SWODY2
SPC AC 201716
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1116 AM CST TUE NOV 20 2007
VALID 211200Z - 221200Z
..THERE IS A SLGT RISK OF SVR TSTMS CENTERED OVER THE MID SOUTH/TN
VALLEY REGION...
..SYNOPSIS...
LARGE COLD TROUGH SHIFTS EWD INTO MIDDLE OF THE CONUS WED WITH A
STRENGTHENING MID/UPPER LEVEL JET FROM THE CENTRAL PLAINS INTO MID
MS VALLEY.
STRONG COLD FRONT BY 12Z WED WILL BE LOCATED ACROSS MID MS VALLEY
SWWD THRU CENTRAL OK TO SERN NM. FRONT PLUNGES RAPIDLY SWD THRU TX
REACHING THE COAST BY 06Z. FRONTAL MOVEMENT FURTHER E WILL BE
SOMEWHAT SLOWER INITIALLY AS A WAVE DEVELOPS SERN MO REGION DURING
THE AFTERNOON. THIS PORTION OF THE FRONT PICKS UP SPEED OVERNIGHT
AS SURFACE LOW TRACKS NEWD ACROSS PA BY 12Z THU.
WITH THE STRONGEST MID/UPPER WIND FIELDS AND JET DYNAMICS REMAINING
ON THE COOL SIDE OF THE FRONTAL ZONE...SEVERE POTENTIAL WILL BE
PRIMARILY SUPPORTED BY THE AMOUNT OF INSTABILITY THAT CAN DEVELOP IN
THE WARM SECTOR DURING THE DAY.
..TN VALLEY SWWD INTO LOWER MS VALLEY...
AN UNSEASONABLY MOIST AIR MASS WILL HAVE SPREAD FROM SRN PLAINS NEWD
ACROSS MS VALLEY INTO TN AND SRN OH VALLEYS S OF OH RIVER BY WED AM.
WITH LOW/MID 60F DEWPOINTS SPREADING AS FAR N AS WRN TN/KY AHEAD OF
FRONT DURING THE DAY INSTABILITY WILL BE SUFFICIENT FOR
THUNDERSTORMS INCREASING IN BOTH NUMBER AND INTENSITY ALONG/AHEAD OF
THE COLD FRONT. AS THE WIND FIELDS AT ALL LEVELS STEADILY INCREASE
WITH APPROACH OF TROUGH AND MID/UPPER JET...STORMS SHOULD GRADUALLY
DEVELOP INTO LINE SEGMENTS AND POSSIBLY ISOLATED SUPERCELLS. WHILE
DEEP LAYER SHEAR EXPECTED TO REMAIN GENERALLY 40KTS OR LESS IN THE
WARM SECTOR...MLCAPES TO NEAR 1000 J/KG COUPLED WITH LOW LFC'S AND
20-25KT OF SFC-1KM SHEAR WOULD SUPPORT TORNADO POTENTIAL WITH ANY
SUPERCELL THAT IS ABLE TO DEVELOP.
INITIAL SEVERE THREAT WILL LIKELY BE MID MS/WRN TN VALLEY AREA IN
REGION OF STRONGEST ASCENT AND SHEAR FIRST PART OF FORECAST PERIOD.
THUNDERSTORMS INCLUDING A SEVERE POTENTIAL WILL THEN DEVELOP E AHEAD
OF FRONT FROM OH RIVER SWD THRU THE EVENING.
FURTHER S INTO ERN TX...WHERE DEWPOINTS TO NEAR 70F AND STRONGER
HEATING IS EXPECTED THE AIR MASS SHOULD BECOME MODERATELY UNSTABLE
BY MID AFTERNOON WITH MLCAPES AOA 2000 J/KG. WHILE DEEP LAYER SHEAR
WILL BE WEAKER SRN PORTION OF SLIGHT RISK...THE COMBINATION OF
GREATER INSTABILITY AND STEEPER LOW LEVEL LAPSE RATES WILL BE
SUFFICIENT FOR AT LEAST ISOLATED SEVERE THUNDERSTORMS ALONG AND
AHEAD OF ADVANCING COLD FRONT. 20-25KT OF LOW LEVEL SHEAR NOTED ON
MODEL SOUNDINGS FROM ERN TX INTO CENTRAL MS WED AFTERNOON/EVENING
SUGGEST ROTATING STORMS ARE POSSIBLE ENHANCING POTENTIAL FOR BOTH
LARGE HAIL AND DOWNBURST WINDS.
.HALES.. 11/20/2007
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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