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 182000
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0300 PM CDT SUN MAR 18 2012
   
   VALID 182000Z - 191200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM W TX TO WRN KS THROUGH
   TONIGHT...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE OH
   VALLEY...
   
   ...OH VALLEY...
   THE SEVERE PROBABILITIES AND CATEGORICAL SLIGHT RISK AREA HAVE BEEN
   EXPANDED NEWD...EWD AND SWD TO ACCOUNT FOR TRENDS IN ONGOING TSTMS
   ACROSS NRN-SRN OH AND SOUTH CENTRAL KY.  AIR MASS IS MODERATELY
   UNSTABLE FROM THE LOWER OH VALLEY INTO KY...WITH INSTABILITY
   DECREASING WITH NEWD EXTENT INTO THE UPPER OH VALLEY.  WIND PROFILER
   DATA IN NWRN IND INDICATED PERSISTENT 30 KT WNWLY WINDS IN THE 3.5-6
   KM AGL LAYER ALONG THE SRN PERIPHERY OF A MIDLEVEL VORTICITY
   MAX...WHICH WAS NOW MOVING THROUGH SERN LOWER MI/NWRN OH.  ALTHOUGH
   INSTABILITY IS WEAKER WITH N/NEWD EXTENT...GREATER DEEP LAYER SHEAR
   ATTENDANT TO THE 30 KT JETLET MAY ENHANCE STORM ORGANIZATION FOR
   STRONG TO SEVERE STORMS YET THIS AFTERNOON/EARLY EVENING ACROSS OH. 
   FARTHER S...BULK SHEAR IS WEAKER...BUT GREATER INSTABILITY MAY
   SUPPORT A STRONGER STORM OR TWO ACROSS KY.
   
   ...SRN HIGH PLAINS...
   NO CHANGES ARE NEEDED WITH THIS SLIGHT RISK AREA.
   
   ..PETERS.. 03/18/2012
   
   .PREV DISCUSSION... /ISSUED 1137 AM CDT SUN MAR 18 2012/
   
   ...SYNOPSIS...
   HIGHLY AMPLIFIED PATTERN WILL PERSIST OVER THE CONUS THROUGH
   TOMORROW WITH A DEEP TROUGH OVER THE GREAT BASIN/ROCKIES AND A
   DOWNSTREAM RIDGE JUST W OF THE APPALACHIANS.  WITHIN THE BROADER
   FLOW REGIME...AN EMBEDDED SPEED MAX OVER SE AZ THIS MORNING WILL
   MOVE NNEWD TO THE CENTRAL/NRN HIGH PLAINS BY MONDAY MORNING...WHILE
   THE PRIMARY TROUGH AXIS REMAINS JUST W OF THE FOUR CORNERS.  AT THE
   SURFACE...A BROAD WARM SECTOR COVERS THE MAJORITY OF THE CONUS E OF
   THE ROCKIES.  BOUNDARY LAYER DEWPOINTS OF 55-60 F HAVE SPREAD AS FAR
   N AS THE MN/MB BORDER...AND AS FAR NE AS THE LOWER GREAT LAKES. 
   THIS MOISTURE...ALONG WITH AN EML PLUME OVER THE PLAINS...WILL
   SUPPORT A LARGE REGION OF WEAK-MODERATE INSTABILITY FROM THE MS/OH
   VALLEYS WWD INTO THE PLAINS THROUGH TONIGHT.
   
