SPC DAY-1 CONVECTIVE OUTLOOK
04 May 1999 - 16:50:15 UTC disclaimer "for information regarding the availability and timeliness of forecasts and products.
ZCZC MKCSWODY1 000 ACUS1 KMKC 041650 MKC AC 041650 CONVECTIVE OUTLOOK...REF AFOS NMCGPH94O. VALID 041630Z - 051200Z REF WW NUMBER 0208...VALID TIL 2100Z THERE IS A HIGH RISK OF SVR TSTMS OVER SERN AND EAST CENTRAL OK...MUCH OF WRN AND CENTRAL AR...NRN LA...AND NERN TX TO THE RIGHT OF A LINE FROM 30 S SHV 10 S TYR 25 E DAL DUA MLC 15 SE MKO FYV 45 S HRO 30 NE LIT 45 W GLH 35 SW MLU 30 S SHV. SURROUNDING THE HIGH RISK AREA...THERE IS A MDT RISK OF SVR TSTMS OVER THE REMAINDER OF ERN OK...N CENTRAL AND NERN TX...NRN AND CENTRAL LA...SRN MO...ERN AR...AND EXTREME WRN MS TO THE RIGHT OF A LINE FROM 10 NNE POE 45 N CLL ACT FTW ADM 55 NW MLC TUL SGF TBN 10 ESE P02 25 WSW MEM 15 W GWO 30 N HEZ 10 WSW ESF 15 WSW ESF 10 NNE POE. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 NW LCH 30 S AUS 25 W HDO 40 ENE DRT 50 NNE DRT 10 E SJT ABI 20 E FSI P28 25 SW HLC MCK 20 E LBF 50 WSW YKN 30 E 3SE 20 E DBQ 25 SSE MMO 35 SSW HUF 15 SSE CKV 40 NE CBM 30 WNW LUL 30 NNE LFT 25 NW LCH. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 55 NNW ELO 15 ESE RHI 25 E SBN 40 ESE LUK 25 NNE TYS 30 SSE RMG 20 WSW PNS ...CONT... 40 ENE CRP 15 WNW LRD ...CONT... 20 WNW DRT 35 WSW ABI 20 WNW SPS FSI 25 WSW P28 LBL 35 NE CAO 25 SSW LHX 25 NNW LHX 10 WNW LIC 40 E FCL 40 E CYS 20 WSW BFF 20 W AIA 50 ESE CDR 25 S PHP 55 WSW Y26 45 WNW BIS 65 NW MOT. ...SEVERE THUNDERSTORM FORECAST DISCUSSION... ACTIVE SEVERE WEATHER EPISODE EXPECTED TO CONTINUE INTO TONIGHT AS VIGOROUS NEGATIVE TILT UPPER TROUGH MOVING INTO THE CENTRAL HIGH PLAINS LIFTS NEWD TOWARD THE LOWER/MIDDLE MO RIVER VALLEY TONIGHT. DEEP SURFACE LOW OVER SWRN KS IS FORECAST TO LIFT NEWD TOWARD S CENTRAL NEB THIS EVENING CONTINUING INTO ERN NEB TONIGHT. DRY LINE ARCING SWD FROM THE LOW ACROSS CENTRAL OK THEN SSWWD ACROSS TX IS MOVING EWD IN ADVANCE OF A COLD FRONT MOVING ACROSS SERN NM AND W TX. THE COLD FRONT MAY ACCELERATE AND MERGE WITH THE DRY LINE OVER PARTS OF CENTRAL TX TONIGHT...WITH THE EFFECTIVE COLD FRONT REACHING EXTREME ERN PARTS OF KS/OK/NERN THROUGH SOUTH CENTRAL TX BY THE END OF THE PERIOD. SATELLITE IMAGERY AND SURFACE DATA ALSO SUGGEST A CONVECTIVE BOUNDARY FROM CENTRAL AR INTO EAST CENTRAL OK WHICH MAY ENHANCE THUNDERSTORM ORGANIZATION AND INTENSITY THIS AFTERNOON AND EVENING. ...OK/AR/NRN TX/NRN LA... STRONG/SEVERE STORMS ARE CURRENTLY DEVELOPING OVER ERN OK AND EXTREME N CENTRAL TX AHEAD OF A SQUALL LINE