SPC AC 151237
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0737 AM CDT FRI AUG 15 2003
   
   VALID 151300Z - 161200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 70 N
   MTC 10 SE MTW 10 SW CWA HIB 30 E INL
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 55 WNW
   MFE 10 ESE COT 45 SE SAT 25 E PSX
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 60 WNW HVR 20 WSW LWT
   45 SW BIL 25 ESE COD 20 SE LND 50 SE RKS 45 WSW LAR 20 NNE 4FC 45
   WSW COS 25 WNW RTN 20 NE TCC 40 ESE PVW 40 NNE ABI 30 E SEP 10 WSW
   TYR 25 SSE FSM 40 NW LIT 25 S POF 25 S STL 15 WSW LNR BRD 75 N GFK
   ...CONT... HUL LCI ALB 25 E AVP BWI 30 WNW ORF RWI FLO 40 ENE CHS
   ...CONT... 15 W CZZ 35 ESE RAL 30 NNE RAL 25 SW DAG 35 SSE DAG 10
   SSW DRA 70 WNW P38 20 E BAM 45 SW S80 45 NW 63S
   
   ...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN AND EVE ACROSS
   PARTS OF THE UPPER GREAT LAKES....
   
   ...THERE IS A SLGT RISK OF SVR TSTMS LATE TONIGHT ACROSS PARTS OF
   DEEP SOUTH FLORIDA....
   
   MODELS SUGGEST SUBTROPICAL RIDGE...WHICH ENCOMPASSES MUCH OF THE
   CENTRAL/EASTERN U.S...WILL WEAKEN SOMEWHAT TODAY.  THIS WILL OCCUR
   IN RESPONSE TO PROGRESSION OF SERIES OF WAVES EMBEDDED WITHIN
   TROPICAL EASTERLIES ON SOUTHERN/WESTERN PERIPHERY OF RIDGE...FROM
   THE GULF OF MEXICO INTO THE INTERMOUNTAIN WEST...AND AMPLIFICATION
   OF UPPER TROUGH EMBEDDED WITAN MAIN BELT OF WESTERLIES FROM THE
   UPPER GREAT LAKES INTO THE NORTHEAST STATES.
   
   ...GREAT LAKES...
   AS NORTHERN AND SOUTHERN BRANCH SHORT WAVE TROUGHS APPROACH THE
   BRITISH COLUMBIA AND PACIFIC NORTHWEST COASTS...RESPECTIVELY...
   DOWNSTREAM SHORT WAVE RIDGE IS ALREADY AMPLIFYING ACROSS THE
   NORTHERN U.S./CANADIAN ROCKIES.  RIDGE AXIS IS PROGGED TO SHIFT
   EASTWARD ACROSS ALBERTA AND SASKATCHEWAN DURING THE DAY...AND FAIRLY
   VIGOROUS DOWNSTREAM SHORT WAVE TROUGH WILL GRADUALLY TURN
   SOUTHEASTWARD ACROSS MANITOBA AND ONTARIO INTO THE UPPER GREAT LAKES
   REGION LATE THIS AFTERNOON AND TONIGHT.  MID/UPPER FORCING FOR
   UPWARD VERTICAL MOTION ASSOCIATED WITH THIS FEATURE IS EXPECTED TO
   CONTRIBUTE TO DESTABILIZATION AND POTENTIAL FOR SCATTERED CONVECTIVE
   DEVELOPMENT...MAINLY ALONG LOW-LEVEL BAROCLINIC ZONE LIKELY TO
   EXTEND FROM THE MINNESOTA  ARROWHEAD INTO LAKE SUPERIOR AND ONTARIO
   BY PEAK AFTERNOON HEATING.
   
   MODELS SUGGEST MEAN MIXED LAYER CAPE OF 1000 TO 2000 J/KG BY LATE
   AFTERNOON NEAR FRONTAL ZONE...WHERE MODERATELY STRONG VERTICAL SHEAR
   WILL BE SUFFICIENT FOR A FEW SEVERE STORMS WITH LARGE HAIL AND
   DAMAGING WIND GUSTS.  ACTIVITY WILL GRADUALLY SPREAD ACROSS THE
   UPPER PENINSULA AND NORTHERN LOWER PENINSULA OF MICHIGAN DURING THE
   EVENING HOURS...WITH MID-LEVEL HEIGHT FALLS/WEAKENING CAP POSSIBLY
   ALLOWING DEVELOPMENT AS FAR WEST AS NORTHERN WISCONSIN.  BY THE
   OVERNIGHT HOURS...STABILIZATION ASSOCIATED WITH LOSS OF DAYTIME
   HEATING SHOULD RESULT IN WEAKENING TRENDS...BUT VIGOROUS CONVECTION
   STILL APPEARS POSSIBLE WITH STRONGEST FORCING...SHIFTING ACROSS
   SOUTHERN ONTARIO INTO THE LEE OF LAKES ERIE/ONTARIO.
   
