[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 020003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON OCT 01 2012

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
VALID THROUGH 2315 UTC.

...SPECIAL FEATURE...

THE CENTER OF TROPICAL STORM NADINE AT 02/0000 UTC IS NEAR 34.8N
39.1W. NADINE IS MOVING SSE AT 8 KNOTS. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 995 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 55 KNOTS WITH GUSTS TO 65 KNOTS. PLEASE READ THE
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/ WTNT24
KNHC...AND THE PUBLIC ADVISORY... MIATCPAT4/WTNT34 KNHC ...FOR
MORE DETAILS. SCATTERED MODERATE CONVECTION IS FROM 35N-37N
BETWEEN 39W-41W...AND FROM 36N-38N BETWEEN 36W-39W.

TROPICAL WAVE EXTENDS FROM 17N32W TO 10N34W THROUGH A 1008 MB
SURFACE LOW NEAR 12N33W. THE WAVE/LOW ARE MOVING WEST NEAR 15
KT. THE SYSTEM COINCIDES WITH A SURFACE OF DEEP LAYER MOISTURE
PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. ENVIRONMENTAL
CONDITIONS ARE CONDUCIVE FOR GRADUAL DEVELOPMENT OF THIS SYSTEM
OVER THE NEXT COUPLE OF DAYS. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 13N-18N BETWEEN 27W-33W...AND FROM 8N-13N
BETWEEN 34W-39W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 16N46W TO 7N49W MOVING WEST AT 10-15 KT.
THE WAVE CONTINUES TO LIE ON THE WESTERN EDGE OF A SURGE OF DEEP
LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. THE
WAVE IS ALSO APPROACHING AN UPPER LEVEL TROUGH...WHICH MAY BE
CONTRIBUTING TO THE ACTIVITY NEAR THE WAVE AXIS. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 8N-17N BETWEEN
45W-51W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA TO THE COAST OF GUINEA
AT 10N14W CONTINUING OVER ATLANTIC WATERS ALONG 14N23W 10N34W
9N43W 7N50W. BESIDES CONVECTION NEAR THE TROPICAL
WAVES...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
6N-9N BETWEEN 26W-29W. SIMILAR ACTIVITY IS FROM 8N-11N BETWEEN
39W-45W.

...DISCUSSION...

THE GULF OF MEXICO...
AS OF 2100 UTC...A COLD FRONT EXTENDS THROUGH ALABAMA AND THE
FLORIDA PANHANDLE INTO THE CENTRAL GULF OF MEXICO ALONG 31N86W
26N86W 22N90W INTO THE YUCATAN PENINSULA ALONG 18N92W 17N95W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60 NM EITHER
SIDE OF THE AXIS. SCATTERED SHOWERS/THUNDERSTORMS CONTINUE
FARTHER EAST ACROSS MUCH OF THE YUCATAN PENINSULA AND ARE ALSO
ACROSS MUCH OF SOUTH FLORIDA WITH ISOLATED ACTIVITY ACROSS THE
REMAINDER OF THE FLORIDA PENINSULA. SOME OF THE ACTIVITY OVER
FLORIDA IS DUE TO MOIST SOUTHERLY FLOW ALOFT STREAMING OVER THE
AREA AROUND AN UPPER LEVEL LOW IN THE NW CARIBBEAN. A LONGWAVE
UPPER TROUGH IS MOVING OVER THE GULF WITH AXIS CURRENTLY
EXTENDING THROUGH TEXAS AND MUCH OF THE CENTRAL CONUS. THE UPPER
TROUGH IS BRINGING DRY AIR AND SUBSIDENCE ACROSS MUCH OF THE
WESTERN GULF WEST OF THE FRONT. WINDS OF 15-20 KTS ARE OBSERVED
BOTH AHEAD AND BEHIND THE FRONT. THE FRONT IS EXPECTED TO
CONTINUE EASTWARD FOR THE NEXT 24 HOURS BEFORE BECOMING
STATIONARY AND THEN RETREATING NW LATE IN THE WEEK. MOIST
CONDITIONS WILL REMAIN OVER MUCH OF THE EASTERN GULF THROUGHOUT
THE WEEK.

THE CARIBBEAN SEA...
AN UPPER LEVEL LOW IN THE NW CARIBBEAN CENTERED NEAR 17N87W IS
PRODUCING A LARGE AREA OF SHOWERS/THUNDERSTORMS ACROSS THE
WESTERN CARIBBEAN. NUMEROUS SHOWERS/SCATTERED THUNDERSTORMS ARE
FROM 14N-21N BETWEEN 77W-84W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE ALSO ACROSS WESTERN CUBA...NICARAGUA...AND
HONDURAS. A SURFACE TROUGH WAS PREVIOUSLY ANALYZED IN THIS
AREA...REMNANTS OF A TROPICAL WAVE THAT HAD BECOME STATIONARY.
AN ASCAT SCATTEROMETER PASS FROM EARLIER TODAY INDICATES THAT
THE SURFACE TROUGH HAS DISSIPATED AND WEAK SURFACE RIDGING IS
NOW PRESENT. THE REMAINDER OF THE CARIBBEAN IS UNDER MOSTLY FAIR
CONDITIONS DUE TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE
EXTENDING FROM THE WESTERN ATLC. A FEW ISOLATED
SHOWERS/THUNDERSTORMS ARE NOTED ACROSS HISPANIOLA AND THE
NORTHERN LEEWARD ISLANDS DUE TO A SMALL AREA OF ENHANCED
MOISTURE MOVING INTO THE AREA FROM THE EAST. EXPECT LITTLE
CHANGE OVER THE NEXT 24 HOURS WITH CONTINUING
SHOWER/THUNDERSTORM ACTIVITY ACROSS THE WESTERN CARIBBEAN.

THE ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE COVERS THE WEST ATLC SUPPORTING BROAD
SURFACE RIDGING ACROSS THE CENTRAL AND WEST ATLC AROUND A 1022
MB HIGH NEAR 35N50W. MOISTURE IS BEING WRAPPED AROUND THE
WESTERN SIDE OF THE UPPER RIDGE FROM THE NW CARIBBEAN PRODUCING
SCATTERED SHOWERS/THUNDERSTORMS FROM THE EAST COAST OF FLORIDA
TO 76W. THE REMAINDER OF THE WEST AND CENTRAL ATLC ARE
EXPERIENCING MOSTLY FAIR CONDITIONS. AN UPPER LEVEL LOW IS
SPINNING NEAR 27N49W HELPING ENHANCE CONVECTION NEAR A TROPICAL
WAVE TO THE SOUTH. IT IS ALSO PRODUCING A FEW ISOLATED SHOWERS
FROM 24N-28N BETWEEN 43W-51W. UPPER LEVEL RIDGING COVERS THE
REMAINDER OF THE BASIN SUPPORTING BROAD SURFACE RIDGING AND
PROVIDING FAIR CONDITIONS ACROSS THE EASTERN ATLC.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON





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