SPC AC 171729
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1229 PM CDT FRI MAY 17 2013
   
   VALID 181200Z - 191200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF NWRN KS/SWRN
   NEB...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM
   EXTREME NWRN TX INTO SERN ND/NWRN MN...
   
   ...PLAINS...
   
   LATEST MODEL GUIDANCE IS IN GENERAL AGREEMENT REGARDING THE
   EVOLUTION OF UPPER TROUGH AS IT PROGRESSES ACROSS THE WRN U.S. INTO
   THE HIGH PLAINS LATE IN THE PERIOD.  OF PARTICULAR CONCERN IS THE
   EXPECTED INCREASE IN MID LEVEL FLOW INTO THE HIGH PLAINS ATOP AN
   INCREASINGLY MOIST/BUOYANT AIRMASS.  LATEST SATELLITE IMAGERY
   DEPICTS EXTENSIVE LOW CLOUDS ACROSS OK WITH A DECIDEDLY ELY LOW
   LEVEL COMPONENT WITHIN THE BOUNDARY LAYER.  THIS CLOUDINESS WILL BE
   STUBBORN TO ERODE DURING THE DAY1 PERIOD AND IN THE ABSENCE OF
   MEANINGFUL THUNDERSTORM ACTIVITY ACROSS THE SRN/CNTRL PLAINS THROUGH
   SATURDAY MORNING ABUNDANT LOW LEVEL MOISTURE SHOULD RAPIDLY RETURN
   ACROSS KS INTO NEB SATURDAY.
   
   LATEST THINKING IS WARM ADVECTION MAY DRIVE A BOUT OF EARLY MORNING
   CONVECTION ACROSS PARTS OF THE ERN DAKOTAS BENEATH MODEST LLJ. 
   WHILE THIS ACTIVITY MAY PRODUCE SOME HAIL...IT SHOULD SPREAD EWD
   INTO THE UPPER MS VALLEY DURING THE MID DAY HOURS AS A WEAK BRANCH
   OF THE LLJ FOCUSES INTO THIS REGION.
   
   LATEST SHORT RANGE MODEL GUIDANCE INSISTS STRONG HEATING WILL OCCUR
   ACROSS SERN CO INTO NWRN TX.  THIS SHOULD ALLOW DRYLINE TO MIX TO A
   POSITION NEAR THE OK BORDER...ARCING NWWD TO A SFC LOW OVER WRN KS
   BY 19/00Z.  WITH SFC DEW POINTS EXPECTED TO RISE WELL INTO THE
   MID-UPPER 60S EAST OF THE DRYLINE...EXTREME INSTABILITY MAY DEVELOP
   ALONG A CORRIDOR FROM WRN OK INTO NWRN KS WHERE SBCAPE COULD EXCEED
   4000 J/KG.  AS TEMPERATURES WARM INTO THE LOWER 90S ACROSS THE TX
   PANHANDLE INTO SWRN KS INHIBITION WILL BE NEGATED AND DISCRETE
   SUPERCELL STRUCTURES ARE EXPECTED TO DEVELOP.  HAVE INCREASED THE
   SEVERE PROBS ACROSS PORTIONS OF KS/NEB AS THIS PORTION OF THE CNTRL
   PLAINS SHOULD EXPERIENCE STRONGER DEEP LAYER SHEAR...POTENTIALLY
   SUPPORTIVE OF TORNADOES.  LATEST 12Z NAM FORECAST SOUNDINGS STRONGLY
   SUPPORT SUPERCELLS ACROSS THE MDT RISK REGION WITH SBCAPE IN EXCESS
   OF 4000 J/KG WITH SFC-6KM SHEAR ON THE ORDER OF 40KT. 
   ADDITIONALLY...VERY LARGE HAIL MAY ACCOMPANY ANY SUPERCELLS THAT
   DEVELOP SATURDAY.  LATEST FORECAST HAIL ALGORITHMS SUGGEST HAIL
   COULD EASILY EXCEED BASEBALL SIZE WITH ORGANIZED ACTIVITY.
   
   SOMEWHAT WEAKER DEEP LAYER FLOW ACROSS THE SRN PLAINS MAY LIMIT
   OVERALL SEVERE THREAT AND FOR THIS REASON HAVE ONLY EXTENDED 15
   PERCENT THREAT INTO PORTIONS OF NWRN TX.
   
   ...TN VALLEY/CNTRL GULF STATES...
   
   WEAKENING UPPER TROUGH WILL TRANSLATE INTO THE MIDDLE TN VALLEY/NRN
   GULF STATES SATURDAY.  MODEST NWLY FLOW ALONG BACKSIDE OF THIS
   FEATURE MAY PROVIDE ENOUGH SHEAR FOR ORGANIZED MULTI-CELL UPDRAFTS
   CAPABLE OF PRODUCING SOME HAIL/WIND.  THIS ACTIVITY SHOULD BE
   MODULATED BY DIURNAL HEATING AND SHOULD WEAKEN WITH AFTER SUNSET.
   
   ..DARROW.. 05/17/2013
   
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