ZCZC SPCSWODY1 ALL ACUS01 KWNS 021249 SPC AC 021248 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS. VALID 021300Z - 031200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 35 ENE SBY RIC FAY 50 NNW AYS DHN JAN MLU POE 45 NE HOU AUS ABI 65 N ABI SPS PRX DYR 25 ESE PAH BWG CRW 20 S MGW PSB IPT PSF ORH 30 S EWB. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 35 SSE LHX LHX 30 WSW LIC 20 SSE CYS BFF AIA 40 NNE IML 55 NNW GCK 25 N EHA 35 SSE LHX. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 4BK 50 ESE SLE EPH 40 NNW 63S ...CONT... 70 N GFK STC ALO 40 S IRK 20 NE COU STL MTO 45 S CGX SBN 45 N FWA FDY 10 W CMH PKB DUJ 25 NNE BGM BHB ...CONT... 35 ENE CRP LRD ...CONT... 35 NW DRT SJT PVW 40 SW DHT RTN 15 W DEN 40 WNW FCL 40 SSE RWL 30 NNW VEL PUC 35 NW GCN IGM 20 NNW SAN. --- SYNOPSIS --- PROGRESSIVE PATTERN IS FORECAST THROUGH PERIOD BETWEEN WELL-DEFINED UPPER LEVEL CYCLONIC CIRCULATIONS OFF CA COAST AND E OF CAROLINAS ATTM. LATTER SHOULD WEAKEN AND LIFT NEWD OVER ATLANTIC WHILE INTENSE PACIFIC CYCLONE APPROACHES NRN CA COAST...MOVING ONSHORE NEAR END OF PERIOD. SHORTWAVE TROUGH -- NOW EVIDENT ON MOISTURE CHANNEL IMAGERY OVER NRN IL/SRN WI...SHOULD MOVE EWD ACROSS LOWER MI AND LE REGION BY 03/00Z. AT SFC...COLD FRONT IS ANALYZED FROM NWRN PA LOW SWWD ACROSS EXTREME SRN IL/WRN KY AREA...CENTRAL AR...TO SRN/ERN PORTIONS DFW METROPLEX...THEN GENERALLY WWD INTO E- CENTRAL NM. FRONT MAY BE REINFORCED BAROCLINICALLY AS IT STALLS OVER CENTRAL/N-CENTRAL TX TODAY...BY COMBINATION OF CONTINUED PRESSURE RISES AND CAA TO ITS N WITH NWD-MOVING OUTFLOW BOUNDARY TO ITS S. --- CENTRAL/NRN TX --- OUTFLOW BOUNDARY FROM OVERNIGHT MCS -- NOW EVIDENT FROM HILL COUNTRY SE SJT...SEWD ACROSS HOU AREA -- SHOULD LIFT NWD SLOWLY TOWARD ABI...ACT AND PERHAPS EVEN METROPLEX. MAIN FOCUS FOR SEVERE POTENTIAL IS THIS BOUNDARY FROM DRYLINE INTERSECTION SEWD. EXPECT DEEP-LAYER SHEAR AROUND BOUNDARY TO BE AT LEAST MARGINALLY FAVORABLE FOR STORM ROTATION WITH 30-40 KT 0-6 KM AGL SHEARS POSSIBLE AND MOTION OF RIGHT-SPLITS DOWN BOUNDARY. EXPECT HEAVY- PRECIP CHARACTER AND PERHAPS QUICK OUTFLOW-DOMINANCE WITH BOW ECHO TRANSITION POSSIBLE...CONSIDERING WEAK LOW-MIDLEVEL FLOW ABOVE BOUNDARY AND DEEP/MOIST INFLOW LAYER FOR ANY CELLS NEAR GULF AIR MASS. EXTREME INSTABILITY POSSIBLE WITH 70S F SFC DEW POINTS AND 8-9 DEG C/KM MIDLEVEL LAPSE RATES CONTRIBUTING TO MLCAPES 3500-5000 J/KG BY LATE AFTERNOON...SUPPORTING POTENTIAL FOR SEVERE HAIL/GUSTS. VERY LARGE/DAMAGING HAIL MAY OCCUR. TORNADO POTENTIAL APPEARS MORE BRIEF AND CONDITIONAL ATTM...BUT ALSO WILL BE RELATIVELY MAXIMIZED