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| Probability of severe weather within 25 miles of a point. Hatched Area: 10% or greater probability of significant severe within 25 miles of a point. |
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SPC AC 260507 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1207 AM CDT WED JUN 26 2013 VALID 271200Z - 281200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS ERN KS/WRN MO... ...SYNOPSIS... SIGNIFICANT MID LEVEL FLOW IS EXPECTED TO TOP THE WRN U.S. RIDGE OVER THE NRN PLAINS/UPPER MS VALLEY FRIDAY WHICH WILL FACILITATE THE DEEPENING OF ERN U.S. TROUGH. WHILE THE STRONGEST FLOW ALOFT WILL REMAIN WITHIN NWLY FLOW ON BACK SIDE OF TROUGH...MODEST FLOW SHOULD EXTEND SWD INTO THE GULF STATES AND ACROSS THE MIDDLE ATLANTIC INTO SRN NEW ENGLAND. SCT CONVECTION IS EXPECTED TO DEVELOP IN EACH OF THESE REGIONS AND ISOLATED DAMAGING WINDS OR PERHAPS HAIL COULD BE NOTED WITHIN POCKETS OF STRONGEST INSTABILITY. ...KS/MO... LATEST MODEL GUIDANCE CONTINUES EARLIER TRENDS REGARDING THE LIKELIHOOD FOR CONVECTIVE DEVELOPMENT ALONG ERN PLUME OF STEEP LAPSE RATES WITHIN WARM ADVECTION ZONE. EARLY IN THE PERIOD VEERED LLJ SHOULD BE FOCUSED ACROSS NEB WHICH SHOULD BE MOSTLY RESPONSIBLE FOR ELEVATED TSTM DEVELOPMENT BY DAYBREAK ALONG NOSE OF LLJ. THIS ACTIVITY SHOULD THEN SPREAD/DEVELOP SSEWD ALONG WARM ADVECTION CORRIDOR ALONG THE MO RIVER. INTENSE BOUNDARY LAYER HEATING IS EXPECTED ACROSS KS AND THERE IS REASON TO BELIEVE SFC READINGS MAY TOP 100F BY 18Z ACROSS MUCH OF CNTRL/WRN PARTS OF THE STATE. BY 21Z NAM FORECAST SOUNDING AT SLN SUGGESTS SFC TEMPERATURE MAY HIT 108F AND THIS PLUME OF AIR SHOULD ADVECT INTO WRN FLANK OF AFOREMENTIONED ELEVATED THUNDERSTORM CLUSTERS. THERE IS SOME CONCERN THAT AS BOUNDARY LAYER DEEPENS AND CONVECTIVE TEMPERATURES ARE BREACHED THE WARM ADVECTION CONVECTION COULD INTENSIFY AND BEGIN TO SURGE SSEWD. PROXIMITY TO INTENSE HEAT PLUME COULD AID IN SIGNIFICANT DOWNBURST POTENTIAL AS MID LEVEL FLOW IS EXPECTED TO INCREASE TO 30-40KT BY AFTERNOON. HAVE INCREASED SEVERE PROBS ACROSS ERN KS/WRN MO TO ACCOUNT FOR THIS POTENTIAL AND IF A SEVERE MCS EVOLVES IT COULD PROGRESS CONSIDERABLY FARTHER DOWNSTREAM INTO SRN MO/NRN AR AFTER DARK. PROBABILITIES WILL BE ADJUSTED ACCORDINGLY IN LATER OUTLOOKS. ...UPPER GREAT LAKES/MIDWEST... 60-70KT 500MB SPEED MAX WILL TOP THE WRN U.S. RIDGE AND DIG SEWD ACROSS SRN MN/NERN IA INTO NRN IL BY 18Z. LARGE SCALE FORCING WITHIN EXIT REGION OF THIS FEATURE SHOULD AID DEEP CONVECTION ACROSS WI AS TEMPERATURES WARM INTO THE LOWER 80S BY NOON. ISOLATED THUNDERSTORMS ARE EXPECTED TO EVOLVE WITHIN A UNIFORM NWLY FLOW REGIME BUT ONE THAT IS CONSIDERABLY SHEARED. GIVEN THE STEEP LAPSE RATE ENVIRONMENT ROBUST UPDRAFTS/DOWNDRAFTS CAN BE EXPECTED. IF STORM COVERAGE IS SUFFICIENT THEN A SLGT RISK MAY NEED TO BE ADDED TO THIS REGION. CONVECTION SHOULD SPREAD/DEVELOP SWD INTO IL DURING THE AFTERNOON HOURS. HAIL/WIND MAY ACCOMPANY THIS ACTIVITY. ...MIDDLE ATLANTIC... LATEST SHORT-RANGE MODEL GUIDANCE HAS REGRESSED REGARDING INSTABILITY ACROSS THE MIDDLE ATLANTIC INTO SERN NY DURING THE DAY2 PERIOD. WITH ONLY MODEST MID LEVEL SWLY FLOW EXPECTED ACROSS THIS REGION IT APPEARS FORECAST INSTABILITY AND WEAK LAPSE RATE ENVIRONMENT SHOULD BE A BIT TOO WEAK TO WARRANT MORE THAN 5 PERCENT SEVERE PROBS FOR LOCALLY DAMAGING WIND GUSTS WITH DIURNALLY ENHANCED CONVECTION. ..DARROW.. 06/26/2013 CLICK TO GET WUUS02 PTSDY2 PRODUCT NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z |