ZCZC SPCSWODY1 ALL ACUS01 KWNS 261250 SPC AC 261250 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS. VALID 261300Z - 271200Z NO SVR TSTM AREAS FCST. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 55 NE FCA 45 ESE LWT 25 SE 81V 20 NE ANW 25 E YKN 25 NNW FRM 40 ENE MCW 15 SE CID UIN 40 NE MKC 30 S MHK 50 S HLC 45 NW GLD 15 WSW COS 60 SW ALS 25 SSW CEZ 20 S CDC 45 W P38 95 NNW WMC 50 ESE RDM 40 N OTH. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 45 SSW HOU 15 N SHV 45 W MEM 15 NNE CSV 35 S EKN 15 NE TTN 25 NW PWM BHB. ...SYNOPSIS... BROAD LONGWAVE TROUGH MOVING ACROSS THE CNTRL PORTION OF THE COUNTRY WILL CONTINUE TO MOVE EWD DURING MID-WEEK. A NRN STREAM IMPULSE CURRENTLY MOVING INTO THE MIDWEST WILL TURN NEWD INTO NEW ENGLAND/MIDDLE ATLANTIC STATES THIS AFTERNOON. MEANWHILE...A STRONGER DISTURBANCE WILL MOVE OVER THE GULF OF MX WATERS THIS AFTERNOON...TURN EAST AND HEAD TOWARDS FL BY THE END OF THE PERIOD. AT THE SURFACE...WAVY FRONT FROM NY-WV-NRN MS-SERN TX WILL MOVE SLOWLY SEWD. BY 27/12 UTC...THIS FRONT WILL HAVE MOVED OFF THE NEW ENGLAND COAST...BUT BE SLOWER TO MOVE ACROSS THE SERN STATES. MEANWHILE...OLD FRONT SITUATED ACROSS THE CNTRL GULF OF MX WILL WAVE BACK NORTH AS A WARM FRONT TOWARD FL BY THE END OF THE PERIOD. ...SCNTRL STATES INTO THE MIDDLE ATLANTIC STATES... TAIL END OF NRN STREAM IMPULSE WILL MOVE ACROSS THE MIDDLE ATLANTIC STATES THIS AFTERNOON DURING PEAK HEATING. PRIND THAT BOUNDARY LAYER WILL MOISTEN WITH SURFACE DEW POINTS INTO THE LOWER 50S BENEATH APPROXIMATELY MINUS 18C 5H TEMPERATURES. TSTMS ARE LIKELY TO DEVELOP ALONG LEE SIDE TROUGH/COLD FRONT OVER MD/VA/NC AND MOVE TOWARD THE MIDDLE ATLANTIC COASTLINE BY EVENING. STEEP MID TROPOSPHERIC LAPSE RATES /7.5-8 C/KM PER IAD/RNK RAOBS/ AND FAVORABLE DEEP LAYER SHEAR MAY CONTRIBUTE TO SOME STORM ORGANIZATION WITH ISOLD MARGINALLY SEVERE HAIL POSSIBLE. ALSO... RELATIVELY LARGE BOUNDARY LAYER DEW POINT DEPRESSIONS COULD AID IN LOCALLY DAMAGING DOWNBURST WINDS. ISOLD CHARACTER OF THE SEVERE THREAT PRECLUDES A CATEGORICAL SLGT RISK ATTM. OTHERWISE...FARTHER SW...COMPOSITE OUTFLOW BOUNDARY IS LIKELY TO STALL INVOF CNTRL AL-NWRN GA. IT APPEARS THAT HIGH CLOUD CANOPY WILL INHIBIT SIGNIFICANT AMOUNTS OF BOUNDARY LAYER HEATING/ DESTABILIZATION. THIS COMBINED WITH WEAKER DEEP LAYER SHEAR THAN EXPECTED FARTHER NORTH WILL LIKELY KEEP THE SEVERE THREAT MINIMAL. ...FL/SRN GA... ENSEMBLE OF SHORT TERM MODELS LENDS CONFIDENCE IN ISOLD TSTMS FORMING ALONG SEABREEZES THIS AFTERNOON. 12 UTC SOUNDINGS INDICATE A SUBSTANTIAL CAP IN THE 750-800 MB LAYER...BUT HEATING AND CONTINUED LOW LEVEL MOISTURE ADVECTION ALONG WITH LOCALIZED CONVERGENCE WILL LIKELY OVERCOME THE CINH BY MID-LATE AFTERNOON. THIS WILL BE AIDED ALONG BY VERTICAL MOTION SPREADING EWD AHEAD OF LEAD MIDLEVEL IMPULSE NOW OVER THE ERN GULF OF MX. DEEP LAYER SHEAR OF 35-45 KTS WILL FAVOR SOME STORM ORGANIZATION AND MINUS 14-16 5H TEMPERATURES COULD LEAD TO LARGE HAIL ALONG WITH AN ISOLD DAMAGING WIND GUST. THE THREAT SHOULD BE ISOLD ENOUGH TO PRECLUDE A CATEGORICAL SLGT RISK ATTM. CONFIDENCE IS LOW ON POSSIBLE APPROACH/DEVELOPMENT OF TSTMS LATE IN THE PERIOD. 00 UTC ETAKF/AVN AGREE THAT UPSTREAM IMPULSE WILL BE SLOWER TO APPROACH THE ERN GULF WITH 06 UTC ETA THE FARTHER EAST SOLUTION. BASED ON LAST EVENING HIGHEST 5H WIND AT EPZ...ON BACKSIDE OF LOW...SLOWER SOLUTIONS ARE PREFERRED. IF THIS IS THE CASE...DEVELOPMENT OF POSSIBLE SEVERE WEATHER OVER FL PENINSULA WILL WAIT UNTIL BEYOND DAY 1. IF A FASTER SOLUTION RESULTS...ISOLD DAMAGING WIND GUSTS/HAIL MAY DEVELOP OVERNIGHT...MAINLY ACROSS WRN/SRN FL. ..RACY/TAYLOR.. 03/26/03 NNNN |