SPC AC 231225
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0725 AM CDT THU MAY 23 2013
   
   VALID 231300Z - 241200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS OVER A SMALL PORTION OF
   NORTHWEST TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF OK/TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE EASTERN
   UNITED STATES...
   
   ...NORTHEAST STATES...
   A BROAD UPPER TROUGH REMAINS OVER THE MS AND OH VALLEYS THIS
   MORNING.  THIS TROUGH WILL MOVE SLOWLY EASTWARD INTO THE
   APPALACHIANS TODAY...PROVIDING A FAVORABLE SYNOPTIC ENVIRONMENT FOR
   SCATTERED THUNDERSTORMS FROM NEW ENGLAND SOUTHWARD INTO THE
   CAROLINAS.  BROKEN CLOUD COVER WILL SLOW DAYTIME HEATING THIS
   MORNING...BUT SUFFICIENT DESTABILIZATION SHOULD RESULT FOR
   THUNDERSTORMS INCREASING IN COVERAGE BY EARLY AFTERNOON.  DEWPOINTS
   IN THE MID 60S COUPLED WITH 20-30 KNOTS OF EFFECTIVE SHEAR SHOULD BE
   SUFFICIENT FOR ORGANIZED MULTICELL STORMS CAPABLE OF DAMAGING WINDS
   AND SOME HAIL.  THE GREATEST COVERAGE OF STRONG STORMS IS EXPECTED
   FROM EASTERN PA/NY INTO WESTERN NEW ENGLAND.  HOWEVER...AT LEAST
   ISOLATED SEVERE STORMS APPEAR POSSIBLE SOUTHWARD INTO PARTS OF MD/VA
   AND NC.  STORMS IN THESE AREAS SHOULD WEAKEN RATHER QUICKLY AFTER
   SUNSET.
   
   ...TX/OK...
   A CLUSTER OF STRONG/SEVERE THUNDERSTORMS IS ONGOING THIS MORNING
   OVER CENTRAL OK.  THESE STORMS WILL LIKELY PERSIST FOR A FEW MORE
   HOURS AND SPREAD SOUTH-SOUTHEASTWARD INTO SOUTHERN OK AND NORTH TX. 
   TO THE SOUTHWEST OF THIS ACTIVITY...SOUTHERLY LOW LEVEL WINDS WILL
   TRANSPORT RICH GULF MOISTURE NORTHWARD BENEATH A RATHER STOUT
   CAPPING INVERSION.  BY LATE AFTERNOON...MOST MODEL SOLUTIONS
   INDICATE SURFACE DEWPOINTS IN THE UPPER 60S AS FAR NORTHWEST AS THE
   CDS AREA ALONG WITH FULL HEATING ALL DAY.  FORECAST SOUNDINGS IN
   THIS AREA SHOW VERY STEEP MID LEVEL LAPSE RATES /OVER 8.0 C/KM/ AND
   MLCAPE VALUES OVER 4000 J/KG.  WHILE THE THERMODYNAMIC PARAMETERS
   ARE FORECAST TO BE EXCEPTIONAL...THIS REGION WILL BE UNDER A WEAK
   UPPER RIDGE WITH ONLY SUBTLE FORCING MECHANISMS EXPECTED TO AID IN
   CONVECTIVE DEVELOPMENT.
   
   CURRENT SATELLITE IMAGERY SUGGESTS A SHORTWAVE TROUGH SOUTH OF TUS. 
   GIVEN CURRENT MOTION...THIS TROUGH WILL BE OVER WEST TX AROUND 21Z. 
   MEANWHILE...SEVERAL MODEL SOLUTIONS INDICATE THAT AN OUTFLOW
   BOUNDARY WILL SAG SOUTHWARD FROM THE MORNING CONVECTION OVER OK AND
   LIE ACROSS NORTHWEST TX AROUND THE SAME TIME.  IF THIS SERIES OF
   EVENTS CAN COME TOGETHER...THERE APPEARS TO BE A RATHER SMALL AREA
   OF ENHANCED THREAT OF SIGNIFICANT SEVERE THUNDERSTORMS LATER TODAY. 
   THIS AREA HAS BEEN UPGRADED TO MODERATE RISK.  LARGE/SLOW-MOVING
   SUPERCELL STORMS ARE FORECAST TO DEVELOP IN THE MODERATE RISK
   AREA...CAPABLE OF VERY LARGE HAIL AND A FEW TORNADOES.  THE STORMS
   MAY GROW UPSCALE AND SPREAD SOUTHEASTWARD BEFORE WEAKENING LATE THIS
   EVENING.
   
   ..HART/LEITMAN.. 05/23/2013
   
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