ZCZC SPCSWODY1 ALL ACUS01 KWNS 231627 SPC AC 231627 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1027 AM CST TUE DEC 23 2003 VALID 231630Z - 241200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 45 WSW HUM 35 SE MCB 30 SSE LUL 50 NNW CEW 15 SSE DHN 10 NW TLH 20 SSE TLH. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 SW CHS 25 SSE RDU 30 WNW DOV 20 SSE NEL. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 ESE 7R4 15 NW MCB 10 WSW GLH 15 SE MKL 45 NW CHA 20 ENE ATL 20 NNE AYS 35 SSE CTY. ...THERE IS A SLGT RISK OF SVR TSTMS ALONG THE GULF COAST... ...SYNOPSIS... PROGRESSIVE UPPER TROUGH IS FORECAST TO INTENSIFY AS IT MOVES FROM THE UPPER MS VALLEY TOWARD THE GREAT LAKES...AS SRN BRANCH SHORT WAVE TROUGH NOW OVER TX ACCELERATES EWD ACROSS THE GULF COAST STATES. AT THE SURFACE...A COLD FRONT FROM THE LOWER OH VALLEY INTO SERN LA WILL CONTINUE EWD...REACHING A WRN PA/WRN CAROLINAS/NWRN FL LINE BY THE END OF THE PERIOD. ...NRN GULF COAST STATES... A PRE-FRONTAL LINE OF CONVECTION IS EVIDENT FROM SRN MS INTO SERN LA AND THE NRN GULF OF MEXICO. THE AIR MASS AHEAD OF THE LINE IS MARGINALLY UNSTABLE AT BEST (MUCAPE AOB 500 J/KG) AS SURFACE DEW POINTS IN THE UPPER 50S ARE CONFINED TO THE IMMEDIATE GULF COAST AND COLDER AIR ALOFT IS LAGGING TO THE WEST OF THE SURFACE WARM SECTOR. VERTICAL WIND PROFILE FROM LIX VWP AHEAD OF THE CONVECTIVE LINE EXHIBITS STRONG WINDS THAT VEER AND INCREASE WITH HEIGHT...RESULTING IN STRONG LOW/MID LEVEL SHEAR WHICH CAN ENHANCE STORM ORGANIZATION AND INTENSITY. WITH TIME THE MODELS INDICATE THE LOW LEVEL WINDS WILL VEER TO A MORE SWLY DIRECTION AND GRADUALLY DIMINISH IN SPEED...BUT SHEAR SHOULD REMAIN SUPPORTIVE FOR STRONG CONVECTION. PRIMARY LIMITING FACTOR WILL BE MINIMAL CAPE IN ADVANCE OF THE LINE. VISIBLE IMAGERY INDICATES CLOUDS SPREADING DOWNSTREAM FROM THE THUNDERSTORM REGION WHICH WILL REDUCE MAGNITUDE OF DIURNAL HEATING. SURFACE DEW POINTS NEAR 60F MAY RETURN INLAND ALONG THE IMMEDIATE COAST OF SRN AL INTO NWRN FL AND CONTRIBUTE TO SBCAPE AOB 750 J/KG. DYNAMIC FORCING FOR LARGE SCALE ASCENT IS EXPECTED TO INCREASE LATER THIS AFTERNOON AND TONIGHT AS THE UPPER SHORT WAVE TROUGH STRENGTHENS AS IT ACCELERATES EWD ALONG THE GULF COAST. THIS WILL MAINTAIN SUPPORT FOR AN EMBEDDED SQUALL LINE CONTINUING EWD THROUGH THE NIGHT WITH THREAT FOR OCCASIONAL STRONG/SEVERE WIND GUSTS WITH ANY BOWING SEGMENTS THAT DEVELOP. MARGINAL INSTABILITY IS EXPECTED TO LIMIT OVERALL COVERAGE OF THE SEVERE THREAT. ..WEISS/RACY.. 12/23/2003 ...NOTICE... FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3. THE INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED. $$ |