SPC 1730Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT WED JUN 27 2012 VALID 281200Z - 291200Z ...NO SVR TSTM AREAS FORECAST... ...GREAT LAKES/OH VALLEY... DOMINANT UPPER HIGH WILL REMAIN IN PLACE ACROSS THE CONUS INTO THE DAY2 PERIOD WITH FLATTENING EXPECTED NEAR THE U.S. CANADIAN BORDER AS MB/ON SHORT-WAVE TROUGH TOPS THE RIDGE AND BEGINS TO DIGS SEWD LATE IN THE PERIOD. VERY WARM EML HAS OVERSPREAD MUCH OF THE COUNTRY AND A STRONG CAP WILL LIKELY PROVE HOSTILE TOWARDS DEEP CONVECTION...ESPECIALLY ORGANIZED ROBUST DEEP CONVECTION. ONE EXCEPTION WILL BE ALONG THE NERN EDGE OF THE STEEP LAPSE RATE PLUME WHICH HAS BEEN DISPLACED UNUSUALLY FAR DOWNSTREAM ACROSS THE GREAT LAKES/OH VALLEY. GIVEN THE VERY WARM MID LEVEL TEMPERATURES IT APPEARS SFC-BASED THUNDERSTORMS WILL STRUGGLE TO DEVELOP AS CONVECTIVE TEMPERATURES WILL LIKELY NOT BE REACHED AHEAD OF THE COLD FRONT. FOR SFC PARCELS TO FREELY CONVECT READINGS WILL NEED TO RISE WELL ABOVE 100F. ADDITIONALLY...LATEST MODEL GUIDANCE IS LIKELY TOO AGGRESSIVE REGARDING FORECAST SFC DEW POINTS IN THE MID 70S AHEAD OF THE WIND SHIFT. EVEN SO...THERE IS SOME CONCERN THAT FRONTAL ASCENT/WEAK WARM ADVECTION ALOFT WILL ENCOURAGE POST-FRONTAL ELEVATED CONVECTION THAT COULD ATTAIN ROBUST LEVELS GIVEN THE STEEP LAPSE RATES. THE MOST LIKELY AREA FOR THIS WILL BE ACROSS THE LOWER GREAT LAKES AFTER DARK WITH SUBSEQUENT SEWD MOVEMENT/DEVELOPMENT ALONG THE ERN EDGE OF STRONG EML THROUGH THE UPPER OH VALLEY INTO PORTIONS OF CNTRL PA BY MORNING. FOR THIS REASON HAVE EXPANDED 5% SEVERE PROBS TO ACCOUNT FOR STRONG ELEVATED TSTMS DURING THE LATTER HALF OF THE PERIOD. ...CNTRL PLAINS/MID MS VALLEY... VERY WARM EML WILL HOLD ACROSS THE REGION WITH LITTLE REASON TO BELIEVE THERMAL PROFILES WILL COOL APPRECIABLY. GIVEN THE OBSERVED MID LEVEL TEMPERATURES INTENSE BOUNDARY LAYER HEATING WILL BE REQUIRED TO FORCE SFC-BASED CONVECTION ALONG THE FRONT THURSDAY. HAVE ADJUSTED THE 5% SEVERE PROBS SWD TO ACCOUNT FOR LATE AFTERNOON FRONTAL POSITION ALONG THE IA/MO BORDER...WWD ALONG THE KS/NEB BORDER AT PEAK HEATING. ANY STORMS THAT FORM ALONG THE WIND SHIFT WILL BE HIGH BASED AND POSE PRIMARILY A LOCALLY DAMAGING WIND THREAT. ..DARROW.. 06/27/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_1730.html
Be First to Comment