Categorical Graphic
Probabilistic Tornado 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
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
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 282000
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0300 PM CDT SAT APR 28 2012
   
   VALID 282000Z - 291200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER AREAS FROM ERN MO THROUGH
   SRN IL/IND AND KY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF OK AND NWRN TX...
   
   ...ERN MO TO LOWER OH VALLEY...
   EARLY AFTERNOON SURFACE ANALYSES SHOWED AN ELONGATED AREA OF LOW
   PRESSURE LOCATED FROM NEAR STL TO SOUTH CENTRAL IL...WITH A WARM
   FRONT EXTENDING SEWD THROUGH SWRN IND TO NRN KY. A
   MODERATELY-STRONGLY UNSTABLE AIR MASS RESIDES ACROSS THE WARM SECTOR
   SWWD INTO SRN MO.  THIS INSTABILITY COMBINED WITH STRONG EFFECTIVE
   BULK SHEAR REMAINS SUPPORTIVE FOR ORGANIZED SEVERE STORMS.  GIVEN
   TRENDS IN REGIONAL RADAR IMAGERY...THE SLIGHT RISK AND ATTENDANT 15
   PERCENT SVR HAIL AND DAMAGING WIND PROBABILITIES HAVE BEEN EXPANDED
   A LITTLE NWD TO INCLUDE MORE OF EAST CENTRAL MO /N OF STL/ TO
   ACCOUNT FOR ONGOING TSTMS /SVR THREAT/ ACROSS THIS AREA. 
   MEANWHILE...THE NWD MOVEMENT OF THE WARM FRONT...AND SOME DRYING
   OVER FAR WRN KY HAS LIMITED THE THREAT FOR SEVERE...AND THUS THE
   PORTION OF THE SLIGHT RISK AREA HAS BEEN SHIFTED A LITTLE NWD.  THE
   5 PERCENT TORNADO PROBABILITY WAS NARROWED SOME ALONG THE WARM FRONT
   AND INVOF OF THE SURFACE LOWS WHERE LOW LEVEL SHEAR SHOULD BE
   MAXIMIZED.  AND...GIVEN THE STRENGTH OF THE INSTABILITY/SHEAR
   PARAMETER SPACE COMBINED WITH STEEP LAPSE RATES...THERE EXISTS A
   SIGNIFICANT HAIL THREAT FROM PARTS OF ERN MO INTO SRN IL/SWRN IND
   AND NWRN KY.
   
   ..PETERS.. 04/28/2012
   
   .PREV DISCUSSION... /ISSUED 1130 AM CDT SAT APR 28 2012/
   
   ...MO TO OH VALLEY...
   SURFACE ANALYSIS REVEALS QUASI-STATIONARY FRONT EXTENDING ESE FROM A
   WEAK SURFACE LOW OVER NERN MO INTO SRN IL/IND AND THEN ACROSS NRN
   KY. A WARM AND MOIST AIRMASS EXISTS NEAR THE SURFACE LOW AND
   ALONG/SOUTH OF THE FRONTAL ZONE BENEATH STEEP MID LEVEL LAPSE RATE
   PLUME SAMPLED WELL BY THE 12Z SGF RAOB. EXPECT THE AIRMASS NEAR THE
   LOW AND FRONT WILL BECOME INCREASINGLY UNSTABLE THROUGH THE
   AFTERNOON WITH SBCAPE FORECAST TO RISE TO AT LEAST 2000 J/KG FROM
   SRN MO TO NRN KY.
   
   WEAK TO MODEST LARGE SCALE ASCENT IN SUPPORT OF TSTM DEVELOPMENT AND
   SUSTENANCE NEAR THE LOW AND FRONT SHOULD BE PROVIDED BY A LOW
   AMPLITUDE SHORT WAVE TROUGH CURRENTLY TRACKING EAST FROM KS PER 
   WATER VAPOR IMAGERY AND SHORT-TERM MODEL DATA. FORCING WITH THIS
   IMPULSE IS EXPECTED TO DRIVE INITIAL DEEP CONVECTIVE DEVELOPMENT
   ALONG AND NORTH OF THE SURFACE FRONT...PERHAPS FROM N OF STL ACROSS
   SCNTRL IL OVER THE NEXT FEW HOURS. DESPITE THIS ACTIVITY LIKELY
   BEING ROOTED WELL ABOVE A STABLE BOUNDARY LAYER...MAGNITUDE OF BOTH
   SHEAR AND ELEVATED INSTABILITY WILL RESULT IN SOME THREAT FOR HAIL.
   
