GUSTS. MARGINALLY SEVERE HAIL WILL ALSO BE POSSIBLE WITH LOW-END SUPERCELL STRUCTURES...GIVEN EFFECTIVE BULK SHEAR AOA 40 KT BY THIS EVENING. ...NRN VA/MD TO DE AREA THIS AFTERNOON... THOUGH LOW-LEVEL MOISTURE WILL BE LIMITED...STRONG SURFACE HEATING/MIXING WILL CONTRIBUTE TO STEEP LOW-LEVEL LAPSE RATES IN ADVANCE OF A REINFORCING COLD FRONT MOVING SEWD FROM OH/NW PA. WEAK/SHALLOW BUOYANCY WILL BE POSSIBLE ALONG THE FRONT IN AN ENVIRONMENT WITH STRONG WNWLY UNIDIRECTIONAL FLOW...SUCH THAT ISOLATED STRONG OUTFLOW GUSTS WILL BE POSSIBLE WITH SHALLOW CONVECTION. ..THOMPSON/DEAN.. 04/26/2014 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z |