NEAR BOUNDARY. ORGANIZED MULTICELLS AND DISCRETELY PROPAGATING STORMS ARE POSSIBLE S OF BOUNDARY CONSIDERING VERY WEAK LOW LEVEL FLOWS OF LESS THAN 10 KT EXPECTED...LOW 0-3 KM SHEAR VALUES AND SMALL HODOGRAPHS. --- SRN/CENTRAL APPALACHIANS TO SRN NEW ENGLAND --- SCATTERED TSTMS POSSIBLE IN CLUSTERS NEAR FRONT FROM PA TO SRN NEW ENGLAND. WIDELY SCATTERED TSTMS POSSIBLE OVER MOUNTAINS AND INVOF PIEDMONT TROUGH THIS AFTERNOON S OF FRONT. PRIMARY THREATS ARE HAIL/GUSTS NEAR SEVERE LEVELS...WITH SOMEWHAT MORE CONCENTRATED COVERAGE OF SEVERE EXPECTED INVOF FRONT WHERE LOW LEVEL ASCENT WILL BE RELATIVELY MAXIMIZED. SIGNIFICANT SFC HEATING/DESTABILIZATION EXPECTED THIS AFTERNOON...WITH INCREASING DEW POINT DEPRESSIONS LEADING TO INVERTED-V BOUNDARY LAYER THERMODYNAMIC SOUNDING PROFILES. MLCAPE 1500-2500 J/KG IS ANTICIPATED OVER PIEDMONT FROM GA NEWD INTO WRN VA. NEARLY UNIDIRECTIONAL VERTICAL WIND PROFILES AND WEAK LOW-MIDLEVEL SHEAR SUGGEST CONVECTIVE MODE PRIMARILY BEING ORGANIZED MULTICELLS...WITH POTENTIAL FOR BOWS AND MCS CONCENTRATED IN NEARLY ZONAL CORRIDOR ALONG INSTABILITY GRADIENT ASSOCIATED WITH FRONTAL ZONE. ACTIVITY SHOULD WEAKEN WITH LOSS OF DIABATIC HEATING AND MLCAPE DURING EVENING HOURS. --- LOWER MS VALLEY...GULF COAST STATES --- SCATTERED TSTMS IN CLUSTERS ARE EXPECTED TO DEVELOP INVOF FRONTAL BOUNDARIES THIS AFTERNOON AND SWD INTO WARM SECTOR...IN ENVIRONMENT OF WEAK LOW-MIDLEVEL SHEAR BUT FAVORABLE INSTABILITY WITH AFTERNOON MLCAPE 2000-2500 J/KG POSSIBLE. POTENTIAL EXISTS FOR SEVERAL MESOBETA SCALE TSTM COMPLEXES TO DEVELOP BY LATE AFTERNOON...LASTING ALMOST TO 06Z WITH POTENTIAL FOR WET MICROBURSTS...A FEW BETTER-ORGANIZED BOW ECHO WIND EVENTS AND OCCASIONAL HAIL. SEVERE POTENTIAL...WHILE GENERALLY MAXIMIZED INVOF SYNOPTIC FRONTS -- WILL BE CONCENTRATED NEAR AND GREATLY DEPENDENT ON LOCATION OF SFC WIND SHIFTS...CONFLUENCE LINES AND OUTFLOW BOUNDARIES YET TO BE PRODUCED. --- CENTRAL HIGH PLAINS --- ISOLATED SUPERCELLS WITH ENHANCED HAIL POTENTIAL ARE POSSIBLE. 50-60 KT 0-6 KM AGL SHEAR AND STRONG VEERING WITH HEIGHT ARE FCST. VERTICAL SHEAR PROFILES WILL BE PRESENT TO SUPPORT SEVERE TSTMS E OF FRONT RANGE TODAY AND INTO PORTIONS WRN KS/SWRN NEB. BY MID- LATE AFTERNOON...SFC-BASED TSTMS ARE OPTIMALLY POSSIBLE WITH MLCAPE 1000-1500 J/KG...USING DEW POINTS UPPER 30S TO MID 40S. MOST AREAS SHOULD EXPERIENCE LESS CAPE AND THERE ARE DOUBTS ABOUT EXTENT OF AIR MASS RECOVERY IN POST-FRONTAL REGIME. HOWEVER...THERE SHOULD BE ENOUGH OROGRAPHICALLY AIDED INITIATION TO RESULT IN AT LEAST MARGINAL CATEGORICAL SEVERE THREAT. ..EDWARDS/NADEN.. 05/02/03 NNNN |