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| Probabilistic Tornado Graphic | |||||||||
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| 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 | |||||||||
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| 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 | |||||||||
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| 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 271247 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0747 AM CDT FRI SEP 27 2013 VALID 271300Z - 281200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT ACROSS PARTS OF THE CNTRL AND SRN PLAINS... ...SYNOPSIS... A SIGNIFICANT VORTICITY MAXIMUM AND ASSOCIATED MID AND UPPER-LEVEL JET STREAKS WITHIN THE BASE OF THE PARENT LONG-WAVE TROUGH OVER THE LOWER CO VALLEY WILL TRANSLATE NEWD INTO THE NRN AND CNTRL HIGH PLAINS BY 28/12Z. THIS UPPER-AIR SYSTEM WILL BE ATTENDED BY A MIGRATORY LEE CYCLONE WHICH WILL DEEPEN OVER ERN CO TODAY BEFORE RAPIDLY DEVELOPING NEWD ALONG A QUASI-STATIONARY BOUNDARY INTO THE UPPER MS VALLEY BY TONIGHT. A TRAILING COLD FRONT WILL ADVANCE SEWD THROUGH THE HIGH PLAINS...GRADUALLY OVERTAKING A DRYLINE WHICH WILL STRETCH FROM THE ERN CO LOW SWD INTO WRN TX DURING THE PEAK OF AFTERNOON HEATING. ...CNTRL/SRN PLAINS THIS AFTERNOON INTO TONIGHT... EARLY MORNING SATELLITE-DERIVED PW IMAGERY INDICATES THE NWD FLUX OF AN INCREASINGLY MOIST AIR MASS INTO CNTRL TX FROM THE NWRN GULF OF MEXICO WITHIN THE SRN EXTENSION OF THE NOCTURNAL LOW-LEVEL WIND MAXIMUM. A DYNAMICALLY FORCED SLY LLJ WILL MAINTAIN THIS PROCESS TODAY WITH DEWPOINTS RISING INTO THE 60S EAST OF THE DRYLINE AS FAR NORTH AS THE TX/OK PNHDLS AND PERHAPS PARTS OF WRN KS. AND WHILE MIDLEVEL LAPSE RATES WILL NOT BE PARTICULARLY STEEP...THIS MOISTURE INCREASE ALONG WITH DAYTIME HEATING WILL SUPPORT THE DIURNAL DESTABILIZATION OF THE WARM SECTOR WITH AFTERNOON MLCAPE VALUES RANGING FROM 500-750 J/KG OVER SWRN NEB/NWRN KS TO 1000-1250 J/KG ACROSS THE ERN TX PNHDL. SCATTERED STORM DEVELOPMENT IS ANTICIPATED BY MID TO LATE AFTERNOON AS LOW-LEVEL CONVERGENCE FROM THE SURFACE TRIPLE POINT SWD ALONG THE DRYLINE IS AUGMENTED BY INCREASING HEIGHT FALLS/DCVA DOWNSTREAM FROM THE MIDLEVEL TROUGH. THE STORM INITIATION WILL BE COINCIDENT WITH A NOTABLE STRENGTHENING OF THE DEEP-LAYER WIND FIELD AND RESULTANT VERTICAL SHEAR WITH A MIXTURE OF SUPERCELLS AND BOWING STRUCTURES POSSIBLE. LARGE HAIL POTENTIAL IS EXPECTED TO BE LIMITED BY THE MARGINALLY STEEP MIDLEVEL LAPSE RATES WITH THE HIGHEST PROBABILITY OF OCCURRENCE BEING ACROSS SRN PORTIONS OF THE SLIGHT RISK AREA WHERE A MORE MOIST BOUNDARY LAYER WILL CONTRIBUTE TO STRONGER INSTABILITY. OTHERWISE...INITIALLY SIZABLE T-TD SPREADS /ESPECIALLY ACROSS KS AND NEB/ WILL LIKELY PROMOTE COLD POOL GENERATION AND AN INCREASING RISK FOR DAMAGING WINDS. TORNADO POTENTIAL MAY INCREASE BY EARLY EVENING WITH ANY STORMS THAT CAN REMAIN MORE DISCRETE OWING TO THE CONTINUED STRENGTHENING OF LOW-LEVEL SHEAR AND GRADUALLY LOWERING LCL HEIGHTS. BY LATE EVENING INTO TONIGHT...STORMS ARE EXPECTED TO GROW UPSCALE INTO A BROKEN QLCS ALONG THE SURGING COLD FRONT WITH AN ISOLATED DAMAGING WIND THREAT PERSISTING UNTIL ABOUT 28/06Z FROM CNTRL NEB INTO WRN OK/NWRN TX. ..MEAD/MOSIER.. 09/27/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z |