Aug 1, 2009 1730 UTC Day 2 Convective Outlook
Updated: Sat Aug 1 17:26:46 UTC 2009
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Categorical Graphic
20090801 1730 UTC Day 2 Outlook Graphic
Probabilistic Graphic
20090801 1730 UTC Day Probabilitic Graphic
Probability Legend Image
   SPC AC 011723
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1223 PM CDT SAT AUG 01 2009
   
   VALID 021200Z - 031200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE DELMARVA INTO
   CNTRL/ERN CAROLINAS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CNTRL/ERN SD INTO
   SWRN/W-CNTRL MN...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF SRN ORE...
   
   ...SYNOPSIS...
   
   LARGE-SCALE PATTERN WILL REMAIN UNCHANGED THROUGH THE
   PERIOD...FEATURING LONGWAVE TROUGH --ANCHORED BY VORTEX OVER JAMES
   BAY-- OVER CNTRL/ERN CANADA INTO THE SERN STATES...AND REX BLOCK
   OVER THE ERN PACIFIC/WRN N AMERICA.  WITHIN THIS BROADER-SCALE
   REGIME...SHORT WAVE TROUGH INITIALLY FROM THE UPPER GREAT LAKES INTO
   CNTRL/SRN APPALACHIANS WILL TRANSLATE NEWD THROUGH THE LOWER GREAT
   LAKES...NEW ENGLAND AND THE MID ATLANTIC STATES.  MEANWHILE...NEXT
   UPSTREAM SHORT WAVE TROUGH WILL PROGRESS SEWD THROUGH THE NRN PLAINS
   AND UPPER GREAT LAKES.
   
   AT THE SURFACE...COLD FRONT ASSOCIATED WITH FORMER SHORT WAVE TROUGH
   MENTIONED ABOVE WILL SHIFT EWD FROM THE LOWER GREAT LAKES AND
   APPALACHIANS TOWARD THE ATLANTIC COAST.  FARTHER W...COLD FRONT
   ATTENDANT TO LATTER-MENTIONED IMPULSE WILL SURGE SEWD THROUGH THE
   NRN PLAINS AND UPPER MS VALLEY.  A PRE-FRONTAL TROUGH WILL PRECEDE
   THIS COLD FRONT...EXTENDING SWWD FROM LOW PRESSURE OVER THE RED
   RIVER VALLEY --OF ND/MN-- INTO THE CNTRL/SRN HIGH PLAINS.
   
   ...NEW ENGLAND INTO THE CNTRL/ERN CAROLINAS...
   
   SCATTERED TO NUMEROUS TSTMS ARE EXPECTED TO DEVELOP ALONG/AHEAD OF
   COLD FRONT SUN AS FORCING FOR ASCENT ASSOCIATED WITH MIGRATORY SHORT
   WAVE TROUGH ACTS ON A MOIST/UNSTABLE AIR MASS.  THE STRONGEST
   FORCING FOR ASCENT AND VERTICAL SHEAR WILL SPREAD EWD/NEWD FROM THE
   LOWER GREAT LAKES THROUGH NEW ENGLAND IN CONJUNCTION WITH PRIMARY
   VORTICITY LOBE.  HOWEVER...FORECAST SOUNDINGS INDICATE THAT LAPSE
   RATES WILL REMAIN WEAK WHICH WILL LIMIT MLCAPE TO LESS THAN 1000
   J/KG.  NONETHELESS...THE MORE INTENSE STORMS WILL REMAIN CAPABLE OF
   SOME MARGINALLY SEVERE HAIL AND/OR LOCALLY STRONG WIND GUSTS.
   
