Apr 17, 2013 1300 UTC Day 1 Convective Outlook
Updated: Wed Apr 17 12:42:36 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms are expected over parts of the southern/central plains later today and tonight....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20130417 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130417 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
20130417 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
20130417 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 60,889 3,877,453 Oklahoma City, OK...Tulsa, OK...Norman, OK...Wichita Falls, TX...Broken Arrow, OK...
SLIGHT 250,346 30,694,687 Chicago, IL...Dallas, TX...Ft. Worth, TX...Kansas City, MO...Wichita, KS...
   SPC AC 171238
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0738 AM CDT WED APR 17 2013
   
   VALID 171300Z - 181200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
   MUCH OF OK...SOUTHEAST KS...WESTERN NORTH TX...AND FAR WESTERN MO...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SOUTHERN PLAINS INTO
   THE MID MS VALLEY...
   
   ...FOCUSED AREA OF SIGNIFICANT SEVERE THUNDERSTORM AND TORNADO
   POTENTIAL IS EXPECTED TODAY...
   
   ...OK/WESTERN NORTH TX/SOUTHEAST KS...
   THE MORNING SURFACE ANALYSIS SHOWS A WARM FRONT EXTENDING FROM
   SOUTHWEST TO NORTHEAST OK.  THIS BOUNDARY IS RAPIDLY RETREATING
   NORTHWARD AND IS EXPECTED TO LIE ROUGHLY FROM WEST-CENTRAL OK INTO
   SOUTHEAST KS BY MID AFTERNOON.  RICH LOW LEVEL MOISTURE SOUTH OF THE
   BOUNDARY WILL COMBINE WITH AMPLE DAYTIME HEATING TO YIELD AFTERNOON
   MLCAPE VALUES OF 3000+ J/KG OVER MOST OF THE SOUTHEAST HALF OF OK
   AND SOUTHEAST KS.  
   
   VARIOUS MODEL SOLUTIONS CONTINUE TO STRUGGLE WITH SHORT-TERM DETAILS
   OF CONVECTIVE POTENTIAL.  THIS APPEARS TO BE DUE TO HANDLING OF
   SUBTROPICAL SHORTWAVE SEEN IN WATER VAPOR IMAGERY OVER SOUTHERN NM. 
   LARGE SCALE FORCING FOR ASCENT WILL OVERSPREAD OK THROUGHOUT THE DAY
   IN ADVANCE OF THIS SYSTEM...BUT IT APPEARS THAT 700MB TEMPERATURES
   APPROACHING 10C WILL SUPPRESS SIGNIFICANT CONVECTION OVER
   WESTERN/CENTRAL OK UNTIL THIS AFTERNOON WHEN PERSISTENT LIFT AND
   STRONG HEATING WILL WEAKEN THE CAP IN VICINITY OF THE DRYLINE.
   
   PRESENT INDICATIONS ARE THAT ISOLATED THUNDERSTORMS WILL DEVELOP BY
   LATE AFTERNOON ALONG THE DRYLINE IN SOUTHWEST OK AND WESTERN NORTH
   TX...AND ALONG THE STALLED BOUNDARY EXTENDING ACROSS NORTH CENTRAL
   OK INTO SOUTHEAST KS.  VERTICAL SHEAR PROFILES WILL BE QUITE STRONG
   THROUGHOUT THIS AREA WITH 0-3KM SRH VALUES EXCEEDING 300 M2/S2 AND
   STRONG EFFECTIVE SHEAR.  DISCRETE SUPERCELL STORMS ARE EXPECTED WITH
   A RESULTANT RISK OF VERY LARGE HAIL AND A FEW STRONG TORNADOES. 
   THESE STORMS ARE EXPECTED TO TRACK NORTHEASTWARD ALONG AND SOUTH OF
   THE SURFACE BOUNDARY INTO NORTHEAST OK AND EVENTUALLY WESTERN MO
   THIS EVENING.
   
   ...MO/IL...
   STRENGTHENING SOUTHERLY LOW LEVEL WINDS ARE FORECAST ACROSS MUCH OF
   MO/IL TODAY...WITH MODERATE CAPE VALUES ALREADY IN PLACE.  OTHER
   THAN LOW LEVEL WARM ADVECTION...LARGE SCALE FORCING MECHANISMS ARE
   SUBTLE.  NEVERTHELESS...STEEP MID LEVEL LAPSE RATES AND SUFFICIENT
   EFFECTIVE SHEAR WILL POSE A CONDITIONAL RISK OF HAIL IN THOSE STORMS
   THAT CAN DEVELOP TODAY.
   
   ...MO/KS/OK/NORTH TX OVERNIGHT...
   THE MAIN UPPER TROUGH IS EXPECTED TO SWING EASTWARD INTO THE PLAINS
   LATE TONIGHT...RESULTING IN A LARGE SQUALL LINE AFFECTING EASTERN
   KS...CENTRAL/EASTERN OK...WESTERN MO...AND NORTH TX.  IT APPEARS
   LIKELY THAT THESE STORMS WILL POSE A RISK OF RATHER WIDESPREAD
   DAMAGING WINDS THROUGH 12Z.
   
   ...TN VALLEY TO CENTRAL/SOUTHERN APPALACHIANS...
   AT LEAST ISOLATED TO WIDELY SCATTERED TSTMS ARE EXPECTED TO
   DIURNALLY INCREASE THIS AFTERNOON ACROSS THE REGION. WHILE FORCING
   ON THE LARGE SCALE WILL BE MODEST AND MID-LEVEL LAPSE RATES/
   VERTICAL SHEAR WILL BE WEAK...STEEPENING LOW LEVEL LAPSE RATES
   DURING THE AFTERNOON MAY CONTRIBUTE TO SOME POTENTIAL FOR EPISODIC
   BOUTS OF LOCALLY DAMAGING WINDS/HAIL.
   
   ..HART/GARNER.. 04/17/2013
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z