[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211054
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...
TROPICAL WAVE IS TILTED ACROSS PUERTO RICO NEAR 19N66W THROUGH A
WEAK 1010 MB LOW NEAR 17N67W TO CURACAO AND THEN INTO NERN
VENEZUELA NEAR 11N70W MOVING W NEAR 10 KT. THIS WAVE IS
GENERATING A LARGE AREA OF CLOUDINESS WITH SCATTERED MODERATE/
STRONG CONVECTION FROM 14N-19N BETWEEN 62W-68W...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 26W S OF 15N MOVING W NEAR 15-20 KT. A
BROAD CYCLONIC CIRCULATION IS EVIDENT ON SATELLITE IMAGERY WITH
A LOW TO MIDDLE LEVEL LOW ALONG THE WAVE NEAR 6N. BROAD AREA OF
CLOUDINESS COVERS THE AREA WITHIN 300 NM ON EITHER SIDE OF THE
WAVE AXIS AS THE WAVE REMAINS EMBEDDED WITHIN THE ITCZ AND
SCATTERED MODERATE CONVECTION IS OBSERVED FROM 7N-12N BETWEEN
25W-29W.

TROPICAL WAVE IS ALONG 39W/40W FROM 11N-18N MOVING W 10-15 KT.
LOW LEVEL CLOUDS INDICATE INVERTED-V CURVATURE BETWEEN 13N-18N.
WAVE REMAINS EMBEDDED UNDER STRONG SUBSIDENCE AND A DRY...STABLE
AIR MASS ALOFT...THUS NO ASSOCIATED CONVECTIVE ACTIVITY.

TROPICAL WAVE IS ALONG 58W S OF 20N MOVING W NEAR 15 KT. WAVE IS
BENEATH AN UPPER RIDGE PROVIDING UPPER LEVEL DIFFLUENCE WITH
MIDDLE TO HIGH LEVEL CLOUDINESS OBSERVED ON THE NORTHERN HALF OF
THE WAVE...MAKING IT DIFFICULT TO DISCERN ON SATELLITE IMAGERY.
THIS AREA OF CLOUDINESS CONTINUES TO DISSIPATE AND CONTAINS
POSSIBLE SCATTERED SHOWERS FROM 17N-21N BETWEEN 55W-61W.

TROPICAL WAVE IS ALONG 86W S OF 20N MOVING W 15 KT. CYCLONIC
CURVATURE IS NOTED OVER THE NW CARIBBEAN SEA WITH CLUSTERS OF
SCATTERED MODERATE CONVECTION ACROSS ADJACENT CARIBBEAN COASTAL
WATERS OF HONDURAS AND NICARAGUA W OF 82W.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 14N15W 9N24W 9N28W 7N40W 6N57W.
ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG
26W...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
12N-15N BETWEEN 19W-23W. WIDELY SCATTERED MODERATE CONVECTION IS
FROM 4N-8N BETWEEN 36W-41W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS ACROSS THE WRN GULF OF MEXICO FROM
28N95W TO THE ERN BAY OF CAMPECHE NEAR 20N92W. A BROAD UPPER
LEVEL RIDGE CENTERED OVER SRN MEXICO NEAR 20N97W DOMINATES THE
GULF EXTENDING NE FROM VERACRUZ TO OVER THE CENTRAL FLORIDA
PENINSULA. THIS COUPLED WITH THE SURFACE TROUGH IS PRODUCING
WIDESPREAD CLOUDINESS IN AN AREA OF UPPER DIFFLUENCE ACROSS THE
CENTRAL GULF WITH CLUSTERS OF SCATTERED SHOWERS N OF 23N BETWEEN
84W-93W AND SCATTERED SHOWERS AND TSTMS S OF 20N AND FROM
20N-24N W OF 95W...INCLUDING THE BAY OF CAMPECHE AND ACROSS
INLAND SRN MEXICO. A SURFACE RIDGE COVERS THE SE US AND EXTENDS
INTO THE FAR NRN GULF N OF 28N 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 ADJACENT COASTAL WATERS OF ERN
HONDURAS AND NICARAGUA. THE UPPER LEVELS ARE DOMINATED BY THE
UPPER RIDGE OVER THE GULF OF MEXICO AND A SECOND UPPER RIDGE
ANCHORED OVER THE ERN CARIBBEAN NEAR 15N63W EXTENDING W TO 82W
AND E ACROSS THE LESSER ANTILLES INTO THE W TROPICAL ATLC. THESE
UPPER LEVEL FEATURES ARE ENHANCING PATCHES OF MULTILAYERED
CLOUDS ACROSS MUCH OF THE BASIN AND POSSIBLE SCATTERED SHOWER
ACTIVITY S OF 14N BETWEEN 71W-84W.

ATLANTIC OCEAN...
A NARROW UPPER TROUGH IS OVER THE FAR W ATLC EXTENDING THROUGH
32N74W TO OVER THE CENTRAL BAHAMAS AND CUBA. A SURFACE TROUGH
ENTERS THE W ATLC FROM A 1015 MB LOW N OF THE REGION THROUGH
32N73W TO NEAR CAPE CANAVERAL FLORIDA. SCATTERED SHOWERS/
ISOLATED TSTMS ARE NE OF THE BAHAMAS FROM 24N-32N BETWEEN
72W-76W AND SIMILAR ACTIVITY IS OFF THE NE COAST OF FLORIDA AND
GEORGIA FROM 29N-32N BETWEEN 79W-82W. A PAIR OF UPPER LOWS ARE
TO THE EAST ACROSS THE CENTRAL ATLC CENTERED NEAR 24N47W AND
25N64W. THE UPPER RIDGE OVER THE ERN CARIBBEAN EXTENDS ACROSS
THE LEEWARD ISLANDS TO OVER THE W TROPICAL ATLC NEAR 17N50W.
WEAK UPPER TROUGHING IS OVER THE NE ATLC EXTENDING FROM A DEEP
LAYERED LOW N OF THE REGION TO 25N E OF 30W TO OVER THE CANARY
ISLANDS. AN E/W UPPER RIDGE CONTROLS THE REMAINDER OF THE
TROPICAL ATLC TO 40W S OF THE UPPER TROUGHING ACROSS THE NE
ATLC. OTHERWISE THE ATLC IS DOMINATED BY A STATIONARY 1025 MB
SURFACE HIGH CENTERED NORTH OF THE REGION NEAR 34N46W AND
INFLUENCES THE ATLC N OF 24N FROM 20W-70W.

$$
HUFFMAN


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