SWODY1
SPC AC 130054
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0654 PM CST THU FEB 12 2009
VALID 130100Z - 131200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
LARGELY ZONAL FLOW ALOFT IS EXPECTED TO CONTINUE OVER MOST OF
CONUS...PERTURBED PRIMARILY BY SHORTWAVE TROUGH OVER GREAT
BASIN...AND UPSTREAM UPPER LOW OFFSHORE PACIFIC NW. GREAT BASIN
TROUGH IS FCST TO MOVE ENEWD ACROSS CENTRAL/SRN ROCKIES TO CENTRAL
HIGH PLAINS BY 12Z. MEANWHILE...PACIFIC SYSTEM -- VERY CLASSICALLY
PRESENTED VORTEX IN VIS/IR SATELLITE IMAGERY -- IS FCST TO PIVOT
SEWD TOWARD SWRN ORE/NWRN CA...BUT REMAIN OFFSHORE UNTIL AFTER END
OF PERIOD.
AT SFC...REMNANT FRONTAL ZONE -- LEFT BEHIND BY FROM DEPARTED
ATLANTIC SYSTEM -- IS EVIDENT IN VIS/IR IMAGERY AND AVAILABLE OBS
ACROSS NRN GULF....ROUGHLY BETWEEN 26N-27N. WRN PORTION OF THIS
BOUNDARY APPEARS TO BE RETREATING NWD ALREADY...AND THIS PROCESS
SHOULD CONTINUE AND SHIFT EWD THROUGH REMAINDER OVERNIGHT HOURS.
SUFFICIENT GULF MOISTURE WILL REMAIN TOO DISPLACED FROM NERN NM/TX
PANHANDLE SFC CYCLOGENESIS OVER S-CENTRAL HIGH PLAINS TO SUPPORT
DEEP CONVECTION IN RELATED CENTRAL PLAINS LOW LEVEL WAA REGIME.
...CENTRAL GULF COAST...LOWER MS DELTA REGION...
LOW LEVEL FRONTAL ZONE IS EXPECTED TO IMPINGE UPON THIS REGION LATE
IN PERIOD. AS THIS OCCURS...WAA REGIME AND RELATED ISENTROPIC
ASCENT OF INCREASINGLY MOIST PARCELS WILL BOOST THETAE JUST ABOVE
STABLE NEAR-SFC LAYER. THIS...IN TURN...WILL OFFSET WEAK LAPSE
RATES ALOFT...OVERCOMING WEAKLY STABLE LAYER BETWEEN 700-500 MB TO
YIELD DEEP BUOYANCY. PRIND ELEVATED MUCAPES WILL INCREASE TO
500-700 J/KG RANGE BY 12Z OVER SERN LA NEAR LOCUS OF STRONGEST
LIFT...DECREASING WITH RADIAL EXTENT FROM THERE FARTHER E...W...AND
INLAND. ALTHOUGH GREATEST CONCENTRATION OF CONVECTION -- ALONG WITH
MRGL SVR THREAT -- IS EXPECTED AFTER 12Z...WIDELY SCATTERED TSTMS IN
CLUSTERS ARE POSSIBLE BEFORE END OF PERIOD. PRIND SVR POTENTIAL
WILL BE TOO CONDITIONAL/ISOLATED TO ASSIGN PROBABILITIES BEFORE 12Z.
...COASTAL ORE/NWRN CA...
MRGL THUNDER PROBABILITIES EXIST FOR CATEGORICAL AREA ALONG ERN
FRINGES OF STRONGEST COOLING ALOFT. MODIFIED/MOISTENED RAOBS FROM
MFR/SLE...ALONG WITH NAM-KF FCST SOUNDINGS...SUGGEST STEEP
LOW-MIDLEVEL LAPSE RATES SUPPORTING HIGHEST MUCAPES AROUND 100 J/KG.
SOME ASSOCIATED CONVECTION MAY REACH FAR ENOUGH INTO IDEAL ICING
LAYERS TO YIELD LIGHTNING.
...4-CORNERS REGION...
ROGUE LIGHTNING FLASH OR TWO STILL MAY OCCUR FROM 4-CORNERS AREA EWD
ACROSS SAN JUANS...IN ZONE OF STG LARGE SCALE ASCENT AND ACCORDINGLY
STEEPENED LAPSE RATES AHEAD OF UPPER TROUGH. HOWEVER...COLD LOW
LEVEL AIR MASS STABILIZING NOCTURNALLY...AND RELATED LACK OF
BUOYANCY...PRECLUDE CONTINUING GEN THUNDER AREA.
..EDWARDS.. 02/13/2009
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