[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180529
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SUN NOV 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...ITCZ/MONSOON TROUGH...

MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC
NEAR 10N14W TO 6N20W WHERE THE ITCZ AXIS CONTINUES ALONG 5N26W
TO 7N35W THEN RESUMES NEAR 10N44W ALONG 8N51W TO SOUTH AMERICA
NEAR 8N59W. A SURFACE TROUGH IS ALONG THE E SIDE OF AN UPPER
TROUGH FROM 20N33W ALONG 17N38W TO 12N41W WITH SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 240 NM EITHER SIDE OF THE TROUGH
AXIS. SCATTERED MODERATE/STRONG CONVECTION IS INLAND AND WITHIN
60 NM ALONG THE COAST OF LIBERIA AND SIERRA LEONE BETWEEN
9W-12W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM
8N-10N BETWEEN 27W-31W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH EXTENDS FROM THE GREAT LAKES OVER THE E CONUS
INTO THE E GULF OF MEXICO E OF 93W CONTINUING S INTO THE NW
CARIBBEAN. A BROAD UPPER RIDGE ANCHORED OVER THE E PACIFIC
REGION COVERS THE REMAINDER OF THE W GULF. A SURFACE RIDGE
DOMINATES THE GULF EXTENDING FROM THE NEW ENGLAND. A SURFACE
TROUGH REMAINS ALONG THE COAST OF MEXICO FROM 23N97W ALONG
21N96W TO 19N94W AND IS GENERATING SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS WITHIN 120 NM ALONG THE COAST S
OF 25N W OF 93W. A SECOND SURFACE TROUGH IS IN THE SE GULF
EXTENDING FROM THE STRAITS OF FLORIDA NEAR 24N81W TO 22N87W WITH
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 60
NM EITHER SIDE OF THE TROUGH AXIS. THE REMAINDER OF THE GULF IS
UNDER FAIR WEATHER AGAIN TONIGHT. SURFACE RIDGE WILL WEAKEN MON
AND TUE. A TIGHT PRESSURE GRADIENT BETWEEN THE RIDGE AND BROAD
TROUGHING OVER THE W ATLC WILL MAINTAIN FRESH NE WINDS OVER THE
NE GULF THROUGH MUCH OF TODAY. THE PRESSURE GRADIENT WILL
INCREASE IN THE E GULF AGAIN WED INTO THU AS A HIGH DEVELOPS
OVER THE LOWER MISSISSIPPI VALLEY.

CARIBBEAN SEA...
A WEAK PRESSURE PATTERN REMAINS ACROSS THE CARIBBEAN TONIGHT.
THE BROAD UPPER TROUGH OVER THE E GULF OF MEXICO EXTENDS OVER
THE NW CARIBBEAN TO CENTRAL AMERICA W OF 77W WHILE AN UPPER
RIDGE DOMINATES THE REMAINDER OF THE CARIBBEAN. THE UPPER RIDGE
EXTENDS FROM AN UPPER HIGH OVER VENEZUELA WITH THE AXIS
EXTENDING OVER THE LESSER ANTILLES CONTINUING OVER THE CENTRAL
ATLC. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N74W INTO
THE SW CARIBBEAN ALONG 11N78W ACROSS COSTA RICA INTO THE E
PACIFIC REGION. CLUSTERS OF SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE S OF 14N BETWEEN 71W-78W AND S OF 12N W OF
80W. THE UPPER RIDGE IS PROVIDING DIFFLUENCE ALOFT TO GENERATE
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ACROSS THE
CENTRAL CARIBBEAN WITHIN 150 NM OF LINE FROM 14N75W ACROSS
HISPANIOLA TO NEAR 20N71W. THIS IS LEAVING THE NW AND E
CARIBBEAN WITH FAIR WEATHER AGAIN TONIGHT. A WEAK PRESSURE
PATTERN WILL MAINTAIN GENERALLY MODERATE TRADE WINDS ACROSS THE
AREA THROUGH TUE INCREASING IN THE NW CARIBBEAN WED AND THU. NE
SWELLS IN THE TROPICAL N ATLC WATERS E OF THE LEEWARD ISLANDS
WILL SUBSIDE THROUGH SUN NIGHT. LOWER PRESSURE IN THE FAR SW
CARIBBEAN IN COMBINATION WITH AN UPPER TROUGH WILL MAINTAIN
UNSETTLED WEATHER OVER MUCH OF THE SW AND CENTRAL CARIBBEAN
THROUGH TUE.

ATLANTIC OCEAN...
THE BROAD UPPER TROUGH IN THE GULF OF MEXICO COVERS THE FAR W
ATLC W OF 70W SUPPORTING A WEAK STATIONARY FRONT THAT EXTENDS
THROUGH 32N73W ALONG 31N74W 32N77W THEN S TO 27N79W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE N OF THE FRONT E OF 77W AND N
OF 28N W OF 80W. THE BROAD UPPER RIDGE OVER THE CARIBBEAN
EXTENDS OVER THE W/CENTRAL ATLC ACROSS THE LEEWARD ISLANDS NEAR
17N62W TO BEYOND 32N53W. A SURFACE TROUGH IS BENEATH THE UPPER
RIDGE EXTENDING THROUGH 32N62W ALONG 29N65W TO 23N68W. THE
SURFACE TROUGH COUPLED WITH THE UPPER RIDGE THAT IS PROVIDING
DIFFLUENCE ALOFT ARE GENERATING CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 150 NM OF LINE FROM HISPANIOLA
NEAR 20N71W TO 25N68W AND WITHIN 225 NM EITHER SIDE OF THE
REMAINDER OF THE SURFACE TROUGH. THE UPPER TROUGH IN THE
E/CENTRAL ATLC HAS BECOME CUTOFF. THE UPPER LOW IS CENTERED NEAR
21N41W WITH THE UPPER TROUGH EXTENDING S INTO THE TROPICS TO
NEAR 10N50W AND IS ALSO ENHANCING THE ACTIVITY ASSOCIATED WITH
THE SURFACE TROUGH IN THE ITCZ/MONSOON TROUGH SECTION ABOVE.
A LARGE SURFACE RIDGE DOMINATES THE ATLC BETWEEN 10W-60W AND IS
ANCHORED BY A 1027 MB HIGH NEAR 33N39W. W ATLC STATIONARY FRONT
WILL REMAIN THROUGH TUE WITH A GRADUALLY WEAKENING SURFACE RIDGE
BEHIND IT OVER THE SE CONUS. A BROAD AREA OF LOW PRESSURE IS
FORECAST TO DEVELOP SUN AND MON OVER W/CENTRAL ATLC N OF 25N AND
LIFT N OF THE AREA LATE MON INTO TUE. A COLD FRONT WILL MOVE
INTO NW WATERS WED AND REACH FROM 32N64W THROUGH THE CENTRAL
BAHAMAS THU.

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

$$
PAW





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