ZCZC SPCSWODY1 ALL ACUS01 KWNS 100055 SPC AC 100055 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0755 PM CDT SAT AUG 09 2003 VALID 100100Z - 101200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 10 ENE OLU HSI MCK AKO SNY CDR 35 NW PIR 30 NNW HON BKX FSD 10 ENE OLU GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM CZZ RAL PMD EDW 40 NNW DAG DRA 60 SSW ELY DPG 10 ENE OGD IDA MQM 27U S06 35 NNW 63S ...CONT... 100 ENE CMX IWD 30 SSW DLH 35 ENE STC MKT FOD 15 ENE FNB HUT P28 45 SSE EHA 35 ENE CVS BGS 65 WSW SJT SAT 20 W HOU 25 NE HOU 20 SSE BPT GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 10 SSW AQQ 10 SW MGR AGS AHN RMG 10 S CKV BMG MIE 40 E TOL GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM TXK 30 NE TXK 30 ENE ELD 40 NNE MLU 20 WSW HEZ 25 ENE POE 45 SSE SHV SHV TXK ...THERE IS A SLGT RISK OF SVR TSTMS THIS EVENING ACROSS PARTS OF THE NORTH CENTRAL PLAINS.... ...CENTRAL PLAINS... SHORT WAVE TROUGH HAS PROGRESSED EAST OF LARGE-SCALE UPPER RIDGE AXIS INTO THE NORTHERN PLAINS...AND WILL CONTINUE TO SLOWLY TURN SOUTHEASTWARD ACROSS THE EASTERN DAKOTAS/MINNESOTA OVERNIGHT. PRIMARY FOCUS FOR CONVECTIVE DEVELOPMENT THROUGH THE REMAINDER OF THE PERIOD IS EXPECTED TO BE ZONE OF ENHANCED LOW-LEVEL WARM ADVECTION/CONVERGENCE...NOW CENTERED BETWEEN PIERRE SD AND NORTH PLATTE NE...AND PROGGED TO SHIFT ONLY SLOWLY SOUTHWARD. GROWING CLUSTER OF STORMS WITH VIGOROUS UPDRAFTS APPEARS LIKELY ACROSS THIS AREA NEXT FEW HOURS IN ENVIRONMENT WITH STEEP MID-LEVEL LAPSE RATES AND MEAN MIXED LAYER CAPE AROUND 2000 J/KG. GIVEN LOW RELATIVE HUMIDITIES IN LOWER/MID-LEVELS...EVIDENT IN 10/00Z SOUNDING FROM NORTH PLATTE...AS PRECIPITATION INCREASES...STRONG EVAPORATIVE COOLING MAY SUPPORT DOWNBURSTS AND EVOLUTION OF SURFACE COLD POOL. THIS WILL POSE RISK FOR DAMAGING SURFACE WIND GUSTS...MAINLY ACROSS WESTERN/CENTRAL NEBRASKA THIS EVENING. CLUSTER OF STORMS IS EXPECTED TO WEAKEN OVERNIGHT AS SOUTHERLY LOW-LEVEL JET REMAINS WEAK...AND ACTIVITY SLOWLY DEVELOPS SOUTHWARD INTO DRIER ENVIRONMENT OVER KANSAS...STABILIZING WITH LOSS OF DAYTIME HEATING. ...MONTANA... SHARPENING/BUILDING UPPER RIDGE ALONG AN AXIS FROM THE FOUR CORNERS REGION INTO THE LEE OF THE CANADIAN ROCKIES IS EXPECTED TO RESULT IN STRENGTHENING CAP ACROSS CENTRAL/EASTERN MONTANA. HOWEVER... MID-LEVEL JET STREAK/ASSOCIATED UPWARD VERTICAL MOTION FIELD NOW LIFTING OUT OF NORTHERN CALIFORNIA...WEST OF RIDGE AXIS...MAY STILL SUPPORT AN ISOLATED STRONG STORM WEST/NORTHWEST OF GREAT FALLS BY LATE EVENING. DESPITE STEEP MID-LEVEL LAPSE RATES...LACK OF MORE SUBSTANTIAL MOISTURE AND LOSS OF DAYTIME HEATING ARE EXPECTED TO PRECLUDE ANYTHING OTHER THAN A VERY ISOLATED/MARGINAL SEVERE THREAT. ...EASTERN STATES... NUMEROUS THUNDERSTORMS ARE STILL ONGOING ACROSS PARTS OF THE LOWER OHIO VALLEY...AND IN AREAS ALONG/EAST THE APPALACHIANS. THIS ACTIVITY IS EMBEDDED WITHIN VERY MOIST ENVIRONMENT WITH WEAK CONDITIONAL INSTABILITY...SUPPORTED BY WEAK LARGE-SCALE ASCENT ASSOCIATED WITH UPPER TROUGH AND EMBEDDED SHORT WAVE TROUGHS. WHILE FORCING FOR UPWARD VERTICAL MOTION MAY MAINTAIN CONVECTIVE DEVELOPMENT THROUGH THE NIGHT...STORMS WILL CONTINUE TO SLOWLY DECREASE IN NUMBER WITH LOSS OF SURFACE HEATING. ..KERR.. 08/10/2003 ...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. $$ |