[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN OCT 23 2011

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 THROUGH
2300 UTC.

...SPECIAL FEATURES...

THE AREA OF LOW PRESSURE THAT HAS BEEN IMPACTING THE WRN
CARIBBEAN IS NOW TROPICAL DEPRESSION EIGHTEEN. T.D. EIGHTEEN IS
CENTERED NEAR 16.1N 82.0W. AT 24/0000 UTC..OR ABOUT 90 NM NE OF
CABO GRACIAS A DIO ON THE HONDURAS/NICARAGUA BORDER...MOVING NNW
AT 10 KT. MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. NUMEROUS
MODERATE/SCATTERED STRONG CONVECTION IS MAINLY N OF THE CENTER
FROM 16N-21N BETWEEN 78W-84W...WITH SCATTERED MODERATE
CONVECTION FROM 14N-19N BETWEEN 84W-86W. SEE LATEST NHC
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT3/WTNT33 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 13N17W
ALONG 12N28W 9N38W. SCATTERED MODERATE/STRONG CONVECTION IS
WITHIN 260 NM N OF THE AXIS...AS WELL AS FROM 5N-12N BETWEEN
38W-46W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH IS SINKING INTO THE GULF OF MEXICO THIS
EVENING FROM ALABAMA TO THE SRN TIP OF TEXAS. HOWEVER...DUE TO
AN EXTREMELY DRY AIRMASS SITTING ACROSS THE BASIN...FAIR WEATHER
PREVAILS AROUND A WEAK SURFACE RIDGE EXTENDING NE TO SW. PATCHES
OF STRATOCUMULUS CLOUDS ARE EVIDENT IN SATELLITE IMAGERY ACROSS
THE SRN HALF OF BASIN WITH ONLY A FEW ISOLATED SHOWERS IN THE
FAR SRN BAY OF CAMPECHE. SURFACE
RIDGING AND MOSTLY FAIR CONDITIONS ARE EXPECTED TO REMAIN ACROSS
THE BASIN FOR THE NEXT SEVERAL DAYS. THE CHANCE FOR SHOWER
ACTIVITY MAY INCREASE OVER THE SE GULF AS MOISTURE FROM T.D.
EIGHTEEN IN THE WRN CARIBBEAN DRIFTS NWD.

CARIBBEAN SEA...
T.D. EIGHTEEN IS THE MAIN INTEREST IN THE CARIBBEAN TONIGHT
PROVIDING MOIST CONDITIONS BETWEEN JAMAICA AND THE YUCATAN
PENINSULA. HEAVY RAINFALL IS POSSIBLE OVER NICARAGUA AND
HONDURAS AS THE SYSTEM MOVES NNW WITH THE POTENTIAL FOR FLOODING
AND MUDSLIDES. A WEAKENING STATIONARY FRONT THAT WAS N OF WHAT
IS NOW T.D. EIGHTEEN HAS DISSIPATED AS OF 2100 UTC. ALOFT...AN
UPPER LEVEL RIDGE IS CENTERED JUST S OF ERN CUBA NEAR 19N76W.
THE REMAINDER OF THE BASIN IS COVERED BY MODERATE DRY AIR
ALOFT...WHICH IS PROVIDING MOSTLY FAIR CONDITIONS E OF 75W. A
FEW ISOLATED SHOWERS ARE BEGINNING TO IMPACT THE LESSER ANTILLES
ASSOCIATED WITH A 1008 MB LOW E OF THE ISLANDS. EXPECT MOIST AND
WINDY CONDITIONS TO REMAIN OVER THE WRN CARIBBEAN IN ASSOCIATED
WITH T.D. EIGHTEEN. THE LOW E OF THE WINDWARD ISLANDS IS
EXPECTED TO MOVE WWD TOWARDS THE BASIN BRINGING A HIGHER CHANCE
OF SHOWERS TO THE ERN CARIBBEAN.

ATLANTIC OCEAN...
A BROAD LONGWAVE UPPER TROUGH IS MOVING ACROSS THE ERN CONUS AND
FAR WRN ATLC SUPPORTING A DISSIPATING STATIONARY FRONT ENTERING
THE DISCUSSION AREA NEAR 31N70W CONTINUING ALONG 27N77W 23N78W.
ISOLATED SHOWERS ARE WITHIN 175 NM W OF THE BOUNDARY. A WEAK
SURFACE TROUGH IS E OF THE FRONT ALONG 28N69W 23N74W CAUSING NO
ACTIVE WEATHER. A SHORTWAVE UPPER TROUGH EXTENDS OFF THE MAIN
TROUGH ALONG 61W SUPPORTING CLUSTERS OF SHOWERS/THUNDERSTORMS N
OF 26N BETWEEN 57W-61W. FARTHER S...A 1008 MB SURFACE LOW IS E
OF THE WINDWARD ISLANDS NEAR 12N56W. THE CIRCULATION IS BROAD
AND WEAK. ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE FROM
9N-16N BETWEEN 53W-61W. THE REMAINDER OF THE BASIN IS DOMINATED
BY SURFACE RIDGING AROUND A 1024 MB HIGH NEAR 34N44W PROVIDING
MOSTLY FAIR WEATHER ACROSS THIS PORTION OF THE BASIN. THE
SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED NEAR
28N43W. A NARROW UPPER LEVEL TROUGH EXTENDS JUST ALONG THE NW
AFRICAN COAST AND WRAPS AROUND THE SE SIDE OF THE UPPER RIDGE.
THIS IS PROVIDING THE DIFFLUENCE ALOFT TO ENHANCE SOME OF THE
ACTIVITY N OF THE MONSOON TROUGH. THE UPPER TROUGH ALSO SUPPORTS
A SURFACE TROUGH ALONG 16N39W TO 12N47W N OF THE CONVECTIVE
ACTIVITY N OF THE MONSOON TROUGH.

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

$$
WALTON




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