   ...INTERMOUNTAIN WEST...
   EXTENSIVE CONVECTIVE DEVELOPMENT YESTERDAY LIKELY WILL MINIMIZE
   SEVERE POTENTIAL FOR TODAY ACROSS SOUTHERN ARIZONA.  HOWEVER...
   SUBSTANTIAL DESTABILIZATION APPEARS LIKELY WITH DAYTIME HEATING
   FARTHER TO THE NORTH...FROM PARTS OF NORTHERN ARIZONA AND UTAH INTO
   EASTERN IDAHO AND WESTERN/NORTHERN WYOMING.  AIDED BY LARGE-SCALE
   FORCING ASSOCIATED WITH EASTERLY WAVE MIGRATING ACROSS THE
   CENTRAL/SOUTHERN ROCKIES INTO THE GREAT BASIN...DEVELOPMENT OF
   SCATTERED STRONG/ISOLATED SEVERE THUNDERSTORMS IS EXPECTED BY 21Z. 
   DEEP MIXED BOUNDARY LAYER WITH LARGE TEMPERATURE/DEW POINT SPREADS
   IN LOWER ELEVATIONS WILL PROVIDE FAVORABLE ENVIRONMENT FOR
   DOWNBURSTS...AND MODELS SUGGEST POCKETS OF CAPE AS HIGH AS 1000 J/KG
   OR SO...SUPPORTIVE OF VIGOROUS UPDRAFTS WITH SOME HAIL.
   
   ...DEEP SOUTH TEXAS...
   EMBEDDED WITHIN TROPICAL EASTERLIES...ERIKA CONTINUES TO RAPIDLY
   PROGRESS INTO THE WESTERN GULF OF MEXICO.  TROPICAL SYSTEM IS
   CURRENTLY FORECAST TO APPROACH THE LOWER TEXAS COAST BY THE END OF
   THE FORECAST PERIOD.  AS THIS OCCURS...POTENTIAL FOR ISOLATED
   TORNADOES WILL INCREASE LATE TONIGHT AS CONVECTIVE BANDS ROTATE
   INLAND.
   
   ...PACIFIC NORTHWEST INTO WESTERN MONTANA...
   LIGHTNING DATA HAS INDICATED PRESENCE OF THUNDERSTORM ACTIVITY IN
   ZONE OF STRONGER MID-LEVEL FORCING ASSOCIATED WITH CENTER OF
   CYCLONIC VORTICITY OFF THE OREGON COAST.  POINT FORECAST SOUNDINGS
   SUGGEST ENVIRONMENT ACROSS WASHINGTON/OREGON WILL NOT DESTABILIZE
   SUFFICIENTLY TO SUPPORT CONVECTIVE DEVELOPMENT TODAY.  HOWEVER... AS
   STRONGER UPWARD VERTICAL MOTION FIELD SHIFTS INTO THE MOUNTAINS OF
   WESTERN MONTANA THIS EVENING...SCATTERED THUNDERSTORMS APPEAR
   LIKELY.  ACTIVITY WILL GRADUALLY SPREAD NORTHWARD OVERNIGHT...TO THE
   EAST OF THE HIGHER TERRAIN...BUT RELATIVE WEAK SHEAR/CAPE AND
   COOLING/STABILIZING BOUNDARY LAYER ARE EXPECTED TO PRECLUDE SEVERE
   THREAT.
   
   ...FLORIDA...
   SHORT WAVE TROUGH MIGRATING AROUND EASTERN/SOUTHEASTERN PERIPHERY OF
   UPPER RIDGE IS SUPPORTING ONGOING CONVECTIVE DEVELOPMENT OFF THE
   GEORGIA/NORTHERN FLORIDA ATLANTIC COAST.  AS UPPER FEATURE CONTINUES
   SOUTHWESTWARD ACROSS THE FLORIDA PENINSULA ...LARGE-SCALE FORCING
   WILL AID CONVECTIVE DEVELOPMENT THIS AFTERNOON ALONG SEA
   BREEZES...PARTICULARLY ACROSS INTERIOR PORTIONS OF THE PENINSULA AND
   THE GULF COAST.
   
   ..KERR/BOTHWELL.. 08/15/2003
   
   ...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.
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 1630Z