ALONG THE DRY LINE FROM CENTRAL OK INTO THE WRN PARTS OF CENTRAL TX. VISIBLE SATELLITE IMAGERY SHOWS AREAS OF DIMINISHING CLOUDS OVER CENTRAL TX AND SERN OK AHEAD OF THE DRY LINE. THIS WILL PERMIT STRONGER DIURNAL HEATING WHICH WILL CONTRIBUTE TO FURTHER AIR MASS DESTABILIZATION DURING THE AFTERNOON. STEEP MID LEVEL LAPSE RATES OF 7.5-8.5 C/KM NOTED ON THE 12Z SOUNDINGS FROM MUCH OF TX WILL SPREAD ENEWD AHEAD OF THE UPPER TROUGH...WITH AXIS OF MOST UNSTABLE AIR MASS /CAPE OF 2500-3500 J/KG/ EXTENDING FROM N CENTRAL TX INTO SERN OK AND SWRN AR. COUPLING OF LOW LEVEL JET OF 45-55 KT FROM NERN TX INTO ERN OK/WRN AR WITH 75-80 KT MID LEVEL JET STREAK LIFTING NEWD ACROSS SERN OK WILL CREATE VERY STRONG VERTICAL SHEAR PROFILES WITH SFC-6 KM SHEAR GREATER THAN 30 M/S AND HELICITY VALUES OF 250-500 M2/S2. THIS INDICATES CONTINUED POTENTIAL FOR SUPERCELL DEVELOPMENT...AND SUFFICIENT MID LEVEL STORM-RELATIVE FLOW OF 20-30 KT SUGGESTS CONDITIONS WILL BECOME INCREASINGLY FAVORABLE FOR TORNADO DEVELOPMENT WITH PERSISTENT SUPERCELLS...INCLUDING THE POSSIBILITY OF A FEW INTENSE TORNADOES. AMPLE DRY AIR ALOFT ABOVE THE MOIST BOUNDARY LAYER WILL ENHANCE THE DOWNDRAFT POTENTIAL WITH THREAT OF DAMAGING WIND GUSTS...AND LARGE INSTABILITY WILL AID IN FORMATION OF LARGE HAIL. SEVERE STORMS ARE EXPECTED TO CONTINUE DEVELOPING AND SPREADING EWD/ENEWD FROM NRN TX/ERN OK INTO PARTS OF AR AND NRN LA INTO TONIGHT. ...CENTRAL PLAINS INTO THE MID MS VALLEY... UNSTABLE AIR MASS EXTENDS NWD INTO MUCH OF KS/NEB/IA/MO WHERE SURFACE DEW POINTS ARE IN THE 55-60 RANGE. DRY LINE IS MOVING NEWD ACROSS WRN/CENTRAL KS WHERE CLEAR SKIES WILL ALLOW STRONG HEATING THIS AFTERNOON. LOW LEVEL CONVERGENCE IS EXPECTED TO INCREASE NEAR THE SURFACE LOW AND DRY LINE WHICH SHOULD SUPPORT ADDITIONAL CONVECTIVE DEVELOPMENT THIS AFTERNOON AND EVENING. DYNAMIC FORCING ALOFT ASSOCIATED WITH LEFT EXIT REGION OF THE UPPER LEVEL JET STREAK WILL ENHANCE LARGE SCALE ASCENT. A FEW SEVERE STORMS ARE LIKELY TO SPREAD ACROSS PARTS OF KS AND INTO NEB THIS AFTERNOON AND EVENING...CONTINUING INTO MO AND WRN IA LATE THIS AFTERNOON AND EVENING. AS THE LOW LEVEL JET LIFTS TOWARD THE MID MS VALLEY LATER TONIGHT STRONG/SEVERE STORMS MAY PERSIST THROUGH THE OVERNIGHT HOURS. PRIMARY THREAT IS EXPECTED TO BE LARGE HAIL AND OCCASIONAL STRONG WIND GUSTS...BUT ISOLATED TORNADOES ARE ALSO POSSIBLE OVER PARTS OF KS AND NEB INTO THE EVENING HOURS. A PUBLIC SEVERE WEATHER OUTLOOK WILL BE ISSUED BY 1730Z. ..WEISS/MCCARTHY.. 05/04/99 NNNN
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