[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 201930
SWODY1
SPC AC 201929

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0129 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....

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