Sep 30, 2008 0600 UTC Day 1 Convective Outlook
Updated: Tue Sep 30 06:01:16 UTC 2008
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Categorical Graphic
20080930 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20080930 1200 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20080930 1200 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20080930 1200 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 300558
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1258 AM CDT TUE SEP 30 2008
   
   VALID 301200Z - 011200Z
   
   ...NO SVR TSTM AREAS FORECAST...
   
   ...SYNOPSIS...
   HIGHLY AMPLIFIED/MERIDIONAL LARGE SCALE UPPER FLOW PATTERN WILL
   PREVAIL THROUGH THE PERIOD OVER THE CONUS. AS AN UPPER RIDGE
   DOMINATES THE WESTERN STATES...A DOWNSTREAM DIGGING UPPER JET WILL
   CONTINUE TO DEEPEN THE LONGWAVE TROUGH OVER THE EASTERN CONUS. IN
   ASSOCIATION WITH THIS UPPER TROUGH...A COLD FRONT WILL TRANSITION
   EASTWARD ACROSS THE APPALACHIANS/MID ATLANTIC REGION...WITH THE
   SOUTHERN PORTION OF THE FRONT ADVANCING SOUTH-SOUTHEASTWARD ACROSS
   THE SOUTHEAST/GULF COAST STATES.
   
   ...MID ATLANTIC STATES/APPALACHIANS TO CAROLINAS...
   AS THE UPPER TROUGH SHIFTS EASTWARD OVER THE GREAT LAKES...STEADY
   LARGE SCALE HEIGHT FALLS ARE EXPECTED OVER THE REGION AS SEVERAL LOW
   AMPLITUDE SHORTWAVE TROUGHS PIVOT EAST-NORTHEASTWARD OVER THE OH
   VALLEY AND CENTRAL/NORTHERN APPALACHIANS THROUGH THE PERIOD. IN
   ASSOCIATION WITH A LEAD MID LEVEL IMPULSE AND THE ADVANCING COLD
   FRONT...AT LEAST ISOLATED SHOWERS/TSTMS AND AMPLE CLOUD COVER SHOULD
   BE SPREADING EASTWARD TOWARD THE APPALACHIANS VICINITY THROUGH
   DAYBREAK THIS MORNING...WITH ADDITIONAL HIGH LEVEL CLOUD COVER
   SPREADING NORTHWARD VIA A SOUTHERN STREAM IMPULSE OVER THE EASTERN
   GULF/SOUTHEAST STATES. IN THE WAKE OF THIS EARLY DAY ACTIVITY...THE
   APPROACH OF A SECONDARY MID LEVEL FEATURE AND DIURNAL
   DESTABILIZATION SHOULD BE FAVORABLE FOR AN UPSWING IN TSTM
   COVERAGE/INTENSITY ALONG THE COLD FRONT AND/OR LEE TROUGH DURING THE
   AFTERNOON. IN SPITE OF FAVORABLE KINEMATICS BENEATH
   CYCLONIC/MODERATELY STRONG FLOW ALOFT...QUESTIONS REGARDING CLOUD
   COVER/EARLY DAY PRECIPITATION AND SUBSEQUENT DESTABILIZATION/WAKE
   REDEVELOPMENT PRECLUDES A CATEGORICAL SLIGHT RISK AT THIS TIME.
   NEVERTHELESS...PENDING SUFFICIENT HEATING/SURFACE BASED
   DESTABILIZATION THIS AFTERNOON...COOL PROFILES ALOFT /-13 TO -18C AT
   500 MB/ AND STEEP MID LEVEL LAPSE RATES WILL BE CONDUCIVE FOR SEVERE
   HAIL WITH THE STRONGEST TSTMS...IN ADDITION TO STRONG WIND GUSTS.
   VERTICAL SHEAR ON THE ORDER OF 30-35 KT WILL BE FAVORABLE FOR THE
   DEVELOPMENT OF MULTICELLS/LINE SEGMENTS...AND PERHAPS A FEW
   SUPERCELLS ACROSS THE MID ATLANTIC REGION.
   
   ...SOUTH FL...
   DESTABILIZATION TODAY MAY BE SOMEWHAT TEMPERED IN THE WAKE OF
   OVERNIGHT SHOWERS/TSTMS ACROSS THE SOUTHERN HALF OF THE FL...BUT THE
   EASTWARD TRANSITION OF A MID LEVEL IMPULSE/ASSOCIATED SURFACE LOW
   WILL CONTINUE TO FOCUS TSTMS ALONG A WEAK BAROCLINIC ZONE ACROSS
   SOUTH FL TODAY. PROVIDED MODEST HEATING/CLOUD BREAKS...SUFFICIENT
   VERTICAL SHEAR MAY FAVOR SOME STRONG/PERHAPS ISOLATED SEVERE TSTMS
   THROUGH THE AFTERNOON. ISOLATED DAMAGING WIND GUSTS AND/OR A BRIEF
   TORNADO/WATERSPOUT WILL BE POSSIBLE.
   
   ..GUYER/HURLBUT.. 09/30/2008
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z