May 27, 2011 1300 UTC Day 1 Convective Outlook | |
Updated: Fri May 27 12:51:08 UTC 2011 | |
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. |
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. |
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. |
SPC AC 271247 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0747 AM CDT FRI MAY 27 2011 VALID 271300Z - 281200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON FROM CENTRAL NC NWD TO CENTRAL PA/NY AND INTERIOR NEW ENGLAND... ...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON INTO TONIGHT FOR CENTRAL/ERN OK AND ADJACENT AREAS OF KS/MO/AR... ...CAROLINAS TO NEW ENGLAND TODAY... A COMPLEX MIDLEVEL TROUGH WITH MULTIPLE EMBEDDED VORTICITY CENTERS OVER THE APPALACHIANS WILL SLOWLY WEAKEN AND MOVE EWD/NEWD THROUGH TONIGHT. A WEAK ASSOCIATED SURFACE FRONT ALONG THE APPALACHIANS WILL MOVE LITTLE TODAY...WHILE REMNANT OUTFLOWS FROM OVERNIGHT CONVECTION GRADUALLY LOSE DEFINITION NEAR AND W OF THE I-95 CORRIDOR. MEANWHILE...A FAVORABLY MOIST ENVIRONMENT REMAINS ACROSS THE ATLANTIC COASTAL PLAIN WHERE BOUNDARY LAYER DEWPOINTS ARE IN THE MID-UPPER 60S THIS MORNING. SURFACE HEATING WITH THINNING CLOUDS WILL RESULT IN DESTABILIZATION ALONG AND E OF THE SLOW-MOVING FRONT...SUPPORTING THE DEVELOPMENT OF SCATTERED THUNDERSTORM CLUSTERS BY MID AFTERNOON FROM INTERIOR NEW ENGLAND TO CENTRAL NY/PA. AFTERNOON MLCAPE VALUES ARE EXPECTED TO REACH 1000-2000 J/KG IN THIS ZONE...WHERE A BELT OF 35-50 KT MIDLEVEL FLOW WILL PERSIST. THESE FACTORS WILL FAVOR ORGANIZED MULTICELL CLUSTERS AND SOME EMBEDDED SUPERCELL STRUCTURES...WITH AN ATTENDANT RISK FOR DAMAGING WINDS AND LARGE HAIL. THE SEVERE THREAT IS EXPECTED TO PEAK LATE THIS AFTERNOON...BUT THEN DIMINISH QUICKLY THIS EVENING WITH THE ONSET OF BOUNDARY LAYER COOLING AND CONTINUED WEAKENING OF THE SYNOPTIC WAVE. FARTHER S INTO THE CAROLINAS...THE THUNDERSTORM CLUSTER OVER THE SAVANNAH RIVER WILL LIKELY PERSIST AS A WEAK VORT MAX ROTATES NEWD AND THE DOWNSTREAM BOUNDARY LAYER DESTABILIZES. THOUGH LOW-MIDLEVEL FLOW HAS WEAKENED THIS MORNING PER REGIONAL VWP/S...FLOW WILL REMAIN SUFFICIENT FOR ORGANIZED MULTICELL CLUSTERS THROUGH MID AFTERNOON FROM NC NWD INTO VA. THE SLIGHT RISK HAS BEEN EXPANDED SWD ACROSS VA/NC TO ACCOUNT FOR THE RISK OF DAMAGING WINDS BY MIDDAY INTO THE AFTERNOON AS THE MORNING CONVECTION EXPANDS NEWD AND INTENSIFIES WITH DAYTIME HEATING. ...SRN PLAINS THIS AFTERNOON INTO TONIGHT... LEE CYCLOGENESIS WILL CONTINUE ACROSS THE SRN HIGH PLAINS IN ASSOCIATION WITH EMBEDDED SPEED MAXIMA EJECTING EWD OVER KS/OK ON THE SRN FRINGE OF THE STRONG MID-UPPER JET OVER THE CENTRAL ROCKIES. THIS WILL MAINTAIN A 25-40 KT SLY LLJ ACROSS CENTRAL/E TX AND OK...AND ALLOW A WARM FRONT ACROSS CENTRAL/SE TX TO MOVE NWD INTO OK THIS AFTERNOON/EVENING. MOISTURE ADVECTION AND DAYTIME HEATING/MIXING WILL PROMOTE DOWNWARD MIXING OF MOISTURE ALONG AND S OF THE WARM FRONT...WHICH COMBINED WITH AFTERNOON TEMPERATURES OF 85-90 F WILL SUPPORT MLCAPE VALUES OF 2000-3000 J/KG IN CENTRAL/ERN OK. A PRONOUNCED LOW-LEVEL WAA REGIME WILL BE PRESENT OVER OK...BENEATH 50 KT WLY/WNWLY FLOW ALOFT...RESULTING IN FAVORABLE VERTICAL SHEAR FOR RIGHT-MOVING SUPERCELLS. CONVECTIVE INITIATION IS MORE PROBABLE THIS AFTERNOON INTO TONIGHT INVOF SE KS. THIS AREA WILL BE N OF THE WARMEST PORTION OF THE EML...AND WILL BE ALONG THE PATH OF A LOW-AMPLITUDE SHORTWAVE TROUGH NOW OVER SW KS. FARTHER S IN OK...FORECAST SOUNDINGS SUGGEST A MORE CONDITIONAL SEVERE THREAT AS CONVECTIVE INHIBITION WEAKENS WITH DAYTIME HEATING/MIXING. IF ISOLATED STORMS FORM LATE THIS AFTERNOON/EVENING ACROSS CENTRAL/NE OK...THE ENVIRONMENT WILL FAVOR SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL AND ISOLATED DAMAGING GUSTS. WILL MAINTAIN ONLY LOW TORNADO PROBABILITIES GIVEN THE UNCERTAINTY REGARDING STORM FORMATION...AND RELATIVELY LARGE TEMPERATURE-DEWPOINT SPREADS IN THE BOUNDARY LAYER. ..THOMPSON/GARNER.. 05/27/2011 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z