[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210600
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN SEP 21 2008

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...
TROPICAL WAVE IS TILTED ACROSS ERN PUERTO RICO NEAR 19N66W
THROUGH A WEAK 1010 MB LOW NEAR 17N67W TO EAST OF BONAIRE INTO
NRN VENEZUELA NEAR 8N68W MOVING W NEAR 10 KT. THIS WAVE IS
GENERATING A LARGE AREA OF CLOUDINESS WITH SCATTERED SHOWERS/
ISOLATED TSTMS FROM 14N-20N BETWEEN 63W-67W...INCLUDING THE NRN
LEEWARD ISLANDS...THE US/UK VIRGIN ISLANDS AND PUERTO RICO. THIS
SYSTEM IS SHOWING SIGNS OF ORGANIZATION AND UPPER LEVEL WINDS
ARE EXPECTED TO BECOME MORE FAVORABLE OVER THE NEXT COUPLE DAYS
FOR ADDITIONAL DEVELOPMENT.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 24W S OF 15N MOVING W NEAR 15 KT. A BROAD
CYCLONIC CIRCULATION IS EVIDENT ON SATELLITE IMAGERY WITH A LOW
TO MIDDLE LEVEL LOW ALONG THE WAVE NEAR 5N. BROAD AREA OF
CLOUDINESS COVERS THE AREA WITH 300 NM ON EITHER SIDE OF THE
WAVE AXIS WITH SCATTERED MODERATE CONVECTION FROM 7N-11N BETWEEN
23W-28W.

TROPICAL WAVE IS ALONG 38W FROM 11N-18N MOVING W 10-15 KT. LOW
LEVEL CLOUDS INDICATE INVERTED-V CURVATURE BETWEEN 14N-20N. WAVE
REMAINS EMBEDDED WITHIN STRONG SUBSIDENCE AND A DRY...STABLE AIR
MASS...THUS NO ASSOCIATED CONVECTIVE ACTIVITY.

TROPICAL WAVE IS ALONG 56W S OF 20N MOVING W 10-15 KT. WAVE IS
BENEATH AN UPPER RIDGE PROVIDING UPPER LEVEL DIFFLUENCE WITH
MIDDLE TO HIGH LEVEL CLOUDINESS OBSERVED MAKING THE WAVE
DIFFICULT TO DISCERN ON SATELLITE IMAGERY. THIS AREA OF
CLOUDINESS CONTAINS SCATTERED MODERATE CONVECTION FROM 15N-20N
BETWEEN 57W-60W.

TROPICAL WAVE IS ALONG 84W S OF 20N MOVING W 15 KT. CYCLONIC
CURVATURE IS NOTED OVER THE WRN CARIBBEAN SEA WITH CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION INLAND ACROSS ERN
NICARAGUA AND SWRN HONDURAS.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 12N15W 9N23W 8N25W 7N50W 11N67W.
ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG
24W...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
12N-15N BETWEEN 18W-20W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS ACROSS THE WRN GULF OF MEXICO FROM
27N92W TO INLAND ACROSS THE NWRN TIP OF THE YUCATAN PENINSULA. A
BROAD UPPER LEVEL RIDGE CENTERED OVER SRN MEXICO NEAR 20N97W
DOMINATES THE GULF EXTENDING NE FROM VERACRUZ TO OVER THE
FLORIDA PENINSULA NEAR NAPLES. THIS COUPLED WITH THE SURFACE
TROUGH IS PRODUCING WIDESPREAD CLOUDINESS WITH CLUSTERS OF
SCATTERED SHOWERS N OF 23N BETWEEN 86W-94W AND SCATTERED SHOWERS
AND TSTMS S OF 20N ACROSS THE WRN BAY OF CAMPECHE AND INLAND SRN
MEXICO. A SURFACE RIDGE COVERS THE SE US AND EXTENDS INTO THE
FAR NRN GULF N OF 29N AND IS EXPECTED TO CONTINUE BUILDING IN
SLOWLY ACROSS THE NRN GULF WATERS THROUGH MIDWEEK.

CARIBBEAN SEA...
AN ERN CARIBBEAN TROPICAL WAVE IS CONTINUING TO EXHIBIT SOME
ORGANIZATION AND ADDITIONAL DEVELOPMENT IS POSSIBLE OVER THE
NEXT FEW DAYS...SEE SPECIAL FEATURES ABOVE. THE WRN CARIBBEAN
TROPICAL WAVE CONTINUES TO MOVE UNDER AN UPPER RIDGE ANCHORED
OVER SRN MEXICO EXTENDING ACROSS THE NW CARIBBEAN W OF 82W AND
IS PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE SCATTERED
SHOWERS AND TSTMS ACROSS THE YUCATAN PENINSULA AND PORTIONS OF
CENTRAL AMERICA. THE UPPER LEVELS ARE DOMINATED BY THE UPPER
RIDGE OVER THE GULF AND A SECOND UPPER RIDGE ANCHORED OVER THE
S/CENTRAL CARIBBEAN NEAR 13N69W EXTENDING NE ACROSS THE LESSER
ANTILLES INTO THE W TROPICAL ATLC. THESE UPPER LEVEL FEATURES
ARE ENHANCING PATCHES OF MULTILAYERED CLOUDINESS ACROSS MUCH OF
THE BASIN AND POSSIBLE SHOWER ACTIVITY FROM 14N-19N BETWEEN
74W-82W.

ATLANTIC OCEAN...
A NARROW UPPER TROUGH IS OVER THE FAR W ATLC EXTENDING THROUGH
32N76W TO OVER CENTRAL CUBA. A SURFACE TROUGH ENTERS THE W ATLC
FROM A 1015 MB LOW N OF THE REGION THROUGH 32N74W TO NEAR PALM
BEACH FLORIDA. ISOLATED SHOWERS ARE NE OF THE BAHAMAS FROM
25N-32N BETWEEN 74W-77W AND SCATTERED SHOWERS/ISOLATED TSTMS ARE
ALSO OFF THE COAST OF NE FLORIDA AND GEORGIA FROM 29N-32N
BETWEEN 77W-81W. A PAIR OF UPPER LOWS ARE TO THE E CENTERED NEAR
25N47W AND 24N66W. AN AREA OF UPPER DIFFLUENCE IS ACROSS THE
CENTRAL ATLC AND IS GENERATING AN AREA OF POSSIBLE SHOWERS
WITHIN 90 NM OF A LINE FROM 26N39W TO 17N48W. THE UPPER RIDGE
OVER THE ERN CARIBBEAN EXTENDS ACROSS THE LEEWARD ISLANDS TO
OVER THE W TROPICAL ATLC NEAR 18N50W. A WEAKENING UPPER TROUGH
IS OVER THE NE ATLC EXTENDING FROM A DEEP LAYERED LOW N OF THE
REGION TO 23N E OF 30W TO OVER THE CANARY ISLANDS. AN E/W UPPER
RIDGE CONTROLS THE REMAINDER OF THE TROPICAL ATLC TO 42W S OF
THE UPPER TROUGH ACROSS THE NE ATLC. OTHERWISE THE ATLC IS
DOMINATED BY A WEAK BUT BROAD SURFACE RIDGE BETWEEN 25W-67W
ANCHORED BY A PAIR OF SURFACE HIGHS N OF THE REGION...A 1025 MB
HIGH NEAR 33N55W AND A 1024 MB HIGH NEAR 32N42W.

$$
HUFFMAN


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