[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180001
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON OCT 17 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
2315 UTC.

...SPECIAL FEATURE...

A BROAD AREA OF LOW PRESSURE COVERS THE FAR NW CARIBBEAN AND THE
SE GULF OF MEXICO CENTERED AROUND A 1003 MB LOW JUST N OF THE
YUCATAN PENINSULA NEAR 22N89W. THE CIRCULATION AROUND THIS
SYSTEM COVERS A GREAT PORTION OF THE BASIN...RAGING FROM 15 KT
TO NEAR GALE FORCE CRITERIA OVER THE SE GULF. THIS SYSTEM IS
INTERACTING WITH AN UPPER LEVEL SHORTWAVE/TROUGH THAT IS
SHEARING THE CONVECTION TO THE EAST OF THE LOW LEVEL CIRCULATION
FROM 20N-26N BETWEEN 81W-87W. SCATTERED HEAVY SHOWERS AND
THUNDERSTORMS ARE IN THIS REGION...WITH THE POSSIBILITY OF
STRONG GUSTY OUT FLOW BOUNDARIES AND WATER SPOUTS. CONDITIONS
ARE EXPECTED TO BECOME LESS FAVORABLE FOR TROPICAL CYCLONE
DEVELOPMENT WITHIN THE NEXT DAY OR TWO. THERE IS A MEDIUM CHANCE
OF IT BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT
MOVES GENERALLY NORTHWARD AT 4-9 KT. REGARDLESS OF DEVELOPMENT
...LOCALLY HEAVY RAINFALL AND GUSTY WINDS ARE EXPECTED OVER
WESTERN CUBA...THE FLORIDA KEYS...AND SOUTH FLORIDA DURING THE
NEXT DAY OR SO.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM CAPE VERDE ISLANDS NEAR 16N23W TO
7N28W MOVING W AT 10-15 KT. THE WAVE IS WELL DEFINED IN THE LOW
LEVEL CLOUD FIELD AND IS EMBEDDED WITHIN A DEEP SURGE OF
MOISTURE DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY.
SCATTERED MODERATE CONVECTION IS W OF THE WAVE AXIS FROM 11N-14N
BETWEEN 25W-29W. ISOLATED MODERATE CONVECTION IS ELSEWHERE S OF
THE CAPE VERDE ISLANDS FROM 9N-16N BETWEEN 22W-34W.

TROPICAL WAVE IS ANALYZED IN THE CENTRAL TROPICAL ATLC FROM
14N44W TO 6N47W MOVING W 10-15 KT. WAVE IS MOVING THROUGH A
REGION OF UNFAVORABLE GROWTH AND HAS BECOME LEES DEFINED ON
SATELLITE IMAGERY. NO SIGNIFICANT CONVECTION IS AROUND THIS
SYSTEM.

TROPICAL WAVE IS ANALYZED OVER THE ERN CARIBBEAN FROM 18N65W TO
10N66W MOVING 10-15 KT. WAVE IS BEING SUPPRESSED BY A DRY AND
SUBSIDENT AIRMASS ALOFT INTRUDING ACROSS THE ERN AND N CENTRAL
BASIN ON WATER VAPOR IMAGERY. WEAK CYCLONIC TURNING IS OBSERVED
ON THE LOW LEVEL CLOUD FIELD ALONG THE WAVE AXIS. NO SIGNIFICANT
CONVECTION IS AROUND THIS SYSTEM.

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

DUE TO THE LARGE CYCLONIC WIND FIELD ASSOCIATED TO THE TROPICAL
WAVES...THE OCEANIC MONSOON TROUGH REMAINS INLAND OVER NRN
AFRICA. CONSEQUENTLY...THE ITCZ IS DISRUPTED BY THE PRESENCE OF
THESE TROPICAL WAVES. NEVERTHELESS...A WEAK 1007 MB LOW IS
ANALYZED NEAR 10N39W. SCATTERED SHOWERS ARE FROM 6N-16N BETWEEN
36W-42W.

...DISCUSSION...

GULF OF MEXICO...
THE MAIN AREA OF ACTIVE WEATHER CONTINUES TO FOCUS AROUND THE
SPECIAL FEATURE LOW IMPACTING THE SE GULF. REFER TO THE SPECIAL
FEATURE SECTION ABOVE FOR MORE DETAILS. SCATTERED MODERATE
CONVECTION IS ALSO OVER THE BAY OF CAMPECHE S OF 20N BETWEEN
93W-96W. FAIR WEATHER CONDITIONS ARE ELSEWHERE OVER THE GULF.
THE FAIR WEATHER AND CLEARING SKIES TO THE NW OF THE SYSTEM ARE
WELL ASSOCIATED TO STRONG SUBSIDENCE AND DRY AIR IN THE MID AND
UPPER LEVELS OF THE ATMOSPHERE NOTICED ON WATER VAPOR IMAGERY...
AS WELL AS WEAK SURFACE RIDGE OF HIGH PRESSURE ANCHORED OVER S
CENTRAL GEORGIA. EXPECT A COLD FRONT TO EXTEND IN 24 HOURS FROM
MOBILE BAY TO TAMPICO MEXICO WITH SHOWERS. ALSO EXPECT A NEW LOW
TO DEVELOP OVER THE NE GULF...WHILE THE CONVECTION OVER THE SE
GULF DRIFTS E.

CARIBBEAN SEA...
THE SPECIAL FEATURE LOW IS PRESENTLY GENERATING CONVECTION OVER
W CUBA AND THE NW CARIBBEAN. SEE ABOVE. IT IS ALSO PRODUCING
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION OVER NW
HONDURAS AND GUATEMALA FROM 15N-16N BETWEEN 86W-91W. SIMILAR
CONVECTION IS OVER THE SW CARIBBEAN N OF PANAMA FROM 10N-12N
BETWEEN 80W-83W. RADAR IMAGERY SHOWS SCATTERED SHOWERS AROUND
PUERTO RICO. SIMILAR SHOWERS ARE NOTED OVER HISPANIOLA...
JAMAICA...AND THE CENTRAL CARIBBEAN FROM 13N-20N BETWEEN
70W-77W. EXPECT THE TROPICAL WAVE TO MOVE W OVER THE NEXT 24
HOURS AND PRODUCE MOVE SHOWERS OVER THE CENTRAL CARIBBEAN. ALSO
EXPECT CONTINUED CONVECTION OVER CENTRAL AMERICA AND THE W
CARIBBEAN.

ATLANTIC OCEAN...
A SURFACE TROUGH IS OVER THE W ATLANTIC FROM 30N67W TO 25N76W.
SCATTERED SHOWERS ARE WITHIN 120 NM OF THE TROUGH TO INCLUDE THE
N BAHAMAS. A 1012 MB LOW IS OVER THE CENTRAL ATLANTIC NEAR
32N34W. A SURFACE TROUGH EXTENDS S TO 25N35W. AN UPPER LEVEL LOW
IS ALSO CENTERED AT 32N34W. UPPER LEVEL DIFFLUENCE E OF THE
CENTER IS PRODUCING WIDELY SCATTERED MODERATE CONVECTION FROM
28N-34N BETWEEN 24W-31W. EXPECT INCREASED CONVECTION OVER THE W
ATLANTIC...FLORIDA...AND THE BAHAMAS OVER THE NEXT 24 HOURS.

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

$$
FORMOSA





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