SPC AC 121726
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1126 AM CST THU NOV 12 2009
VALID 131200Z - 141200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
LARGE-SCALE PATTERN WILL UNDERGO AMPLIFICATION THROUGH THE DAY TWO
PERIOD AS STRONG MID/UPPER-JET STREAKS DIG EQUATOR-WARD ALONG THE W
COAST...EFFECTIVELY CONTRIBUTING TO INTENSIFICATION OF BROAD TROUGH
OVER THE WRN STATES. DOWNSTREAM FROM AMPLIFYING WRN U.S.
TROUGH...OPENING MIDLEVEL WAVE WILL TRANSLATE ENEWD THROUGH THE
N-CNTRL STATES...WHILE FARTHER E...DEEP-LAYER CYCLONE SHIFTS EWD
ACROSS THE WRN ATLANTIC.
AT THE SURFACE...A COLD FRONT WILL SHIFT EWD THROUGH THE UPPER MS
VALLEY AND SWD THROUGH THE CNTRL INTO SRN PLAINS. THE WRN EXTENSION
OF THIS BOUNDARY IS FORECAST TO STALL OVER THE CNTRL ROCKIES AND
GREAT BASIN IN RESPONSE TO DEVELOPING LOW PRESSURE OVER THE
REGION.
...FOUR CORNERS REGION INTO CNTRL PLAINS...
SWD PROGRESSION OF COLD FRONT THROUGH THE GULF OF MEXICO HAS SHUNTED
MT AIR MASS TO THE S OF THE YUCATAN CHANNEL. AS A RESULT...A
MODIFIED CP AIR MASS WILL RETURN NWD THROUGH THE WRN GULF BASIN
THROUGH THE SRN PLAINS WITH DEWPOINTS RANGING FROM THE 50S OVER
CNTRL/ERN OK TO LOWER/MID 60S ALONG THE TX COAST. HOWEVER...GIVEN
RELATIVELY WARM MIDLEVEL THERMAL PROFILES EXPECTED...NO APPRECIABLE
CONVECTIVE INSTABILITY IS FORECAST WITHIN PRE-FRONTAL WARM SECTOR
THROUGH THE DAY TWO PERIOD.
ISOLATED TO WIDELY SCATTERED TSTMS WILL BE POSSIBLE ALONG
INTENSIFYING LOW TO MID-TROPOSPHERIC BAROCLINIC ZONE WHERE INCREASED
FORCING FOR ASCENT ACTS ON STEEP LAPSE RATE PLUME PRECEDING
AMPLIFYING WRN CONUS TROUGH. NO SEVERE WEATHER IS EXPECTED.
...PACIFIC NW COAST...
SIGNIFICANT FORCING FOR ASCENT ON CYCLONIC SIDE OF DIGGING POLAR JET
WILL CONTRIBUTE TO STEEPENING LAPSE RATES AND THE POTENTIAL FOR
ISOLATED...LOW-TOPPED TSTMS WITHIN MOIST...POST-FRONTAL AIR MASS.
..MEAD.. 11/12/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0700Z
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