SPC AC 020659
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CST FRI JAN 02 2015
VALID 031200Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SOUTHEAST LA...SOUTHEAST
MS...AND FAR SOUTHWEST AL...
...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLGT RISK AREA
ACROSS THE LOWER MS VALLEY AND CENTRAL GULF COAST...
...SUMMARY...
ISOLATED SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY ACROSS
SOUTHERN PORTIONS OF LOUISIANA AND MISSISSIPPI...AND EXTREME
SOUTHWEST ALABAMA. DAMAGING WINDS AND A TORNADO THREAT WILL BE THE
PRIMARY SEVERE WEATHER POTENTIAL.
...SYNOPSIS...
MODELS ARE IN FAIRLY GOOD AGREEMENT SHOWING THE STRONGEST FORCING
FOR ASCENT WILL REMAIN NORTH OF THE LOWER MS VALLEY/CENTRAL GULF
COAST SATURDAY...AS A SHORTWAVE TROUGH TRACKS ACROSS NORTH TX/OK/KS
SATURDAY AFTERNOON. THIS FEATURE THEN WILL ACCELERATE NEWD TO THE
LOWER GREAT LAKES SATURDAY NIGHT. A SURFACE LOW WILL TRACK FROM
NEAR THE ARKLATEX REGION AT 12Z SATURDAY NEWD INTO THE MID MS
VALLEY...BEFORE FAIRLY RAPID DEEPENING IS FORECAST AS THIS LOW MOVES
INTO LOWER MI/LAKE HURON LATE SATURDAY NIGHT. A COLD FRONT TRAILING
SWWD FROM THE LOW AND WARM SECTOR EXPECTED INTO THE SLIGHT RISK AREA
WILL BE THE PRIMARY FOCUS REGIONS FOR TSTM DEVELOPMENT THIS PERIOD.
AT 12Z SATURDAY...THE COLD FRONT SHOULD EXTEND FROM SWRN AR TO THE
TX COAST. THIS FRONT WILL ADVANCE E/NEWD ACROSS THE OH/TN AND LOWER
MS VALLEYS...AND SHOULD EXTEND FROM UPPER OH VALLEY TO THE SRN
APPALACHIANS TO NEAR MOBILE BY 12Z SUNDAY.
...LA/MS/WRN AND SWRN AL/FAR WRN FL PANHANDLE...
HEIGHT FALLS WILL REMAIN QUITE WEAK ACROSS SRN LA TO SRN AL AND WRN
FL PANHANDLE AS STRONGER FORCING FOR ASCENT REMAINS NORTH OF THE
SLIGHT AND MARGINAL RISK AREAS...ALONG THE TRACK OF THE SRN PLAINS
SHORTWAVE TROUGH. DESPITE THE LACK OF GREATER FORCING FOR ASCENT
AND GENERALLY WEAK LAPSE RATES...A POLEWARD RETURN OF MOISTURE /PW
OF 1.5-1.75 INCHES AND SURFACE DEW POINTS IN THE MID-UPPER 60S/ IS
EXPECTED ACROSS THE SLIGHT RISK AREA. THIS LATTER FACTOR WILL
SUPPORT MUCAPE OF 500 TO AROUND 1000 J/KG PER NAM/GFS FORECAST
SOUNDINGS.
TSTMS WILL LIKELY BE ONGOING SATURDAY MORNING ALONG THE COLD
FRONT...AND POSSIBLY WITHIN THE WARM SECTOR ACROSS SRN PORTIONS OF
LA/MS. AN INCREASE IN DEEP-LAYER WIND FIELDS...NEARLY PARALLEL TO
THE COLD FRONT...WILL TEND TO RESULT IN LINEAR FORCING FOR A
CONTINUED LINE OF STORMS SPREADING EWD SATURDAY. THE 00Z NAM 4 KM
DID INDICATE THE POTENTIAL FOR A FEW DISCRETE STORMS IN THE WARM
SECTOR...AND GIVEN STRONG DEEP-LAYER AND LOW-LEVEL SHEAR...SUPERCELL
STRUCTURES WILL BE POSSIBLE. DAMAGING WINDS AND A TORNADO THREAT
WILL BE THE PRIMARY SEVERE RISKS...ESPECIALLY ACROSS THE SLIGHT-RISK
AREA WHERE HIGHER MOISTURE/INSTABILITY WILL ENHANCE THIS POTENTIAL.
..PETERS.. 01/02/2015
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