ACUS02 KWNS 240623
SWODY2
SPC AC 240621
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1221 AM CST THU NOV 24 2011
VALID 251200Z - 261200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
AMPLIFYING MID-UPPER PATTERN FCST THROUGH PERIOD...MAIN FEATURE FOR
THIS FCST BEING STG SHORTWAVE TROUGH NOW EVIDENT IN MOISTURE CHANNEL
IMAGERY OFFSHORE CA AND NRN BAJA...NEAR 127W. THIS TROUGH IS FCST
TO MOVE ASHORE DAY-1...REACHING 4-CORNERS REGION..ERN AZ...SONORA
AND CENTRAL BAJA BY BEGINNING OF PERIOD. TROUGH THEN SHOULD ASSUME
POSITIVE TILT...REACHING OK PANHANDLE...SERN NM...CHIHUAHUA AND SRN
BAJA BY 26/00Z.
MEANWHILE...SPEED MAX AND CURRENTLY LOW-AMPLITUDE SHORTWAVE....NOW
OVER EXTREME NRN PAC S OF ALEUTIANS...SHOULD AMPLIFY AND MOVE ASHORE
PAC NW LATE DAY-1. THIS PERTURBATION WILL STRENGTHEN FURTHER AS IT
CROSSES MT/WY AROUND 26/00Z. THEREAFTER...NRN AND SRN STREAM
TROUGHS ARE EXPECTED TO BECOME PHASED. BY END OF
PERIOD...FULL-LATITUDE/PROGRESSIVE TROUGH IS FCST FROM MB/SK BORDER
SSEWD ACROSS CENTRAL/ERN KS...SWD OVER OK...THEN SWWD ACROSS TX
BIG-BEND REGION AND NWRN MEX.
AT SFC...FRONTOGENESIS IS FCST DAY-1 OVER NRN ROCKIES/NRN
PLAINS...RESULTING BY 25/12Z IN COLD FRONT FROM MN SFC LOW SWWD
ACROSS NWRN KS AND ERN CO. BY 26/00Z...COLD FRONT SHOULD EXTEND
FROM WI/SERN MN LOW SWWD ACROSS SERN KS TO WEAK/SECONDARY LOW OVER
TX PANHANDLE. FRONT SHOULD STRENGTHEN/ACCELERATE OVER UPPER MS
VALLEY AND CENTRAL PLAINS DURING LATTER HALF OF PERIOD WITH CLOSER
APCH OF NRN-STREAM WAVE. BY 26/12Z...EXPECT SFC LOW OVER WI TO WRN
UPPER MI...AND FRONT SWWD ACROSS ERN IA...NRN MO...SERN KS...SRN
OK...AND W-CENTRAL TX.
...SWRN/S-CENTRAL CONUS...
SEVERAL EPISODES OF ISOLATED TO WIDELY SCATTERED...MAINLY LOW-TOPPED
TSTMS ARE POSSIBLE THROUGH PERIOD...EACH WITH TOO LITTLE MOISTURE
AND/OR NEAR-SFC INSTABILITY TO WARRANT SVR RISK ATTM. THERE LIKELY
WILL BE SPATIAL GAPS BETWEEN THESE...AND POCKETS OF GEN TSTM AREA
THAT DO NOT EXPERIENCE TSTMS. HOWEVER...SUFFICIENT COVERAGE/TIMING
UNCERTAINTY REMAINS IN PROGS OF EACH OF THESE REGIMES...AND THEIR
OVERLAP...SUCH THAT IT IS TOO SOON TO OUTLINE SPECIFIC GAPS.
CONVEYOR OF LOW-LEVEL WAA AND LOW-MIDLEVEL MOISTURE TRANSPORT WILL
TRANSLATE EWD ACROSS NRN MEX...NM AND W TX THROUGH FIRST HALF OF
PERIOD...WITH SPORADIC THUNDER PSBL. THIS REGIME SHOULD SPREAD NEWD
ACROSS SRN HIGH PLAINS DURING DAY...MAIN LIMITING FACTOR BEING LACK
OF RICHER MOISTURE. EARLY-PERIOD THUNDER ALSO MAY OCCUR OVER SERN
AZ/SRN NM REGION AS 500-MB LOW AND ASSOCIATED VORTICITY MAX MOVE
OVER AREA...STEEPENING LOW-MIDLEVEL LAPSE RATES ATOP MOISTURE LEFT
BY PRECIP FROM WAA CONVEYOR.
GULF MOISTURE RETURN WILL BE SCANT TROUGH PERIOD...DUE TO
INCOMPLETENESS OF MARINE AIR-MASS MODIFICATION BEHIND STG FRONT NOW
CROSSING CENTRAL/ERN GULF. STILL...LOW-LEVEL MOISTURE CHARACTERIZED
BY SFC DEW POINTS UPPER 40S TO MID 50S F MAY BE SUFFICIENT TO
SUPPORT INCREASE IN THUNDER POTENTIAL AFTER DARK...FROM W-CENTRAL/NW
TX NEWD TOWARD SERN KS/SWRN MO...AS
AS STRENGTHENING COLD FRONTAL ZONE UNDERCUTS WAA PLUME.
..EDWARDS.. 11/24/2011
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