SPC AC 061252

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0752 AM CDT WED AUG 06 2014

   VALID 061300Z - 071200Z

   ...NO SVR TSTM AREAS FORECAST...

   ...SUMMARY...
   A FEW STRONG THUNDERSTORMS WILL DEVELOP ACROSS PARTS OF THE CENTRAL
   PLAINS AND MISSOURI VALLEY...AS WELL AS NEAR THE MID ATLANTIC COAST.
   GUSTY WINDS AND HAIL MAY OCCUR WITH THE STRONGEST ACTIVITY.

   ...SYNOPSIS...
   UPPER-AIR PATTERN CONTINUES GENERAL SHIFT TOWARD LOWER AMPLITUDE
   SYNOPTICALLY...DOMINATED BY SERIES OF SHORTWAVES OF VARYING
   STRENGTHS.  LONG-LIVED/MID-UPPER CYCLONE CENTERED OVER NRN CA IS
   EXPECTED TO WEAKEN THROUGH PERIOD...AS ITS CENTER DRIFTS ERRATICALLY
   BACK SWD TOWARD SRN CA.  SECONDARY CLOSED CIRCULATION -- EVIDENT IN
   MOISTURE-CHANNEL IMAGERY OVER NWRN UT/SRN ID -- SHOULD MEANDER EWD
   TO NEWD OVER SERN UT THROUGH PERIOD.  PLUME OF RELATIVELY MAXIMIZED
   LOW-MIDDLE-LEVEL MOISTURE CONNECTING THESE FEATURES...ALONG WITH
   POCKETS OF BOTH LARGE-SCALE LIFT AND FAVORABLE DIABATIC SFC
   HEATING...WILL CONTRIBUTE TO TSTM POTENTIAL FROM SIERRAS ACROSS NRN
   GREAT BASIN TO N-CENTRAL ROCKIES. 

   FARTHER E...WEAK SHORTWAVE TROUGH WITH SOME LOCALIZED
   CONVECTIVE-VORTICITY REINFORCEMENT WAS EVIDENT FROM WRN NEB SWD TO
   TX PANHANDLE.  THIS FEATURE WILL MOVE EWD TO IA...MO...AND OK/AR
   BORDER REGION BY 12Z.  CYCLONIC FLOW STILL PREVAILS OVER MUCH OF ERN
   CONUS RELATED TO MEAN TROUGH THERE.  AS STRONGER SHORTWAVE MOVES EWD
   FROM SK...PRECEDING PERTURBATION NOW OVER UPPER MI AND WI WILL SHIFT
   SEWD THROUGH AFOREMENTIONED CYCLONIC FLOW...REACHING WRN PA/OH BY
   00Z.

   AT SFC...WAVY/QUASISTATIONARY FRONTAL ZONE WAS EVIDENT FROM OFFSHORE
   MAINE WWD OVER NRN NY THEN SWWD ACROSS OH/SRN INDIANA THEN WNWWD TO
   SFC LOW OVER SWRN NEB.  THIS BOUNDARY SHOULD MOVE SLOWLY SSEWD OVER
   MID ATLC AND MID-UPPER OH VALLEY...WHILE SFC LOW WEAKENS AND ANOTHER
   FORMS OVER SWRN KS.  

   ...MID-ATLC REGION...
   WIDELY SCATTERED TO SCATTERED TSTMS ARE EXPECTED TO DEVELOP THIS
   AFTN AND MOVE ESEWD TO SEWD ACROSS INCREASINGLY WELL-HEATED/MIXED
   BOUNDARY LAYER.  STRONGER CELLS MAY PRODUCE POTENTIALLY DAMAGING
   GUSTS APCHG SVR LIMITS.  APCHG SHORTWAVE TROUGH ALOFT WILL
   CONTRIBUTE SOME LARGE-SCALE ASCENT-DESTABILIZATION IN
   MIDLEVELS...CONTERMINOUS WITH SFC HEATING TO STEEPEN SUBCLOUD LAPSE
   RATES.  TSTM INITIATION IS POSSIBLE NEAR FRONT...OVER MTNS...AND
   INVOF WEAK SFC TROUGH E OF MTNS.  ACTIVITY SHOULD MOVE THROUGH
   LOW-MID 60S F SFC DEW POINTS OVER ELEVATED TERRAIN AND UPPER 60S TO
   NEAR 70 F OVER COASTAL PLAIN AND LOWER PIEDMONT.  500-1200 J/KG
   MLCAPE MAY BE ATTAINED...AND SOME ACTIVITY MAY AGGREGATE INTO
   MULTICELLS OR SHORT LINES.  ORGANIZATION OF CONVECTION AND OF SVR
   THREAT WILL BE TEMPERED BY RATHER WEAK DEEP-LAYER LAPSE
   RATES...LIMITING BUOYANCY...AND BY LIGHT/WLY COMPONENT OF NEAR-SFC
   WINDS THAT WILL KEEP BOTH CONVERGENCE AND SHEAR VALUES SMALL. 

   ...CENTRAL PLAINS...LOWER-MID MO VALLEY...
   WIDELY SCATTERED TO SCATTERED TSTMS SHOULD DEVELOP THIS AFTN WITH
   SVR THREAT BEING MRGL AND POORLY ORGANIZED IN NATURE. 
   ONGOING/ELEVATED CONVECTION...PRIMARILY NE OF SFC FRONT FROM SRN SD
   TO WRN IL...WILL REINFORCE FRONTAL BAROCLINICITY THROUGH COMBINED
   EFFECTS OF PRECIPITATIVE OUTFLOW AND DIFFERENTIAL HEATING.  AS WEAK
   SHORTWAVE TROUGH APCHS THIS AREA FROM CENTRAL HIGH PLAINS...BOUNDARY
   LAYER ALONG AND S OF FRONT WILL BECOME WELL-HEATED IN PATCHES NOT
   PERSISTENTLY SHADED BY MORNING/EARLY-AFTN CLOUDINESS.  THESE FACTORS
   WILL STEEPEN LOW-MIDDLE-LEVEL LAPSE RATES AMIDST SFC DEW POINTS
   MAINLY 60S F...LEADING TO MLCAPE MOSTLY AROUND 1500 J/KG AND LOCALLY
   2000-2500 J/KG.  ALTHOUGH DIRECTIONAL SHEAR WILL BE STG...ESPECIALLY
   ALONG FRONT...WEAK LOW-MIDLEVEL FLOW WILL KEEP EFFECTIVE-SHEAR
   MAGNITUDES GENERALLY UNDER 30 KT IN MOST AREAS.  STILL...GIVEN
   STRENGTH OF BUOYANCY AND PRESENCE OF WELL-MIXED SUBCLOUD
   LAYERS...ISOLATED GUSTS APCHG SVR LIMITS AS WELL AS MRGL HAIL CANNOT
   BE RULED OUT.

   ..EDWARDS/SMITH.. 08/06/2014

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