[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 291731
SWODY2
SPC AC 291729

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CST WED NOV 29 2006

VALID 301200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL GULF COAST
ACROSS THE MS/TN AND LOWER OH VALLEYS TO SRN APPALACHIANS...

...SYNOPSIS...
POWERFUL AND PROGRESSIVE SHORT WAVE IMPULSE WILL INTENSIFY THROUGH
THE DAY TWO PERIOD ACROSS THE SRN PLAINS BEFORE TAKING ON A NEGATIVE
TILT AND EJECTING NEWD FROM THE OZARKS TO THE OH VALLEY BY FRIDAY.
IN ADDITION TO SIGNIFICANT 12H 500MB HEIGHT FALLS OF AROUND 300M
ACROSS THE MO BOOTHEEL/SRN IL...AN INTENSE MID LEVEL JET OF
100-120KT WILL ROTATE THROUGH THE BASE OF THE EJECTING SHORT WAVE
TROUGH...MOVING NEWD FROM THE ARKLATEX TO THE LOWER OH VALLEY AREA
THROUGH THURSDAY NIGHT. VERY STRONG DYNAMIC AND KINEMATIC FORCING
WILL INDUCE SURFACE CYCLOGENESIS ALONG AN ASSOCIATED COLD FRONT
ACROSS ERN AR BY THURSDAY AFTERNOON. THE INTENSIFYING SURFACE
CYCLONE IS FORECAST TO TRACK NEWD FROM ERN AR TO OH AS POTENT COLD
FRONT SWEEPS EWD FROM THE MS VALLEY TO THE APPALACHIANS THROUGH
EARLY FRIDAY.

LARGE-SCALE PATTERN AS FORECAST BY NAM AND GFS HAS AN ANALOG IN 1996
NOVEMBER 7-8 EVENT WHICH RESULTED IN A SWATH OF SEVERE CONVECTIVE
WIND EVENTS FROM LA TO OH. THIS ANALOG WAS ALSO A STRONGLY
DYNAMIC...LOW CAPE/HIGH SHEAR...SEVERE WEATHER EPISODE.

...CNTRL GULF COAST ACROSS THE MS/TN AND LOWER OH VALLEYS...TO SRN
APPALACHIANS...

LATEST OBSERVATIONS INDICATE SURFACE DEWPOINTS INCREASING AND
SPREADING NNEWD FROM THE GULF ACROSS THE LOWER MS RIVER VALLEY AND
INTO THE LOWER OH VALLEY. WITH SWLY LLJ BEING MAINTAINED IN ADVANCE
OF THE APPROACHING UPPER TROUGH...EXPECT AN INCREASINGLY MOIST
BOUNDARY LAYER TO EXPAND NWD AND EWD ACROSS THE MS/TN AND OH VALLEYS
THROUGH EARLY THURSDAY. HOWEVER...LATEST GUIDANCE CONTINUES TO
INDICATE THAT ONLY MARGINAL INSTABILITY /MUCAPES OF 200-500 J PER
KG/ WILL DEVELOP AHEAD OF THE INTENSE COLD FRONT ON THURSDAY DUE TO
WEAK LOW TO MID-LEVEL LAPSE RATES.

DESPITE INSTABILITY CONSTRAINTS...INCREASINGLY STRONG LARGE-SCALE
FORCING AND SLAB ASCENT ACROSS COLD FRONT SHOULD CONTRIBUTE TO THE
INTENSIFICATION OF A LOW-TOPPED CONVECTIVE LINE BY AFTERNOON FROM
THE CONFLUENCE OF THE MS/OH RIVERS SWWD TO ERN AR AND CNTRL LA.
PRIMARY CONVECTIVE MODE IS EXPECTED TO BE LINEAR WITH EMBEDDED
LEWP/BOW STRUCTURES. STRENGTH OF THE DEEP-LAYER WIND FIELDS WILL
SUPPORT STORM MOTIONS OF 50+KT WITH THE POTENTIAL FOR DAMAGING WINDS
FROM A FAST MOVING LOW-TOPPED SQUALL LINE.

GIVEN MAGNITUDE OF SHEAR AND FORCING...A FEW LOW-TOPPED SUPERCELLS
ALSO APPEAR POSSIBLE...PERHAPS EMBEDDED WITHIN THE LINE...OR FORMING
AS MORE DISCRETE STORMS AHEAD OF THE LINE. LOW LCL HEIGHTS AND
STRONG LOW-LEVEL SHEAR IN THE WARM SECTOR SHOULD SUPPORT SOME THREAT
FOR TORNADOES. POTENTIAL FOR TORNADOES MAY BE ESPECIALLY ENHANCED
NEAR THE DEEPENING SURFACE CYCLONE WHERE LOW LEVEL SHEAR/FORCING
WILL BE LOCALLY MORE INTENSE.

SQUALL LINE...WITH THE POSSIBILITY OF LIMITED CG LIGHTNING DUE TO
LOW CAPE...WILL SHIFT EAST ACROSS THE MS VALLEY AND INTO THE SRN OH
AND TN VALLEYS...AS WELL AS THE CNTRL GULF COAST THROUGH THURSDAY
NIGHT. WITH CONTINUING INTENSIFICATION OF THE DEEP-LAYER CYCLONE AND
CONTINUED SHARPENING OF THE FRONTAL ZONE...THE THREAT OF DAMAGING
WINDS AND ISOLATED TORNADOES MAY PERSIST INTO EARLY FRIDAY AS THE
FRONT/SQUALL LINE MOVES EAST TOWARD THE UPPER OH VALLEY AND EXTENDS
SWD TO THE SRN APPALACHIANS.

..CARBIN.. 11/29/2006