SPC AC 152000

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0300 PM CDT MON AUG 15 2016

   VALID 152000Z - 161200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER THE A PORTION OF THE OH
   VALLEY THROUGH THE MID ATLANTIC AREA...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER WRN AND CNTRL ND...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER WRN SD...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER CNTRL THROUGH NERN NEB...

   ...SUMMARY...
   ISOLATED STRONG TO POSSIBLY SEVERE THUNDERSTORMS ARE EXPECTED ACROSS
   THE NORTHERN PLAINS AS WELL AS THE OHIO VALLEY TO MID-ATLANTIC
   STATES THIS AFTERNOON AND EVENING.

   ...NRN PLAINS AREA...

   HAVE FOCUSED MARGINAL RISK AREAS PRIMARILY FOR STORMS DEVELOPING
   ALONG BOUNDARY ACROSS WRN ND /REF SWOMCD 1537 FOR MORE INFORMATION/
   AND FOR STORMS MOVING OFF THE BLACK HILLS OF SD. STEEP LAPSE RATE
   ENVIRONMENT WITH MODEST INSTABILITY WILL CONTINUE TO SUPPORT A FEW
   INSTANCES OF DOWNBURST WINDS AND HAIL THROUGH EARLY EVENING WITH
   THIS ACTIVITY.

   ...MID ATLANTIC AREA THROUGH OH VALLEY...

   NO SIGNIFICANT CHANGES TO THIS AREA. NUMEROUS MULTICELL STORMS WILL
   CONTINUE TO POSE  A FEW INSTANCES OF DOWNBURST WINDS THROUGH EARLY
   EVENING.

   FARTHER WEST INTO THE OH VALLEY...STRONGER VERTICAL SHEAR IS
   SUFFICIENT FOR A FEW STORMS TO DEVELOP ROTATING UPDRAFTS WITH AN
   OUTSIDE CHANCE FOR A BRIEF TORNADO. HOWEVER...THE VERY MARGINAL
   THERMODYNAMIC ENVIRONMENT SHOULD LIMIT OVERALL THREAT IN THIS AREA
   TO A MARGINAL RISK CATEGORY.

   ..DIAL.. 08/15/2016

   .PREV DISCUSSION... /ISSUED 1122 AM CDT MON AUG 15 2016/

   ...OH VALLEY AREA THROUGH TONIGHT...
   THE REMNANTS OF THE FLOOD-PRODUCING TROPICAL LOW ARE NOW MOVING NEWD
   OVER IL/INDIANA...AND WILL CONTINUE NEWD TO LOWER MI...IN ADVANCE OF
   A SHORTWAVE TROUGH MOVING ENEWD FROM OK.  HIGH PW VALUES AND POOR
   LAPSE RATES WITHIN THE TROPICAL MOISTURE PLUME FROM THE NW GULF
   COAST TO THE OH VALLEY DO NOT APPEAR FAVORABLE FOR STRONG UPDRAFTS. 
   STILL...A BELT OF ENHANCED LOW-MIDLEVEL FLOW/SHEAR ACROSS THE LOWER
   OH VALLEY MAY SUPPORT EMBEDDED STORMS WITH WEAK ROTATION...AND AN
   ATTENDANT RISK FOR ISOLATED STRONG GUSTS AND/OR A BRIEF TORNADO AS
   CONVECTION SPREADS NEWD OVER THE OH VALLEY.

   ...CENTRAL/SRN APPALACHIANS AND PIEDMONT THIS AFTERNOON...
   STRONG SURFACE HEATING IS UNDERWAY ACROSS MUCH OF NC/VA IMMEDIATELY
   E OF THE HIGHER TERRAIN.  SURFACE TEMPERATURES IN THE 90S WITH
   DEWPOINTS IN THE LOW-MID 70S WILL DRIVE MLCAPE NEAR 2500 J/KG THIS
   AFTERNOON.  VERTICAL SHEAR WILL BE SLIGHTLY STRONGER WITH NWD
   EXTENT...BUT THE PRIMARY RISK WILL BE ISOLATED DAMAGING DOWNBURST
   WINDS WITH MULTICELL CLUSTERS IN AN ENVIRONMENT WITH MODERATE
   BUOYANCY AND DCAPE AOA 1000 J/KG.  STORMS SHOULD FORM FIRST OVER THE
   HIGH TERRAIN BY EARLY AFTERNOON...AND DEEPENING CUMULUS IN VISIBLE
   IMAGERY AS OF 16Z SUGGESTS AT LEAST ISOLATED STORMS WILL FORM WELL E
   OF THE MOUNTAINS ACROSS VA/NC.

   ...NRN PLAINS AREA THIS AFTERNOON/EVENING...
   AN MCV OVER NE SD WILL DRIFT EWD TODAY TOWARD CENTRAL MN AS AN
   UPSTREAM WAVE MOVES ESEWD FROM ERN MT...AS PART OF BROAD CYCLONIC
   FLOW OVER THE NRN PLAINS.  THERE WILL BE THREE POTENTIAL FOCI FOR
   STORM INITIATION THIS AFTERNOON - A WEAK BOUNDARY ACROSS NE NEB/SE
   SD TRAILING THE MCV...A DIFFUSE SURFACE TROUGH ACROSS CENTRAL
   ND...AND SURFACE HEATING OVER THE HIGHER TERRAIN OF THE BLACK HILLS.
   DEEP-LAYER VERTICAL SHEAR WILL BE MARGINAL FOR SUPERCELLS AT BEST
   /PRIMARILY INVOF SE SD AND WEAKER TOWARD ND/...WHILE CONVECTION OVER
   THE BLACK HILLS SHOULD BE HIGH BASED.  ISOLATED STRONG OUTFLOW GUSTS
   AND LARGE HAIL WILL BE POSSIBLE THIS AFTERNOON/EVENING.

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