Categorical Graphic
Probabilistic Tornado Graphic
Probabilistic Damaging Wind Graphic
Probabilistic Large Hail Graphic

   SPC AC 201938
   
   DAY 1 CONVECTIVE OUTLOOK CORR 1
   NWS STORM PREDICTION CENTER NORMAN OK
   0138 PM CST MON MAR 20 2006
   
   VALID 202000Z - 211200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS LATE THIS AFTN/EVE ACROSS PARS
   OF S CNTRL MS INTO W CNTRL AL....
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREAS
   ACROSS THE CNTRL/ERN GULF STATES....
   
   ...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN ACROSS PARTS OF
   THE SRN PLAINS RED RIVER VALLEY....
   
   CORRECTED TO CLARIFY 5% AND 2% LINES ON TORNADO PROBABILITY GRAPHIC
   
   CONFLUENT UPPER FLOW PATTERN EAST OF THE MISSISSIPPI VALLEY INTO THE
   WESTERN ATLANTIC PERSISTS...PROVIDING CONTINUING LARGE-SCALE SUPPORT
   FOR HIGH SURFACE PRESSURE ACROSS MUCH OF EASTERN NORTH AMERICA. 
   THUS...WHILE DEEP SURFACE CYCLONE HAS DEVELOPED ACROSS THE SOUTH
   CENTRAL HIGH PLAINS IN RESPONSE TO SOUTHERN STREAM IMPULSE LIFTING
   EAST OF THE SOUTHERN ROCKIES...THIS FEATURE SHOULD WEAKEN AS IT
   MIGRATES ALONG LOW-LEVEL BAROCLINIC ZONE NEAR THE RED RIVER VALLEY
   LATE THIS AFTERNOON AND EVENING.
   
   12Z GFS/NAM CONTINUE TO SUGGEST WEAK SECONDARY SURFACE DEVELOPMENT
   WILL OCCUR ACROSS THE LOWER MISSISSIPPI VALLEY LATER TODAY INTO THE
   TENNESSEE VALLEY BY 12Z TUESDAY...AS UPPER IMPULSE IS SHEARED
   NORTHEASTWARD INTO THE MIDDLE MISSISSIPPI VALLEY.  HOWEVER...MODELS
   MAY BE A BIT TO FAR TO THE NORTH/WEST WITH THIS FEATURE...AS A BROAD
   AREA OF CONVECTIVE PRECIPITATION IS PRECLUDING NORTHWARD RETURN OF
   MOIST UNSTABLE BOUNDARY LAYER THROUGH THE LOWER MISSISSIPPI VALLEY.
   
   NORTHWARD RETURN OF THIS AIR MASS HAS STALLED SOUTH OF JACKSON MS
   THROUGH SOUTH CENTRAL LOUISIANA...AND THIS FRONTAL ZONE IS EXPECTED
   TO BECOME THE FOCUS FOR DEVELOPING WEAK SURFACE LOW AND ASSOCIATED
   SEVERE THREAT THROUGH THE REMAINDER OF THE PERIOD.  THIS SEEMS MOST
   LIKELY TO OCCUR IN RESPONSE TO FORCING BENEATH DIFLUENT UPPER REGIME
   BETWEEN SOUTHERN POLAR JET STREAK AND ACCOMPANYING SUBTROPICAL JET.
   
   ...CENTRAL/EASTERN GULF STATES**...
   ALONG/SOUTH OF AFOREMENTIONED SURFACE FRONT...SURFACE DEW POINTS ARE
   ALREADY IN THE MID/UPPER 60S ACROSS MUCH OF SOUTHERN LOUISIANA/
   MISSISSIPPI.  SIMILAR MOISTENING IS EXPECTED ACROSS EASTERN GULF
   COASTAL AREAS INTO THE VICINITY OF DEVELOPING WARM FRONT ACROSS
   SOUTH CENTRAL ALABAMA/SOUTHERN GEORGIA LATER TODAY/TONIGHT.  THIS
   WILL CONTRIBUTE TO MIXED BOUNDARY LAYER CAPE ON THE ORDER OF 1000
   J/KG...DESPITE LACK OF STEEPER MID-LEVEL LAPSE RATES.
   
   WHILE COLD CORE OF UPSTREAM MID-LEVEL TROUGH WILL LIFT WELL TO THE
   NORTH/WEST OF REGION...STRENGTHENING FLOW FIELDS/SHEAR PROFILES ON
   ITS SOUTHERN PERIPHERY ARE EXPECTED TO CONTRIBUTE TO INCREASING RISK
   FOR SUPERCELLS IN WARM SECTOR ENVIRONMENT.  ALTHOUGH POTENTIAL FOR A
   WIDESPREAD SEVERE WEATHER OUTBREAK SEEMS LOW... FORCING MAY STILL
   BECOME SUPPORTIVE OF AN ISOLATED LONG-LIVED SUPERCELL OR TWO.  THIS
   APPEARS MOST LIKELY SOUTH/EAST OF THE JACKSON MS AREA LATE THIS
   AFTERNOON...PERHAPS INTO AREAS NORTH/WEST OF SELMA/MONTGOMERY AL
   THIS EVENING...WHERE LARGE CLOCKWISE TURNING LOW-LEVEL HODOGRAPHS
   WILL BE FAVORABLE FOR STRONG TORNADOES.
   
   ...RED RIVER VALLEY**...
   FRONTAL ZONE EAST OF WEAKENING SURFACE CYCLONE...FROM PARTS OF
   NORTHWEST TEXAS THROUGH SOUTHWEST/SOUTH CENTRAL OKLAHOMA...SEEMS
   LIKELY TO PROVIDE FOCUS FOR ANY SIGNIFICANT CONVECTIVE DEVELOPMENT
   LATE THIS AFTERNOON.  AIDED BY FORCING IN EXIT REGION OF 100+ KT 500
   MB JET STREAK...DESTABILIZATION PROBABLY WILL BECOME SUFFICIENT FOR
   LOW-TOPPED THUNDERSTORMS.  SOME OF THIS ACTIVITY MAY BE STRONG
   ENOUGH TO PRODUCE SOME HAIL BRIEFLY APPROACHING OR EXCEEDING SEVERE
   LIMITS...BEFORE BEGINNING TO WEAKEN AFTER DARK.
   
   **PLEASE MONITOR FOR THE LATEST SPC MESOSCALE DISCUSSIONS...FOR MORE
   SPECIFIC INFORMATION ON ONGOING OR IMMINENT CONVECTIVE THREATS.
   
   ..KERR.. 03/20/2006
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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