SPC AC 280600

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT THU MAY 28 2015

   VALID 281200Z - 291200Z

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

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF NEW
   ENGLAND...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER A PORTION OF THE NERN
   STATES...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER MUCH OF THE PLAINS INTO
   THE MIDDLE AND LOWER MS VALLEY...

   ...SUMMARY...
   SCATTERED SEVERE THUNDERSTORMS WITH LARGE HAIL AND WIND DAMAGE MAY
   DEVELOP ACROSS PARTS OF THE SOUTHERN AND CENTRAL HIGH PLAINS ON
   THURSDAY. OTHER STRONG TO SEVERE THUNDERSTORMS MAY DEVELOP ACROSS
   PARTS OF NEW ENGLAND THURSDAY AFTERNOON WHERE STRONG WIND GUSTS WILL
   BE POSSIBLE. OTHER STRONG THUNDERSTORMS MAY ALSO DEVELOP IN THE
   NORTHERN PLAINS AND ACROSS THE SOUTHERN PLAINS EASTWARD INTO THE
   ARKLATEX AND LOWER MISSISSIPPI VALLEY THURSDAY AFTERNOON.

   ...SYNOPSIS...

   SYNOPTIC UPPER PATTERN WILL REMAIN PROGRESSIVE THURSDAY. POSITIVE
   TILT UPPER TROUGH OVER THE GREAT LAKES WILL MOVE THROUGH THE NERN
   STATES AND NEW ENGLAND DURING THE DAY ACCOMPANIED BY A COLD FRONT
   THAT WILL MOVE OFF THE NERN U.S. SEABOARD BY THURSDAY EVENING. A
   COLD FRONT WILL MOVE THROUGH THE DAKOTAS AND NRN MN IN ASSOCIATION
   WITH A SLOW-MOVING NRN STREAM TROUGH. A SERIES OF VORTICITY MAXIMA
   EMBEDDED WITHIN BROAD UPPER TROUGH OVER THE WRN STATES WILL EMERGE
   OVER THE HIGH PLAINS DURING THE AFTERNOON WHERE A LEE TROUGH WILL
   RESIDE. AT LEAST A COUPLE OF MCVS HAVE EMERGED OVER KS AND SWD INTO
   OK/NWRN TX...AND THESE FEATURES WILL PLAY A ROLE IN EVOLUTION OF
   CONVECTION OVER THE CNTRL AND SRN PLAINS DURING THE DAY.

   ...CNTRL AND SRN HIGH PLAINS...

   IN WAKE OF EARLY STORMS...THE ATMOSPHERE WILL DESTABILIZE OVER THE
   CNTRL THROUGH SRN HIGH PLAINS WHERE LOW-LEVEL DEWPOINTS WILL RANGE
   FROM THE UPPER 60S OVER SWRN TX TO LOW 60S IN WRN KS BENEATH 7-7.5
   C/KM 700-500 MB LAPSE RATES. DIABATIC WARMING SHOULD BOOST MLCAPE TO
   2500-3000 J/KG MLCAPE IN THIS CORRIDOR. AREAS OF ENHANCED LARGE
   SCALE ASCENT ASSOCIATED WITH THE APPROACHING VORTICITY MAXIMA AND
   CONVERGENCE/MIXING ALONG AND WEST OF LEE TROUGH WILL FOSTER THE
   REDEVELOPMENT OF STORMS FROM WRN NEB SWD THROUGH ERN NM AND WRN TX.
   SSELY LOW-LEVEL WINDS BENEATH MODEST WINDS ALOFT /25-30 KT AT 500
   MB/ WILL SUPPORT 30-40 KT EFFECTIVE BULK SHEAR. BOTH MULTICELL AND
   SUPERCELLS WITH LARGE HAIL AND DAMAGING WIND WILL BE THE MAIN
   THREATS. A WINDOW WILL EXIST FOR ISOLATED TORNADOES AS THE LLJ
   STRENGTHENS FROM LATE AFTERNOON AND EARLY EVENING AND BEFORE THE
   BOUNDARY LAYER DECOUPLES. STORMS MAY GROW UPSCALE AND EVOLVE INTO
   FORWARD PROPAGATING MCSS WITH A CONTINUED THREAT FOR HAIL AND
   DAMAGING WIND INTO MID-LATE EVENING.

   ...SRN OK THROUGH NRN TX...

   STRONG TO SEVERE STORMS MAY REDEVELOP IN ASSOCIATION WITH OUTFLOW
   BOUNDARIES ACCOMPANYING ONGOING CONVECTION FROM SRN OK THROUGH NRN
   TX DURING THE DAY. MODEST VERTICAL SHEAR AND STRONG INSTABILITY WILL
   SUPPORT MULTICELL AND POSSIBLE MARGINAL SUPERCELL STRUCTURES WITH
   LARGE HAIL AND DAMAGING WIND THE MAIN THREATS.

   ...NEW ENGLAND AREA...

   DIABATIC WARMING OF THE MOIST BOUNDARY LAYER /LOW 60S DEWPOINTS/
   WILL SUPPORT 800-1200 J/KG MLCAPE DURING THE DAY. BELT OF STRONGER
   WINDS ALOFT WITHIN BASE OF APPROACHING UPPER TROUGH WILL RESULT IN
   35-45 KT UNIDIRECTIONAL SHEAR...AND STORMS ARE EXPECTED TO DEVELOP
   IN THE WEAKLY CAPPED WARM SECTOR BY LATE MORNING. SOME OF THE STORMS
   WILL ACQUIRE UPDRAFT ROTATION...BUT SOME OF THIS ACTIVITY MAY ALSO
   EVOLVE INTO LINE SEGMENTS. PRIMARY THREAT WILL BE A FEW DAMAGING
   WIND GUSTS. EXPECTED WEAK THERMODYNAMIC ENVIRONMENT SHOULD LIMIT A
   MORE SUBSTANTIAL HAIL THREAT...BUT SOME HAIL COULD ACCOMPANY THE
   STRONGER STORMS WHERE MID-LEVEL ROTATION CAN BOOST UPDRAFT STRENGTH.

   ..DIAL/COOK.. 05/28/2015

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