[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 200527
SWODY2
SPC AC 200526

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1226 AM CDT THU APR 20 2006

VALID 211200Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM SE TX INTO THE CNTRL AND
SRN APPALACHIANS...EWD INTO CENTRAL PARTS OF VA...NC AND SC...

...SYNOPSIS...

SRN STREAM SHORT WAVE TROUGH OVER THE ARKLATEX FRIDAY MORNING WILL
PHASE WITH UPPER LOW OVER THE GREAT LAKES...WITH FULL LATITUDE
TROUGH EVOLVING E OF THE MS VALLEY DURING THE LATTER HALF OF THE
FORECAST PERIOD.  IN THE LOW-LEVELS...SURFACE LOW ASSOCIATED WITH
THE SRN STREAM WAVE INITIALLY OVER AR WILL DEVELOP RAPIDLY NEWD
ALONG BAROCLINIC ZONE INTO THE UPPER OH VALLEY BY FRIDAY EVENING. 
TRAILING COLD FRONT WILL PUSH EWD THROUGH THE LOWER MS AND TN
VALLEYS AND CNTRL GULF COAST...WITH NAM AND ENSEMBLE MEAN FORECASTS
INDICATING THE DEVELOPMENT A SECONDARY SURFACE LOW WHICH WILL TRACK
MORE EWD ACROSS NRN MS/AL INTO NRN GA OR ERN TN BY FRIDAY NIGHT.

...SERN TX EWD TO THE CNTRL / SRN APPALACHIANS...

CONSIDERABLE TSTM ACTIVITY IS EXPECTED TO BE ONGOING AT THE ONSET OF
THE PERIOD FROM VICINITY OF SURFACE LOW OVER AR ENEWD WITHIN WAA
REGIME INTO THE TN VALLEY...AS WELL AS ALONG TRAILING COLD FRONT
INTO ERN TX.  CONSIDERABLE CLOUDINESS ACROSS WARM SECTOR WILL TEND
TO LIMIT DAYTIME HEATING...THOUGH BOUNDARY-LAYER SHOULD REMAIN MOIST
WITH DEWPOINTS IN THE 60S...WHICH WILL LARGELY CONTRIBUTE TO POCKETS
OF MODERATE INSTABILITY WITH MLCAPES APPROACHING 1000-1500 J/KG.

SEVERE THREAT SHOULD INCREASE FROM LATE MORNING THROUGH THE
AFTERNOON AS HEIGHT FALLS ASSOCIATED WITH INTENSIFYING TROUGH BEGIN
TO OVERSPREAD DESTABILIZING WARM SECTOR ACROSS THE LOWER MS INTO TN
VALLEYS.  STRONGEST STORMS WILL LIKELY OCCUR NEAR INITIAL SURFACE
LOW DEVELOPING NEWD ALONG BAROCLINIC ZONE...AS WELL AS ALONG
SECONDARY LOW TRACK OVER MS/AL WHERE STRONGER INSTABILITY IS
FORECAST.  LOCALLY STRONGER LOW-LEVEL SHEAR NEAR THESE SURFACE LOWS
WILL ENHANCE THE POTENTIAL FOR SUPERCELLS CAPABLE OF
TORNADOES...DAMAGING WINDS AND PERHAPS SOME HAIL.  OTHERWISE...MAIN
SEVERE THREAT SHOULD BE ASSOCIATED WITH BOWS AND OTHER EMBEDDED MORE
INTENSE LINE SEGMENTS.

THIS SEVERE THREAT SHOULD DIMINISH LATE FRIDAY EVENING OVER THE
CNTRL APPALACHIANS INTO UPPER OH VALLEY AS AIR MASS COOLS AND
STABILIZES.  FARTHER S...SEVERE THREAT MAY CONTINUE OVERNIGHT INTO
GA AND THE WRN FL PNHDL.

...VA / NC / SC...

RETREAT OF WARM FRONT NWD INTO THE MIDDLE ATLANTIC STATES WILL ALLOW
AIR MASS TO DESTABILIZE IN THE LEE OF THE APPALACHIANS WITH
DEWPOINTS INCREASING INTO THE 60S...SUPPORTING MLCAPES OF AROUND
1000 J/KG.  INCREASING LOW-LEVEL WAA AHEAD OF EVOLVING MID-LEVEL
TROUGH COUPLED WITH BROAD LOW-LEVEL CONFLUENCE AND PERHAPS
OROGRAPHIC FORCING SHOULD ALL CONTRIBUTE TO AN INCREASE IN TSTM
COVERAGE THROUGH THE DAY.  ISALLOBARIC RESPONSE TO DEEPENING SURFACE
LOW W OF THE MOUNTAINS WILL EFFECTIVELY BACK LOW-LEVEL SURFACE
WINDS...RESULTING IN VERTICAL SHEAR PROFILES EXHIBITING STRONG
VEERING WITH HEIGHT.

INITIALLY...MID AND HIGH-LEVEL WIND FIELDS WILL BE MARGINALLY STRONG
FOR ORGANIZED...SEVERE STORMS...THOUGH THEY ARE FORECAST TO INCREASE
THROUGH THE AFTERNOON INTO EVENING.  THREAT WILL EXIST FOR A COUPLE
BRIEF TORNADOES IN ADDITION TO DAMAGING WINDS AND PERHAPS SOME HAIL.

..MEAD.. 04/20/2006