SWODY1
SPC AC 310532
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1232 AM CDT FRI AUG 31 2007
VALID 311200Z - 011200Z
..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL/ERN
ORE...SERN/ERN WA...NWRN ID...
..SYNOPSIS...
IN MID/UPPER LEVELS...SYNOPTIC PATTERN WILL CONTINUE TO BE DOMINATED
BY TROUGHING FROM CANADIAN MARITIMES SWWD ACROSS CENTRAL GULF OF
MEXICO...STRONG RIDGING OVER 4-CORNERS REGION AND CENTRAL/NRN
PLAINS...AND PERSISTENT CYCLONIC VORTEX OVER ERN GULF OF AK.
SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY W OF ORE
AND NRN CA NEAR 136W -- IS FCST TO EJECT NEWD TODAY FROM MEAN TROUGH
POSITION. THIS PERTURBATION WILL CROSS MUCH OF ORE/WA DURING
31/18Z-01/06Z TIME FRAME...THEN DEAMPLIFY AS IT MOVES THROUGH
CANADIAN ROCKIES TOWARD MEAN RIDGE. AHEAD OF THAT TROUGH...LOW
LEVEL COLD FRONT IS FCST TO MOVE EWD ACROSS WA...ORE AND NWRN CA.
SRN PORTION OF FRONTAL ZONE SHOULD WEAKEN OVER INLAND PACIFIC NW AND
NRN GREAT BASIN DURING OVERNIGHT HOURS AS TROUGH EJECTS AWAY FROM
AREA.
OTHERWISE...LOOSELY ORGANIZED TROUGHING...WITH SEVERAL
EMBEDDED/ERRATICALLY DRIFTING CYCLONIC CENTERS ALOFT...WILL PREVAIL
ACROSS MOST OF GULF COAST REGION...AND WILL BE AT LEAST LOOSELY
PHASED WITH DIFFUSE SRN END OF SYNOPTIC TROUGHING ON ATLANTIC
SEABOARD. DIFFUSE SFC FRONTAL ZONE WILL EXTEND FROM VA AND CENTRAL
APPALACHIANS SWWD ACROSS MS/LA INTO CENTRAL/NRN TX. GEN TSTM
POTENTIAL -- OVER A LARGE AREA OF GULF/ATLANTIC COASTAL PLAINS --
WILL BE SUPPORTED BY COMBINATION OF SUBTLE ASCENT/DESTABILIZATION
ASSOCIATED WITH TROUGHING ALOFT...STG SFC HEATING...WEAKENING
CINH...MODEST FRONTAL FORCING...AND ASSORTED MESOSCALE BOUNDARIES
FROM PREVIOUS DAY.
..INLAND NWRN CONUS...
SCATTERED TSTMS ARE EXPECTED TO DEVELOP AGAIN TODAY -- PRIMARILY
AFTERNOON INTO EARLY EVENING -- AND MOVE NEWD ACROSS OUTLOOK AREA.
ACTIVITY MAY ORGANIZE INTO LINE SEGMENTS AND/OR BOWS WITH DAMAGING
WIND BEING MAIN THREAT. ISOLATED LARGE HAIL ALSO IS
POSSIBLE...PARTICULARLY FROM ANY DISCRETE TSTMS OVER NRN/WRN
PORTIONS OUTLOOK AREA WHERE SHEAR WILL BE SOMEWHAT MORE FAVORABLE
FOR STORM ROTATION. DAMAGING WIND POTENTIAL MAY EXTEND NEWD ACROSS
NRN ID INTO BITTERROOT AND ADJOINING HIGHER TERRAIN...BEFORE
DIMINISHING DURING MID-LATE EVENING.
LARGE SCALE ASCENT IS EXPECTED TO SPREAD NEWD ACROSS WA/ORE E OF
CASCADES...DURING AND JUST PRIOR TO FROPA. THIS WILL COMBINE WITH
DIURNAL SFC HEATING TO STEEPEN LOW-MIDLEVEL LAPSE RATES ACROSS
REGION...CREATING DEEP AND WELL-MIXED PRECONVECTIVE BOUNDARY LAYERS
SUITABLE FOR MAINTAINING STG-SVR DOWNDRAFTS. ALSO...TIGHTENING
HEIGHT GRADIENTS AHEAD OF TROUGH WILL CONTRIBUTE TO STRENGTHENING OF
DEEP-LAYER BULK SHEAR PROFILES DURING DAY. ALTHOUGH NEARLY
UNIDIRECTIONAL WINDS ARE PROGGED...EFFECTIVE SHEAR MAGNITUDES OF
35-45 KT MAY DEVELOP IN SUPPORT OF SVR POTENTIAL. EXPECT SFC DEW
POINTS 40S/50S F ACROSS MUCH OF THIS REGION...WITH
EVAPOTRANSPIRATIVE BOOST FROM WIDESPREAD PRECIP THAT FELL ON
THURSDAY...HELPING TO YIELD MLCAPES 500-1000 J/KG.
.EDWARDS/CROSBIE.. 08/31/2007
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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 chris@lib.siu.edu.
No comments:
Post a Comment