SPC AC 301254

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0754 AM CDT THU MAY 30 2013

   VALID 301300Z - 311200Z

   ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF OK AND KS...

   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK
   AREA...FROM THE SRN PLNS NNE INTO THE MID MO AND MID/UPR MS VLYS...

   ...SYNOPSIS...
   NE WY UPR LOW WILL DRIFT SLOWLY E ACROSS SD THIS PERIOD AS ATTENDANT
   NEGATIVE-TILT TROUGH SWEEPS NE ACROSS THE SRN PLNS/OZARKS
   TODAY...AND NNE ACROSS THE LWR MO VLY/UPR MS VLY TNGT/EARLY FRI.
   STRENGTHENED WNW FLOW IN WAKE OF TROUGH --- WITH 500 MB SPEEDS AOA
   50 KTS --- WILL MAINTAIN LEE SFC TROUGH OVER THE CNTRL/SRN HIGH
   PLNS...WHILE THE MAIN SFC LOW REMAINS NEARLY STNRY ALONG THE ND/SD
   BORDER.  

   A WEAK COLD FRONT/WIND-SHIFT LINE ARCING SSW FROM THE ND/SD LOW
   SHOULD ADVANCE ESE ACROSS CNTRL PARTS OF SD/NEB/KS THROUGH THE
   DAY...WHILE FARTHER S...A DRY LINE WILL MIX E INTO SW KS...WRN
   OK...AND W CNTRL TX BY EARLY EVE. THE TRUE SYNOPTIC WARM FRONT
   ASSOCIATED WITH THE ND/SD LOW WILL REMAIN NEARLY STNRY ACROSS NRN
   MN/LK SUPERIOR. BUT A SHALLOWER WARM FRONT-LIKE FEATURE ---
   ESSENTIALLY THE BOUNDARY MARKING THE SW EDGE OF OVERNIGHT CONVECTIVE
   OUTFLOW --- SHOULD EDGE NEWD THROUGH THE DAY ACROSS CNTRL/ERN
   OK...PERHAPS REACHING PARTS OF AR AND SW MO BY EVE. THE 
   COLD FRONT/WIND-SHIFT...THE DRY LINE...AND THE SHALLOW WARM FRONTAL
   FEATURE ALL MAY SERVE TO FOCUS STRONG TO SVR TSTM DEVELOPMENT LATER
   TODAY INTO TNGT.

   ...S CNTRL PLNS THIS AFTN INTO TNGT...
   ARGUABLY THE MOST INTENSE...ALTHOUGH CONDITIONAL...SVR THREAT
   APPEARS TO BE THAT ASSOCIATED WITH ISOLD TO WDLY SCTD STORMS FORMING
   ALONG THE DRY LINE IN RESPONSE TO STRONG SFC HEATING BENEATH SRN
   FRINGE OF UPR TROUGH. GIVEN 40+ KT WNWLY DEEP SHEAR /WITH A SIZABLE
   DIRECTIONAL COMPONENT/...CONTINUING PRESENCE OF RICH LOW-LVL
   MOISTURE /PW AOA 1.25 INCHES WITH SFC DEWPOINTS IN THE UPR 60S F/
   ...AND A DEEP EML...SETUP COULD YIELD LONG-LIVED SUPERCELLS WITH
   VERY LARGE HAIL...DMGG WIND...AND TORNADOES.

   BASED ON CURRENT AND FCST AFTN SFC CONDITIONS...THE AREA MOST LIKELY
   TO EXPERIENCE SUCH ACTIVITY WOULD APPEAR TO EXTEND FROM S CNTRL KS
   THROUGH CNTRL/ERN OK AND WRN AR INTO N TX. IF DISCRETE SUPERCELLS DO
   FORM...AND...MORE IMPORTANTLY...REMAIN SUSTAINED...THE
   WIND/THERMODYNAMIC SETUP LIKELY WILL BE MORE THAN SUFFICIENT FOR A
   COUPLE STRONG TORNADOES. THIS THREAT MAY MAXIMIZE NEAR SHALLOW WARM
   FRONTAL FEATURE OVER CNTRL/ERN OK...WHERE SFC FLOW IS LIKELY TO
   REMAIN SLIGHTLY BACKED. IN ADDITION...IF STORMS LINGER INTO THE
   EVE...THEY WILL FIND THEMSELVES IN AN ENVIRONMENT OF INCREASING
   LOW-LVL SHEAR AS THE LLJ NOT ONLY STRENGTHENS NOCTURNALLY...BUT ALSO
   IN RESPONSE TO THE APPROACH OF UPSTREAM JET STREAK NOW OVER THE GRT
   BASIN.

   UNCERTAINTIES DO REMAIN REGARDING THE COVERAGE OF STORMS IN THE AREA
   OF GREATEST BUOYANCY AS /1/ HEIGHTS WILL RISE THROUGH THE DAY
   /ESPECIALLY FROM CNTRL OK SWD/ IN WAKE OF PASSING NEGATIVE-TILT
   TROUGH...AND /2/ EML CAP WILL BE STRONG...ESPECIALLY S OF THE RED
   RVR. NEVERTHELESS...GIVEN THE HIGH-END HAIL/TORNADO POTENTIAL WITH
   ANY SUSTAINED STORMS THAT DO FORM...A MODERATE RISK SEEMS WARRANTED
   ATTM.  

   ...MID/UPR MS VLY THIS AFTN/EVE...
   MODERATE SFC HEATING SHOULD OCCUR OVER PARTS OF MO...IA...IL...AND
   WI TODAY...AHEAD OF REMNANT MID/HIGH-LEVEL CONVECTIVE DEBRIS. REGION
   WILL LIE ON ERN FRINGE OF DCVA ASSOCIATED WITH PROGRESSIVE
   NEGATIVE-TILT TROUGH. WITH MORNING RAOB AND VWP DATA SHOWING
   MODERATE TO STRONG...DEEP SSW FLOW ALREADY IN PLACE ACROSS
   REGION...AND WITH WIND FIELDS LIKELY TO INCREASE SOMEWHAT
   TODAY...SETUP MAY PROVE FAVORABLE FOR THE DEVELOPMENT OF BROKEN
   BANDS OF STORMS ORIENTED ROUGHLY PARALLEL TO THE DEEP FLOW. WITH
   AMPLE CLOUD-LAYER SHEAR PRESENT FOR ORGANIZED/SUSTAINED
   UPDRAFTS...POTENTIAL WILL EXIST FOR SMALL SCALE LEWPS/BOWS WITH DMGG
   WIND AND PERHAPS A COUPLE TORNADOES DESPITE COMPARATIVELY MODEST
   BUOYANCY /SBCAPE 1000-2000 J PER KG/.  

   ...N CNTRL PLNS/MID MO VLY THIS AFTN...
   WDLY SCTD STORMS MAY FORM WITH DAYTIME HEATING ALONG WEAK COLD FRONT
   OVER PARTS OF THE ERN DAKOTAS...NEB...WRN IA AND SW MN...WHERE DEEP
   ASCENT WILL BE AUGMENTED BY DCVA AHEAD OF UPR TROUGH. WHILE WIND
   PROFILES WILL BE FAIRLY WEAK...THEY WILL BE SUFFICIENT FOR A FEW
   ORGANIZED/SUSTAINED STORMS WITH A RISK FOR HAIL AND PERHAPS A BRIEF
   TORNADO OR TWO GIVEN COOL MID-LVL TEMPS.

   ..CORFIDI/BOTHWELL.. 05/30/2013

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