[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 281730
SWODY2
SPC AC 281729

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CST TUE FEB 28 2006

VALID 011200Z - 021200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
IN MID/UPPER LEVELS...PROGRESSIVE PATTERN FCST FOR LOW-AMPLITUDE
SHORTWAVES AS FLOW ACROSS MOST OF CONUS EVOLVES TO ZONAL OR WSWLY
DIRECTION.  STRONG TROUGH FCST TO DEVELOP JUST OFFSHORE PACIFIC
COAST BY END OF PERIOD...WITH CLOSED MIDLEVEL LOW OFF WA/ORE. 
LATTER FEATURE SHOULD EVOLVE FROM SPEED MAX NOW DIGGING SWD AROUND
WRN SIDE OF GULF OF ALASKA CYCLONE.  MEANWHILE...LOW-AMPLITUDE SRN
STREAM PERTURBATION -- EVIDENT IN MOISTURE CHANNEL IMAGERY OVER
PACIFIC ABOUT 800 NM WSW OF BAJA SPUR -- MAY EJECT NEWD ACROSS SWRN
CONUS DOWNSTREAM FROM AN EVEN STRONGER TROUGH NOW EVIDENT NEAR
30N135W.

SHORTWAVE TROUGH NOW MOVING INLAND PACIFIC COAST IS FCST TO
PENETRATE NRN PLAINS MEAN RIDGE POSITION DURING MIDDLE OF
PERIOD...THEN ACCELERATE SEWD ACROSS UPPER GREAT LAKES.  ASSOCIATED
SFC CYCLONE SHOULD MOVE/DEVELOP EWD ACROSS MID MS VALLEY...EWD
TOWARD OH/PA BY 2/12Z. TRAILING SFC COLD FRONT WILL SWEEP SWD
ACROSS CENTRAL/SRN HIGH PLAINS AND SEWD OVER MOST OF OK/MO/IL BY END
OF PERIOD.

...OH VALLEY TO PA/LE...
NEWD FRINGE OF PARTIALLY MODIFIED RETURN FLOW AIR...ORIGINATING OVER
WRN GULF...IS EXPECTED TO BECOME ISENTROPICALLY LIFTED TO LFC DURING
LAST 6-12 HOURS OF PERIOD.  WAA REGIME -- ASSOCIATED WITH 50-60 KT
LLJ AND AHEAD OF NRN STREAM TROUGH -- WILL ALSO CONTRIBUTE TO
STEEPENED LOW-MIDLEVEL LAPSE RATES.  MODIFIED ETA/ETA-KF SOUNDINGS
SUGGEST UP TO ABOUT 500 J/KG ELEVATED MUCAPE MAY DEVELOP ACROSS THIS
REGION.  STRONGEST ASCENT FOR CONVECTION SHOULD BE NE-E OF SFC LOW
AND ROOTED NEAR 850 MB.  VERTICAL SHEAR THROUGH ELEVATED BUOYANT
LAYER SHOULD BE TOO SMALL TO SUPPORT ORGANIZED SEVERE POTENTIAL.

...SRN HIGH PLAINS...
TSTM POTENTIAL WILL INCREASE AFTER 2/6Z N OF SFC FRONT...WITH STRONG
LOW LEVEL FRONTOGENETIC FORCING AND AT LEAST MARGINAL LOW-MIDLEVEL
MOISTURE ABOVE FRONTAL SURFACE.  ADDITIONAL SUPPORT IS POSSIBLE WITH
WEAK LARGE SCALE ASCENT ALOFT...AHEAD OF EJECTING SRN STREAM
PERTURBATION...CONTRIBUTING TO STEEPENING MIDLEVEL LAPSE RATES AND
MUCAPES GENERALLY BELOW 500 J/KG.  TSTM COVERAGE SHOULD BE ISOLATED
TO WIDELY SCATTERED...OVER SOME SMALL SUBSET OF OUTLINED AREA.

...CENTRAL/NRN PACIFIC COASTAL AREA...
ISOLATED TO WIDELY SCATTERED TSTMS ARE POSSIBLE BOTH WITHIN INITIAL
BAND OF BAROCLINIC FORCING...FCST TO MOVE ONSHORE ORE AND NRN CA
AROUND MIDDLE OF PERIOD...AND BENEATH SUBSEQUENT COLD-CORE REGIME.
LAPSE RATES SHOULD STEEPEN BEHIND FRONTAL ZONE WITH WEAK
CINH...RESULTING IN OCCASIONAL THUNDER FROM GLACIATED/SHALLOW
CONVECTION.  THIS WOULD BE A SEWD TRANSLATION OF CLOUD TRENDS AND
REGIME NOW EVIDENT IN IR IMAGERY INVOF 45N145W...PERHAPS STRONGER BY
THEN AS LARGE SCALE FORCING BUILDS IN ASSOCIATION WITH MIDLEVEL
CYCLOGENESIS.

..EDWARDS.. 02/28/2006