DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 300535
SWODY1
SPC AC 300533

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1133 PM CST THU NOV 29 2012

VALID 301200Z - 011200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
WHILE BLOCKING REMAINS PROMINENT UPSTREAM...MODELS INDICATE THAT
UPPER FLOW ACROSS THE EASTERN PACIFIC INTO THE WESTERN U.S. WILL
BECOME LESS AMPLIFIED DURING THIS FORECAST PERIOD. AND SHORT WAVE
IMPULSES COMPRISING THE CURRENT LARGER SCALE CLOSED LOW/UPPER TROUGH
OVER THE EASTERN PACIFIC APPEAR LIKELY TO PROGRESS INLAND WITHIN AN
INCREASINGLY ZONAL REGIME...WHICH WILL EXTEND EASTWARD ACROSS MUCH
OF THE NORTHERN AND CENTRAL TIER OF THE UNITED STATES. FARTHER
SOUTH...A LOW AMPLITUDE UPPER TROUGH WITHIN THE SUBTROPICAL STREAM
IS FORECAST TO GRADUALLY SHIFT EAST SOUTHEAST OF THE SOUTHEASTERN
GULF OF MEXICO.

WHILE A MODEST RETURN FLOW OF MOISTURE MAY COMMENCE OFF THE WESTERN
GULF OF MEXICO...SUBSTANTIVE NEAR SURFACE DESTABILIZATION APPEARS
LIKELY TO BE CONFINED TO PORTIONS OF CENTRAL/SOUTHERN TEXAS...WHERE
WARMING AND GENERALLY SUBSIDENT MID/UPPER FLOW IS EXPECTED TO
INHIBIT CONVECTIVE DEVELOPMENT. AS A RESULT... CONVECTIVE POTENTIAL
ACROSS MOST AREAS EAST OF THE ROCKIES...IN ADDITION TO MUCH OF THE
WEST...APPEARS LOW TO NEGLIGIBLE THROUGH 12Z SATURDAY AND BEYOND.

...PACIFIC NORTHWEST...
LATEST OBSERVATIONAL DATA CONTINUES TO SUGGEST PROBABILITIES FOR
SCATTERED THUNDERSTORM ACTIVITY WILL INCREASE ACROSS OREGON AND
NORTHERN CALIFORNIA COASTAL AREAS PRIOR TO 12Z...WITH THE APPROACH
OF ONE SIGNIFICANT SHORT WAVE IMPULSE. THIS POTENTIAL MAY LINGER
INTO THE 15-16Z TIME FRAME...BEFORE THE IMPULSE PROGRESSES INLAND
AND WEAKENS. THEREAFTER...THE RISK FOR THUNDERSTORMS IS EXPECTED TO
DIMINISH UNTIL MID-LEVEL COOLING AND LARGE-SCALE ASCENT INCREASE
ACROSS OREGON/WASHINGTON COASTAL AREAS THIS EVENING... AHEAD OF
ANOTHER SIGNIFICANT SHORT WAVE TROUGH. ALTHOUGH LOWER/MID
TROPOSPHERIC WIND FIELDS WILL LIKELY BECOME MODERATELY STRONG WITH
THE PASSAGE OF THESE FEATURES...THE POTENTIAL FOR CONVECTIVELY
ENHANCED SURFACE GUSTS SEEMS TOO REMOTE BY THE START OF THE PERIOD
TO INCLUDE LOWER THRESHOLD SEVERE WIND PROBABILITIES...MAINLY DUE TO
VERY LIMITED AVAILABLE INSTABILITY.

...FLORIDA KEYS...
ALTHOUGH PROBABILITIES APPEAR NEAR THE LOWER THRESHOLD FOR A
CATEGORICAL THUNDERSTORM OUTLOOK...BOUNDARY LAYER INSTABILITY MAY
BECOME SUFFICIENT TO SUPPORT A FEW WEAK THUNDERSTORMS ACROSS THE
LOWER KEYS TODAY...AIDED BY LARGE-SCALE FORCING ASSOCIATED WITH THE
APPROACHING UPPER IMPULSE.

..KERR/ROGERS.. 11/30/2012

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.