   FARTHER S...A WARMER AND MORE MOIST BOUNDARY LAYER WILL CONTRIBUTE
   TO POCKETS OF MODERATE INSTABILITY /MLCAPE OF 1000-1500 J PER KG/
   AHEAD OF COLD FRONT BY AFTERNOON.  VERTICAL SHEAR WILL CONCURRENTLY
   STRENGTHEN WITH APPROACH OF SHORT WAVE TROUGH WITH ENVIRONMENT
   BECOMING SUPPORTIVE OF ORGANIZED STORM CLUSTERS CAPABLE OF DAMAGING
   WINDS AND HAIL ACROSS THE PIEDMONT AND COASTAL PLAIN INTO SUN
   EVENING.
   
   ...NRN PLAINS INTO UPPER MIDWEST...
   
   WHILE BOUNDARY LAYER MOISTURE WILL REMAIN SOMEWHAT LIMITED /I.E.
   DEWPOINTS IN THE UPPER 40S TO 50S/ AHEAD OF COLD FRONT...LAPSE RATES
   WILL STEEPEN...YIELDING MLCAPE OF 500-1000 J/KG BY AFTERNOON. 
   STRONG DYNAMIC FORCING FOR ASCENT AND 40-50 KT OF DEEP NWLY SHEAR
   WILL SUPPORT THE DEVELOPMENT OF SCATTERED STRONG/SEVERE STORMS ALONG
   SURFACE FRONT BY MID/LATE AFTERNOON.  THE PRESENCE OF DEEPLY MIXED
   BOUNDARY LAYER CONDITIONS AND STEEP MIDLEVEL LAPSE RATES WILL
   PROMOTE HAIL AND LOCALLY DAMAGING WIND GUSTS WITH THE STRONGEST
   STORMS THROUGH SUN EVENING.
   
   SOME POTENTIAL FOR HAIL MAY CONTINUE INTO SUN NIGHT EWD INTO WI AS
   ELEVATED STORMS INCREASE IN COVERAGE ALONG NOCTURNAL LLJ.
   
   ...SRN ORE/NRN CA...
   
   STEEP LAPSE RATES...MODERATE CONVECTIVE INSTABILITY /MLCAPE OF
   1000-1500 J PER KG/ AND 30-40 KT DEEP SELY SHEAR WILL BE SUPPORTIVE
   OF A FEW ORGANIZED...DIURNAL STORMS WITHIN NERN QUADRANT OF
   DEEP-LAYER LOW OFF THE CA COAST.  THE MORE INTENSE STORMS WILL BE
   CAPABLE OF DAMAGING WIND GUSTS AND HAIL INTO SUN NIGHT.
   
   ...CNTRL/SRN HIGH PLAINS...
   
   EML/STEEP MIDLEVEL LAPSE RATES WILL BE ADVECTED EWD OVER THE HIGH
   PLAINS IN ADVANCE OF SHORT WAVE TROUGH DIGGING SEWD THROUGH THE NRN
   PLAINS.  THIS PROCESS WILL OCCUR BENEATH A MOISTENING BOUNDARY LAYER
   E OF SURFACE TROUGH WITH AIR MASS BECOMING MODERATELY UNSTABLE WITH
   MLCAPE OF 1500-2000 J/KG.  WEAK MIDLEVEL IMPULSE NOW OVER SRN ID IS
   FORECAST TO TRANSLATE SEWD THROUGH CO INTO WRN KS SUN...PROVIDING
   BACKGROUND FORCING FOR ISOLATED STORM DEVELOPMENT.
   
   CURRENT MODEL GUIDANCE SUGGESTS THAT VERTICAL SHEAR WILL REMAIN ON
   THE MARGINS OF THAT SUPPORTIVE OF ORGANIZED/ROTATING UPDRAFTS.  ONLY
   LOW SEVERE PROBABILITIES WILL BE MAINTAINED IN THIS
   FORECAST...THOUGH AN UPGRADE TO SLIGHT RISK MAY BE REQUIRED FOR WRN
   KS INTO THE OK/TX PNHDLS IN SUBSEQUENT DAY ONE OUTLOOKS.
   
   ..MEAD.. 08/01/2009
   
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