Aug 4, 2007 1100 UTC Day 3 Severe Thunderstorm Outlook
Updated: Sat Aug 4 07:09:36 UTC 2007
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Categorical Graphic
20070804 1100 UTC Day 3 Outlook Graphic
Probabilistic Graphic
20070804 1100 UTC Day Probabilitic Graphic
   SPC AC 040706
   
   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0206 AM CDT SAT AUG 04 2007
   
   VALID 061200Z - 071200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS N-CENTRAL PLAINS TO
   UPPER MS VALLEY...
   
   ...SYNOPSIS...
   STRONG SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY
   OVER CANADIAN ROCKIES...IS EXPECTED TO MOVE EWD ACROSS MOST OF
   CANADA THROUGH LATE DAY-3 PERIOD...REACHING FROM CENTRAL/ERN QUE SWD
   ACROSS NEW ENGLAND IN 07/00Z-07/06Z TIME RANGE.  ASSOCIATED SFC COLD
   FRONT SHOULD MOVE EWD/SEWD OVER SAME AREA -- PRECEDED BY LOW LEVEL
   SWLYS AND WAA REGIME.  FRONTAL ZONE SHOULD EXTEND SWWD ACROSS SRN
   LOWER MI/NRN OH/NRN INDIANA REGION AT 07/00Z...THEN WNWWD ACROSS
   N-CENTRAL PLAINS AS WARM FRONT INTO SFC CYCLONE OVER SD.  SFC
   TROUGHING SHOULD CONNECT THIS LOW WITH ANOTHER OVER ERN CO/WRN KS
   VICINITY.  MAIN N-CENTRAL PLAINS SFC LOW SHOULD MOVE EWD TOWARD
   UPPER MS VALLEY OVERNIGHT...WITH COLD FRONT MOVING SEWD ACROSS
   CENTRAL HIGH PLAINS.  SREF MEMBERS AND OPERATIONAL SPECTRAL/NAM
   MODELS DO SHOW CONSIDERABLE VARIATION IN MORE PRECISE
   PLACEMENT/STRENGTH OF SFC LOW...WITH ASSOCIATED ISALLOBARIC FORCING
   AND BACKING OF SFC WINDS BEING CRUCIAL TO LOCATION OF GREATEST SVR
   PROBABILITIES.
   
   ...CENTRAL/NRN PLAINS TO UPPER MS VALLEY...
   BASIC PATTERN SHOULD BE CHARACTERIZED BY AREA OF SFC DEW POINTS 70S
   F...BENEATH 30-40 KT WSWLY 500 MB FLOW...FROM NEAR SFC LOW EWD INVOF
   WARM FRONT.  MODIFIED NAM/NAM-KF SOUNDINGS SUGGEST VERY UNSTABLE AIR
   MASS IS POSSIBLE WITH MLCAPES POSSIBLY NEAR 5000 J/KG...AND
   FAVORABLE LOW LEVEL HODOGRAPHS FOR BOTH SUPERCELLS AND BOWS.  ONE OR
   MORE COMPLEXES OF TSTMS SHOULD EVOLVE DURING EVENING/OVERNIGHT
   HOURS...SHIFTING SVR THREAT EWD TOWARD UPPER MS VALLEY.  GIVEN
   FAVORABLE SHEAR/THERMODYNAMIC PROFILES LIKELY TO OVERLAP SOMEWHERE
   ACROSS OUTLOOK AREA IN THIS SYNOPTIC PATTERN...SMALLER AREA OF MORE
   CONCENTRATED SVR PROBABILITIES MAY BE REQUIRED IN FUTURE
   UPDATES...ONCE FCST PLACEMENT/GEOMETRY OF SFC FEATURES BECOMES MORE
   CERTAIN.
   
   ALTHOUGH STG SFC HEATING AND FAVORABLE MOISTURE WILL EXTEND SWD
   ACROSS MUCH OF NEB/KS AND POSSIBLY INTO ERN CO...WEAKENING OF BOTH
   DEEP-LAYER SHEAR PROFILES AND DEEP-LAYER LIFT ARE EXPECTED WITH SWD
   EXTENT...RENDERING SVR POTENTIAL MORE CONDITIONAL AND ISOLATED.
   
   ...NERN CONUS...
   NARROW CORRIDOR OF INCREASING LOW LEVEL THETAE SHOULD EXTEND NEWD
   ACROSS MID-ATLANTIC AND NEW ENGLAND REGIONS AHEAD OF COLD
   FRONT...DURING AFTERNOON/EARLY EVENING HOURS.  MEANWHILE SRN LOBE OF
   LARGE SCALE ASCENT ASSOCIATED WITH MID-UPPER TROUGH WILL PASS ACROSS
   AT LEAST NRN NY AND NEW ENGLAND...PERHAPS EXTENDING SWD TOWARD NJ. 
   THIS REGIME MAY SUPPORT DEVELOPMENT OF TSTMS WITH POTENTIAL FOR
   STG-SVR HAIL AND GUSTS...THOUGH STRENGTH OF MOISTURE RETURN IS IN
   QUESTION AT THIS EARLY STAGE.  THEREFORE MRGL SVR PROBABILITIES ARE
   ASSIGNED ATTM.
   
   ..EDWARDS.. 08/04/2007
   
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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1100Z