DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 170745
SWODY3
SPC AC 170744

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0144 AM CST SAT NOV 17 2012

VALID 191200Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
IN MID-UPPER LEVELS...EXPECT PATTERN OVER CONUS TO REMAIN
PROGRESSIVE AND TO TEMPORARILY BECOME MORE ZONAL THIS PERIOD. MAIN
EXCEPTION WILL BE OVER PAC NW...WHERE STRENGTHENING HEIGHT GRADIENT
AND SWLYS ALOFT ARE PROGGED...AS MAJOR GULF OF AK CYCLONE SHIFTS SWD
ACROSS NERN PAC. POSITIVELY TILTED SHORTWAVE TROUGH AND RELATED
VORTICITY BANNER...RELATED TO SPEED MAX NOW OVER BERING SEA...IS
EXPECTED TO MOVE ASHORE WA/ORE DURING 19/21Z-20/06Z TIME FRAME.

WEAK SFC COLD FRONT...ASSOCIATED WITH NRN-STREAM PERTURBATION ALOFT
-- SHOULD MOVE EWD ACROSS UPPER MIDWEST AND CENTRAL
PLAINS...BECOMING DIFFUSE AND HARD TO DISTINGUISH FROM AMBIENT LEE
TROUGHING REGIME OVER SRN HIGH PLAINS. DIFFUSE DRYLINE MAY DEVELOP
BY MID-AFTERNOON FROM NW OK SWWD ACROSS PERMIAN BASIN REGION.

...SW OK TO SW TX...
CONTINUING LOW-LEVEL WAA/ISENTROPIC LIFT REGIME WILL SUPPORT
POTENTIAL FOR BLEND OF CONVECTIVE AND STRATIFORM PRECIP OVER THIS
REGION...INCLUDING SOME DIURNALLY-AIDED/SFC-BASED CONVECTION DURING
MIDDAY TO LATE AFTERNOON TIME FRAME ALONG/E OF DRYLINE. THIS AREA
ALSO WILL LIE ON SRN FRINGE OF LEE TROUGHING...AND WRN FRINGE OF
INCOMPLETELY MODIFIED RETURN-FLOW AIR MASS...WITH SFC DEW POINTS 50S
F. ISOLATED TO WIDELY SCATTERED TSTMS ARE POSSIBLE...WITH
COVERAGE/INTENSITY LIMITED BY COMBINATION OF WEAK LAPSE
RATES/BUOYANCY ALOFT...AND LACK OF MORE ROBUST LOW-LEVEL FORCING.

...COASTAL PAC NW...
LOW-LEVEL FRONTAL/CONVERGENCE BAND PRECEDING MID-UPPER SHORTWAVE
TROUGH WILL BE ACCOMPANIED BY STEEPENING LOW-MIDDLE LEVEL LAPSE
RATES AND ENHANCED LIFT. THIS REGIME...ALONG WITH CONTINUED
POSTFRONTAL/MIDLEVEL COOLING ABOVE MARINE LAYER...WILL SUPPORT
POTENTIAL FOR ISOLATED/EPISODIC TSTMS INVOF COAST.

..EDWARDS.. 11/17/2012

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