[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 210436
SWODY1
SPC AC 210435

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1135 PM CDT THU APR 20 2006

VALID 211200Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MS VALLEY NWD
ACROSS THE TN VALLEY TO THE CNTRL APPALACHIANS...

...SYNOPSIS...
HIGH AMPLITUDE FLOW WILL BECOME MORE PROGRESSIVE ACROSS THE WEST AND
SOUTH THIS PERIOD WHILE NRN STATES CUT-OFF LOW MAKES ONLY SLOW EWD
PROGRESS OVER THE WRN GREAT LAKES REGION. PRIMARY FEATURE EXPECTED
TO DRIVE SEVERE THUNDERSTORM POTENTIAL THROUGH TODAY WILL BE THE SRN
BRANCH SHORT WAVE TROUGH CURRENTLY MOVING ACROSS TX. THIS MID-LEVEL
WAVE IS FORECAST TO TRANSLATE EWD ACROSS THE MS VALLEY THROUGH LATE
TODAY WITH STRONGEST 12H HEIGHT FALLS OF 30-60M MOVING OVER THE
SOUTHEAST U.S. BY THE END OF THE PERIOD...SATURDAY MORNING.

A NUMBER OF WEAK FRONTAL WAVES MAY EXIST ALONG DEEP-LAYER BAROCLINIC
ZONE SITUATED FROM THE UPPER TX COAST TO THE TN VALLEY TODAY. BASED
ON LATEST TRENDS...AN MCS OR TWO MAY SURVIVE INTO THE MORNING HOURS
NEAR THE FRONT. PRIMARY SURFACE LOW/WAVE ASSOCIATED WITH THE SRN
BRANCH SHORT WAVE TROUGH SHOULD BE COINCIDENT WITH A LARGE MCS
MOVING ACROSS LA/AR/MS AREA DURING THE MORNING. LATEST NAM-ETA AND
SREF MEAN FORECASTS INDICATE THAT THIS PRIMARY LOW WILL TRACK NEWD
ACROSS THE MS RIVER TO NRN MS DURING THE AFTERNOON...AND THEN INTO
NRN AL DURING THE EVENING. TRAILING COLD FRONT WILL MOVE EAST INTO A
MOIST AND UNSTABLE AIR MASS FROM THE LOWER MS VALLEY...TO THE WRN FL
PNHDL THROUGH EARLY SATURDAY.

...LA/MS ACROSS TN VALLEY...
DIURNAL DESTABILIZATION AHEAD OF MCS OUTFLOW/SFC FRONT AND FRONTAL
WAVE WILL PROMOTE THUNDERSTORM INTENSIFICATION DURING THE AFTERNOON
ACROSS MS. FURTHERMORE...MID LEVEL WIND MAX ROUNDING THE BASE OF
MID/UPPER TROUGH WILL ENHANCE DEEP LAYER SHEAR AND STORM
ORGANIZATION ACROSS THE WARM SECTOR. WHILE DEEP LAYER S/SWLY FLOW
MAY LIMIT HODOGRAPH CURVATURE...POTENTIAL FOR LOCALLY STRONGER LOW
LEVEL SHEAR MAY EVOLVE NEAR THE SURFACE LOW WHERE A FEW LONGER-LIVED
SUPERCELLS WILL BE POSSIBLE. CONVECTION WILL CONTINUE TO INCREASE IN
AREAL COVERAGE AND INTENSITY INTO THE EVENING WITH STORMS IN BANDS
OR CLUSTERS PRODUCING HAIL/WIND DAMAGE...AND PERHAPS A COUPLE
TORNADOES...FROM NRN/ERN MS TO AL AND MIDDLE TN.

ADDITIONAL STORMS...PERHAPS IN THE FORM OF SUPERCELLS OR LINE
SEGMENTS WITH ISOLATED DAMAGING WINDS...SHOULD PRECEDE THE COLD
FRONT DEVELOPING EAST FROM THE MS DELTA TO THE FL PNHDL THROUGH THE
NIGHT.

...FL...
SEA BREEZE CONVECTION IN MODERATELY UNSTABLE AIR MASS HAS THE
POTENTIAL TO BE A BIT MORE ROBUST TODAY AS WEAK HEIGHT FALLS MOVE
TOWARD THE REGION FROM THE WEST. WHILE LARGE SCALE DEEP LAYER SHEAR
WILL BE WEAK...ONE OR TWO CELL INTERACTIONS WITHIN SEA BREEZE
COLLISION ZONE OVER THE ERN PENINSULA COULD PRODUCE AN ISOLATED HAIL
OR WIND EVENT.

..CARBIN/JEWELL.. 04/21/2006