SWODY3
SPC AC 110618
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0118 AM CDT SUN SEP 11 2011
VALID 131200Z - 141200Z
...SYNOPSIS...
UPPER-AIR PATTERN ACROSS MUCH OF CONUS WILL BE DOMINATED BY TWO
REGIMES...
1. BROADLY CYCLONIC FLOW OVER UPPER MIDWEST...GREAT LAKES...NY AND
NEW ENGLAND...WITH SERIES OF EMBEDDED SHORTWAVES...RELATED TO GYRE
OVER HUDSON BAY REGION. LEADING SHORTWAVE TROUGH WILL WEAKEN AND
EJECT NEWD OVER NERN ONT/NWRN QUE...AS HEIGHTS FALL AHEAD OF NEXT
SIGNIFICANT SHORTWAVE DIGGING SEWD ACROSS NERN MB/NWRN ONT.
2. SLOWLY WEAKENING/CUT-OFF LOW OVER COASTAL SRN CA. FEATURE MAY
BEGIN TO MOVE EWD TO NEWD AND INLAND TOWARD SRN NV THIS PERIOD.
SFC COLD FRONT...ASSOCIATED WITH LEADING NRN-STREAM SHORTWAVE...WILL
MOVE SEWD ACROSS UPPER GREAT LAKES AND CENTRAL PLAINS THROUGH
AFTERNOON...TO NEAR BUF-CLE-STL-TUL-AMA LINE BY 14/00Z.
FRONTAL-WAVE LOW MAY DEVELOP BY THEN OVER MAIN BODY OF OK...RELATED
TO WEAK SRN-STREAM PERTURBATION MOVING NEWD FROM SRN ROCKIES. BY
END OF PERIOD...FRONT SHOULD EXTEND FROM COASTAL MID-ATLANTIC REGION
ACROSS TN VALLEY TO RED RIVER REGION OF SRN OK/N TX...BECOMING
QUASISTATIONARY W OF MS RIVER.
...LOWER GREAT LAKES TO OH VALLEY AND AR...
STRONGEST DEEP-LAYER FORCING AND LOW-LEVEL SHEAR WILL REMAIN N OF
REGION...ACROSS SERN ONT AND SWRN QUE. HOWEVER...TSTMS SHOULD
BACKBUILD SWWD ALONG FRONT AND/OR DEVELOP DISCRETELY DURING MID-LATE
AFTERNOON...MOVING EWD ACROSS LOWER GREAT LAKES REGION WITH AT LEAST
ISOLATED POTENTIAL FOR SVR HAIL AND DAMAGING GUSTS. DEEP-LAYER
SHEAR IS FCST TO INCREASE WITH NEWD EXTENT...WHILE FRONT IMPINGES ON
DIABATICALLY HEATED BOUNDARY-LAYER AIR MASS CHARACTERIZED BY SFC DEW
POINTS GENERALLY 60S F. MIDLEVEL FLOW SHOULD WEAKEN WITH SWWD
EXTENT OVER OH VALLEY...WITH SOMEWHAT MORE SLY SFC COMPONENT AND
STRONGER DEEP-LAYER SHEAR POSSIBLE OVER UPSTATE NY WHERE BUOYANCY IS
PROGGED TO BE RELATIVELY WEAK. THOUGH UNCERTAINTIES ARE TOO LARGE
NOW FOR UNCONDITIONAL 15% LINE...SOME PORTIONS OF THIS AREA MAY
REQUIRE CATEGORICAL OUTLOOK UPGRADE.
MORE ISOLATED/BRIEF THREAT MAY DEVELOP FARTHER SW INVOF SFC COLD
FRONT FROM LOWER OH VALLEY REGION INTO AR AND ERN OK. STG VEERING
OF FLOW WITH HEIGHT IS FCST...CONTRIBUTING TO MRGL DEEP-LAYER SHEAR
DESPITE LACK OF MORE ROBUST LOW-LEVEL WINDS. ATTM TSTM COVERAGE AND
SVR RISK APPEAR TOO ISOLATED/CONDITIONAL FOR SVR PROBABILITIES.
..EDWARDS.. 09/11/2011
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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