SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0753 AM CDT TUE JUL 31 2012 VALID 311300Z - 011200Z ...THERE IS A SLGT RISK OF SVR TSTMS TODAY FROM SRN MS/AL TO THE SE ATLANTIC COAST... ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON FOR SE IL...SRN INDIANA...EXTREME NRN KY...AND SW OH... ...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON INTO EARLY TONIGHT FOR NRN ND AND NW MN... ...SE STATES TODAY... A REMNANT MCS IS MOVING SWD OVER CENTRAL AL THIS MORNING...WITH NEW STORMS FORMING ON AN APPARENT OUTFLOW BOUNDARY FROM SW GA INTO THE FL PANHANDLE. MULTIPLE BOUTS OF STORMS DURING THE NIGHT HAVE STABILIZED MUCH OF CENTRAL/NRN AL...SUCH THAT ADDITIONAL SEVERE STORMS ARE UNLIKELY IN THESE AREAS. WITH THE NEW CONVECTION ALREADY FORMING ACROSS THE FL PANHANDLE...AND WITH WIDESPREAD CLOUDS/RAIN UPSTREAM...THE DEGREE OF ADDITIONAL DESTABILIZATION WILL BE LIMITED TODAY FROM SW GA AND THE FL PANHANDLE TO SE AL. MEANWHILE...A MIDLEVEL SHORTWAVE TROUGH WILL CONTINUE TO MOVE SSEWD FROM NRN AL/NW GA THROUGH THE AFTERNOON...WITH THE STRONGER MIDLEVEL FLOW/GRADIENTS REMAINING ON THE W SIDE OF THE TROUGH...IN THE AREAS IMPACTED BY CONVECTION THIS MORNING. THE POOR PHASING OF THE STRONGER FLOW AND STRONGER SURFACE HEATING...AS WELL AS EARLY ARRIVAL OF THE CLOUDS/CONVECTION ACROSS SRN AL/WRN FL PANHANDLE...SUGGEST THAT THE DAMAGING WIND RISK WILL BE SOMEWHAT REDUCED COMPARED TO EARLIER EXPECTATIONS. STILL...THE NEW STORMS ACROSS THE FL PANHANDLE COULD POSE AN ISOLATED DAMAGING WIND RISK THIS MORNING...WHILE THE CENTRAL AL CLUSTER COULD DEVELOP PREFERENTIALLY SWWD TOWARD THE RICHER MOISTURE/ STRONGER INSTABILITY ACROSS SW AL/MS...WHERE DEEP-LAYER VERTICAL SHEAR WILL BE SUFFICIENT TO MAINTAIN THE STORMS. OTHER DEVELOPMENT COULD ALSO OCCUR FARTHER E ACROSS S GA/N FL...BUT VERTICAL SHEAR WILL BE WEAKER COMPARED TO AREAS FATHER W/NW. ...CENTRAL/SRN INDIANA AND WRN OH THIS AFTERNOON... THE REMNANTS OF OVERNIGHT CONVECTION WILL SLOWLY WEAKEN THIS MORNING ACROSS NRN INDIANA...THOUGH OUTFLOW WITH THIS CONVECTION MAY PERSIST INTO EARLY AFTERNOON WHILE MOVING SWD INTO W CENTRAL OH...CENTRAL INDIANA...AND NE/E CENTRAL IL. SURFACE HEATING AND SOME MOISTENING FROM THE W WILL OCCUR IN ADVANCE OF THE OUTFLOW BOUNDARY...AS WELL AS IN ADVANCE OF A WEAK SYNOPTIC COLD FRONT MOVING SEWD FROM NW IL AND LOWER MI /ASSUMING THE COLD POOL WEAKENS/. NEW THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE BY EARLY-MID AFTERNOON ALONG THE WEAK SURFACE BOUNDARIES...WHERE MODERATE INSTABILITY WILL COINCIDE WITH NWLY BULK SHEAR OF 25-30 KT. THUS...A FEW STORMS COULD PRODUCE DAMAGING WINDS AND MARGINALLY SEVERE HAIL THIS AFTERNOON. ...NRN ND/NW MN THIS AFTERNOON/TONIGHT... AN INITIAL EMBEDDED SPEED MAX AND ASSOCIATED THUNDERSTORM CLUSTER WILL CONTINUE TO MOVE EWD OVER ND THIS MORNING. STRONG SURFACE HEATING IN THE WAKE OF THIS CONVECTION WILL LEAD TO THE DEVELOPMENT OF INVERTED-V PROFILES IN AN ENVIRONMENT OF MODERATE INSTABILITY AND VERTICAL SHEAR ACROSS NRN ND...IN ADVANCE OF A SERIES OF LOW-AMPLITUDE SHORTWAVE TROUGHS CRESTING THE HIGH PLAINS RIDGE. THUNDERSTORM INITIATION WILL BE POSSIBLE LATE THIS AFTERNOON/EVENING ALONG A SURFACE TROUGH ACROSS CENTRAL ND...AND CONVECTION WILL SPREAD EWD LATE THIS EVENING THROUGH EARLY TONIGHT. ISOLATED DAMAGING GUSTS SHOULD BE THE MAIN SEVERE THREAT...THOUGH MIDLEVEL LAPSE RATES WILL BE STEEP ENOUGH TO SUPPORT SOME RISK FOR ISOLATED LARGE HAIL. ...ERN CO/WRN KS THIS EVENING... SIMILAR TO PREVIOUS DAYS...WEAK EMBEDDED MIDLEVEL PERTURBATIONS WILL ROTATE EWD FROM CO TOWARD NW KS...AROUND THE NRN PERIPHERY OF THE UPPER HIGH. RELATIVELY WIDESPREAD CONVECTION OVERNIGHT...WETTING RAINS...AND LINGERING CLOUDS WILL LIKELY SLOW SURFACE HEATING SOMEWHAT ACROSS CO COMPARED TO PREVIOUS DAYS. STILL...THERE WILL BE THE POTENTIAL FOR ANOTHER CLUSTER OF RELATIVELY HIGH-BASED STORMS TO MOVE EWD FROM CO TO WRN KS LATE THIS AFTERNOON INTO EARLY TONIGHT...WITH AN ACCOMPANYING RISK FOR ISOLATED STRONG OUTFLOW GUSTS. ...LOWER CO RIVER VALLEY LATER THIS AFTERNOON... SURFACE HEATING AND A BELT OF SOMEWHAT STRONGER SLY/SELY FLOW ON THE E SIDE OF A WEAK MIDLEVEL LOW COULD PROMOTE STRONG THUNDERSTORM DEVELOPMENT THIS AFTERNOON INVOF THE CA/AZ/NV BORDER. ISOLATED STRONG OUTFLOW GUSTS WILL BE THE MAIN CONCERN. ..THOMPSON/LEITMAN.. 07/31/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1300.html
Be First to Comment