SWODY2
SPC AC 301717
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1217 PM CDT SAT AUG 30 2008
VALID 311200Z - 011200Z
...THERE IS A SLGT RISK OF SVR TSTMS LATE SUNDAY NIGHT INTO MONDAY
MORNING ALONG THE SERN LA COAST...
...SYNOPSIS...
LARGE-SCALE PATTERN WILL CONTINUE TO AMPLIFY THROUGH THE DAY TWO
PERIOD AS WRN U.S. TROUGH INTENSIFIES AND EFFECTIVELY BUILDS
DOWNSTREAM RIDGE OVER THE GREAT LAKES INTO ERN CANADA.
ELSEWHERE...HURRICANE GUSTAV WILL MOVE TOWARD THE SHELF WATERS OFF
THE SERN LA COAST.
...THE FL KEYS INTO THE SERN LA COAST...
LATEST GFS AND NHC GUIDANCE TAKES THE CENTER OF HURRICANE GUSTAV
FROM APPROXIMATELY 230 W EYW AT 31/12Z TO NEAR 100 S BVE BY 01/12Z.
OUTER CONVECTIVE BANDS ALONG THE ERN SEMICIRCLE OF SYSTEM WILL
LIKELY BE IMPACTING THE LOWER KEYS AT THE ONSET OF THE PERIOD WITH
AT LEAST A MARGINAL THREAT FOR EMBEDDED SUPERCELLS AND BRIEF
TORNADOES. THEREAFTER...THE SUPERCELL/TORNADO THREAT WILL LIKELY
REMAIN OFFSHORE UNTIL MONDAY MORNING WHEN BOTH VERTICAL SHEAR AND
CONVECTIVE INSTABILITY WILL INCREASE ACROSS THE SERN LA COAST.
AS MENTIONED ABOVE...A SMALL TORNADO RISK /GENERALLY LESS THAN 5
PERCENT PROBABILITY/ WILL EXIST FROM THE FL KEYS ALONG THE IMMEDIATE
WRN FL PENINSULAR COAST WITH THE GREATEST THREAT LATE OVER SERN LA.
THEREFORE...THE 5 PERCENT PROBABILITY LINE AND A CATEGORICAL SLIGHT
RISK WILL BE INCLUDED IN THIS AREA.
...NRN PLAINS...
SURFACE LOW INITIALLY OVER FAR SERN MT WILL SLOWLY DRIFT EWD INTO
NWRN SD THROUGH THE PERIOD WITH ATTENDANT COLD FRONT SAGGING SEWD
THROUGH ERN MT...NRN WY AND THE WRN DAKOTAS. STRONG HEATING AND THE
DEVELOPMENT OF STEEP LOW-LEVEL LAPSE RATES ARE EXPECTED TO OCCUR
ALONG AND AHEAD OF FRONT SUNDAY. HOWEVER...A WARM EML IN
CONJUNCTION WITH ONLY MODEST BOUNDARY LAYER MOISTURE /I.E. DEWPOINTS
IN THE 50S/ MAY CAP MODERATELY UNSTABLE ENVIRONMENT /MLCAPES OF
1000-1500 J PER KG/ THROUGH MUCH OF THE AFTERNOON. TSTMS ARE
EXPECTED TO DEVELOP BY LATE AFTERNOON OR EVENING ALONG OR PERHAPS IN
IMMEDIATE POST-FRONTAL AIR MASS AS SUSTAINED MESOSCALE ASCENT ALONG
THE FRONT OVERCOMES CAP.
LATEST MODEL GUIDANCE SUGGESTS THAT THE STRONGEST VERTICAL SHEAR
WILL RESIDE TO THE N/NW OF FRONTAL ZONE WHICH MAY TEND TO LIMIT A
MORE SUBSTANTIAL SEVERE THREAT IN THE WARM SECTOR. NONETHELESS...A
FEW ORGANIZED STORMS WILL BE POSSIBLE WITH THE THREAT FOR DAMAGING
WINDS AND LARGE HAIL.
...ERN GREAT BASIN/LOWER CO VALLEY INTO THE CNTRL ROCKIES...
PACIFIC COLD FRONT WILL PUSH EWD/SEWD THROUGH THE GREAT BASIN IN
ASSOCIATION WITH INTENSIFYING MIDLEVEL TROUGH. PW VALUES OF 0.7-1.0
INCH COMBINED WITH STEEP LAPSE RATES WILL CONTRIBUTE TO POCKETS OF
STRONGER INSTABILITY AHEAD OF THE FRONT WITH MLCAPES APPROACHING
500-1000 J/KG. VERTICAL SHEAR WILL STRENGTHEN MOST SUBSTANTIALLY
ACROSS NRN/CNTRL UT INTO SERN ID/WRN WY...COINCIDENT WITH 40-50 KT
MIDLEVEL JET STREAK EMERGING FROM THE BASE OF EVOLVING TROUGH. AS
SUCH...THE POTENTIAL WILL EXIST FOR A FEW SEVERE STORMS DURING THE
AFTERNOON AND EVENING HOURS WITH THE THREAT FOR DAMAGING WINDS AND
HAIL. CURRENTLY...IT APPEARS THAT THE MARGINAL INSTABILITY MAY TEND
TO LIMIT A MORE SUBSTANTIAL SEVERE THREAT.
..MEAD.. 08/30/2008
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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