SPC AC 311255
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0755 AM CDT SAT JUL 31 2004
   
   VALID 311300Z - 011200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 65 NNE
   DVL STC 30 ENE MCW 40 NNW OTM P35 STJ BIE PIR 55 S GDV GDV ISN 70
   NNE ISN.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM HUL
   CON POU ABE CXY AOO 25 SSE DUJ ART 35 ENE MSS.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM TYR DYR 25 W LUK 35 E
   TOL FNT HTL MBL 30 NNW MMO COU LTS 25 SSW HOB 30 SSW INK SJT TYR
   ...CONT... 85 S GBN 20 SE PHX INW 75 NNE INW 55 WSW FMN 35 SSE MTJ
   40 SSW CAG 40 NE VEL 50 NNE ENV 30 NNW WMC RBL 30 SE EKA 30 ESE CEC
   45 WNW MFR EUG 55 NE BKE 60 E S80 35 E 3TH 65 ENE 63S.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS CENTRAL PA TO NRN NY AND NWRN
   NEW ENGLAND....
   
   ...THERE IS A SLGT RISK OF SVR TSTMS NRN HIGH PLAINS TO ERN NEB/WRN
   IA...
   
   ...SYNOPSIS...
   SIGNIFICANT MID-UPPER LEVEL PATTERN EVOLUTION IS COMMENCING...TOWARD
   MORE CLIMATOLOGICALLY TYPICAL MIDSUMMER REGIME.  4-CORNERS AREA HIGH
   WILL CONTINUE TO STRENGTHEN...AS WILL RIDGE EXTENDING ESEWD ACROSS
   WRN/CENTRAL GULF COAST STATES. HEIGHTS WILL RISE ACROSS MUCH OF
   UPPER MIDWEST AND GREAT LAKES REGIONS TODAY AS STRONG SHORTWAVE
   TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER LS -- WEAKENS
   AND ACCELERATES NEWD ACROSS JAMES BAY REGION.  THIS WILL LEAVE
   BEHIND A BROAD BELT OF WNWLY MID-UPPER LEVEL FLOW FROM SRN BC ESEWD
   TO WI...AND 70-80 KT 250 MB SPEED MAX ALONG AND JUST N OF CANADIAN
   BORDER.  MEANWHILE...NEARLY CUT-OFF UPPER LOW OFFSHORE CAPE
   MENDOCINO WILL DRIFT ERRATICALLY THROUGH REMAINDER PERIOD.
   
   AT SFC...LOW ANALYZED OVER ERN UPPER MI WITH WEAK COLD FRONT SWWD
   ACROSS IA.  EXPECT BOTH LOW AND FRONT TO WEAKEN AS THEY MOVE
   NEWD...AND AS [PARENT TROUGH EJECTS ACROSS JAMES BAY.  MAIN
   CONVECTIVE FOCUS IN NERN STATES INSTEAD WILL BE CONVERGENCE BOUNDARY
   ASSOCIATED WITH ONGOING CONVECTION FROM NY SWWD ACROSS ERN KY. 
   FARTHER W...WEAK/BROAD AREA OF LOW PRESSURE IS ANALYZED OVER ERN
   MT...CENTRAL/WRN SD AND WRN ND -- ALONG WITH TROUGH EXTENDING ESEWD
   TOWARD SRN MN.
   
   ...NRN PLAINS...UPPER MIDWEST...
   HEIGHT RISES ALOFT OF 30-60 M -- ALONG WITH NEWD ADVECTION OF
   ELEVATED MIXED LAYER FROM HIGHER TERRAIN -- WILL CONTRIBUTE TO
   STRENGTHENING CAPPING ACROSS MUCH OF THIS AREA.  THEREFORE THERE IS
   SOME CONCERN THAT AFTERNOON CONVECTION MAY BE LIMITED OR ALTOGETHER
   SUPPRESSED...DESPITE LARGE BUOYANCY RESULTING FROM INCREASING LAPSE
   RATES AND SURFACE MOISTURE/HEATING.  ALTHOUGH CONVECTION MAY
   INITIATE ALMOST ANYWHERE WITHIN CATEGORICAL OUTLOOK CORRIDOR...BEST
   POTENTIAL ATM APPEARS TO BE OVER ERN SD/SWRN MN AREA WHERE CAP MAY
   BE RELATIVELY WEAK.  MODIFIED RAOBS AND RUC SOUNDINGS INDICATE
   MLCAPE WILL INCREASE FROM ABOUT 1000 J/KG WRN DAKOTAS TO 2500-3000
   J/KG RANGE BETWEEN ABR AND NWRN IA.
   
   ANY DIURNAL CONVECTION THAT DEVELOPS MAY TURN SSEWD AS SUPERCELLS
   WITH POTENTIAL FOR DAMAGING WIND AND LARGE HAIL...BUT COVERAGE MAY
   BE LIMITED BY CAPPING. AFTER DARK...ELEVATED LOW LEVEL WAA AND
   MOIST ADVECTION WILL FURTHER DESTABILIZE AIR MASS JUST ABOVE
   SFC...CONTRIBUTING TO ADDITIONAL TSTM DEVELOPMENT AND POTENTIAL FOR
   AN MCS WITH SEVERE WIND/HAIL.  TSTMS MAY THEN PROPAGATE SEWD TO SWD
   DOWN MO VALLEY OVERNIGHT.
   
   ...NERN CONUS...
   BAND OF CONVECTION WITH SCATTERED TSTMS WILL INTENSIFY LATE MORNING
   INTO AFTERNOON AS FOREGOING BOUNDARY LAYER DIABATICALLY HEATS...WITH
   SFC DEW POINTS MID 60S TO LOW 70S F IN INFLOW AIR.  MAIN THREAT WILL
   BE DAMAGING WIND FROM BOW/LEWP FORMATIONS.  LOW LCL AND RELATIVELY
   LARGE VALUES OF LOW LEVEL SHEAR INDICATE THAT ANY SUSTAINED/DISCRETE
   SUPERCELLS THAT DEVELOP MAY PRODUCE A TORNADO...BUT THIS IS A MORE
   CONDITIONAL RISK THAN FOR DAMAGING WIND.
   
   DEEP-TROPOSPHERIC SHEAR WILL INCREASE WITH NWD EXTENT WHILE MLCAPE
   INCREASES SWD. MODIFIED RAOBS AND RUC FCST SOUNDINGS INDICATE SOME
   COMBINATION OF BUOYANCY AND VERTICAL SHEAR WILL BECOME FAVORABLE FOR
   ORGANIZED SEVERE DURING 15-18Z TIME FRAME OVER PORTIONS WRN NY AND
   WRN PA...PROGRESSING EWD THROUGHOUT DAY.  EXPECT  150-300 J/KG 0-3
   KM SRH AND 20-30 KT VECTOR SHEAR THROUGH LOWEST 2 KM. 
   MEANWHILE...HEATING AND MOISTURE AT SFC WILL OVERCOME WEAKLY
   UNSTABLE MIDLEVEL LAPSE RATES TO YIELD AROUND 1500 J/KG MLCAPE
   CENTRAL PA...BECOMING LESS THAN 500 J/KG ALONG CANADIAN BORDER. 
   SEVERE POTENTIAL IS EXPECTED TO DIMINISH MARKEDLY AFTER
   APPROXIMATELY 00Z...WITH LOSS OF INSOLATION AND OF MOST OF REMAINING
   SFC-BASED INSTABILITY.
   
   ..EDWARDS/GUYER.. 07/31/2004
   
   ...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 1630Z