SPC AC 221957

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0257 PM CDT WED APR 22 2015

   VALID 222000Z - 231200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS OVER PARTS OF NORTH TX...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF NERN NM/TX/SRN
   OK/SRN AR/NRN AND WRN LA...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER MUCH OF THE SRN PLAINS TO
   LOWER MS VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF THE MID-ATLANTIC
   STATES TO CAROLINAS...

   ...SUMMARY...
   SCATTERED THUNDERSTORMS WILL POSE A RISK OF DAMAGING WIND...A FEW
   TORNADOES...AND VERY LARGE/DESTRUCTIVE HAIL OVER PARTS OF THE
   SOUTHERN PLAINS TODAY AND THIS EVENING.  A FEW THUNDERSTORMS ALSO
   MIGHT INTENSIFY BRIEFLY TO SEVERE LEVELS TODAY FROM THE MID ATLANTIC
   REGION TO THE SOUTHERN APPALACHIANS.

   ...NORTH TX/FAR SRN OK...
   NO CHANGES ARE NEEDED FOR THIS REGION.  FOR SHORT-TERM
   DETAILS...REFER TO SPC MESOSCALE DISCUSSION 419.

   ...PARTS OF CENTRAL TO SOUTH TX...
   THE 15 PERCENT SEVERE HAIL/WIND AREAS HAVE BEEN EXPANDED WWD SOME TO
   ACCOUNT FOR STORMS DEVELOPING IN THE SAN ANTONIO AND SAN ANGELO
   COUNTY WARNING AREAS WHERE MODERATELY STRONG INSTABILITY AND STRONG
   BULK SHEAR FAVOR THE THREAT FOR SEVERE STORMS.

   THE SEVERE THREAT HAS GREATLY DIMINISHED ACROSS IN THE SHORT-TERM
   ACROSS THE CRP COUNTY WARNING AREA...RESULTING IN LOWER SEVERE
   WEATHER PROBABILITIES FOR THAT PART OF SOUTH TX.  FOR ADDITIONAL
   SHORT-TERM DETAILS...REFER TO SPC MESOSCALE DISCUSSION 420.

   ...MID-ATLANTIC STATES TO SRN APPALACHIANS...
   OBJECTIVE ANALYSES INDICATED VERY STEEP SURFACE-3 KM LAPSE RATES
   /APPROACHING DRY ADIABATIC/.  THIS FACTOR COMBINED WITH WEAK
   INSTABILITY WILL CONTINUE TO FAVOR STRONG DAMAGING WIND GUSTS AS THE
   BAND OF CONVECTION ALONG THE COLD FRONT ADVANCES EWD LATE THIS
   AFTERNOON TO EARLY EVENING THROUGH SERN NY...NJ...THE DELMARVA
   PENINSULA...AND SERN VA.  MUCH OF ERN PA TO WRN VA HAVE BEEN REMOVED
   FROM THE MARGINAL SEVERE RISK...GIVEN THE EWD PROGRESSION OF THE
   COLD FRONT.

   ..PETERS.. 04/22/2015

   .PREV DISCUSSION... /ISSUED 1129 AM CDT WED APR 22 2015/

   ...NORTH TX...
   LATEST SURFACE ANALYSIS SHOWS A RESIDUAL OUTFLOW BOUNDARY FROM
   OVERNIGHT CONVECTION LYING ACROSS NORTH TX.  SOUTHEASTERLY LOW LEVEL
   WINDS ON THE COOL SIDE OF THE BOUNDARY WILL HELP TO TRANSPORT
   MOISTURE INTO THE EASTERN TX PANHANDLE...WHERE LOW CLOUDS WILL
   SLOWLY ERODE THIS AFTERNOON.  DESPITE A GENERAL TRENDS OF MID LEVEL
   HEIGHT RISES...A WEAK SHORTWAVE TROUGH IS MOVING ACROSS EASTERN
   NM/WEST TX THAT MAY HELP TO INITIATE ISOLATED THUNDERSTORMS NEAR AMA
   BY MID/LATE AFTERNOON.  THE STORMS WILL FORM IN A REGION OF
   FAVORABLE EFFECTIVE SHEAR PROFILES AND SUFFICIENT INSTABILITY FOR
   SUPERCELL STRUCTURES CAPABLE OF HAIL AND WIND.  AS THE STORMS TRACK
   EAST-SOUTHEASTWARD INTO A MORE MOIST AND UNSTABLE AIR
   MASS...CONDITIONS WILL BE MORE FAVORABLE FOR INTENSE SUPERCELLS
   CAPABLE OF VERY LARGE HAIL AND A FEW TORNADOES.  BY MID
   EVENING...MULTIPLE 12Z CAM SOLUTIONS SUGGEST AN UPSCALE GROWTH INTO
   A BOWING COMPLEX THAT MIGHT TRACK ACROSS NORTH TX AFTER DARK.

   OTHER STORMS MAY INTENSIFY THIS AFTERNOON ALONG THE LEADING EDGE OF
   THE OUTFLOW BOUNDARY AFFECTING NORTHEAST TX...WITH HAIL AND DAMAGING
   WINDS THE MAIN THREATS.

   ...SOUTH TX...
   A SMALL CLUSTER OF THUNDERSTORMS HAS FORMED OVER SOUTH TX WEST OF
   VCT/CRP.  THESE STORMS ARE IN A MOIST AND FAVORABLY SHEARED
   ENVIRONMENT WITH BACKED LOW LEVEL WINDS SHOWING 3KM SRH VALUES OVER
   200 M2/S2 ON CRP VAD.  THESE STORMS WILL TRACK TOWARD THE COAST THIS
   AFTERNOON WITH A RISK OF HAIL...DAMAGING WINDS...AND PERHAPS A
   TORNADO OR TWO.

   ...EASTERN STATES...
   DESPITE A DRY BOUNDARY LAYER...SCATTERED SHOWERS AND THUNDERSTORMS
   WILL AFFECT MUCH OF THE MID ATLANTIC AND CAROLINAS TODAY.  STRONG
   WINDS ALOFT AND STEEP LAPSE RATES WILL CONTRIBUTE TO A RISK OF
   LOCALLY DAMAGING GUSTS IN THE STRONGER CELLS.

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