SPC DAY-1 CONVECTIVE OUTLOOK
10 Feb 1998 - 19:45:37 UTC
ZCZC MKCSWODY1 000 ACUS1 KMKC 101945 MKC AC 101945 CONVECTIVE OUTLOOK...REF AFOS NMCGPH94O. VALID 101930Z - 111200Z REF WW NUMBER 0027...VALID TIL 2100Z REF WW NUMBER 0028...VALID TIL 2200Z REF WW NUMBER 0029...VALID TIL 0100Z THERE IS A HIGH RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 WSW GLS 30 N HOU 20 SW LFK 40 NW POE 30 NNE HEZ 30 NNW LUL 40 SE MEI 20 WNW PNS. THERE IS A MDT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 35 N GGG 30 NW HOT MEM TUP 45 SE MEI 30 NNW LUL 30 NNE HEZ 45 NW POE 20 SW LFK 35 N GGG. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 WNW PNS 45 SE MEI TUP MEM 30 NW HOT 35 NNW LIT 20 E JBR 45 WSW BNA 35 W CHA AUO 10 SE AQQ. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 ESE PSX 25 ENE CLL 40 E ACT DAL 30 W MLC UMN SGF 45 SSE SZL 20 NNW SZL 40 NE MKC 30 SW P35 3OI 25 W OTM 15 SSE ALO DBQ MMO 20 SW LAF LUK 35 E LEX 25 SE TYS 35 WNW CTY. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 50 E BLI 45 E PDX 25 WSW LMT 40 NW UKI. ...SEVERE THUNDERSTORM FORECAST DISCUSSION... UPPER LEVEL TROUGH FROM SERN NM SEWD ALONG THE RIO GRANDE RIVER HAS BEGUN TO LIFT NEWD PER LATEST SATELLITE PICTURES. THE INCREASING UPPER LEVEL DIVERGENCE IS RESULTING IN RAPIDLY FALLING SURFACE PRESSURES ACROSS SERN TX DURING THE PAST COUPLE OF HOURS. SURFACE LOW APPEARS TO HAVE DEVELOPED SW OF LFK ALONG STATIONARY FRONT EXTENDING NEWD ACROSS NERN TX /SRN AR. COLD FRONT SOUTH OF SURFACE LOW IS SURGING RAPIDLY EWD AS STRONG SUBSIDENCE AND COLD ADVECTION BEHIND UPPER LEVEL TROUGH SWEEPS INTO THE AREA AS EVIDENCED BY LARGE SURFACE PRESSURE RISES CENTERED NEAR SAT. SURFACE LOW IS EXPECTED TO CONTINUE TO DEEPEN RAPIDLY THIS AFTERNOON/EVENING DUE TO INCREASING UVV/LOW LEVEL CONVERGENCE IN RESPONSE TO INCREASING UPPER LEVEL DIVERGENCE. VERY STRONG DYNAMICAL FORCING...MODERATE INSTABILITY AND EXTREME VERTICAL SHEAR PROFILES SUGGEST THE POTENTIAL FOR A SIGNIFICANT SEVERE WEATHER EPISODE FROM EXTREME ERN TX EWD INTO MS THIS AFTERNOON AND EVENING. STRONG TO SEVERE THUNDERSTORMS ACROSS ERN TX WL CONTINUE TO MOVE RAPIDLY EASTWARD ACRS LA/SRN AR THIS AFTERNOON AND INTO MS/SERN LA AROUND 00Z. STRONG SOUTHERLY SURFACE WINDS OF 30-40 KT HAVE ADVECTED DEWPOINTS INTO THE LOWER/MID 60S IN ADVANCE OF STORMS. WITH STEEP MID LEVEL LAPSE RATES...AND SURFACE TEMPERATURES IN LOWER/MID 70S...CAPES RANGE FROM 1500-2000 J/KG SERN TX/SWRN LA. THE MODERATE INSTABILITY IS EXPECTED TO SPREAD NEWD THROUGH THE AFTERNOON. FORECAST VERTICAL SOUNDINGS FOR MODERATE/HIGH RISK AREA...VERIFIED BY VAD WIND PROFILES AT LCH AND IAH...SHOW VERY STRONG LOW LEVEL VEERING WINDS /50-70 KT/ RESULTING IN LONG CYCLONICALLY CURVED HODOGRAPHS. DEPENDING ON ACTUAL STORM MOTIONS...STORM RELATIVE HELICITIES VARY FROM 400 TO 800 M**2/S**2. THE PRONOUNCED PRESSURE RISE/FALL COUPLET OVER SOUTHEASTERN TEXAS WILL BACK AND ENHANCE THE LOW LEVEL WINDS CREATING A FAVORABLE MESOSCALE ENVIRONMENT FOR ROTATING STORMS. ALTHOUGH STORMS ARE EXPECTED TO ORGANIZE INTO A SQUALL LINE...FAVORABLE STORM RELATIVE FLOW SUGGEST POTENTIAL FOR NUMEROUS EMBEDDED ROTATING STORMS/SUPERCELLS/ WITH A POTENTIAL FOR A FEW VERY STRONG TORNADOES. BOW ECHOES ARE ALSO EXPECTED WITHIN THE LINE AND WITH VERY STRONG WINDS ALOFT...VERY DAMAGING WIND GUSTS MAY OCCUR. THE SQUALL LINE IS EXPECTED TO MOVE INTO PTNS OF TN/AL LATE TNGT WITH THE MAIN SEVERE WEATHER THREAT EXPECTED TO BE DAMAGING WINDS AS STRONG WINDS ALOFT BECOME MORE UNIDIRECTIONAL. ..IMY.. 02/10/98 NNNN
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