ZCZC SPCSWODY1 ALL ACUS01 KWNS 271247 SPC AC 271247 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0747 AM CDT WED AUG 27 2003 VALID 271300Z - 281200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 40 NE ELO 30 SE BRD 15 SW FSD 60 SSE 9V9 55 NW MHN 55 SSE 81V 55 N REJ 75 NE ISN THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 15 E ORF 25 NNW LYH 10 ESE LUK 35 E IND 35 WSW MFD 30 WSW CLE YNG 20 WSW PSB 15 SE CXY 15 ENE ACY GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 E CRP 55 NW LRD ...CONT... 10 ESE CZZ 30 S DAG 10 NE BIH 60 ENE BNO 25 ESE LWS 50 N FCA ...CONT... 30 SE CMX 20 N MSP 45 SSW SPW 25 NNW BMI 15 ESE BEH 15 NE TOL 15 SSW BUF 15 N BID ...CONT... 35 WSW HSE 20 NE SOP 15 WNW GSP 35 NW AHN 45 NNE MCN 60 NNW AYS SSI GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 NNE PWM 15 SE MWN 20 WNW EFK ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NRN PLAINS... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS OH / SERN PA ESEWD ACROSS THE DELMARVA REGION... ...SYNOPSIS... UPPER TROUGH ACROSS THE NORTHEAST WILL SHIFT EWD THIS PERIOD AS UPSTREAM TROUGH NOW MOVING ACROSS ID MOVES RAPIDLY EWD TOWARD THE WRN GREAT LAKES REGION THROUGH THE PERIOD. AT THE SURFACE...FRONT ASSOCIATED WITH ERN U.S. TROUGH WILL MOVE EWD ACROSS NEW ENGLAND / SEWD TOWARD THE OH VALLEY. WRN PORTION OF THIS BOUNDARY NOW OVER THE CENTRAL PLAINS WILL LIFT NWD AS A WARM FRONT AS DEEPENING SURFACE LOW MOVES INTO THE NRN PLAINS. COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE EWD ACROSS THE NRN PLAINS AND SEWD INTO THE CENTRAL PLAINS BY THE END OF THE PERIOD. LACK OF NEW MODEL DATA PRECLUDES MAJOR CHANGES TO THE ONGOING FORECAST. ...NRN PLAINS... ALTHOUGH LOW-LEVEL MOISTURE IS LACKING ATTM ACROSS THE NRN PLAINS NORTH OF SURFACE FRONT...DEEPENING SURFACE LOW OVER THE NRN HIGH PLAINS DURING THE FIRST HALF OF THE PERIOD WILL ALLOW AN INCREASE IN SLY FLOW ACROSS THE PLAINS...AND ASSOCIATED THETA-E ADVECTION. DEGREE OF DESTABILIZATION REMAINS DIFFICULT TO FORECAST ATTM -- PARTICULARLY GIVEN LACK OF MODEL DATA. HOWEVER...WILL CONTINUE WITH ONGOING FORECAST WHICH SUGGESTS SUFFICIENT DESTABILIZATION FOR SURFACE-BASED THUNDERSTORM DEVELOPMENT NEAR SURFACE LOW / COLD FRONT ACROSS THE WRN / CENTRAL DAKOTAS DURING THE AFTERNOON. WITH 35 TO 45 KT MID-LEVEL FLOW FORECAST ACROSS THE DAKOTAS ABOVE STRONG SLY LOW-LEVEL JET...WIND FIELD WILL BE FAVORABLE FOR SEVERE / SUPERCELL STORMS GIVEN SUFFICIENT INSTABILITY...BUT MAIN STORM MODE SHOULD BE LINEAR GIVEN STRONG FORCING ALONG FRONT / AHEAD OF COMPACT UPPER SYSTEM. WITH CLOUD BASES EXPECTED TO BE HIGH GIVEN LIKELIHOOD OF LIMITED SURFACE MOISTURE...EXPECT LARGE HAIL AND DAMAGING WINDS TO BE THE MAIN SEVERE THREATS. OVERNIGHT...STORMS SHOULD CONTINUE EWD INTO MN...WITH A CONTINUED THREAT FOR DAMAGING WINDS AT LEAST THROUGH THE EVENING. ...UPPER OH VALLEY INTO THE DELMARVA REGION... SEVERE THREAT -- PRIMARILY IN THE FORM OF DAMAGING WINDS -- APPEARS TO EXIST ACROSS THIS REGION AHEAD OF VORT MAX NOW INDICATED BY WV IMAGERY OVER CENTRAL OH. AS THIS FEATURE MOVES EWD / ESEWD ACCOMPANIED BY MODERATELY-STRONG DEEP-LAYER WIND FIELD...STORMS SHOULD INTENSIFY / SPREAD ESEWD AS AIRMASS DESTABILIZES THROUGH THE AFTERNOON. NERN EXTENT OF THE THREAT SHOULD BE LIMITED BY ANTICIPATED LACK OF INSTABILITY...WHILE SERN EXTENT SHOULD BE LIMITED BY WEAKER DEEP-LAYER WIND FIELD. HOWEVER...FAVORABLE COLLOCATION OF SHEAR / INSTABILITY SHOULD EXIST AHEAD OF VORT MAX / ACROSS SLIGHT RISK AREA TO WARRANT UPGRADE TO SLIGHT RISK ATTM. ..GOSS.. 08/27/2003 ...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. $$ |