DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1249 AM CDT THU APR 22 2004 VALID 221200Z - 231200Z THERE IS A MDT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 30 WSW DYR 55 NNW LIT 40 SSE MLC 35 NE DUA 20 NNW DUA 10 ENE ADM 25 NW ADM 20 SE OKC 45 NE OKC 20 SW BVO 35 S JLN 35 W UNO 40 ENE UNO 30 NNW POF 25 WSW CGI 40 ESE POF 30 WSW DYR. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 S MSV 20 NE TTN 35 NW BWI 45 ESE MGW 65 E BWG 45 WSW BNA 15 SSW MKL 55 SSW JBR 20 NNW LIT 35 S PGO 30 SSE DUA 40 NNW FTW 25 SE FSI 35 E CSM 35 SSW GAG 45 NNE AMA 25 WSW DHT 25 SSW CAO 20 WNW CAO 45 NNE CAO 30 NE EHA 45 SSE DDC 30 NW PNC 20 NW JLN 20 ESE TBN 30 W MVN 45 NNW EVV 35 WSW DAY 20 NE DAY 25 ENE PIT 25 NNW PSB 25 NW AVP 25 S MSV. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 SSW ACY 10 S ROA 45 WNW MSL 10 N ELD 35 SE PRX 30 S DAL 15 NNE SEP 20 ESE LTS 55 W CSM 40 S DHT 45 NNE 4CR 30 NW INW 30 WNW SGU 15 ENE EKO 50 NNW PIH 20 NE BZN 65 WSW GGW 60 N OLF ...CONT... 75 N GFK 45 N REJ 45 ESE 81V 25 ENE SNY 30 S BIE COU 25 NNE IND 30 S FKL 25 NNE BGM 20 SW RUT 20 SSE MPV 35 ENE EFK. ...THERE IS A MDT RISK OF SVR TSTMS FROM ERN OK ACROSS THE OZARKS/NRN AR TO SERN MO... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE TX/OK PNHDLS ACROSS THE MIDDLE MS VALLEY...ALONG THE OH VALLEY...TO SRN PA... ...SYNOPSIS... AN ACTIVE SPLIT FLOW REGIME WILL EVOLVE OVER THE CONUS ON THURSDAY WITH A STRONG FOUR CORNERS UPPER LOW DEVELOPING...AND AN AMPLIFYING NRN BRANCH SHORT WAVE TROUGH MOVING FROM SRN CANADA TO THE UPPER MS VALLEY. FAST CONFLUENT MID LEVEL FLOW WILL EXIST DOWNSTREAM FROM THESE TWO LARGE SCALE FEATURES...FROM THE MIDWEST TO THE ERN GREAT LAKES. PRIMARY BAROCLINIC ZONE OF INTEREST WILL BE AN EXTENSIVE SW TO NE ORIENTED QUASI-STATIONARY FRONT SITUATED FROM OK TO THE OH VALLEY. THE NRN PORTION OF THIS BOUNDARY WILL BE IN THE FORM OF A COLD FRONT WHICH WILL MOVE ACROSS NRN NEW ENGLAND DURING THE DAY. RELATIVELY LOW AMPLITUDE AND CONVECTIVELY ENHANCED MID LEVEL IMPULSES WILL INDUCE WEAK FRONTAL WAVES ALONG THE BOUNDARY FROM THE CONFLUENCE OF THE MS/OH RIVERS NEWD ALONG THE OH VALLEY AND INTO ERN PA. SUFFICIENT INSTABILITY SHOULD DEVELOP OVER THESE AREAS FOR AT LEAST SCATTERED SEVERE WEATHER DURING THE AFTERNOON AND EVENING. STRONGEST DESTABILIZATION WILL OCCUR ALONG AND SOUTH OF THE BOUNDARY OVER ERN OK/AR WHERE MORE VIGOROUS AND WIDESPREAD SEVERE WEATHER IS POSSIBLE LATE TODAY INTO EARLY FRIDAY. ...ERN OK ACROSS THE OZARKS TO THE MO BOOTHEEL... STRONG MID LEVEL IMPULSE AND DEVELOPING MCS NOW ACROSS NERN OK AND THE OZARKS WILL LIFT NEWD FROM THE MO BOOTHEEL AND ALONG THE LOWER OH VALLEY DURING THE LATE MORNING TO EARLY AFTERNOON. SHORT WAVE RIDGING AND SURFACE HEATING IN THE WAKE OF THIS SYSTEM...COUPLED WITH CONTINUING STRONG LOW LEVEL MOISTURE TRANSPORT FROM THE NRN GULF...AND PERSISTENT EML PLUME ON WLY MID LEVEL FLOW...WILL RESULT IN VERY UNSTABLE CONDITIONS ACROSS THE MDT RISK AREA BY AFTERNOON. DESPITE RELATIVELY WEAK UPPER LEVEL SUPPORT FOR ASCENT...OTHER THAN BROADLY DIFFLUENT MID/UPPER FLOW...STRONG LOW LEVEL FORCING NEAR THE BOUNDARY AND WEAKENING INHIBITION SHOULD PROVE ADEQUATE FOR STORM INITIATION. STRONG VERTICAL SPEED SHEAR WILL RESULT IN SUPERCELLS WITH THE POTENTIAL FOR NUMEROUS LARGE HAIL EVENTS...HIGH WINDS...AND PERHAPS A COUPLE OF TORNADOES. ...OH VALLEY TO SRN PA/NWRN NJ... LOW TO MID 60S F DEWPOINTS WILL EXIST IN A RELATIVELY NARROW AXIS ALONG THE STATIONARY FRONTAL ZONE FROM SRN IL TO SERN PA. POCKETS OF STRONGER SURFACE HEATING AND MODEST LAPSE RATES WILL CONTRIBUTE TO THE DEVELOPMENT OF MLCAPE OF 500-1000 J/KG. THIS INSTABILITY... COUPLED WITH ENHANCED CONVERGENCE/ASCENT NEAR FRONTAL WAVES AND ALONG THE BOUNDARY...SHOULD PROMOTE INCREASING TSTM DEVELOPMENT DURING THE AFTERNOON. KINEMATIC ENVIRONMENT IS CHARACTERIZED BY UNIDIRECTIONAL DEEP LAYER SHEAR WHICH SHOULD SUPPORT A FEW BETTER ORGANIZED CELLS/CLUSTERS WITH SOME HAIL AND WIND POTENTIAL INTO THE EVENING. ...TX/OK PNHDLS... DEEP LAYER ASCENT WILL INTENSIFY LATER IN THE PERIOD ACROSS THE SRN HIGH PLAINS AS DPVA INCREASES AHEAD OF STRONG FOUR CORNERS UPPER LOW. THIS ASCENT WILL MOST LIKELY OCCUR ATOP DEEPENING SURFACE-BASED COLD DOME AND POST FRONTAL AIRMASS ACROSS THE PNHDLS. LAPSE RATES...DYNAMIC FORCING...AND MOISTENING ACROSS THE REGION APPEAR SUFFICIENT TO SUSTAIN A FEW ELEVATED SUPERCELLS WITH LARGE HAIL BEING THE MAIN HAZARD. SOME OF THIS ACTIVITY MAY SPREAD INTO NWRN OK/SRN KS BEFORE DAYBREAK FRIDAY. ..CARBIN/CROSBIE.. 04/22/2004