May 31, 2013 2000 UTC Day 1 Convective Outlook
Updated: Fri May 31 20:05:40 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe weather outbreak possible over parts of the southern plains to the ozark plateau late this afternoon into tonight....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20130531 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130531 2000 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 2000 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 2000 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 36,273 3,265,267 Oklahoma City, OK...Tulsa, OK...Norman, OK...Broken Arrow, OK...Joplin, MO...
SLIGHT 356,829 45,827,900 Chicago, IL...Indianapolis, IN...Detroit, MI...Milwaukee, WI...Kansas City, MO...
   SPC AC 312002

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0302 PM CDT FRI MAY 31 2013

   VALID 312000Z - 011200Z

   ...THERE IS A MDT RISK OF SVR TSTMS FROM CNTRL OK INTO SWRN MO...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM FAR NRN TX INTO NERN MN
   AND WI...

   ...OK...SERN KS INTO SWRN MO...
   STORMS ARE BEGINNING TO FORM OVER SERN KS ALONG THE COLD FRONT...AS
   WELL AS ALONG THE OUTFLOW BOUNDARY INTO W CNTRL MO. 18Z SGF SOUNDING
   SHOWED A LOADED GUN PROFILE WITH STEEP MIDLEVEL LAPSE RATES AND A
   VERY DEEP MOIST BOUNDARY LAYER AND A SUPERCELL TORNADO HODOGRAPH.
   WITH LIFTED INDICIES OF -10 TO -12...A COUPLE STRONG TORNADOES WILL
   BE POSSIBLE IN ADDITION TO VERY LARGE HAIL.

   FARTHER S INTO OK...THE 18Z OUN SOUNDING SHOWED A PRONOUNCED CAPPING
   INVERSION...WITH A VERY MOIST AND DEEPENING BOUNDARY LAYER WITH
   PRECIPITABLE WATER AROUND 1.50 INCHES. OK MESONET OBSERVATIONS
   CONTINUE TO SHOW DEWPOINTS HOLDING IN THE LOWER 70S F WITH EXTREME
   INSTABILITY IN PLACE.

   HIGHER BASED CU HAVE RECENTLY FORMED OVER NW TX AND SWRN OK WHERE
   TEMPERATURES WERE NEARING 100 F...AND THE GREATEST PRESSURE FALLS
   ARE CENTERED IN THIS REGION AS WELL. MODELS ALSO CONTINUE TO SHOW
   CYCLOGENESIS THROUGH THE EVENING...WITH WINDS OVER CNTRL OK BECOMING
   MORE BACKED WITH TIME. THIS WILL HAVE THE EFFECT OF ENLARGING
   HODOGRAPHS AND SRH VALUES. THIS WILL ALSO LIKELY PULL THE STATIONARY
   BOUNDARY...NOW FROM N CNTRL INTO WRN OK...SWD TO NEAR I-40. CELLS
   THAT FORM OVER SWRN OR W CNTRL OK WILL MOVE E WITH A VERY HIGH
   THREAT OF GIANT HAIL AND A FEW STRONG TO VIOLENT TORNADOES. ONE
   CAVEAT IS INITIAL LCL HEIGHTS IN THE HOTTER AIR...AND POTENTIAL
   OUTFLOW MAGNITUDE. HOWEVER...THE EXTREMELY FAVORABLE SUPERCELL
   ENVIRONMENT IS EXPECTED TO KEEP STORMS MAINLY CELLULAR...HELPING TO
   COUNTERACT ANY NEGATIVE OUTFLOW EFFECTS. 

   LATER IN THE EVENING...A SEVERE MCS AND/OR ADDITIONAL SUPERCELLS ARE
   STILL LIKELY ACROSS MUCH OF NRN AND NERN OK INTO SWRN MO...WITH
   DAMAGING WINDS AND A FEW TORNADOES.

   ...ERN MN...WI...ERN IA...
   EXPANDED THE SLIGHT RISK FARTHER W INTO MN AS STORMS CONTINUE TO
   FORM W OF THE MS RIVER WHERE DESTABILIZATION CONTINUES AND WITH
   COOLING ALOFT OVERSPREADING THE WARM SECTOR. COOL TEMPERATURES ALOFT
   AND SUFFICIENT DEEP LAYER SHEAR WILL FAVOR SEVERE HAIL. STORMS
   SHOULD PERSIST WITH A SWD EXTENSION LIKELY INTO IA BY LATE
   AFTERNOON/EARLY EVENING.

