ZCZC SPCSWODY1 ALL ACUS01 KWNS 190557 SPC AC 190557 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1257 AM CDT TUE AUG 19 2003 VALID 191200Z - 201200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 60 NNE MQT 25 WNW DBQ 35 WSW OTM 15 ENE MHK 30 W HUT 25 SSW DDC 50 WNW GCK 35 NW LBF 40 WNW YKN 25 NNW ATY 20 WNW BJI INL GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 WSW CZZ 20 ENE RAL 15 N LAX 50 NNE BFL 40 N FAT 15 S TVL 35 S WMC 70 NNW WMC 40 NNE LMT 10 SE RDM 15 NNE PDT 50 NE 4OM GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 SSE SLC 25 NW 4HV 60 WSW FMN DRO 50 NNE DRO 45 W COS 25 SE FCL 30 NNW CYS 20 N CPR 50 ESE BIL 45 ESE LVM 20 SW JAC 35 SSE SLC GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 125 ENE APN PLN 35 SSE MTW 10 W RFD 30 SSW SPI 10 SW PAH 30 SSW CKV 35 S BLF 20 ENE CLT 30 S SOP 30 SW GSB 45 ENE RWI 30 ESE ECG GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 10 NW LRD 40 S JCT 35 ENE ABI 30 WSW OKC 45 N CSM 35 ENE AMA 15 WNW PVW 25 NNE HOB 55 W MRF ...THERE IS A SLGT RISK OF SVR TSTMS FROM SWRN KS NEWD INTO THE UPPER MS VALLEY / WRN GREAT LAKES REGION... ...SYNOPSIS... FAIRLY PROGRESSIVE MID-LEVEL FLOW PATTERN FORECAST ACROSS THE NRN HALF OF THE CONUS THIS PERIOD AS ERN U.S. TROUGH DEPARTS...THE TROUGH OVER THE ROCKIES SHIFTS EWD INTO CENTRAL AND NRN PLAINS... AND STRONG SHORT-WAVE TROUGH JUST OFF THE PAC NW COAST MOVES RAPIDLY EWD INTO THE NRN ROCKIES BY THE END OF THE PERIOD. A SURFACE COLD FRONT IS FORECAST TO MOVE EWD ACROSS THE PAC NW / NRN ROCKIES AHEAD OF UPPER TROUGH...BUT ELSEWHERE SURFACE PATTERN IS FORECAST TO BE RELATIVELY WEAK. ...CENTRAL PLAINS NEWD INTO THE MIDDLE MO AND UPPER MS VALLEYS... WIDESPREAD CONVECTION IS ONGOING ATTM ACROSS KS / NEB / IA / SRN MN AHEAD OF UPPER TROUGH IN BROAD AREA OF WARM ADVECTION ASSOCIATED WITH LOW-LEVEL JET. STORMS WILL LIKELY BE ONGOING AT THE START OF THE PERIOD...BUT MAY WEAKEN SOMEWHAT EARLY IN THE PERIOD BEFORE STORMS REDEVELOP / INTENSIFY -- LIKELY INVOF CONVECTIVE OUTFLOW BOUNDARY / BOUNDARIES AS AIRMASS DESTABILIZES. LIKELY AREAS FOR STORM DEVELOPMENT ARE DIFFICULT TO DETERMINE ATTM DUE TO ONGOING CONVECTION AND WEAK SYNOPTIC-SCALE SURFACE PATTERN. HOWEVER...BELT OF 20 TO 40 KT SWLY MID-LEVEL FLOW AHEAD OF TROUGH WILL CONTRIBUTE TO SUFFICIENT DEEP-LAYER SHEAR FOR MULTICELL CLUSTERS AND A FEW SUPERCELLS. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN SEVERE THREATS. ALTHOUGH OVERALL STORM COVERAGE MAY DIMINISH OVERNIGHT...CLUSTERS OF STORMS AND ASSOCIATED SEVERE THREAT SHOULD PERSIST THROUGH THE END OF THE PERIOD AS SSWLY LOW-LEVEL JET REINTENSIFIES OVERNIGHT FROM THE SRN HIGH PLAINS NNEWD INTO THE WRN GREAT LAKES REGION. ...PAC NW / NRN ROCKIES... WITH A STRONG SHORT-WAVE TROUGH AND ASSOCIATED 50 KT MID-LEVEL JET STREAK PROGGED TO MOVE EWD ACROSS THE PAC NW AND INTO THE NRN ROCKIES...A LOW PROBABILITY SEVERE THREAT APPEARS TO EXIST. MAIN LIMITING FACTOR WILL BE INSTABILITY...WHICH IS FORECAST TO BE MARGINAL AT BEST. NONETHELESS...STRENGTH OF UPPER FEATURE AND STRONG MID-LEVEL FLOW SUGGESTS THAT DAMAGING WINDS / MARGINALLY- SEVERE HAIL WILL BE POSSIBLE WITH ANY STORM WHICH CAN PERSIST. ...SERN CONUS... DESPITE VERY WEAK DEEP-LAYER SHEAR...VERY MOIST LOW-LEVEL AIRMASS WILL COMBINE WITH DAYTIME HEATING TO RESULT IN MODERATELY-UNSTABLE AIRMASS BY AFTERNOON. STORMS WILL LIKELY DEVELOP INVOF WEAK SURFACE BOUNDARY AS SUBTLE MID-LEVEL FEATURE NOW OVER ERN KY MOVES SWD. STORMS SHOULD REMAIN LARGELY DISORGANIZED...ALTHOUGH AMOUNT OF INSTABILITY AND WEAK SURFACE AND UPPER FEATURES MAY ALLOW LOCALLY DAMAGING WINDS / MARGINALLY-SEVERE HAIL WITH A FEW STRONGER PULSE STORMS / WEAK MULTICELL CLUSTERS. ..GOSS.. 08/19/2003 ...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. $$ |