SPC AC 181633
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1133 AM CDT WED AUG 18 2004
   
   VALID 181630Z - 191200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 WNW
   CLE 60 W UNI 35 N LEX BMG 45 NNW COU STJ OMA 40 ESE MSP 15 NW IWD.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 N CTB 45 W LWT 30
   SE SHR 35 NNW CDR VTN 10 SW MHE 20 WNW BRD 40 NNW ELO ...CONT... 20
   E PNS 25 ENE CSG 45 ESE ATL 30 NW AHN 60 S TYS 25 ESE CHA 35 NW BHM
   20 WSW TUP 20 E JBR 20 SW CGI 35 W MDH 45 SW STL 35 WNW TBN 20 WSW
   JLN 15 S TUL 10 ENE DUA 25 NNW LFK 50 N BPT 40 WSW 7R4 ...CONT... 20
   SSE YUM 35 WSW BLH 35 N TRM 15 NNE DAG 15 NNE NID 45 S BIH 55 NE MER
   15 SSW RNO 80 SE 4LW 45 SSE BNO 55 NNE BNO 45 ESE YKM 30 NNE SEA 20
   NE BLI.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE UPPER MIDWEST AND
   GREAT LAKES AREA....
   
   ...UPPER MIDWEST AND GREAT LAKES AREA...
   AN INTENSE MID LEVEL TROUGH IS DIGGING ESEWD FROM SRN MANITOBA
   TOWARD WI/MI PER WATER VAPOR IMAGERY AND 100 M HEIGHT FALLS AT INL
   IN 12Z UPPER AIR ANALYSES.  AN ASSOCIATED STRONG SURFACE COLD FRONT
   IS SURGING SWD ACROSS SD AND SEWD ACROSS MN AS OF MID MORNING...AND
   THIS FRONT WILL CONTINUE SEWD ACROSS THE GREAT LAKES AND SWD INTO KS
   BY TONIGHT.  A BAND OF ASCENT ALONG THE COLD FRONT WILL PROVIDE A
   FOCUS FOR THUNDERSTORM INITIATION THROUGH THE PERIOD.
   
   A W-E ORIENTED BAND OF CLOUDS/SCATTERED THUNDERSTORMS FROM IA ACROSS
   NRN IL TO SRN LOWER MI DENOTES A WEAK LOW-MID LEVEL BAROCLINIC
   ZONE...WITH THE RICHER LOW-LEVEL MOISTURE /SURFACE DEWPOINTS
   MID-UPPER 60S/ GENERALLY CONFINED TO AREAS ALONG AND S OF THIS BAND.
    THE DEGREE OF INSTABILITY IS IN QUESTION N OF THIS BAND...WITH ONLY
   A NARROW CORRIDOR OF MUCAPE VALUES FROM 500-1250 J/KG EXPECTED ALONG
   THE FRONT ACROSS WI/UPPER MI THIS AFTERNOON.  STRONG DEEP LAYER WIND
   FIELDS AND SHEAR VECTORS ORIENTED ACROSS THE COLD FRONT FROM THE
   COLD SIDE TO THE WARM SIDE WOULD APPEAR TO FAVOR DISCRETE SUPERCELLS
   ALONG THE COLD FRONT ACROSS WI/MI THIS AFTERNOON. 
   HOWEVER...EXPECTED STORM MOTIONS ROUGHLY MATCH THE MOTION OF THE
   SURFACE COLD FRONT.  THE COMBINATION OF STORMS REMAINING IN THE
   FRONTAL ZONE...STRONG LINEAR FORCING...AND A NARROW INSTABILITY
   CORRIDOR SHOULD INSTEAD FAVOR SQUALL LINE DEVELOPMENT WITH DAMAGING
   WINDS AS THE PRIMARY THREAT.  THE DAMAGING WIND THREAT WILL DEVELOP
   BY EARLY AFTERNOON ACROSS WI/WRN UPPER MI...AND THEN SPREAD SEWD
   ACROSS LOWER MI/NRN IL/NRN INDIANA BY LATE THIS EVENING.
   
   FARTHER S...SCATTERED THUNDERSTORMS WILL BE POSSIBLE INVOF THE WEAK
   LOW-MID LEVEL BAROCLINIC ZONE AND AXIS OF MODERATE INSTABILITY FROM
   THE IA/MO BORDER AREA EWD ACROSS CENTRAL/NRN IL AND INDIANA TO WRN
   OH THIS AFTERNOON.  MLCAPE VALUES AROUND 1500 J/KG AND 0-6 KM BULK
   SHEAR OF 30-40 KT MAY SUPPORT SUPERCELLS CAPABLE OF PRODUCING AT
   LEAST ISOLATED LARGE HAIL AND DAMAGING GUSTS.
   
   ...ATLANTIC COAST AREA...
   MORNING SOUNDINGS SHOW MOIST PROFILES WITH THE POTENTIAL FOR
   MODERATE INSTABILITY THIS AFTERNOON FROM FL NWD TO THE MID ATLANTIC
   REGION...WITH LESSER INSTABILITY FARTHER N INTO NY. 
   MEANWHILE...DEEP LAYER VERTICAL IS MODEST FROM THE MID ATLANTIC TO
   NY...AND WEAK FARTHER S ACROSS THE CAROLINAS/FL.  LOCAL TERRAIN
   FEATURES AND SUBTLE SURFACE BOUNDARIES/SEA BREEZE CIRCULATIONS WILL
   FOCUS THUNDERSTORM INITIATION THIS AFTERNOON...WITH THE POTENTIAL
   FOR ISOLATED HAIL AND STRONG DOWNBURST WINDS.
   
   ...AZ RIM COUNTRY...
   12Z SOUNDINGS ACROSS THIS AREA CONTINUE TO SHOW A NW FLOW REGIME
   WITH THE POTENTIAL FOR MLCAPE OF 1500-2000 J/KG WITH DAYTIME
   HEATING.  THE PERSISTENT MID LEVEL CYCLONIC SHEAR AXIS HAS DRIFTED A
   LITTLE E OF ITS POSITION FROM THE PAST FEW DAYS...THUS THE STRONGER
   STORMS /WITH THE POTENTIAL FOR ISOLATED LARGE HAIL AND STRONG
   DOWNBURST WINDS/ MAY BE CONFINED MORE TO THE HIGHER TERRAIN THIS
   AFTERNOON.
   
   ..THOMPSON/MEAD.. 08/18/2004
   
   ...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 2000Z