SPC AC 160543
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1243 AM CDT THU SEP 16 2004
   
   VALID 161200Z - 171200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 S
   MOB MOB TCL HSV CHA AHN 65 ESE MCN VLD 35 ESE TLH.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 SE GPT 35 NW LUL
   20 S GWO 30 N GLH 25 NE TXK 20 WSW TYR 20 ENE AUS 40 NE CRP
   ...CONT... 25 SSW P07 25 ENE HOB 40 WSW DHT 15 ENE AKO 25 SW MHN 30
   ESE ANW 30 N GRI 25 SSE HSI 20 NE ICT 30 NNW BVO 20 WSW UMN 25 SE
   TBN BLV 40 NE LAF 55 SE OSC ...CONT... 20 WNW EFK 25 SE GFL 30 NE
   MSV 35 SW ABE 15 NW DCA SHD ROA 35 SE PSK 15 E RDU 35 ESE RWI 10 N
   HSE.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 80 NW CMX 10 N IWD 40
   N EAU MSP 50 SSW AXN 30 N ABR 45 E BIS 75 NW MOT.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 E ISP ORH 20 S
   PWM.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE EASTERN
   GULF STATES....
   
   BELT OF STRONGER SUBTROPICAL WESTERLIES WAS EVIDENT IN 16/00Z
   SOUNDING DATA...CURVING ACROSS THE TEXAS BIG BEND THROUGH THE LOWER
   MISSISSIPPI/TENNESSEE VALLEYS INTO THE MID ATLANTIC COAST STATES. 
   AS HURRICANE IVAN GRADUALLY MAKES LANDFALL AND MERGES INTO THIS MORE
   STRONGLY SHEARED ENVIRONMENT...A STEADY WEAKENING WILL ENSUE AS
   SYSTEM SLOWLY MIGRATES NORTHEASTWARD ACROSS ALABAMA DURING THIS
   FORECAST PERIOD.
   
   MEANWHILE...POLAR WESTERLIES WILL REMAIN CONFINED TO THE VICINITY OF
   THE CANADIAN/U.S. BORDER.  HOWEVER...SIGNIFICANT AMPLIFICATION OF
   EMBEDDED SHORT WAVE IS PROGGED OFF THE PACIFIC NORTHWEST COAST LATE
   THIS AFTERNOON INTO TONIGHT.  AS THIS OCCURS...DOWNSTREAM RIDGE WILL
   BEGIN TO BUILD FROM THE NORTHERN INTERMOUNTAIN REGION INTO THE UPPER
   MISSISSIPPI VALLEY...WHILE ANOTHER SIGNIFICANT SHORT WAVE TROUGH
   LIFTS OUT OF THE UPPER GREAT LAKES INTO THE EASTERN CANADIAN
   PROVINCES.
   
   ...EASTERN GULF STATES INTO SOUTHERN APPALACHIANS...
   DESPITE WEAKENING TRENDS TO TROPICAL SYSTEM...LOW-LEVEL SHEAR
   PROFILES ALONG/EAST OF TRACK OF CIRCULATION CENTER WILL REMAIN MORE
   THAN SUFFICIENT TO MAINTAIN RISK OF TORNADIC ACTIVITY THROUGH THIS
   FORECAST PERIOD.  IT APPEARS BEST POTENTIAL FOR TORNADOES AFTER
   LANDFALL WILL SHIFT TO THE EAST/SOUTHEAST QUADRANT OF TROPICAL
   CYCLONE... WHERE BOUNDARY LAYER WILL BECOME MOST BUOYANT AS DEW
   POINTS CLIMB INTO THE MID/UPPER 70S.  INSTABILITY...AND ATTENDANT
   RISK FOR TORNADOES...LIKELY WILL BECOME MAXIMIZED DURING THE PEAK
   AFTERNOON HEATING ACROSS PARTS OF SOUTHEAST/EAST CENTRAL ALABAMA AND
   SOUTHWEST GEORGIA.  THREAT FOR TORNADOES MAY CONTINUE AFTER
   DARK...BUT PROBABILITIES SHOULD BEGIN TO DECREASE...AS STRONGER
   FORCING SHIFTS INTO PARTS OF NORTHEAST ALABAMA/NORTHERN GEORGIA.
   
   ...OHIO VALLEY INTO LOWER GREAT LAKES REGION...
   WHILE UPPER TROUGH LIFTS INTO EASTERN CANADA...ASSOCIATED FRONTAL
   ZONE WILL TRAIL BACK ACROSS THE LOWER GREAT LAKES REGION INTO THE
   LOWER OHIO VALLEY.  THIS FEATURE SHOULD REMAIN FOCUS FOR SCATTERED
   THUNDERSTORM ACTIVITY. IN WAKE OF DEPARTING UPPER TROUGH AND AHEAD
   OF APPROACHING SUBTROPICAL SHORT WAVE TROUGH/REMNANTS OF IVAN...
   STRONGEST LARGE-SCALE FORCING FOR CONVECTIVE DEVELOPMENT MAY BECOME
   FOCUSED ACROSS PARTS OF EASTERN OHIO/WESTERN PENNSYLVANIA LATE THIS
   AFTERNOON.  GIVEN EXPECTED EVOLUTION OF WEAK TO MODERATELY UNSTABLE
   BOUNDARY LAYER ALONG FRONT...FLOW/SHEAR PROFILES ACROSS THIS REGION
   MAY REMAIN STRONG ENOUGH TO ENHANCE THUNDERSTORM ACTIVITY.  AN
   ISOLATED DAMAGING WIND GUST OR TWO...PERHAPS SOME HAIL...IS POSSIBLE
   BEFORE ACTIVITY WEAKENS THIS EVENING.
   
   ...SOUTHERN NEW ENGLAND...
   SCATTERED THUNDERSTORMS APPEAR POSSIBLE THROUGH EARLY AFTERNOON
   ...FROM PARTS OF EASTERN LONG ISLAND INTO SOUTHEAST MASSACHUSETTS
   AND CAPE COD...BEFORE FLOW ACROSS THIS REGION TAKES ON INCREASINGLY
   WESTERLY COMPONENT IN WAKE OF MID-LEVEL TROUGH SHIFTING OFFSHORE.
   
   ...PLAINS INTO UPPER MISSISSIPPI VALLEY...
   DAYTIME HEATING MAY CONTRIBUTE TO CONVECTIVE DEVELOPMENT IN WARM
   ADVECTION REGIME FROM THE EASTERN DAKOTAS INTO NORTHERN MINNESOTA/
   PARTS OF NORTHWEST WISCONSIN.  MEANWHILE WARMING MID-LEVEL
   ENVIRONMENT...WELL IN ADVANCE OF AMPLIFYING TROUGH OFF THE PACIFIC
   NORTHWEST COAST...LIKELY WILL SUPPRESS THUNDERSTORM ACTIVITY ACROSS
   THE REMAINDER OF THE PLAINS THROUGH THE DAY. HOWEVER...
   TONIGHT...FORCING/ DESTABILIZATION ALONG STRENGTHENING SOUTHERLY
   LOW-LEVEL JET MAY SUPPORT WIDELY SCATTERED THUNDERSTORMS ABOVE
   NOCTURNAL INVERSION LAYER.
   
   ..KERR/BANACOS.. 09/16/2004
   
   ...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.
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 1300Z