   THERE IS SOMEWHAT GREATER UNCERTAINTY REGARDING THE DEVELOPMENT OF
   TRUE SURFACE-BASED CONVECTION ALONG AND SOUTH OF THE FRONT THROUGH
   THE AFTERNOON. WITH LATEST VISIBLE IMAGERY DEPICTING GOOD POTENTIAL
   FOR STRONG INSOLATION FROM SERN MO TO NRN KY...EXPECT THAT
   INHIBITION IN THIS CORRIDOR SHOULD CONTINUE TO WEAKEN. LIFT ACROSS
   THIS CORRIDOR IS NOT AS PRONOUNCED AS NORTH OF THE SURFACE FRONT.
   HOWEVER...IT SEEMS REASONABLE TO EXPECT MORE ROBUST TSTM DEVELOPMENT
   NEAR THE LOW ON THE MO/IL BORDER...AND PERHAPS ALONG LOCALLY
   REINFORCED FRONT/OUTFLOW BOUNDARIES EAST TO NRN KY IN THE 20-00 UTC
   TIME FRAME. ANY STORMS DEVELOPING IN THIS REGIME ARE LIKELY TO
   ACQUIRE SUPERCELL STRUCTURE AND POSE A RISK OF LARGE HAIL AND WIND.
   TORNADO POTENTIAL WILL BE LOCALLY ENHANCED NEAR THE LOW AND
   IMMEDIATELY ON THE FRONT WHERE MESO/STORM-SCALE INFLUENCES MAY BOOST
   LOW LEVEL SRH AND STORM INFLOW. STORMS MAY MERGE AND GROW SOMEWHAT
   UPSCALE THROUGH THE EVENING WITH LOCAL WIND DAMAGE POTENTIAL
   POSSIBLY SPREADING ESEWD ACROSS THE OH RIVER FROM IND/SWRN OH INTO
   NRN KY BEFORE BOUNDARY LAYER STABILIZATION SETS IN AND LIMITS
   PROSPECTS FOR STRONGER WINDS REACHING THE SURFACE.
   
   ...TX/OK TONIGHT...
   VERY UNSTABLE CONDITIONS EXPECTED TO EVOLVE ALONG THE STALLED
   SEGMENT OF THE DEEPER FRONTAL ZONE FROM SWRN MO ACROSS CNTRL/ERN OK
   AND INTO TX. LARGER SCALE FORCING FOR ASCENT ACROSS THIS ZONE IS
   MORE NON-DESCRIPT/AMBIGUOUS THROUGH THE DAY WHEN COMPARED TO AREAS
   NORTH AND EAST. HOWEVER...WATER VAPOR IMAGERY AND MODEL DATA SUGGEST
   A SHORT WAVE TROUGH...CURRENTLY ROUNDING THE BASE OF THE LARGER
   SCALE TROUGH OVER THE LOWER CO RIVER VALLEY AND GREAT BASIN...WILL
   BEGIN TO HAVE SOME INFLUENCE OVER THE SRN PLAINS BY EVENING. IN
   CONCERT WITH DIURNAL STRENGTHENING OF THE LOW LEVEL JET...EXPECT
   PROSPECTS FOR TSTM DEVELOPMENT TO INCREASE ALONG AND NORTH OF THE
   FRONT...FROM TX TO OK...DURING THE EVENING HOURS. LATEST MODEL
   GUIDANCE CONTINUES TO SUPPORT THE EVOLUTION OF ONE OR MORE
   CONVECTIVE SYSTEMS EXPANDING NWD/NEWD ACROSS THE SRN PLAINS DURING
   THE NIGHT. MAGNITUDE OF EFFECTIVE SHEAR AND AMBIENT INSTABILITY
   SHOULD RESULT IN AN INCREASING RISK OF LARGE HAIL AND POSSIBLY FAST
   MOVING CONVECTIVE ELEMENTS CAPABLE OF DAMAGING WINDS INTO EARLY
   SUNDAY.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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