SPC Day 2 Convective Outlook Valid 1730Z 13 October 2014

   SPC AC 131730

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1230 PM CDT MON OCT 13 2014

   VALID 141200Z - 151200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS TUES INTO TUES NIGHT ACROSS
   PORTIONS OF THE LOWER OHIO VALLEY INTO THE CENTRAL AND SOUTHERN
   APPALACHIANS...AND ACROSS THE EASTERN GULF INTO SOUTH ATLANTIC COAST
   STATES...

   ...SUMMARY...
   THE RISK FOR POTENTIALLY DAMAGING WIND GUSTS AND A FEW TORNADOES IS
   EXPECTED TO ACCOMPANY THUNDERSTORM ACTIVITY TUESDAY INTO TUESDAY
   NIGHT ACROSS PARTS OF THE LOWER OHIO VALLEY INTO CENTRAL AND
   SOUTHERN APPALACHIANS...AS WELL AS ACROSS THE EASTERN GULF COAST
   INTO THE SOUTH ATLANTIC COAST.

   ...SYNOPSIS...
   THE MID/UPPER CLOSED LOW...NOW OVER THE SOUTHERN PLAINS...APPEARS
   LIKELY TO DEVELOP NORTHEASTWARD INTO THE MIDDLE MISSISSIPPI
   VALLEY...BEFORE GENERALLY BECOMING CUT-OFF FROM THE STRONGER
   WESTERLIES.  HOWEVER...A SLOW EASTWARD PROGRESSION OF THE CYCLONIC
   CIRCULATION...AND UPPER TROUGHING TRAILING TO THE SOUTH...IS
   FORECAST TUESDAY THROUGH TUESDAY NIGHT...AS A SIGNIFICANT UPSTREAM
   TROUGH WITHIN THE WESTERLIES PROGRESSES INTO THE PACIFIC COAST.

   MODELS DO INDICATE SUBSTANTIAL WEAKENING OF THE ASSOCIATED SURFACE
   CYCLONE ACROSS THE MIDDLE MISSISSIPPI INTO LOWER OHIO VALLEYS DURING
   THIS PERIOD.  HOWEVER...LARGE-SCALE FORCING FOR UPWARD VERTICAL
   MOTION...IN THE PRESENCE OF SUFFICIENTLY MOIST CONDITIONS TO SUPPORT
   WEAK TO MODEST CONDITIONAL INSTABILITY...IS EXPECTED TO SUPPORT
   CONSIDERABLE CONVECTION...INCLUDING THUNDERSTORM ACTIVITY...ACROSS
   THE GREAT LAKES...OHIO VALLEY AND SOUTHEASTERN STATES.  AND
   WEAKENING OF LOWER/MID TROPOSPHERIC WIND FIELDS MAY BE SLOW ENOUGH
   TO MAINTAIN A RISK FOR SEVERE THUNDERSTORMS ACROSS PARTS OF THE
   LOWER OHIO VALLEY INTO CENTRAL AND SOUTHERN APPALACHIANS...AS WELL
   AS ACROSS PARTS OF THE EASTERN GULF STATES INTO THE SOUTH ATLANTIC
   COAST.

   ...OHIO VALLEY INTO APPALACHIANS AND SOUTHEAST...
   BY 12Z TUESDAY...MODELS GENERALLY SUGGEST THAT A PRE-COLD FRONTAL
   50-70 KT SOUTHERLY 850 MB JET CORE WILL EXTEND FROM THE UPPER
   TENNESSEE VALLEY NORTHWARD ACROSS THE LOWER OHIO VALLEY...TOWARD THE
   GREAT LAKES REGION.  WHILE WEAKENING OF THIS FEATURE IS FORECAST
   THROUGH THE PERIOD AS IT SHIFTS EASTWARD ACROSS THE APPALACHIANS AND
   LOWER GREAT LAKES REGION...IT APPEARS THAT THIS MAY BE SLOW...AT
   LEAST DURING THE DAYTIME HOURS...WHEN BOUNDARY LAYER DESTABILIZATION
   MAY BECOME JUXTAPOSED WITH STRONG TO EXTREME LOW-LEVEL SHEAR. 
   ALTHOUGH THIS INSTABILITY PROBABLY WILL BE LIMITED DUE TO WEAK
   LOWER/MID TROPOSPHERIC LAPSE RATES...A BAND OF FRONTAL FORCING
   OVERSPREADING CENTRAL AND EASTERN KENTUCKY AND TENNESSEE DURING THE
   DAY PROBABLY WILL BE SUFFICIENT TO SUPPORT THUNDERSTORM ACTIVITY. 
   GIVEN THIS DEVELOPMENT...AND THE SIZE OF THE FORECAST LOW-LEVEL
   HODOGRAPHS...STRONGEST STORMS WILL BE ACCOMPANIED BY THE RISK FOR
   POTENTIALLY DAMAGING WIND GUSTS AND TORNADOES...AND COULD REACH THE
   WESTERN SLOPES OF THE APPALACHIANS BEFORE WEAKENING TUESDAY EVENING.

   FARTHER SOUTH...ACROSS THE EASTERN GULF STATES...SOUTHERLY DEEP
   LAYER MEAN FLOW FIELDS AND SHEAR WILL BE WEAKER /30-50 KT/...BUT
   STILL SUFFICIENTLY STRONG FOR ORGANIZED CONVECTIVE DEVELOPMENT IN
   THE PRESENCE OF MIXED LAYER CAPE ON THE ORDER OF 500-1000 J/KG BY
   TUESDAY AFTERNOON.  ALTHOUGH FORCING FOR UPWARD VERTICAL MOTION
   APPEARS LIKELY TO BE WEAKER...OR LESS FOCUSED...BROKEN BANDS OR
   CLUSTERS OF STORMS APPEAR POSSIBLE WITHIN BROADLY CONFLUENT
   LOW-LEVEL FLOW.  THIS MAY INCLUDE DISCRETE SUPERCELL
   DEVELOPMENT...WITH THE RISK FOR A COUPLE OF TORNADOES...IN ADDITION
   TO LOCALLY DAMAGING WIND GUSTS.

   ..KERR.. 10/13/2014

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z