SPC AC 260520

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1220 AM CDT FRI JUN 26 2015

   VALID 271200Z - 281200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE MID-ATLANTIC...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM PA SOUTH AND SOUTHWEST TO
   THE GULF COAST...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER THE NORTHERN PLAINS...

   ...SUMMARY...
   SEVERE THUNDERSTORMS WITH DAMAGING WIND GUSTS AND PERHAPS A COUPLE
   OF TORNADOES ARE POSSIBLE SATURDAY AFTERNOON OVER PARTS OF THE
   MID-ATLANTIC REGION FROM DELMARVA SOUTH ACROSS NORTH CAROLINA.
   MARGINALLY SEVERE STORMS WILL ALSO BE POSSIBLE FROM SOUTH
   CAROLINA...ACROSS THE DEEP SOUTH...TO THE GULF COAST STATES. A
   CHANCE FOR EVENING SEVERE STORMS MAY ALSO DEVELOP OVER PORTIONS OF
   EASTERN DAKOTAS AND WESTERN MINNESOTA.

   ...OVERVIEW...
   THE LARGE-SCALE UPPER-AIR PATTERN WILL UNDERGO CONSIDERABLE
   AMPLIFICATION THROUGH THE WEEKEND AS AN UPPER RIDGE INTENSIFIES OVER
   THE WESTERN CONUS AND AN EQUALLY IMPRESSIVE DOWNSTREAM TROUGH
   DEVELOPS EAST OF THE MISSISSIPPI VALLEY. THE EASTERN TROUGH WILL
   INDUCE AN UNSEASONABLY DEEP OCCLUDED CYCLONE NEARING OHIO/LAKE ERIE
   BY SATURDAY AFTERNOON WITH AN ONLY SLIGHTLY WEAKER SECONDARY LOW
   FORECAST TO TRACK NEAR THE DELMARVA REGION DURING THE DAY. THE
   PRE-FRONTAL TROUGH AND COLD FRONT ASSOCIATED WITH THESE SYSTEMS WILL
   EXTEND SOUTH-SOUTHWESTWARD FROM THE SPINE OF THE APPALACHIANS AND
   INTO THE PIEDMONT/MIDLANDS REGIONS OF THE CAROLINAS ACROSS THE DEEP
   SOUTH TO NEAR THE ARKLATEX. THESE BOUNDARIES WILL TRANSLATE
   RELATIVELY QUICKLY TO EAST IN THE NORTHERN AREAS...BUT SETTLE MORE
   SLOWLY SOUTH ACROSS THE GULF COAST REGION AND NORTHEAST TX THROUGH
   SUNDAY MORNING.

   A LOW-AMPLITUDE SHORTWAVE TROUGH IS FORECAST TO CREST THE UPPER
   RIDGE OVER SOUTH-CENTRAL CANADA ON SATURDAY AFTERNOON WITH WEAK
   HEIGHT FALLS SPREADING ACROSS THE INTERNATIONAL BORDER FROM ND TO MN
   BY LATE AFTERNOON. THIS IMPULSE WILL CONTRIBUTE TO A STRENGTHENING
   SURFACE TROUGH/LOW THAT WILL TRACK SOUTHEAST ACROSS THE UPPER MS
   VALLEY LATE IN THE FORECAST PERIOD.

   ...MID-ATLANTIC TO GULF COAST...
   LATEST GUIDANCE DEPICTS A STRONG SURFACE LOW UNDERGOING OCCLUSION
   ACROSS NORTHEAST OH SATURDAY AFTERNOON AS A SECONDARY CIRCULATION
   AND STRONG FRONTAL SURGE OCCUR FROM SRN PA SOUTH ACROSS DELMARVA
   INTO NC. A WELL-DEFINED WARM FRONT IS INDICATED ACROSS THE DELMARVA
   REGION WITH ABUNDANT MOISTURE AND POTENTIAL INSTABILITY SITUATED
   ALONG AND SOUTH OF THIS BOUNDARY. LARGE-SCALE ASCENT IN THE BASE OF
   THE UPPER TROUGH WILL PIVOT EAST ACROSS THE WARM SECTOR AROUND THE
   TIME OF MAX HEATING AND SHOULD PROMOTE STRONG TO SEVERE THUNDERSTORM
   DEVELOPMENT ALONG LEE/PRE-FRONTAL TROUGH AS WELL AS ALONG/NEAR THE
   WARM FRONT AND DEVELOPING SECONDARY LOW CROSSING DELMARVA.

   THE COMBINATION OF SHEAR AND INSTABILITY FORECAST ACROSS NC COULD
   SUPPORT AN NUMBER OF CONVECTIVE MODES FROM FAST-MOVING LINE SEGMENTS
   TO SUPERCELLS. CLUSTERS OF ELEVATED CONVECTION APPEAR LIKELY NORTH
   OF THE WARM FRONT INTO PA/NJ WITH THE POTENTIAL FOR SUPERCELLS...AND
   PERHAPS A TORNADO OR TWO...IN CLOSER PROXIMITY TO SECONDARY LOW AND
   WARM FRONT IF SURFACE-BASED DESTABILIZATION CAN OCCUR IN THESE
   AREAS. DAMAGING WINDS APPEAR TO BE THE PRIMARY THREAT OVER MUCH OF
   THE SLGT RISK AREA THROUGH SATURDAY EVENING.

   SHEAR AND LAPSE RATES DIMINISH WITH SOUTHWESTWARD EXTENT ALONG THE
   TRAILING FRONT FROM SC TO THE GULF COAST. HOWEVER...SCATTERED STRONG
   TO LOCALLY SEVERE STORMS APPEAR LIKELY GIVEN WEAK HEIGHT FALLS AND
   MODEST MID-LEVEL FLOW OF 30-40KT.

   ...NORTHERN PLAINS...
   LIFT ASSOCIATED WITH A SHORTWAVE IMPULSE EMBEDDED WITHIN MODEST
   NORTHWEST FLOW ALOFT WILL COINCIDE WITH MAX DIURNAL HEATING TO
   FOSTER AT LEAST ISOLATED THUNDERSTORMS FROM NORTHEAST ND INTO
   ADJACENT AREAS OF MN BY SATURDAY EVENING. STORMS SHOULD DEVELOP
   AMIDST A WARM AND MODESTLY UNSTABLE AIRMASS WHERE DEEP-LAYER SHEAR
   IS FORECAST TO BE SUPPORTIVE OF UPDRAFT PERSISTENCE/ROTATION. A
   RELATIVELY DRY BOUNDARY LAYER IN THE WAKE OF RECENT FRONTAL PASSAGES
   COULD CONTRIBUTE TO GUSTY SURFACE WINDS WHILE STEEP LAPSE RATES
   ALOFT ALSO FAVOR HAIL FROM SOME OF THE STRONGER CELLS. STORM
   COVERAGE IS UNCERTAIN AT THIS FORECAST RANGE AND PRECLUDES A HIGHER
   SEVERE PROBABILITY BUT A SMALL SLGT RISK MAY BE ADDED IN LATER
   OUTLOOKS.

   ..CARBIN.. 06/26/2015

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z