Apr 22, 2011 2000 UTC Day 1 Convective Outlook
Updated: Fri Apr 22 20:00:10 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110422 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110422 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
20110422 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
20110422 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.
   SPC AC 221956
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0256 PM CDT FRI APR 22 2011
   
   VALID 222000Z - 231200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS FROM PARTS OF ERN OK THROUGH
   NWRN AR INTO MUCH OF SRN MO...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS EXTENDS FROM THE OH/MID MS
   VALLEYS TO THE SRN PLAINS...
   
   ...MO/AR/OK/TX...
   FORECAST REMAINS ON TRACK ACROSS THIS REGION...INCLUDING THE
   MODERATE RISK.  FOR MESOSCALE DETAILS...REFER TO SPC MESOSCALE
   DISCUSSIONS 516 AND 518.  THE LAST FEW RUNS OF THE EXPERIMENTAL HRRR
   HAVE INDICATED THE POTENTIAL FOR DISCRETE STORMS IN NORTH CENTRAL
   TX.  THIS COMBINED WITH THE DEGREE OF INSTABILITY /3000-3500 J PER
   KG/ AND EFFECTIVE BULK SHEAR 35-40 KT WARRANTS THE SWD EXTENSION OF
   THE 5% TORNADO PROBABILITY INTO NRN TX.  
   
   ...OH VALLEY/MIDWEST...
   EARLY AFTERNOON SURFACE ANALYSIS SHOWED AN AREA OF LOW PRESSURE HAD
   MOVED INTO NWRN MO...WITH A WARM FRONT EXTENDING EWD THROUGH SRN
   IL...SRN IND TO NRN-NERN KY.  FORWARD PROPAGATING MCS LOCATED OVER
   IND TO SERN IL PER REGIONAL RADAR/SATELLITE IMAGERY IS EXPECTED TO
   REMAIN PROGRESSIVE AS AIR MASS CONTINUES TO DESTABILIZE SOME ACROSS
   SRN IND INTO CENTRAL/NRN KY.  SLIGHT RISK REMAINS ON TRACK ACROSS
   THIS PART OF THE OH VALLEY ATTENDANT TO ONGOING ACTIVITY...AND A
   SECOND ROUND OF STRONG TO SEVERE STORMS THAT ARE FORECAST TO ADVANCE
   EWD INTO THIS REGION ALONG A COLD FRONT LATER THIS EVENING.  
   
   GIVEN THE EXISTENCE OF A MORE STABLE AIR MASS WITH NWD EXTENT...
   ESPECIALLY ACROSS NRN IL/IND WITH THE PASSAGE OF THE ONGOING MCS...
   THE SLIGHT RISK AREA HAS BEEN REMOVED FROM A SMALL PART OF THESE
   STATES.
   
   ..PETERS.. 04/22/2011
   
   .PREV DISCUSSION... /ISSUED 1132 AM CDT FRI APR 22 2011/
   
   CORRECTED FOR ERRORS IN SLIGHT RISK LINE OVER TN
   
   A FAST-MOVING UPPER TROUGH OVER THE CENTRAL PLAINS WILL TRACK
   EAST-NORTHEASTWARD DURING THIS FORECAST PERIOD INTO THE UPPER
   MIDWEST.  AS THIS OCCURS...STRONG SOUTH-SOUTHWESTERLY LOW LEVEL
   WINDS ACROSS THE PLAINS AND MS VALLEY WILL TRANSPORT GULF MOISTURE
   RAPIDLY NORTHWARD AND RESULT IN A RATHER LARGE AREA OF THUNDERSTORM
   POTENTIAL.  THE GREATEST CONCENTRATION OF SEVERE WEATHER WILL LIKELY
   EXTEND FROM OK INTO SOUTHERN MO.
   
   ...MO/IL INTO OH VALLEY...
   A CLUSTER OF INTENSE THUNDERSTORMS IS ONGOING THIS MORNING NEAR THE
   STL AREA.  THESE STORMS APPEAR TO BE ASSOCIATED WITH WARM ADVECTION
   NEAR THE NOSE OF THE LOW LEVEL JET...AND IN REGION OF MODERATE
   ELEVATED INSTABILITY.  THIS ACTIVITY APPEARS TO BE SUFFICIENTLY
   ORGANIZED TO MAINTAIN INTENSITY AND TRACK EASTWARD INTO THE OH
   VALLEY DURING THE AFTERNOON AND EVENING.  A RETREATING SURFACE WARM
   FRONT OVER THE OH VALLEY WILL LIKELY HELP FOCUS THE CONVECTION. 
   DAMAGING WINDS AND LARGE HAIL ARE THE MAIN THREATS.
   
   ...MO/AR/OK/TX...
   A SURFACE COLD FRONT IS SURGING SOUTHEASTWARD ACROSS NORTHWEST
   OK...AND SHOULD EXTEND FROM SOUTHEAST KS INTO CENTRAL OK BY LATE
   AFTERNOON.  AHEAD OF THE FRONT...SOUTHERLY WINDS HELPING TO ADVECT
   MOISTURE NORTHWARD WITH MID 60S DEWPOINTS LIKELY ACROSS THE REGION
   LATER TODAY.  CONSIDERABLE DAYTIME HEATING WILL WEAKEN THE CAPPING
   INVERSION AND HELP THE DEVELOPMENT OF SCATTERED THUNDERSTORMS ALONG
   THE FRONT...AND POTENTIALLY MORE DISCRETELY IN THE WARM SECTOR. 
   FORECAST SOUNDINGS SHOW RATHER LARGE HODOGRAPHS AND STEEP MID LEVEL
   LAPSE RATES.  THIS SUGGESTS SUPERCELL STORMS ARE LIKELY WITH VERY
   LARGE HAIL AND DAMAGING WINDS POSSIBLE.  TORNADOES APPEAR OF
   GREATEST CONCERN OVER SOUTHERN MO...FAR NORTHERN AR...AND EVENTUALLY
   INTO SOUTHERN IL WHERE ENHANCED LOW LEVEL SHEAR NEAR THE RETREATING
   WARM FRONT WILL BE PRESENT.  STORMS MAY PERSIST THROUGH MUCH OF THE
   NIGHT WITH ACTIVITY SPREADING ACROSS THE MID MS AND INTO THE OH
   VALLEY.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z