   ..JEWELL.. 05/31/2013

   .PREV DISCUSSION... /ISSUED 1156 AM CDT FRI MAY 31 2013/

   CORRECTED FOR TYPOS

   ...REGIONAL SEVERE WEATHER OUTBREAK POSSIBLE TODAY OVER PARTS OF
   CENTRAL/EASTERN OK...SOUTHEAST KS...AND SOUTHWEST MO.  VERY LARGE
   HAIL...WIDESPREAD DAMAGING WINDS...AND A FEW STRONG/VIOLENT
   TORNADOES ARE POSSIBLE...

   ...OK/KS/MO...
   ANOTHER VERY VOLATILE ENVIRONMENT IS IN PLACE ACROSS PARTS OF THE
   SOUTHERN PLAINS AND MID MS VALLEY TODAY.  WIDESPREAD VERY STEEP MID
   LEVEL LAPSE RATES AND DEWPOINTS IN THE UPPER 60S/LOWER 70S ARE
   RESULTING IN THE POTENTIAL FOR AFTERNOON MLCAPE VALUES OVER 4000
   J/KG.  THIS AIR MASS IS CURRENTLY CAPPED...AND THE CAP SHOULD
   RESTRAIN DEEP CONVECTION THROUGH MUCH OF THE DAY ALLOWING STRONG
   HEATING.

   BY MID/LATE AFTERNOON...A SHORTWAVE TROUGH INDICATED IN WATER VAPOR
   IMAGERY OVER THE TX PANHANDLE...ALONG WITH A SECOND AND STRONGER
   TROUGH OVER CO...WILL APPROACH THE REGION.  THIS WILL RAPIDLY WEAKEN
   THE CAP AND ALLOW EXPLOSIVE THUNDERSTORM DEVELOPMENT ALONG THE
   DRYLINE OVER WEST-CENTRAL OK...AND ALONG THE COLD FRONT EXTENDING
   FROM CENTRAL OK INTO SOUTHWEST MO.  DEEP LAYER EFFECTIVE SHEAR
   VALUES ARE FAVORABLE FOR SUPERCELL STORMS CAPABLE OF VERY LARGE
   HAIL...DAMAGING WINDS...AND TORNADOES.  SHEAR VECTORS PERPENDICULAR
   TO THE N-S DRYLINE OVER CENTRAL OK WILL FAVOR DISCRETE STORM
   STRUCTURES.  ALL 12Z MODEL GUIDANCE INDICATES RAPID INTENSIFICATION
   OF THE LOW LEVEL JET OVER CENTRAL OK BY EVENING AS THE UPPER TROUGH
   APPROACHES.  GIVEN THESE PARAMETERS...IT APPEARS THE THREAT OF A FEW
   STRONG/VIOLENT TORNADOES ARE IN PLACE.  HAVE INCREASED SEVERE
   PROBABILITIES OVER THIS REGION...AND PORTIONS OF CENTRAL/EASTERN OK
   WILL BE CONSIDERED FOR AN UPGRADE TO HIGH RISK AT 20Z IF
   SHORTER-TERM MESOSCALE MODELS MAINTAIN THIS SCENARIO.

   DURING THE EVENING...NUMEROUS THUNDERSTORMS ARE EXPECTED TO CONGEAL
   INTO A FAST-MOVING MCS THAT TRACKS NORTHEASTWARD ACROSS NORTHEAST OK
   INTO SOUTHWEST MO.  HIGH CAPE VALUES AND AN INCREASING LOW LEVEL JET
   WILL PROMOTE THE POTENTIAL FOR WIDESPREAD WIND DAMAGE...ALONG WITH
   LARGE HAIL AND ISOLATED TORNADOES.

   ...IA/MN/WI...
   AN UPPER LOW IS PRESENT THIS MORNING OVER WESTERN SD...WITH MULTIPLE
   SHORTWAVE TROUGHS ROTATING NORTHWARD ACROSS IA/MN.  STRONG DAYTIME
   HEATING IS OCCURRING AHEAD OF THE SHORTWAVE TROUGHS OVER PARTS OF
   MN/WI/IA WHERE MODERATE AFTERNOON CAPE IS EXPECTED.  SCATTERED
   THUNDERSTORMS ARE EXPECTED TO FORM BY MID AFTERNOON OVER MN/IA AND
   TRACK NORTHEASTWARD.  A FEW OF THESE STORMS COULD BE SUPERCELLULAR
   WITH A RISK OF HAIL/DAMAGING WINDS OR AN ISOLATED TORNADO.

   ...IL/IND...
   AN ONGOING CLUSTER OF THUNDERSTORMS IN THE STL AREA MAY RE-INTENSIFY
   THIS AFTERNOON AS IT TRACKS INTO AN INCREASINGLY MOIST/UNSTABLE AIR
   MASS OVER IL/IND.  IF THIS OCCURS...LOCALLY DAMAGING WINDS AND HAIL
   WILL BE POSSIBLE.

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