309 
ACUS01 KWNS 060555
SWODY1
SPC AC 060552

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1152 PM CST MON JAN 05 2009

VALID 061200Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SERN PARTS OF LA/MS EWD
THROUGH MUCH OF AL/FL PANHANDLE TO WRN GA...

...SYNOPSIS...
NRN AND SRN STREAM SHORT WAVE TROUGHS ARE EXPECTED TO UNDERGO BETTER
PHASING AS THEY MOVE EWD THROUGH THE CENTRAL STATES TODAY...AND THEN
EVOLVE INTO A MORE AMPLIFIED FULL LATITUDE TROUGH AS THIS FEATURE
REACHES THE MS VALLEY BY 12Z WEDNESDAY.  A WEAK SUB-TROPICAL MID
LEVEL IMPULSE IS EXPECTED TO PRECEDE THE UPPER TROUGH AND TRACK FROM
THE LOWER MS VALLEY INTO THE SRN APPALACHIANS BY 00Z...AND THEN
ACROSS THE MID ATLANTIC STATES.

AT 12Z TODAY...A SURFACE BOUNDARY IS EXPECTED TO EXTEND FROM MIDDLE
TN SWWD TO SRN LA.  A SURFACE WAVE IS FORECAST TO DEVELOP ALONG THIS
BOUNDARY...MOST LIKELY IN NWRN AL...AT THE START OF THE PERIOD
ATTENDANT TO THE LEAD IMPULSE AND THEN TRACK TOWARD ERN TN.  THE
TRAILING BOUNDARY WILL MOVE EWD AND EXTEND SWWD THROUGH CENTRAL AL
TO SERN LA BY LATE AFTERNOON.  THIS FRONT IS EXPECTED TO SURGE EWD
TONIGHT THROUGH THE CENTRAL GULF COAST STATES REACHING CENTRAL SC/GA
TO FL PANHANDLE BY 12Z WEDNESDAY.

...LOWER MS VALLEY TO SERN STATES...
DESPITE A MOIST WARM SECTOR TODAY...LIMITED SURFACE HEATING AND WEAK
LAPSE RATES WILL RESULT IN A WEAKLY UNSTABLE AIR MASS.  FORCING FOR
ASCENT WITH THE LEAD IMPULSE IS EXPECTED TO SPREAD NEWD SUPPORTING
TSTM DEVELOPMENT MAINLY ALONG AND N OF THE EWD MOVING FRONT. 
INCREASING WINDS THROUGH A DEEP LAYER FROM THE LOWER MS VALLEY TO
SRN APPALACHIANS/CAROLINAS WILL RESULT IN STRENGTHENING DEEP LAYER
SHEAR /40-60 KT/ SUPPORTING LINE SEGMENTS AND EMBEDDED ROTATING
STORMS WITH ANY SUSTAINED ACTIVITY ALONG THE FRONT.  GIVEN THE WEAK
INSTABILITY...THE LACK OF PRE-FRONTAL MESOSCALE FORCING SUGGESTS THE
POTENTIAL FOR DISCRETE STORMS AHEAD OF THE FRONT SHOULD REMAIN LOW. 
THE LIKELIHOOD FOR A STRONGLY SHEARED ENVIRONMENT...INCLUDING IN THE
LOW LEVELS...WILL MAINTAIN A SLIGHT RISK ACROSS THIS AREA TODAY. 
THE GREATEST SEVERE WEATHER HAZARD IS EXPECTED TO BE DAMAGING
WINDS...BUT THE THREAT FOR ISOLATED TORNADOES CANNOT BE RULED OUT.

A GREATER THREAT FOR DAMAGING WINDS REMAINS POSSIBLE FROM TUESDAY
EVENING INTO EARLY WEDNESDAY MORNING AS STRONGER FORCING FOR ASCENT/
HEIGHT FALLS WITH THE UPPER TROUGH SPREAD EWD ACROSS THE GULF COAST
STATES AND THE COLD FRONT SURGES EWD.  THIS THREAT IS EXPECTED TO
EXTEND MAINLY FROM SERN MS/LA EWD THROUGH SRN AL/FL PANHANDLE TO
WRN-SWRN GA.  IN ADDITION TO THE OVERNIGHT WIND THREAT...STRONG LOW
LEVEL SHEAR WITHIN A MOIST AND SLIGHTLY MORE UNSTABLE AIR MASS WITH
SWD EXTENT TOWARD THE COAST SUGGESTS AN ISOLATED TORNADO THREAT
ALONG AND AHEAD OF THE COLD FRONT.

...ERN TN/WRN CAROLINAS...
TSTMS WILL BE POSSIBLE BY EARLY AFTERNOON OVER ERN TN AS ASCENT WITH
THE LEAD IMPULSE MOVES ACROSS THIS REGION...WITH THE TSTM POTENTIAL
SPREADING EWD INTO THE WRN CAROLINAS AND PERSISTING INTO THE
EVENING.  ALTHOUGH INSTABILITY WILL BE EVEN WEAKER ACROSS THIS
AREA...STRENGTHENING SWLY LOW LEVEL WINDS IN EXCESS OF 50-55 KT
SUGGEST THAT ANY DOWNDRAFT THAT CAN REACH THE SURFACE WILL HAVE THE
POTENTIAL TO PRODUCE AT LEAST ISOLATED DAMAGING WIND GUSTS.

..PETERS.. 01/06/2009