[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 270003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN AUG 26 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
THROUGH 2315 UTC.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM ISAAC AT 27/0000 UTC IS NEAR 24.1N
82.6W. THIS POSITION IS ABOUT 50 NM SW OF KEY WEST FLORIDA...AND
ABOUT 460 NM SE OF THE MOUTH OF THE MISSISSIPPI RIVER. ISAAC IS
MOVING WNW AT 13 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS
991 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO
65 KT. PLEASE READ THE FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY...MIATCPAT4/WTNT34
KNHC FOR MORE DETAILS. ISAAC IS PRODUCING SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ACROSS A GOOD PORTION OF
FLORIDA FROM 25N-30N BETWEEN 76W-84W. SIMILAR ACTIVITY IS SE OF
THE STORM CENTER ACROSS CUBA FROM 19N-23N BETWEEN 77W-80W. SOME
LARGER CLUSTERS OF STRONG CONVECTION HAVE POPPED UP WEST OF THE
CENTER FROM 24N-26N BETWEEN 82W-84W.

TROPICAL WAVE EXTENDS FROM 26N34W TO A 1009 MB SURFACE LOW NEAR
18N37W MOVING NW AT 10-15 KT. THE WAVE/LOW LIES WITHIN A LARGE
SURGE OF DEEP LAYER MOISTURE PRESENT ACROSS MUCH OF THE CENTRAL
TROPICAL ATLC. BROAD CYCLONIC FLOW IS AROUND THE WAVE/LOW...BUT
DOES NOT SHOW SIGNS OF WELL-DEFINED ORGANIZATION. CURRENTLY A
CLUSTER OF STRONG CONVECTION IS FROM 21N-23N BETWEEN 33W-37W.
ISOLATED MODERATE CONVECTION IS FROM 17N-21N BETWEEN 35W-40W.
DEVELOPMENT OF THIS SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF
DAYS.

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

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
MAURITANIA AT 20N16W CONTINUING TO THE CAPE VERDE ISLANDS AT
17N27W. THE MONSOON TROUGH THEN SPLITS DUE TO THE NW MOTION OF
THE TROPICAL WAVE/LOW IN THE CENTRAL ATLC. THE AXIS BEGINS AGAIN
AT THE LOW CENTER AT 18N37W ALONG 13N40W 8N48W. THE ITCZ
CONTINUES AT 8N48W TO 11N61W. ISOLATED MODERATE CONVECTION IS
OFF THE COAST OF AFRICA FROM 10N-16N BETWEEN 17W-25W ASSOCIATED
WITH THE NEXT TROPICAL WAVE THAT WILL EMERGE OFF THE COAST
LIKELY TONIGHT. SIMILAR ACTIVITY IS FROM 11N-13N BETWEEN
43W-46W.

...DISCUSSION...

THE GULF OF MEXICO...
TROPICAL STORM ISAAC CONTINUES TO IMPACT THE EASTERN GULF OF
MEXICO AS IT MOVES THROUGH THE FLORIDA STRAITS INTO THE SE GULF.
WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS ARE ACROSS MUCH OF
THE FLORIDA PENINSULA AND FLORIDA KEYS. FLOODING IS POSSIBLE
THROUGHOUT THE FLORIDA KEYS AND THE SOUTHERN HALF OF THE FLORIDA
PENINSULA. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS ON ISAAC.
ELSEWHERE ACROSS THE GULF...WEAK SURFACE RIDGING IS OVER THE FAR
WESTERN GULF EXTENDING FROM A HIGH CENTER OVER NORTHERN GEORGIA.
DRY AIR ALOFT IS WRAPPING AROUND AN INVERTED UPPER TROUGH
EXTENDING FROM CENTRAL LOUISIANA TO THE YUCATAN
PENINSULA...WHICH IS HELPING PROVIDE FAIR CONDITIONS WEST OF
89W. STORMY CONDITIONS WILL BEGIN TO SPREAD INTO THE CENTRAL AND
NORTHERN GULF AS ISAAC BEGINS A MORE NORTHWESTWARD TRACK.
INTERESTS IN THE NORTHERN GULF SHOULD MONITOR THE PROGRESS OF
ISAAC CLOSELY.

