SPC AC 301236

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0736 AM CDT WED APR 30 2014

   VALID 301300Z - 011200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE CNTRL
   APPALACHIANS AND MID ATLANTIC TO THE SERN STATES...

   ...SUMMARY...
   SCATTERED SEVERE THUNDERSTORMS CAPABLE OF HAIL...DAMAGING
   WINDS...AND TORNADOES ARE EXPECTED TODAY INTO TONIGHT FROM PORTIONS
   OF THE MID-ATLANTIC AND CENTRAL APPALACHIANS TO THE SOUTHEAST
   STATES.

   ...SYNOPSIS...

   A DEEP-LAYER CYCLONE OVER THE UPPER MIDWEST WILL EDGE ONLY SLIGHT
   EWD DURING THE DAY ONE PERIOD WITH A BELT OF STRONG MIDLEVEL FLOW
   PERSISTING FROM THE SRN PLAINS THROUGH LOWER MS/TN/UPPER OH VALLEYS
   EWD INTO THE APPALACHIANS. EMBEDDED WITHIN THIS HIGH-MOMENTUM AIR
   STREAM...AN 80-100 KT JET STREAK AT 500 MB WILL PROGRESS FROM THE
   SRN PLAINS THROUGH THE LOWER MS/TN VALLEYS INTO THE CNTRL
   APPALACHIANS AND UPPER OH VALLEY BY TONIGHT. THIS UPPER-AIR PATTERN
   EVOLUTION WILL MAINTAIN A 40-50 KT SLY LLJ EAST OF THE APPALACHIANS
   TODAY WHICH WILL ENHANCE VERTICAL SHEAR AND THE POLEWARD FLUX AND
   HEAT AND MOISTURE WITHIN THE NWD-EXPANDING WARM SECTOR.

   AT THE SURFACE...LOW PRESSURE OVER ERN TN WILL DEVELOP NNEWD INTO
   THE UPPER OH VALLEY BY EVENING WITH A TRAILING COLD FRONT ADVANCING
   EWD THROUGH THE CNTRL AND SRN APPALACHIANS INTO THE PIEDMONT REGION
   BY 01/12Z. MEANWHILE...A WEDGE OR WARM FRONT ALIGNED SW-NE FROM WRN
   PARTS OF SC/NC TO E-CNTRL VA WILL MOVE NWD TO NEAR OR NORTH OF THE
   MASON-DIXON LINE BY LATE AFTERNOON/EARLY EVENING.

   ...MID-ATLANTIC/CNTRL APPALACHIANS TO SERN STATES TODAY INTO
   TONIGHT...

   CURRENT SURFACE OBSERVATIONS AND 12Z SOUNDING DATA INDICATE THE
   PRESENCE OF A SEASONABLY MOIST AIR MASS TO THE SOUTH OF THE WARM
   FRONT WITH BOUNDARY LAYER DEWPOINTS IN THE MID 60S TO LOWER 70S AND
   LOWEST 100-MB MEAN MIXING RATIOS OF AROUND 14 G/KG. THIS MOISTURE
   WILL COMBINE WITH DAYTIME HEATING TO PROMOTE AFTERNOON MLCAPE VALUES
   APPROACHING 500-1000 J/KG OVER NRN PORTIONS OF THE SLIGHT RISK AREA
   TO AS HIGH AS 1500-2000 J/KG ACROSS CNTRL/ERN PARTS OF THE
   CAROLINAS.

   LATEST MODEL GUIDANCE OFFERS VARYING SOLUTIONS WITH REGARD TO
   SURFACE-BASED TSTM DEVELOPMENT AND SUBSEQUENT EVOLUTION LATER TODAY.
   POTENTIAL FOCI FOR STORM INITIATION WILL BE THE WARM
   FRONT...TERRAIN...AND RESIDUAL OUTFLOW BOUNDARIES AS DEEP-LAYER
   FORCING FOR ASCENT IS ENHANCED BY THE ABOVE-MENTIONED MIDLEVEL JET
   STREAK PROGRESSING INTO THE CNTRL APPALACHIANS. AN ADDITIONAL
   CLUSTER OR BAND OF TSTMS MAY EVOLVE WEST OF THE APPALACHIANS THIS
   AFTERNOON FROM THE VICINITY OF THE MIGRATORY SURFACE LOW SWD ALONG
   THE COLD FRONT.

   THE MOST FAVORABLE OVERLAP OF INSTABILITY AND VERTICAL SHEAR /I.E.
   EFFECTIVE SRH OF 200-350 M2 PER S2 AND 40-50 KT OF EFFECTIVE BULK
   SHEAR/ WILL RESIDE OVER THE PIEDMONT THIS AFTERNOON INTO EARLY
   EVENING WHERE THE POTENTIAL WILL EXIST FOR SUPERCELLS CAPABLE OF
   TORNADOES...LARGE HAIL AND DAMAGING WINDS. THIS NOTION IS GENERALLY
   SUPPORTED BY A NUMBER OF CONVECTION-ALLOWING MODELS WHICH INDICATE A
   MIXTURE OF SUPERCELLS AND BOWING LINES AFFECTING PRIMARILY THE
   PIEDMONT INTO COASTAL PLAIN FROM THIS AFTERNOON INTO TONIGHT.

   OVER SRN GA/NRN FL...SEVERE WEATHER POTENTIAL MAY BE LIMITED BY THE
   STABILIZING EFFECTS OF THE NOCTURNAL MCS MOVING ACROSS THE REGION
   THIS MORNING. AS SUCH...IT IS POSSIBLE THAT THIS PART OF THE SLIGHT
   RISK AREA MAY BE DOWNGRADED IN THE SUBSEQUENT DAY ONE UPDATE.

   ...FL PENINSULA THIS AFTERNOON...

   SCATTERED TSTMS ARE EXPECTED TO DEVELOP ALONG THE SEA-BREEZE OVER
   THE CNTRL PENINSULA THIS AFTERNOON AMIDST A MOIST AND MODERATELY
   UNSTABLE /I.E. MLCAPE UP TO 2000-2500 J PER KG/ AIR MASS. WHILE
   VERTICAL SHEAR WILL REMAIN RELATIVELY WEAK...THE POTENTIAL FOR
   STRONG UP/DOWNDRAFTS MAY YIELD ISOLATED OCCURRENCES OF HAIL AND
   LOCALLY DAMAGING WINDS.

   ..MEAD/MOSIER.. 04/30/2014

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z