SWODY1
SPC AC 280524
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1124 PM CST THU NOV 27 2008
VALID 281200Z - 291200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS INDICATE THAT A LARGE UPPER CLOSED LOW/TROUGH...WITHIN A
NORTHERN BRANCH OF SPLIT POLAR WESTERLIES...WILL LINGER OVER THE
EASTERN CANADIAN PROVINCES AND NORTHEASTERN U.S. THROUGH THIS
FORECAST PERIOD. AT THE SAME TIME...A STRONG UPPER RIDGE IS PROGGED
TO CONTINUE BUILDING ACROSS THE EASTERN PACIFIC INTO THE PACIFIC
COAST STATES. AND...THIS IS EXPECTED TO FORCE THE SIGNIFICANT SHORT
WAVE IMPULSE...NOW DIGGING ACROSS THE CANADIAN/ NORTHERN U.S.
ROCKIES...SOUTHWARD TOWARD THE SOUTHERN PLAINS. THIS IS FORECAST TO
MAINTAIN UPPER TROUGHING ACROSS THE FOUR CORNERS STATES INTO THE
SOUTHERN PLAINS...EVEN AS THE LAST IN A SERIES OF SIGNIFICANT
SOUTHERN BRANCH IMPULSES SHIFTS EAST OF THE SOUTHERN ROCKIES THROUGH
A CONFLUENT REGIME ACROSS THE SOUTH CENTRAL PLAINS INTO THE OZARK
PLATEAU.
...GULF STATES...
THE STRONGEST FORCING FOR UPWARD VERTICAL MOTION ASSOCIATED WITH THE
IMPULSE EMANATING FROM THE SOUTHWEST WILL LIKELY REMAIN TO THE
NORTHWEST OF THE GULF STATES TODAY. BUT...WEAK MID-LEVEL HEIGHT
FALLS AND A TRANSITION TO AT LEAST BROADLY CYCLONIC FLOW IS EXPECTED
TO OCCUR ACROSS EASTERN TEXAS THROUGH PARTS OF THE CENTRAL/EASTERN
GULF STATES. THIS SHOULD SUPPORT INCREASING CONVECTIVE DEVELOPMENT
IN AN ENVIRONMENT WHICH HAS MOISTENED DURING THE PAST DAY OR
SO...ASSOCIATED WITH GULF OF MEXICO BOUNDARY LAYER MODIFICATION AND
INLAND RETURN FLOW.
THE BULK OF ANY THUNDERSTORM ACTIVITY WILL PROBABLY BE BASED ABOVE A
RESIDUAL NEAR SURFACE STABLE LAYER...WITH WEAK MID-LEVEL LAPSE RATES
LIMITING THE VIGOR OF THE UPDRAFTS. HOWEVER...THERE ARE INDICATIONS
AMONG MODEL GUIDANCE THAT WEAK SURFACE FRONTAL WAVE DEVELOPMENT MAY
BE ACCOMPANIED BY BOUNDARY LAYER BASED DESTABILIZATION...WITH CAPE
OF 500-1000 J/KG...ACROSS THE SOUTHEAST TEXAS COASTAL PLAIN INTO
SOUTHERN LOUISIANA BY LATE TODAY...PERHAPS INTO SOUTHERN MISSISSIPPI
TONIGHT. IF THIS OCCURS...AND IS ACCOMPANIED BY STORM
DEVELOPMENT...DEEP LAYER SHEAR BENEATH 50+ KT WESTERLY 500 MB FLOW
WILL BE SUPPORTIVE OF ISOLATED SUPERCELLS. AND...MODEST
STRENGTHENING OF SOUTHWESTERLY 850 MB FLOW MAY CONTRIBUTE TO
SUFFICIENTLY LARGE LOW-LEVEL HODOGRAPHS FOR THE DEVELOPMENT OF
LOW-LEVEL MESOCYCLONES...ACCOMPANIED BY THE RISK FOR AN ISOLATED
TORNADO OR LOCALIZED DAMAGING WIND GUSTS.
..KERR.. 11/28/2008
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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.
No comments:
Post a Comment