SWODY2
SPC AC 211730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CST FRI DEC 21 2007
VALID 221200Z - 231200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
MODELS SHOW PHASED NRN AND SRN STREAM SHORT WAVE TROUGHS ENTERING
THE PLAINS STATES AT 12Z SATURDAY MORNING WILL EVOLVE INTO A CLOSED
NEGATIVELY TILTED UPPER TROUGH EXTENDING FROM THE UPPER MS VALLEY TO
OH/TN VALLEYS BY 12Z SUNDAY. IN RESPONSE TO THIS CONSOLIDATION OF
UPPER LEVEL FEATURES...DEEP LAYER WIND FIELDS ARE EXPECTED TO
STRENGTHEN FROM THE ARKLATEX/LOWER MS VALLEY INTO MID MS/LOWER OH
VALLEYS. IN THE LOW LEVELS...SURFACE LOW IS EXPECTED TO TRACK FROM
NRN TX NEWD INTO ERN MO BY 23/00Z...AND THEN DEEPEN RAPIDLY SATURDAY
NIGHT IN RESPONSE TO STRONG HEIGHT FALLS WITH THE UPPER TROUGH. THE
LOW SHOULD REACH LAKE MICHIGAN BY 12Z SUNDAY. TRAILING COLD FRONT
WILL MOVE QUICKLY EWD SATURDAY NIGHT FROM THE LOWER MS VALLEY INTO
THE OH/TN VALLEYS AND EXTEND SWD INTO THE CENTRAL GULF OF MEXICO BY
EARLY SUNDAY MORNING.
..E TX/LOWER MS VALLEY TO MID MS/LOWER TN VALLEYS...
INCREASING SLY LOW LEVEL FLOW AHEAD OF THE SRN STREAM TROUGH WILL
ADVECT MOISTURE NWD ALONG AND E OF A PRE-FRONTAL CONVERGENCE ZONE
WITH SURFACE DEWPOINTS IN THE UPPER 50S TO LOWER 60S REACHING SERN
AR/NWRN MS BY LATE SATURDAY AFTERNOON. MODELS SUGGEST GREATER
INSTABILITY /MUCAPE 500-700 J/KG/ WILL BE POSSIBLE ACROSS PARTS OF
LA INTO SRN MS WHERE LOW LEVEL MOISTURE WILL BE HIGHER.
STRONG FORCING ALOFT ATTENDANT TO THE SRN STREAM TROUGH WILL SPREAD
ENEWD ACROSS MOISTURE RETURN AND COMBINED WITH FRONTAL CONVERGENCE
AS THE COLD FRONT OVERTAKES THE PRE-FRONTAL TROUGH IS EXPECTED TO
SUPPORT TSTM DEVELOPMENT ACROSS SRN MO/NRN AR SATURDAY AFTERNOON.
TSTM DEVELOPMENT SHOULD ALSO OCCUR SWD ALONG THE FRONT INTO THE
LOWER MS VALLEY WHERE THE INSTABILITY WILL BE GREATER. DESPITE
STRONG FORCING AND INCREASING DEEP LAYER WIND FIELDS/SHEAR...THE
FAST MOVEMENT OF THIS SYSTEM IS EXPECTED TO LIMIT THE DURATION OF
ANY SEVERE TSTM DEVELOPMENT ALONG THE FRONT GIVEN LIMITED MOISTURE
RETURN/WEAK INSTABILITY. THUS...THE STORM SYSTEM IS EXPECTED TO
OUTRUN THE MOISTURE RETURN AND LIMIT THE THREAT FOR SEVERE STORMS.
THIS OUTLOOK WILL MAINTAIN LOW SEVERE PROBABILITIES FROM THE LOWER
MS VALLEY AND EXTEND NWD INTO MID MS VALLEY...SINCE ANY TSTMS THAT
DO DEVELOP WILL MOVE QUICKLY NEWD AND COULD PRODUCE ISOLATED
DAMAGING WINDS.
.PETERS.. 12/21/2007
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment