May 31, 2013 1300 UTC Day 1 Convective Outlook
Updated: Fri May 31 12:48:41 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms expected from central oklahoma to parts of the ozarks this afternoon and tonight....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20130531 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130531 1300 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
20130531 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
20130531 1300 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MODERATE 32,762 3,822,397 Oklahoma City, OK...Tulsa, OK...Springfield, MO...Norman, OK...Broken Arrow, OK...
SLIGHT 318,917 43,586,348 Chicago, IL...Indianapolis, IN...Detroit, MI...Milwaukee, WI...Kansas City, MO...
   SPC AC 311245

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0745 AM CDT FRI MAY 31 2013

   VALID 311300Z - 011200Z

   ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
   TONIGHT FROM SW MO TO CENTRAL OK...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM NW TX TO THE MID MS
   VALLEY...WI...AND LOWER MI...

   ...SYNOPSIS...
   A CLOSED MIDLEVEL LOW OVER THE NRN PLAINS WILL DRIFT EWD AND
   GRADUALLY EVOLVE INTO MORE OF AN OPEN WAVE BY EARLY SATURDAY...AS
   EMBEDDED SPEED MAXIMA ROTATE AROUND THE SRN PERIPHERY OF THE LOW
   /ACROSS THE CENTRAL PLAINS TO THE MID MS VALLEY/.  THE PRIMARY
   SURFACE CYCLONE WILL SLOWLY WEAKEN TODAY ACROSS THE
   DAKOTAS/MN...WHILE A TRAILING COLD FRONT DRIFTS SEWD INTO SE KS AND
   NRN OK...AND SECONDARY CYCLOGENESIS OCCURS INVOF CDS THIS AFTERNOON.
    A DRYLINE WILL MIX EWD BY MID AFTERNOON TO NW AND W CENTRAL TX TO
   THE S OF THE SECONDARY LOW.

   ...MO/IL TO OK/NRN AR THROUGH TONIGHT...
   THE COMBINATION OF LOW-LEVEL MOISTURE ADVECTION FROM THE WRN GULF
   BASIN AND SOME EVAPOTRANSPIRATION WILL SUPPORT BOUNDARY LAYER
   DEWPOINTS IN THE LOW 70S INTO THE OK WARM SECTOR.  THIS
   MOISTURE...ALONG WITH DAYTIME TEMPERATURES WARMING INTO THE 80S
   BENEATH STEEP MIDLEVEL LAPSE RATES...WILL SUPPORT STRONG-EXTREME
   INSTABILITY /MLCAPE VALUES OF 3500-4500 J PER KG/ IN OK THIS
   AFTERNOON...WITH SOMEWHAT WEAKER BUOYANCY FARTHER NE INTO MO.  THE
   SHORT-TERM MODEL FORECASTS OF MID 70S DEWPOINTS AND MLCAPE IN EXCESS
   OF 5000 J/KG IN OK APPEAR A LITTLE OVERDONE BASED ON REGIONAL
   OBSERVATIONS.  MEANWHILE...DEEP-LAYER VERTICAL SHEAR WILL BE
   FAVORABLE FOR SUPERCELLS FROM THE MID MS VALLEY SWWD TO CENTRAL
   OK...ALONG THE SERN FRINGE OF THE STRONGER MID-UPPER FLOW.

   THE MOST PROBABLE SCENARIO TODAY IS FOR THE MORNING CONVECTION
   ACROSS NRN MO TO SPREAD INTO ERN MO AND CENTRAL IL.  NEW STORM
   DEVELOPMENT IS ALSO EXPECTED BY EARLY AFTERNOON ACROSS CENTRAL
   MO...ALONG THE SRN FRINGE OF THE MORNING CONVECTION AS THE LOW
   LEVELS RECOVER FROM OVERNIGHT CONVECTION THAT IS WEAKENING ACROSS
   WRN TN.  THE CAP WILL DELAY STORM DEVELOPMENT FARTHER SW INTO OK
   UNTIL MID-LATE AFTERNOON...WITH RAPID THUNDERSTORM DEVELOPMENT
   EXPECTED BY 21-22Z ALONG OR N OF THE I-44 CORRIDOR...AND W OF I-35
   ALONG THE DRYLINE WHERE INTENSE SURFACE HEATING WILL OCCUR.  THE
   STRONG-EXTREME CAPE AND EFFECTIVE BULK SHEAR AOA 50 KT WILL FAVOR
   THE PRODUCTION VERY LARGE HAIL /BASEBALL OR LARGER/...ESPECIALLY
   WITH THE MORE DISCRETE STORMS EARLIER IN THE CONVECTIVE EVOLUTION. 
   THE TORNADO THREAT IS A BIT MORE IN QUESTION GIVEN THE NECESSARY
   RECOVERY ACROSS ERN MO/IL WHERE LOW-LEVEL SHEAR WILL BE
   STRONGER...AND RATHER MODEST LOW-LEVEL FLOW/SHEAR FARTHER SW INTO
   OK.  STILL...AN ISOLATED STRONG TORNADO MAY OCCUR AS THE EXTREME
   INSTABILITY COMPENSATES TO SOME EXTENT FOR THE WEAKER LOW-LEVEL
   SHEAR.  LATER DURING THE EVENING AND INTO TONIGHT...STORM
   MERGERS/OUTFLOW INTERACTIONS WILL LEAD TO UPSCALE GROWTH OF LARGER
   CLUSTERS/BANDS OF STORMS...AND THE STORMS WILL BE MAINTAINED
   OVERNIGHT BY A STRENGTHENING LOW-LEVEL WAA REGIME. 

   ...ERN IA...SE MN...WRN WI THIS AFTERNOON/EVENING...
   THE ONGOING STORMS IN NRN MO RAISE SOME QUESTIONS ABOUT THE DEGREE
   OF RECOVERY TODAY FARTHER TO THE N IN IA...THOUGH THE DVN AND TOP
   SOUNDINGS SHOW THE POTENTIAL FOR SOMEWHAT RICHER MOISTURE TO MIX
   DOWNWARD TODAY WITH SOME SURFACE HEATING.  WITH POTENTIALLY MODERATE
   INSTABILITY IN THE WARM SECTOR...SCATTERED THUNDERSTORM DEVELOPMENT
   WILL BE POSSSIBLE ALONG THE SYNOPTIC COLD FRONT AS AN EMBEDDED SPEED
   MAX ROTATES NEWD OVER IA THIS EVENING.  DEEP-LAYER SPEED SHEAR WILL
   BE STRONG...AND A FEW ORGANIZED STORMS COULD PRODUCE AT LEAST
   ISOLATED DAMAGING GUSTS AND LARGE HAIL.

   ..THOMPSON/GARNER.. 05/31/2013

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