Mar 19, 2012 2000 UTC Day 1 Convective Outlook
Updated: Mon Mar 19 20:03:27 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

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

Categorical Graphic
20120319 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120319 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
20120319 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
20120319 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 192000
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0300 PM CDT MON MAR 19 2012
   
   VALID 192000Z - 201200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS OVER MUCH OF CNTRL AND NERN
   TEXAS...SERN OKLAHOMA...AND EXTREME WRN ARKANSAS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
   FROM THE RIO GRANDE TO THE NRN PLAINS...
   
   ...CENTRAL TX TO ERN OK/WRN AR THROUGH TONIGHT...
   LITTLE CHANGE IN PREVIOUS FORECAST REASONING. DEEP UPPER TROUGH
   ACROSS THE WRN CONUS WILL MAKE ONLY SLOW EWD PROGRESS THROUGH
   TONIGHT AS SEVERAL SMALLER-SCALE IMPULSES ROTATE THROUGH THE LARGER
   SCALE SYSTEM. AN EXTENSIVE WARM/MOIST CONVEYOR BELT ON THE ERN FLANK
   OF THE UPPER TROUGH WAS COMPRISED OF A 50-70KT LOW LEVEL JET TOPPED
   BY AN 80-100KT MID/UPPER JET. PRONOUNCED MOISTURE TRANSPORT DIRECTED
   ACROSS SW-NE ORIENTED COMPOSITE OUTFLOW FROM NCNTRL TX INTO OK/KS
   WAS CONTRIBUTING TO WIDESPREAD STRATIFORM RAIN REGION ACROSS THE
   PLAINS. THE LEADING EDGE OF THIS BOUNDARY WILL CONTINUE TO PROVIDE A
   FOCUS FOR DEEP CONVECTION THAT WILL BE FUELED BY ABUNDANT WARM
   SECTOR CAPE AS SAMPLED BY LATEST RAOBS FROM FWD AND DRT. CAPPING ON
   THESE SOUNDINGS ALSO EXPLAINS LACK OF ANY TRUE WARM SECTOR STORMS AT
   THIS TIME. HOWEVER...ONGOING INCREASE IN STORMS ROOTED ATOP
   COMPOSITE OUTFLOW...ALONG THE EDWARDS PLATEAU/CAPROCK...WILL BE
   QUITE CAPABLE OF PRODUCING VERY LARGE HAIL THROUGH THE REST OF THE
   AFTERNOON.
   
   ENTIRE ZONE OF DEEPER ASCENT IS FORECAST TO SPREAD EAST AND RESULT
   IN WEAKENING CAP AND SUBSEQUENT INCREASE IN SEVERE STORM POTENTIAL
   THROUGH THIS EVENING...PRIMARILY FROM DFW AREA SOUTH AND EAST. AS
   COLD POOL DEPTH AND WLY COMPONENT OF DEEP-LAYER FLOW
   INCREASE...EXPECT SEVERE LINEAR MCS TO SPREAD EAST WITH THE CHANCE
   FOR BOTH DAMAGING STRAIGHT LINE WINDS AND TORNADOES INCREASING
   THROUGH THE NIGHT AND INTO EARLY TUESDAY.
   
   ...MO TO MN/ERN ND...
   DIURNAL HEATING OF MOIST AIRMASS HAS CONTRIBUTED TO A CORRIDOR OF
   GREATER MLCAPE ON THE ORDER OF 500-1000 J/KG FROM MO NORTH ACROSS IA
   TO ERN ND AND MN. LARGE SCALE UPPER DIFFLUENCE IN THE EXIT REGION OF
   EXTENSIVE JET ON THE ERN FLANK OF THE LARGE SCALE TROUGH MAY AID
   LIFT AND SCATTERED TSTM DEVELOPMENT ACROSS THESE AREAS INTO THIS
   EVENING. EFFECTIVE VERTICAL SHEAR ON THE ORDER OF 30-40KT SHOULD
   SUPPORT UPDRAFT PERSISTENCE IN A FEW OF THESE STORMS WITH A THREAT
   FOR HAIL...LOCALLY GUSTY WINDS...AND PERHAPS A BRIEF/WEAK TORNADO.
   
   ..CARBIN.. 03/19/2012
   
   .PREV DISCUSSION... /ISSUED 1130 AM CDT MON MAR 19 2012/
   
   ...SYNOPSIS...
   A HIGHLY AMPLIFIED PATTERN PERSISTS ACROSS THE CONUS WITH A DEEP
   TROUGH OVER THE ROCKIES AND A DOWNSTREAM RIDGE OVER THE TN/OH VALLEY
   REGION.  AN INITIAL OCCLUDED CYCLONE IN NE MT WILL MOVE NNEWD INTO
   SK AS A TRAILING FRONT MOVES SLOWLY EWD ACROSS THE ERN DAKOTAS TODAY
   AND WRN MN TONIGHT.  FARTHER S...A REMNANT LEE CYCLONE PERSISTS IN
   ERN CO...WITH THE PAC COLD FRONT EXTENDING SWD INTO W TX.  THE FRONT
   IS PRECEDED BY AN OUTFLOW BOUNDARY FROM OVERNIGHT CONVECTION...WHICH
   NOW EXTENDS FROM ERN NEB SWD ACROSS EXTREME ERN KS...AND THEN SWWD
   ACROSS CENTRAL OK INTO NW TX.  E OF THE NRN PLAINS FRONT AND
   CENTRAL/SRN PLAINS OUTFLOW...A BROAD WARM SECTOR COVERS AREAS EWD
   ACROSS THE ENTIRE MS VALLEY REGION.  THESE FRONTAL/OUTFLOW SEGMENTS
   WILL PROVIDE THE PRIMARY FOCUS FOR SEVERE STORM DEVELOPMENT THROUGH
   TONIGHT.  
   