   ...SRN HIGH PLAINS LATE THIS AFTERNOON THROUGH TONIGHT...
   REGIONAL 12Z SOUNDINGS CONTINUED TO SHOW BOUNDARY LAYER DEWPOINTS
   AOA 60 F BENEATH A PLUME OF MIDLEVEL LAPSE RATES AOA 8 C/KM.  A
   PRONOUNCED CAP ACCOMPANIES THE EML FROM TX NWD ACROSS THE CENTRAL
   PLAINS...WITH THE RICHEST MOISTURE AND RELATIVELY WEAKER CAP
   EXPECTED THIS AFTERNOON ALONG THE TX/OK PORTION OF THE DRYLINE. 
   THUS...EXPECT CONVECTIVE INITIATION PRIMARILY NEAR AND S OF THE
   KS/OK BORDER LATE THIS AFTERNOON/EVENING AS SURFACE TEMPERATURES
   WARM TO 78-80 F IN A NARROW ZONE OF SURFACE HEATING BETWEEN BANDS OF
   HIGH CLOUDS.  FORCING FOR ASCENT WILL BE CONFINED TO THE DRYLINE
   CIRCULATION THIS AFTERNOON SINCE THE MAJORITY OF THE LARGE SCALE
   ASCENT WILL REMAIN FARTHER TO THE W.  OF NOTE IS THE PERSISTENT
   CONVECTIVE PRECIPITATION SIGNAL THIS AFTERNOON ALONG THE I-35
   CORRIDOR IN TX...PER A MAJORITY OF SREF RSM AND ARW MEMBERS.  SUCH
   WIDESPREAD CONVECTION APPEARS UNLIKELY GIVEN THE CAP OBSERVED ACROSS
   TX...AND COULD BE RELATED TO MIDLEVEL MOISTENING FROM ABOVE AND ITS
   IMPACTS ON THE CONVECTIVE SCHEMES.  EXPECT ANY WARM SECTOR
   CONVECTION FROM CENTRAL TX NEWD INTO OK TO REMAIN RATHER ISOLATED
   TODAY AND BASED ABOVE THE CAP...BUT WILL MAINTAIN LOW SEVERE
   PROBABILITIES TO REFLECT THE SMALL CHANCE OF SURFACE-BASED
   CONVECTION.
   
   ISOLATED-WIDELY SCATTERED STORM DEVELOPMENT IS EXPECTED BY 22-00Z
   ALONG THE DRYLINE FROM W TX NWD INTO THE ERN TX PANHANDLE.  THE
   STORM ENVIRONMENT WILL BE CHARACTERIZED BY MLCAPE VALUES OF
   2000-2500 J/KG AND FAVORABLE DEEP-LAYER VERTICAL SHEAR FOR
   SUPERCELLS...WITH VERY LARGE HAIL THE MAIN SEVERE CONCERN THIS
   EVENING.  ADDITIONALLY...SUFFICIENT LOW-LEVEL MOISTURE AND AN
   INCREASE IN LOW-LEVEL SHEAR THROUGH THE EVENING WILL SUPPORT THE
   RISK FOR A FEW TORNADOES...THOUGH THE WINDOW OF OPPORTUNITY COULD BE
   JUST A FEW HOURS BEFORE CONVECTIVE INHIBITION INCREASES AND THE
   DIURNAL STORMS WEAKEN.  OVERNIGHT...THE PACIFIC COLD FRONT WILL
   OVERTAKE THE DRYLINE AND MORE WIDESPREAD THUNDERSTORM DEVELOPMENT
   WILL BE POSSIBLE DURING THE EARLY MORNING HOURS MONDAY.  THIS
   ACTIVITY WILL POSE A RISK FOR LARGE HAIL AND DAMAGING WINDS. 
   
   ...ERN INDIANA/NRN KY/SW OH THIS AFTERNOON...
   A REMNANT MIDLEVEL VORT MAX IS DRIFTING EWD OVER NE INDIANA AS OF
   LATE MORNING.  STRONG SURFACE HEATING AND SOME MOISTURE ADVECTION
   WILL BOOST AFTERNOON MLCAPE VALUES TO 1000-1500 J/KG INVOF THE
   SRN/SWRN FLANK OF THIS VORT MAX...WHERE ADDITIONAL THUNDERSTORM
   DEVELOPMENT IS EXPECTED THIS AFTERNOON.  THE COMBINATION OF MODERATE
   INSTABILITY AND A BELT OF ENHANCED /AOA 30 KT/ WNWLY MIDLEVEL FLOW
   COULD SUPPORT A FEW ORGANIZED MULTICELL CLUSTERS AND/OR MARGINAL
   SUPERCELL STRUCTURES WITH AN ATTENDANT RISK FOR LARGE HAIL AND
   DAMAGING WINDS.
   
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