SWODY2
SPC AC 071658
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1058 AM CST SAT MAR 07 2009
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE OZARK PLATEAU INTO
PARTS OF THE OH VALLEY...
...SYNOPSIS...
PROGRESSIVE...SPLIT FLOW PATTERN WILL EXIST OVER THE CONUS DURING
THE DAY TWO PERIOD. THIS REGIME IS CHARACTERIZED BY AN INTENSIFYING
LARGE-SCALE TROUGH OVER THE WRN STATES AND THE RESULTANT NEWD
TRANSLATION OF A COMPACT SHORTWAVE FROM THE CNTRL PLAINS INTO THE
LOWER GREAT LAKES. THIS LATTER FEATURE WILL BE THE PRIMARY FOCUS
FOR STRONG TO SEVERE TSTM DEVELOPMENT SUNDAY INTO SUNDAY NIGHT.
IN THE LOW LEVELS...SURFACE CYCLONE OVER NERN MO WILL DEEPEN
SLIGHTLY WHILE DEVELOPING ENEWD INTO NRN IND BY SUNDAY
AFTERNOON...BEFORE EVENTUALLY OCCLUDING OVER THE LOWER GREAT LAKES
SUNDAY NIGHT. AN ASSOCIATED WARM FRONT WILL CONCURRENTLY LIFT NWD
THROUGH THE OH VALLEY AND LOWER GREAT LAKES IN ADVANCE OF THIS LOW.
MEANWHILE TRAILING COLD FRONT WILL PUSH EWD/SEWD THROUGH THE OH AND
TN VALLEYS. SWRN EXTENSION OF THE COLD FRONT WILL SAG SEWD INTO THE
ARKLATEX BEFORE LIFTING NWD/NWWD AS A WARM FRONT DURING THE LATTER
HALF OF THE FORECAST PERIOD.
...OZARK PLATEAU INTO OH VALLEY...
CLUSTERS OF STRONG TO SEVERE TSTMS ARE EXPECTED TO BE ONGOING WITHIN
ZONE OF DEEP ASCENT IN ADVANCE OF SHORT WAVE TROUGH FROM VICINITY OF
SURFACE LOW OVER NERN MO SWWD ALONG COLD FRONT INTO SWRN MO AND
PERHAPS NWRN AR. EWD MIGRATION OF 40-50 KT SWLY LLJ ACROSS THE OH
VALLEY WILL MAINTAIN A MOIST BOUNDARY LAYER WITHIN SYSTEM WARM
SECTOR WITH DEWPOINTS REMAINING LARGELY IN THE 50S TO PERHAPS LOWER
60S. CONSIDERABLE CLOUDINESS WILL LIMIT DAYTIME HEATING AND OVERALL
DESTABILIZATION...THOUGH THE MODEST MOISTURE CONTENT AND SOME CLOUD
BREAKS WILL SUPPORT MLCAPE APPROACHING 500-700 J/KG.
THE INITIAL PRESENCE OF STRONG VERTICAL SHEAR /BOTH THROUGH A DEEP
LAYER AND IN THE LOW LEVELS/ SUGGESTS THE POTENTIAL FOR EMBEDDED
SUPERCELL STRUCTURES SUNDAY MORNING ACROSS PARTS OF MO INTO NRN AR.
THE PRIMARY SEVERE WEATHER THREAT IS THEN EXPECTED TO DEVELOP EWD
INTO PARTS OF IL/IND BY AFTERNOON ALONG AND S OF SURFACE LOW TRACK.
HERE...SIMULATED GOES WATER VAPOR DATA SUGGEST THAT MIDLEVEL DRY
SLOT ATTENDANT TO SHORT WAVE TROUGH WILL OVERSPREAD SURFACE TRIPLE
POINT...POTENTIALLY CONTRIBUTING TO AIR MASS DESTABILIZATION WITHIN
A ZONE OF ENHANCED LOW-LEVEL SHEAR.
THUS...EXPECT THE THREAT FOR EMBEDDED SUPERCELL AND/OR BOWING
STRUCTURES TO CONTINUE THROUGH THE DAY WITH THE POTENTIAL FOR A FEW
TORNADOES IN ADDITION TO DAMAGING WINDS AND SOME HAIL. THE
POTENTIAL FOR ORGANIZED SEVERE WEATHER WILL EXTEND SWD ALONG COLD
FRONT INTO WRN PARTS OF KY/TN...ALONG SRN FRINGE OF STRONGER HEIGHT
FALLS ATTENDANT TO SHORT WAVE TROUGH. WHILE ISOLATED SEVERE STORMS
WILL REMAIN POSSIBLE EWD INTO THE UPPER OH AND TN VALLEYS SUNDAY
NIGHT...DECREASING INSTABILITY WITH TIME SHOULD TEND TO LIMIT A MORE
SUBSTANTIAL NOCTURNAL SEVERE THREAT.
...ARKLATEX...
LARGE-SCALE ASCENT AND CONVERGENCE ALONG SURFACE FRONT ARE FORECAST
TO WEAKEN SUNDAY WITH THE NEWD PROGRESSION OF UPPER SYSTEM AWAY FROM
THE REGION. NONETHELESS...POTENTIALLY STRONGER DIABATIC HEATING
/COMPARED TO AREAS TO THE NE/ MAY BE SUFFICIENT TO INITIATE ISOLATED
STORMS ALONG FRONT SUNDAY AFTERNOON INTO EVENING. GENERALLY WEAK
MIDLEVEL LAPSE RATES WILL TEND TO LIMIT INSTABILITY DESPITE LOWER TO
MID 60S BOUNDARY LAYER DEWPOINTS. THIS MARGINAL INSTABILITY MAY BE
OFFSET BY MODESTLY STRONG /45-60 KT/ MIDLEVEL FLOW WHICH COULD
ENHANCE ANY MORE SUSTAINED UPDRAFTS WITH SOME HAIL AND/OR LOCALLY
STRONG WIND GUSTS POSSIBLE.
..MEAD.. 03/07/2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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