Apr 26, 2015 1300 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   1128 AM CDT SUN APR 26 2015

   VALID 261630Z - 271200Z

   ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF NRN AND CNTRL
   TX...

   ...THERE IS AN ENH RISK OF SVR TSTMS FROM NRN INTO CNTRL AND ERN
   TX...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE SRN PLAINS...

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

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER A PART OF THE FL
   PENINSULA...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER SC...

   ...SUMMARY...
   SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED OVER PARTS OF THE
   SOUTHERN PLAINS THIS AFTERNOON THROUGH TONIGHT...WITH THE STORMS
   SPREADING SOUTH AND EAST TOWARD THE TEXAS GULF COAST EARLY MONDAY. 
   VERY LARGE HAIL...TORNADOES...A COUPLE OF WHICH COULD BE
   STRONG...AND DAMAGING WINDS WILL ACCOMPANY THESE STORMS. ISOLATED
   STRONG TO POTENTIALLY SEVERE STORMS ALSO MAY OCCUR THIS AFTERNOON
   OVER PARTS OF SOUTH CAROLINA AND FLORIDA.

   ...SYNOPSIS...

   THE SRN SEGMENT OF AN AMPLIFIED TROUGH OVER THE INTERIOR WEST WILL
   FORM A CLOSED UPPER LOW WHICH WILL DEVELOP FROM THE SRN ROCKIES INTO
   SRN HIGH PLAINS BY 12Z/MONDAY.  AN ASSOCIATED 70-80 KT MID-LEVEL JET
   STREAK CURRENTLY ROUNDING THE TROUGH BASE OVER NWRN MEXICO WILL
   DEVELOP EWD INTO CNTRL TX WITHIN THE SRN SEMICIRCLE OF THE EVOLVING
   LOW.

   AT THE SURFACE...A LEE CYCLONE OVER ERN NM WILL DEVELOP GENERALLY
   ESEWD INTO CNTRL TX IN RESPONSE TO THE EVOLVING UPPER LOW WITH A
   DRYLINE BECOMING ESTABLISHED BY AFTERNOON FROM THE VICINITY OF THE
   SURFACE LOW SWD INTO THE EDWARDS PLATEAU.  MEANWHILE...A BACKING AND
   STRENGTHENING LOW-LEVEL FLOW REGIME WILL PROMOTE THE NWD MOVEMENT OF
   A WARM FRONT THROUGH THE RED RIVER VALLEY.

   ...SRN PLAINS TODAY THROUGH TONIGHT...

   MID-MORNING SATELLITE DATA INDICATE A BELT OF IMPLIED ASCENT
   SPREADING EWD THROUGH FAR WRN TX AND FAR ERN NM IN ASSOCIATION WITH
   A LEAD VORTICITY MAXIMUM PRECEDING THE MAIN UPPER-AIR SYSTEM.  AT
   THE SAME TIME...AN INCREASINGLY MOIST BOUNDARY LAYER IS RAPIDLY
   DEVELOPING NWD THROUGH W-CNTRL TX ALONG AND TO THE S OF THE WARM
   FRONT AND BENEATH A PLUME OF STEEP MID-LEVEL LAPSE RATES /SEE 12Z
   DRT SOUNDING/.  THE OVERLAP OF THESE PROCESSES SHOULD FOSTER AN
   INCREASE IN MAINLY ELEVATED TSTMS LATE THIS MORNING INTO AFTERNOON
   NWD THROUGH THE RED RIVER VALLEY.  INCREASING CLOUD-BEARING SHEAR
   AND THE DESTABILIZING ENVIRONMENT WILL PROMOTE VIGOROUS UPDRAFTS
   WITH A RISK FOR PRIMARILY LARGE HAIL.  FOR ADDITIONAL
   INFORMATION...SEE MCD 465.

   IN THE WAKE OF THIS EARLY-DAY ACTIVITY OR ALONG ITS SRN
   FLANK...SURFACE-BASED STORM DEVELOPMENT IS EXPECTED TO OCCUR BY MID
   TO LATE AFTERNOON INTO EVENING FROM THE VICINITY OF THE SURFACE
   TRIPLE POINT OVER NWRN TX SWD ALONG THE DRYLINE.  THIS ACTIVITY WILL
   BE ENCOURAGED BY THE FORCING FOR ASCENT WITHIN THE EXIT REGION OF
   THE MID-LEVEL JET STREAK EMERGING FROM SWRN TX WHERE THE COMBINATION
   OF 1500-2000+ J/KG MLCAPE AND STEADILY STRENGTHENING LOW-LEVEL AND
   DEEP-LAYER SHEAR WILL PROMOTE INTENSE SUPERCELLS CAPABLE OF VERY
   LARGE HAIL AND TORNADOES...SOME OF WHICH COULD BE STRONG.

   EXPECT STORMS TO GROW UPSCALE INTO ONE OR MULTIPLE MCSS OVERNIGHT
   WITH THE RISK FOR POTENTIALLY MORE WIDESPREAD DAMAGING WINDS
   INCREASING ACROSS PORTIONS OF CNTRL INTO ERN TX.  LARGE HAIL AND A
   FEW TORNADOES WILL ALSO REMAIN A CONCERN.  

   ...FL TODAY...

   TSTMS HAVE INCREASED IN AREAL COVERAGE THIS MORNING ALONG A RESIDUAL
   OUTFLOW BOUNDARY/CONFLUENCE ZONE FROM THE FAR NERN GULF OF MEXICO
   EWD ALONG AN OCF-DAB LINE.  TO THE SOUTH OF THIS ACTIVITY...DIABATIC
   SURFACE HEATING IN CONJUNCTION WITH BOUNDARY-LAYER DEWPOINTS IN THE
   LOWER 70S SHOULD RESULT MODERATE AFTERNOON INSTABILITY AMIDST A
   KINEMATIC ENVIRONMENT EXHIBITING A RELATIVELY STRONG WLY DEEP-LAYER
   WIND FIELD.  AS SUCH...THE POTENTIAL WILL EXIST FOR SOME SUPERCELL
   AND/OR BOWING STRUCTURES CAPABLE OF MAINLY DAMAGING WIND GUSTS.

   FOR ADDITIONAL NEAR-TERM GUIDANCE...SEE MCD 464.

   ...SC THIS AFTERNOON...

   HEATING OF A MOIST AIR MASS PRECEDING A SWD-MOVING COLD FRONT WILL
   SUPPORT THE DEVELOPMENT OF STEEP LOW-LEVEL LAPSE RATES AND AT LEAST
   A MARGINALLY UNSTABLE AIR MASS LATER TODAY.  DIRECT THERMAL
   CIRCULATIONS ARISING FROM DIFFERENTIAL HEATING ALONG THE FRONT
   SHOULD FOSTER A FEW STORMS BY AFTERNOON WITH LOCALLY STRONG WIND
   GUSTS POSSIBLE OWING TO THE DOWNWARD TRANSPORT OF STRONG WNWLY FLOW
   ALOFT.