   ...CENTRAL TX TO ERN OK/WRN AR THROUGH TONIGHT...
   OVERNIGHT CONVECTION PERSISTS FROM CENTRAL OK INTO NW TX...WITH NEW
   DEVELOPMENT OCCURRING IN RESPONSE TO 40-50 KT LOW-LEVEL SLY FLOW
   OVER THE LEADING EDGE OF THE COLD POOL.  REGIONAL 12Z SOUNDINGS
   REVEALED MODERATE INSTABILITY ACROSS OK/TX IN ADVANCE OF THIS
   CONVECTION...WITH SOME WEAKENING OF CONVECTIVE INHIBITION NOTED
   ALREADY ACROSS CENTRAL/N TX WHERE SURFACE HEATING IS OCCURRING
   WITHIN CLOUD BREAKS.  EXPECT THIS CONVECTIVE BAND TO CONTINUE TO
   SLOWLY INTENSIFY THROUGH THE AFTERNOON ACROSS N TX AND ERN OK AS
   DESTABILIZATION CONTINUES...AND AN EMBEDDED MID-UPPER SPEED MAX
   ROTATES NEWD FROM THE TX BIG BEND.  DEEP-LAYER AND LOW-LEVEL SHEAR
   WILL BE FAVORABLE FOR ORGANIZED BOWING SEGMENTS AND EMBEDDED
   SUPERCELLS WITHIN THE LARGER CONVECTIVE SYSTEM...AND MORE DISCRETE
   STORM DEVELOP COULD OCCUR WITHIN THE WARM SECTOR FROM E TX INTO ERN
   OK/WRN AR THIS AFTERNOON.  GIVEN THE PREDOMINATELY LINEAR CONVECTIVE
   MODE...DAMAGING WINDS WILL BE A PRIMARY CONCERN...ALONG WITH A FEW
   TORNADOES AND LARGE HAIL WITH THE STRONGER EMBEDDED STORMS.
   
   OVERNIGHT...THE UPSTREAM TROUGH WILL CONTINUE TO EVOLVE INTO A
   CLOSED LOW OVER SE NM/FAR W TX.  SUBSTANTIAL ASCENT AND A NOTABLE
   LOW-LEVEL MASS RESPONSE TO THE NM/W TX TROUGH WILL SUPPORT
   ADDITIONAL SEVERE STORM DEVELOPMENT TONIGHT IN CENTRAL TX ALONG THE
   PAC COLD FRONT/REMNANT OUTFLOW BOUNDARY.  THIS CONVECTION APPEARS
   LIKELY TO EVOLVE INTO ANOTHER LARGE MCS WITH AN ACCOMPANYING RISK
   FOR DAMAGING WINDS AND TORNADOES WITH EMBEDDED ROTATING STORMS...IN
   ADDITION TO LARGE HAIL.  RELATIVELY SLOW EWD PROGRESS OF THE BAND
   AND TRAINING CONVECTION WILL ALSO RESULT IN LOCALLY HEAVY RAINFALL.
   
   ...MO/IA NWD TO THE ERN DAKOTAS/WRN MN THROUGH TONIGHT...
   BOUNDARY LAYER DEWPOINTS IN THE MID-UPPER 50S BENEATH STEEP MIDLEVEL
   LAPSE RATES WILL SUPPORT A CORRIDOR OF WEAK-MODERATE INSTABILITY IN
   ADVANCE OF THE COMPOSITE OUTFLOW BOUNDARY IN MO/IA...AND THE SURFACE
   FRONT ACROSS THE ERN DAKOTAS.  SOMEWHAT UNIDIRECTIONAL PROFILES WILL
   SUPPORT A RISK FOR ISOLATED DAMAGING WINDS/HAIL WITH A BROKEN BAND
   OF STORMS ALONG/AHEAD OF THE FRONT THIS AFTERNOON/EVENING ACROSS THE
   ERN DAKOTAS/WRN MN.  STORM COVERAGE IS MORE CERTAIN FARTHER S INTO
   MO/IA WHERE CONVECTION IS EXPECTED TO INTENSIFY THIS AFTERNOON ALONG
   THE COMPOSITE OUTFLOW BOUNDARY NOW MOVING INTO WRN MO/IA.  SOMEWHAT
   STRONGER LOW-LEVEL SHEAR /COMPARED TO FARTHER N/ WILL PROMOTE A RISK
   FOR EMBEDDED ROTATING STORMS IN A PREDOMINATELY LINEAR CONVECTIVE
   MODE...WITH AN ATTENDANT RISK FOR DAMAGING WINDS/ISOLATED TORNADOES.
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z