SWODY1
SPC AC 311629
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT SUN AUG 31 2008
VALID 311630Z - 011200Z
...THERE IS A SLGT RISK OF SVR TSTMS TONIGHT ACROSS THE N CENTRAL
GULF COAST...
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR THE
NW UT AREA...
...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON INTO EARLY
TONIGHT FOR N/NW ND...
...N CENTRAL GULF COAST TONIGHT...
HURRICANE GUSTAV IS MOVING NWWD AT ROUGHLY 15 KT ACROSS THE ERN GULF
OF MEXICO AND IS EXPECTED TO MAKE LANDFALL ON THE LA COAST MONDAY
/SEE LATEST NHC ADVISORIES FOR DETAILS/. THE OUTER NRN/NERN
CONVECTIVE BANDS WILL SPREAD INLAND OVER THE N CENTRAL GULF COAST
LATER TODAY INTO TONIGHT...AND THE PRIMARY INCREASE IN LOW-LEVEL
SHEAR AND THE CLOSEST APPROACH OF GUSTAV TO THE COAST WILL OCCUR THE
LAST HALF OF THE FORECAST PERIOD. EXPECT THE THREAT FOR SUPERCELLS
AND A COUPLE OF TORNADOES TO INCREASE GRADUALLY LATER THIS EVENING
THROUGH MONDAY MORNING...THOUGH THE DIURNAL MINIMUM IN INSTABILITY
OVER LAND COULD BE A LIMITING FACTOR OVERNIGHT.
...NW UT AREA THIS AFTERNOON/EVENING...
A MID LEVEL SHORTWAVE TROUGH OVER NRN CA THIS MORNING WILL EJECT
EWD/ENEWD TOWARD NW UT/SE ID BY EARLY TONIGHT...WHILE THE LARGER
SCALE MID LEVEL TROUGH PROGRESSES INLAND OVER THE INTERIOR NW. THE
MID LEVEL TROUGH WILL BE ACCOMPANIED BY A STRONG EARLY SEASON COLD
FRONT. THUNDERSTORM DEVELOPMENT IS EXPECTED THIS AFTERNOON/EVENING
ALONG THE FRONT AS IT ENCOUNTERS THE WRN FRINGE OF THE MONSOONAL
MOISTURE PLUME THAT EXTENDS NWD FROM AZ INTO UT. STEEP LAPSE
RATES...SUFFICIENT LOW-MID LEVEL MOISTURE...AND INCREASING DEEP
LAYER VERTICAL SHEAR SHOULD SUPPORT A BAND OF THUNDERSTORMS WITH
EMBEDDED BOW/SUPERCELL STRUCTURES...CAPABLE OF PRODUCING DAMAGING
WINDS AND LARGE HAIL BEFORE INSTABILITY WEAKENS OVERNIGHT.
...NRN HIGH PLAINS THROUGH TONIGHT...
REGIONAL 12Z SOUNDINGS SHOW A WARM ELEVATED MIXED LAYER ATOP A
SHALLOW MOIST BOUNDARY LAYER WITH DEWPOINTS IN THE LOW-MID 60S IN
THE WARM SECTOR ACROSS SD/ND. WITH SURFACE TEMPERATURES OF 95-100 F
NEEDED TO MINIMIZE CONVECTIVE INHIBITION...IT APPEARS THAT
THUNDERSTORM DEVELOPMENT WILL REQUIRE SUSTAINED MESOSCALE ASCENT
ALONG EITHER THE LEE TROUGH ACROSS WRN NEB/SD...OR THE SLOW-MOVING
FRONT ACROSS NW ND TO THE NE OF THE SE LOW IN SW ND. VERTICAL SHEAR
WILL BE STRONGER ALONG THE FRONT IN ND COMPARED TO THE LEE TROUGH
FARTHER TO THE S...THUS THE THREAT FOR MORE ORGANIZED/SUPERCELL
STORMS WILL BE GREATER ALONG THE FRONT IN ND. THE COMBINATION OF
STEEP LAPSE RATES...MODEST CAPE...AND EFFECTIVE BULK SHEAR IN EXCESS
OF 40 KT WILL SUPPORT A THREAT FOR LARGE HAIL AND ISOLATED DAMAGING
GUSTS WITH THE STRONGEST STORMS LATE THIS AFTERNOON INTO EARLY
TONIGHT.
...SRN AND WRN FL TODAY...
THE OUTER ERN BANDS OF GUSTAV ARE IMPACTING THE SRN AND WRN PORTIONS
OF THE FL PENINSULA. HOWEVER...WITH CONTINUED NW MOTION OF THE
STORM...WIND PROFILES WILL GRADUALLY WEAKEN ACROSS FL FROM SE TO
NW...AND THE GREATER THREAT FOR SUPERCELLS SHOULD REMAIN OFFSHORE
ACROSS THE ERN GULF OF MEXICO.
..THOMPSON/GRAMS.. 08/31/2008
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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