SWODY2
SPC AC 210626
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 AM CST MON NOV 21 2011
VALID 221200Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL/WRN GULF COAST
TO SRN APPALACHIANS AND OH VALLEY...
...SYNOPSIS...
HIGH-AMPLITUDE SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL
IMAGERY FROM NRN CA SWD ACROSS SRN CA OFFSHORE WATERS -- IS FCST TO
MOVE EWD ACROSS SWRN CONUS AND SRN/CENTRAL HIGH PLAINS DAY-1. BY
22/12Z...TROUGH SHOULD ASSUME POSITIVE TILT FROM ERN KS TO W-CENTRAL
TX...IN STG AGREEMENT WITH PAST FEW RUNS OF OPERATIONAL PROGS AND
SREF CONSENSUS THAT...IN TURN...HAVE AGREED WELL WITH EACH OTHER.
MODELS DIVERGE WITH SHAPE/AMPLITUDE OF THIS SYSTEM EARLY DAY-2...BUT
REMAIN IN GEN AGREEMENT WITH TROUGH POSITION FROM LM/LOWER MI AREA
TO N-CENTRAL TX BY 23/00Z. BY END OF PERIOD...TROUGH SHOULD EXTEND
FROM LOWER GREAT LAKES SWWD ACROSS MS...ITS NRN PERIPHERY PHASING
WITH NRN-STREAM TROUGH NOW LOCATED OFFSHORE PAC NW COAST.
AT SFC...STG COLD FRONT WAS ANALYZED AT 21/05Z FROM LOWER OH VALLEY
SWWD ACROSS CENTRAL AR...CENTRAL TX BETWEEN ACT-CLL...BECOMING
QUASISTATIONARY ACROSS SRN HILL COUNTRY AND SERN EDWARDS PLATEAU
REGION TO NEAR DRT. FRONTAL-WAVE CYCLONE SHOULD DEVELOP ALONG THIS
BOUNDARY OVER N TX DURING DAY-1...DEEPENING AND MOVING NEWD ACROSS
SERN MO BY 22/12Z. LOW WILL CONTINUE TO STRENGTHEN THROUGH MOST OF
PERIOD...REACHING INTERIOR MID-ATLANTIC/NRN APPALACHIANS REGION BY
END OF PERIOD. BY 23/00Z...COLD FRONT SHOULD EXTEND FROM INDIANA/OH
LOW SWWD NEAR MEM-CRP LINE. BY 23/12Z...FRONT SHOULD EXTEND FROM
CENTRAL/ERN PA SWWD DOWN APPALACHIANS...ACROSS NRN GA...TO SWRN AL
AND NWRN GULF.
...CENTRAL/WRN GULF COAST TO SRN APPALACHIANS AND OH VALLEY...
BAND OF TSTMS SHOULD BE ONGOING AT START OF PERIOD INVOF SFC COLD
FRONT...BACKBUILDING THROUGH MORNING TOWARD TX GULF COASTAL PLAIN.
ALTHOUGH FCST SOUNDINGS SUGGEST SFC-BASED EFFECTIVE-INFLOW
PARCELS...RELATIVE MORNING MIN IN BOUNDARY-LAYER INSTABILITY
SUGGESTS AT LEAST MRGL POTENTIAL FOR DAMAGING WIND...CONCENTRATED
LOCALLY WITH EMBEDDED BOW/LEWP FORMATIONS.
SVR POTENTIAL IS EXPECTED TO INCREASE FROM MIDDAY THROUGH AT LEAST
LATE AFTERNOON...SHIFT EWD ACROSS DELTA/TN VALLEY REGION...AND
EXPAND NWD TO OH VALLEY REGION. PRIMARY SVR TYPE WILL BE DAMAGING
WIND...THOUGH TORNADOES AND ISOLATED HAIL ALSO ARE POSSIBLE. BAND
OF CONVECTIVE FORCING IS FCST TO ENCOUNTER PROGRESSIVELY MORE MOIST
AND UNSTABLE WARM SECTOR THROUGH DAYLIGHT HOURS. SFC DEW POINTS
RANGING FROM UPPER 60S TO NEAR 70 NEAR I-10 IN MS/LA/AL...TO MID 60S
TN VALLEY...SHOULD OFFSET WEAK MID-UPPER LEVEL LAPSE RATES ENOUGH TO
SUPPORT MLCAPE 500-1500 J/KG. SOME WLY SFC WIND COMPONENT IS
PROGGED OVER THAT CORRIDOR...ALONG WITH 2-4 KM AGL LAYER CONTAINING
SOME BACKING WITH HEIGHT. STILL...LOW-LEVEL HODOGRAPHS SHOULD BE
LARGE ENOUGH TO SUPPORT EFFECTIVE SRH 150-300 J/KG AND POTENTIAL FOR
EMBEDDED SUPERCELLS/BOWS...AS WELL AS CONDITIONAL RISK FOR
SUPERCELLS FOR ANY SUSTAINED DEVELOPMENT THAT CAN OCCUR AHEAD OF
MAIN TSTM LINE.
CAPE IS EXPECTED TO DIMINISH WITH NWD EXTENT OVER KY AND OH VALLEY
PORTIONS OF OUTLOOK...WITH MORE LIMITED TIME WINDOW OF OPPORTUNITY
FOR THETAE ADVECTION AND DIURNAL HEATING TO DESTABILIZE BOUNDARY
LAYER BEFORE FROPA. BUOYANCY ALSO WILL DIMINISH WITH TIME AND EWD
EXTENT AFTER DARK...ACROSS CENTRAL/SRN APPALACHIANS INTO ERN AL/WRN
GA. THEREFORE SVR POTENTIAL IN EACH REGIME BECOMES MORE
CONDITIONAL...THOUGH STG FRONTAL FORCING CAN YIELD POTENTIAL FOR SVR
EVEN IN PRESENCE OF NEAR-NEUTRAL MIDLEVEL LAPSE RATES AND MLCAPE
BELOW 500 J/KG. WITH RESPECT TO CINH...LOW-LEVEL FORCING SHOULD
LESSEN WITH SWD EXTENT...MAKING SVR POTENTIAL LOWER ALONG IMMEDIATE
COAST RELATIVE TO FARTHER N AND NE.
..EDWARDS.. 11/21/2011
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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