THE CARIBBEAN SEA...
EVEN THOUGH TROPICAL STORM ISAAC HAS MOVED NORTH OF THE
BASIN...PORTIONS OF THE NORTHERN CARIBBEAN ARE STILL FEELING
THE IMPACTS. SHOWERS AND ISOLATED THUNDERSTORMS ARE ACROSS
CENTRAL CUBA FROM 19N-23N BETWEEN 77W-81W. REPORTS FROM CUBA
STILL INDICATE THAT HEAVY AMOUNTS OF RAIN HAVE FALLEN WITHIN THE
LAST 24 HOURS WITH SOME AREAS SUCH AS SAN ANTONIA DEL SUR IN
GUANTANAMO RECEIVING OVER 14 INCHES. OTHER AREAS IN GUANTANAMO
AS WELL AS SANTIAGO DE CUBA HAVE REPORTED ANYWHERE FROM 4 TO 8
INCHES. WITH RAIN STILL FALLING...FLOODING AND MUDSLIDES ARE
STILL POSSIBLE ACROSS THE ISLAND. HISPANIOLA IS CURRENTLY
DRY...BUT WIDESPREAD MOISTURE STILL COVERS THE EASTERN
CARIBBEAN. AN UPPER LEVEL LOW CENTERED NORTH OF THE VIRGIN
ISLANDS NEAR 20N64W IS PROVIDING WESTERLY FLOW ALOFT ACROSS THE
NE CARIBBEAN...WHICH IS DRAWING MOISTURE FROM THE EASTERN EXTENT
OF ISAAC. WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS COVER
MUCH OF THE EASTERN CARIBBEAN E OF 72W. LUCKILY SOME DRY AIR IS
SINKING SOUTHWARD FROM THE ATLC KEEPING THE ALREADY SATURATED
GROUNDS OF THE NE ISLANDS DRY. THE MAJORITY OF THE WESTERN
CARIBBEAN...BESIDES PORTIONS OF CUBA...IS MOSTLY DRY DUE TO DRY
AIR ALOFT AROUND A WEAK UPPER LEVEL RIDGE COVERING THE WESTERN
HALF OF THE BASIN. CYCLONIC SURFACE FLOW IS STILL PRESENT ACROSS
THE NW CARIBBEAN DUE TO THE CIRCULATION OF ISAAC. STRONG
SHOWERS/THUNDERSTORMS ARE PRESENT ACROSS PORTIONS OF CENTRAL
AMERICA ALONG THE MONSOON TROUGH AXIS WHICH EXTENDS FARTHER
NORTH THAN USUAL FROM WESTERN HONDURAS DOWN WESTERN NICARAGUA
AND ACROSS COSTA RICA AND PANAMA TO NORTHERN COLUMBIA.
CONDITIONS ACROSS CUBA SHOULD IMPROVE AS ISAAC MOVES FURTHER
INTO THE GULF OF MEXICO. HOWEVER... THE MOISTURE CURRENTLY OVER
THE EASTERN CARIBBEAN IS EXPECTED TO MOVE WESTWARD OVER THE NEXT
SEVERAL DAYS AND COULD BRING ANOTHER BATCH OF RAIN TO BOTH
HISPANIOLA AND CUBA.

THE ATLANTIC OCEAN...
TROPICAL STORM ISAAC IS PRODUCING SHOWERS AND ISOLATED
THUNDERSTORMS ACROSS PORTIONS OF THE BAHAMAS INTO THE FLORIDA
PENINSULA W OF 75W. THE REMAINDER OF THE W ATLC IS UNDER MOSTLY
FAIR CONDITIONS DUE TO DRY AIR WRAPPING AROUND AN UPPER LEVEL
RIDGE CENTERED NEAR 29N73W. AN UPPER LEVEL LOW IS JUST N OF THE
VIRGIN ISLANDS NEAR 20N63W PRODUCING A FEW ISOLATED
SHOWERS/THUNDERSTORMS FROM 20N-23N BETWEEN 62W-67W. A SURFACE
TROUGH...REMNANTS OF JOYCE...STILL EXISTS FROM 27N59W TO 24N59W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE TO THE NORTH FROM
28N-32N BETWEEN 59W-63W. THE REMAINDER OF THE ATLC IS DOMINATED
BY BROAD SURFACE RIDGING AROUND A PAIR OF HIGH CENTERS N OF THE
AREA. THE RIDGE IS SUPPORTED BY A BROAD UPPER LEVEL RIDGE
CENTERED NEAR 31N49W WITH A SECOND UPPER RIDGE CENTERED NEAR
22N26W. THE LAST VISIBLE SATELLITE IMAGES ALONG WITH GOES-R
ENHANCEMENT IMAGERY INDICATE AN AREA OF DUST EXTENDS BETWEEN THE
TROPICAL WAVE IN THE CENTRAL TROPICAL ATLC AND THE SURFACE
TROUGH IN THE CENTRAL ATLC TO THE NORTH. AN AREA OF DUST ALSO
EXTENDS OFF THE COAST OF AFRICA BEHIND THE WAVE AND AROUND A
WAVE JUST EMERGING OFF THE COAST.

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

$$
WALTON





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