SPC AC 081729
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1229 PM CDT TUE JUL 08 2008
   
   VALID 091200Z - 101200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS WED AFTN/EVE ACROSS THE MID AND
   NRN ATLANTIC COAST STATES....
   
   ...SYNOPSIS...
   MODERATE TO STRONG MID-LATITUDE WESTERLIES WILL REMAIN CONFINED TO 
   THE NORTHERN TIER STATES THROUGH THIS FORECAST PERIOD.  FLOW WILL
   REMAIN BROADLY CYCLONIC ASSOCIATED WITH A SLOW MOVING LARGE-SCALE
   TROUGH ACROSS THE GREAT LAKES INTO THE NORTHEASTERN STATES...WHILE
   BECOMING INCREASINGLY CYCLONIC ASSOCIATED WITH ANOTHER SLOW MOVING
   ...DIGGING TROUGH ACROSS THE WESTERN CANADIAN PROVINCES INTO THE
   PACIFIC NORTHWEST AND NORTHERN ROCKIES STATES.
   
   MEANWHILE...FAIRLY STRONG SUBTROPICAL RIDGING WILL PERSIST ACROSS
   THE EAST CENTRAL PACIFIC INTO THE GREAT BASIN...AND ACROSS THE
   SOUTHWESTERN ATLANTIC INTO THE GULF COAST STATES.
   
   ...ATLANTIC COAST STATES...
   MODELS ARE SUGGESTIVE THAT THE MOST PROMINENT SHORT WAVE IMPULSE
   /EMBEDDED WITHIN THE LARGER SCALE TROUGH ASSOCIATED WITH THE
   STRONGER WESTERLIES/ WILL PROBABLY NOT BEGIN TO SHIFT EAST OF THE
   GREAT LAKES REGION UNTIL LATE IN THE PERIOD.  BUT...AT LEAST WEAKLY
   DIVERGENT OR DIFLUENT MID/UPPER FLOW WILL EXIST ACROSS MUCH THE
   MIDDLE AND NORTH ATLANTIC COAST STATES WEDNESDAY.  AND...THIS LIKELY
   WILL CONTRIBUTE TO CONVECTIVE DEVELOPMENT...PERHAPS AS EARLY AS
   09/18-21Z ACROSS PARTS OF NORTHERN NEW ENGLAND...POSSIBLY A BIT
   LATER IN THE AFTERNOON/EVENING ACROSS VIRGINIA/NORTH CAROLINA. 
   WHILE SEVERE POTENTIAL MAY BE LIMITED BY GENERALLY WEAK MID-LEVEL
   LAPSE RATES AND DEEP LAYER SHEAR...MODELS DO SUGGEST A BELT OF
   STRONGER SOUTHWESTERLY LOWER TROPOSPHERIC FLOW NEAR THE LEE SURFACE
   TROUGH /ON THE ORDER OF 20-30 KTS/ COULD SOMEWHAT ENHANCE THE RISK
   FOR DAMAGING SURFACE GUSTS...ESPECIALLY WHERE THE BOUNDARY LAYER
   HEATING BECOMES STRONGEST.
   
   ...UPPER TENNESSEE VALLEY INTO SOUTHERN HIGH PLAINS...
   GENERALLY WELL SOUTH OF THE STRONGER WESTERLIES...WEAK IMPULSES
   MIGRATING AROUND THE NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE
   WILL AID STORM DEVELOPMENT WEDNESDAY/WEDNESDAY NIGHT.  STORMS MAY
   BECOME FOCUSED ON A WEAK SURFACE WIND SHIFT...ENHANCED BY CONVECTIVE
   OUTFLOWS...AND COULD CONSOLIDATE INTO A FEW STORM CLUSTERS.  WHILE
   THE THERMODYNAMIC ENVIRONMENT MAY NOT BE CONSIDERABLY DIFFERENT THAN
   THAT PROGGED TO THE LEE OF THE APPALACHIANS...WEAKER LOW-LEVEL FLOW
   FIELDS COUPLED WITH NEGLIGIBLE DEEP LAYER SHEAR MAY RESULT IN A MORE
   LOCALIZED/MARGINAL RISK FOR DAMAGING WINDS AND HAIL.
   
   ...SOUTHERN PLATEAU...
   MODERATE NORTHEASTERLY MID-LEVEL FLOW IS PROGGED TO DEVELOP LATE
   WEDNESDAY AFTERNOON/EVENING...AROUND THE SOUTHEASTERN PERIPHERY OF
   THE SUBTROPICAL RIDGE...AND AHEAD OF AN APPROACHING WAVE IN THE
   TROPICAL EASTERLIES.  COUPLED WITH AT LEAST WEAK SOUTHWESTERLY HIGH
   LEVEL WIND FIELDS...STORM-RELATIVE FLOW CONFIGURATIONS SEEM LIKELY
   TO BECOME FAVORABLE FOR PROPAGATION OFF THE HIGHER TERRAIN INTO THE
   VERY WARM DEEPLY MIXED BOUNDARY LAYER ACROSS THE LOWER DESERTS. 
   PRIMARY UNCERTAINTY CONCERNS LOW-LEVEL WIND FIELDS AND POTENTIAL
   STRENGTH OF LOW-LEVEL CONVERGENCE...BUT AT LEAST LOCALIZED DAMAGING
   WIND GUSTS APPEAR POSSIBLE IN SCATTERED STORMS BY EARLY WEDNESDAY
   EVENING.
   
   ...NORTHERN/CENTRAL PLAINS...
   THE EXTENT OF THE CONVECTIVE POTENTIAL ACROSS THE REGION IS A BIT
   UNCERTAIN.  BUT...STRONGLY VEERING LOW-LEVEL WIND PROFILES WITH
   HEIGHT BENEATH MODEST NORTHWESTERLY MID-LEVEL FLOW WILL CONTRIBUTE
   TO FAVORABLE SHEAR PROFILES FOR SUPERCELLS NEAR THE LEE SURFACE
   TROUGH...FROM THE BLACK HILLS VICINITY INTO WESTERN NEBRASKA.  UPPER
   FORCING IS UNCERTAIN...AND MID-LEVEL INHIBITION MAY BE
   CONSIDERABLE...BUT AT LEAST ISOLATED CONVECTIVE DEVELOPMENT SEEMS
   POSSIBLE IN THE PEAK AFTERNOON HEATING.
   
   MEANWHILE...MODELS ARE SUGGESTIVE THAT BETTER POTENTIAL FOR STORM
   DEVELOPMENT MAY EXIST IN A STRENGTHENING WARM ADVECTION REGIME
   ACROSS THE EASTERN DAKOTAS INTO MINNESOTA LATE WEDNESDAY NIGHT. 
   WHILE THE THERMODYNAMIC ENVIRONMENT MAY NOT BE OPTIMAL AT THIS TIME
   OF DAY...IT MAY STILL BE SUFFICIENT TO SUPPORT AT LEAST SOME
   POTENTIAL FOR MARGINALLY SEVERE HAIL/WIND GUSTS.
   
   ..KERR.. 07/08/2008
   
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