ZCZC SPCSWODY1 ALL ACUS01 KWNS 161217 SPC AC 161217 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0717 AM CDT SAT AUG 16 2003 VALID 161300Z - 171200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 10 NNE ROC DUJ 45 ENE EKN SSU 35 W BLF JKL LEX RFD AZO 15 S DTW GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 WSW CZZ 60 ENE MER 20 ESE EKO 35 N BKE 35 S EPH 70 NW 4OM ...CONT... 70 NW GGW 60 W MLS 55 SW GCC 50 WSW SNY 50 W AMA 30 NNE BGS 20 E SEP 10 S HOT 20 N STL 25 NW MLI 20 NNW LNR 30 SSW CWA 10 SSE OSC ...THERE IS A SLGT RISK OF SVR TSTMS TODAY FROM PARTS OF THE GREAT LAKES INTO THE UPPER OHIO VALLEY/CNTRL APPALACHIANS.... STRONGER BELT OF WESTERLIES CURVES FROM BASE OF BROAD UPPER TROUGH OVER THE NORTHERN PACIFIC THROUGH CREST OF LOW AMPLITUDE RIDGE ACROSS THE NORTHERN CANADIAN PROVINCES. MODELS SUGGEST A SIGNIFICANT SHORT WAVE TROUGH EMBEDDED WITHIN THIS FLOW REGIME WILL PROGRESS RAPIDLY EASTWARD ACROSS THE NORTHEAST PACIFIC DURING THIS FORECAST PERIOD. THIS WILL CONTRIBUTE TO AN EASTWARD ACCELERATION OF A CLOSED LOW/UPPER TROUGH...EMBEDDED WITHIN A WEAKER SOUTHERN BRANCH OF WESTERLIES...OUT OF THE NORTHWEST PACIFIC COAST STATES INTO THE NORTHERN ROCKIES. DOWNSTREAM RIDGE AXIS IS PROGGED TO SHIFT EASTWARD ACROSS THE NORTHERN PLAINS AND WEAKEN...AS ANOTHER SOUTHERN BRANCH TROUGH DIGS SOUTHEASTWARD/ AMPLIFIES FROM THE GREAT LAKES STATES INTO THE OHIO VALLEY. ...GREAT LAKES/OHIO VALLEY... EXIT REGION OF HIGH-LEVEL JET IS NOW NOSING SOUTHEASTWARD ACROSS LOWER MICHIGAN...WITH ASSOCIATED FORCING FOR UPWARD VERTICAL MOTION SUPPORTING ONGOING CONVECTIVE CLUSTER SOUTHEAST OF GEORGIAN BAY. ADDITIONAL CONVECTIVE DEVELOPMENT IS OCCURRING WESTWARD ALONG LOW-LEVEL FRONTAL ZONE...ON LEADING EDGE OF MID-LEVEL COOLING... INTO NORTHERN LAKE MICHIGAN. ACTIVITY WILL CONTINUE TO SPREAD SOUTHEASTWARD WITH STRONGER MID/UPPER FORCING INTO THE LEE OF LAKE ERIE/NORTHERN OHIO/NORTHERN INDIANA BY MID DAY...WHERE/WHEN INTENSIFICATION IS EXPECTED TO OCCUR IN DESTABILIZING ENVIRONMENT. SURFACE HEATING OF BOUNDARY LAYER WITH 70F+ DEW POINTS ACROSS OHIO/INDIANA WILL CONTRIBUTE TO MEAN MIXED LAYER CAPE IN EXCESS OF 2000 J/KG...SUPPORTIVE OF VIGOROUS UPDRAFTS WITH POTENTIAL FOR LARGE HAIL. THIS THREAT WILL BE ENHANCED BY STRENGTHENING VERTICAL SHEAR PROFILES...AS 30-40 KT NORTHWESTERLY MID-LEVEL FLOW DEVELOPS ABOVE 20+ KT WEST NORTHWESTERLY PRE-FRONTAL LOW-LEVEL JET... BECOMING MARGINALLY FAVORABLE FOR ISOLATED SUPERCELLS. RELATIVELY DRY MID-LEVEL AIR MASS WILL CONTRIBUTE TO POTENTIAL FOR DAMAGING WIND GUSTS...AS SCATTERED STRONG/SEVERE THUNDERSTORM ACTIVITY DEVELOPS SOUTHEASTWARD ACROSS OHIO/WESTERN PENNSYLVANIA INTO THE NORTH CENTRAL APPALACHIANS BY EARLY THIS EVENING. ACTIVITY IS EXPECTED TO DIMINISH DURING THE EVENING HOURS WITH ONSET OF RADIATIONAL SURFACE COOLING. ...MID/SOUTH ATLANTIC COAST STATES AND ERN GULF COAST STATES... BOUNDARY LAYER REMAINS VERY MOIST WITH SURFACE DEW POINTS AT OR ABOVE 70F ACROSS MUCH OF THE SOUTHEAST. WITH DAYTIME HEATING... ENVIRONMENT WILL BECOME MODERATELY UNSTABLE WITH MEAN MIXED LAYER CAPE IN EXCESS OF 2000 J/KG. THOUGH MEAN ENVIRONMENTAL FLOW/VERTICAL SHEAR WILL BE QUITE WEAK...WEAK CAPPING AND FORCING ASSOCIATED WITH SHORT WAVE TROUGH NOW PROGRESSING SOUTHEASTWARD THROUGH THE SOUTHERN APPALACHIANS/TENNESSEE VALLEY REGION WILL SUPPORT NUMEROUS THUNDERSTORMS. SOME OF THESE WILL BECOME QUITE STRONG...HOWEVER SEVERE THREAT APPEARS LIMITED TO VERY ISOLATED... BUT POTENTIALLY DAMAGING WET MICROBURSTS. ...DEEP SOUTH TEXAS... CENTER OF TROPICAL CYCLONE HAS PROGRESSED INLAND SOUTH OF BROWNSVILLE...AND WILL CONTINUE RELATIVELY RAPIDLY WESTWARD INTO MEXICAN PLATEAU WEST OF THE LOWER RIO GRANDE RIVER VALLEY BY LATE AFTERNOON. BY LATE THIS MORNING...STRONGER LOW-LEVEL SHEAR PROFILES AND ASSOCIATED RISK OF ISOLATED TORNADOES IN TROPICAL ENVIRONMENT APPEAR LIKELY TO BECOME CONFINED TO THE VICINITY OF THE RIVER BETWEEN BROWNSVILLE AND LAREDO. ...INTERMOUNTAIN WEST/ROCKIES... LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION/WEAK CAP AHEAD OF SHORT WAVE TROUGH PROGRESSING INTO THE NORTHERN ROCKIES...AND NEAR SHEAR AXIS ACROSS THE EASTERN GREAT BASIN/CENTRAL AND SOUTHERN ROCKIES...WILL SUPPORT CONVECTIVE DEVELOPMENT TODAY. ACTIVITY WILL BECOME MOST NUMEROUS DURING PEAK AFTERNOON HEATING...WHEN THERMODYNAMIC ENVIRONMENT WILL BE SUPPORTIVE OF ISOLATED DOWNBURSTS AND SOME LARGE HAIL IN STRONGEST STORMS. ..KERR/BOTHWELL.. 08/16/2003 ...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. $$ |