[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 302355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED SEP 30 2009

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 30W S OF 12N MOVING W NEAR 15 KT. THE
WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE AS NOTED IN
TOTAL PRECIPITABLE WATER IMAGERY...AS WELL AS EXHIBITING LOW- TO
MIDDLE-LEVEL CYCLONIC FLOW EVIDENT IN SATELLITE IMAGERY AND
SATELLITE DERIVED WINDS. CIMSS WAVETRAK MODEL GUIDANCE ALSO
INDICATES A BROAD AREA OF 850 MB RELATIVE VORTICITY OVER THE ERN
ATLC FROM 5N-15N BETWEEN 25W-35W. WIDELY SCATTERED MODERATE
CONVECTION IS FROM 9N-12N BETWEEN 27W-34W.

TROPICAL WAVE IS ALONG 48W S OF 18N MOVING W NEAR 15 KT. THE
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. ALSO...CIMSS WAVETRAK MODEL
GUIDANCE INDICATES A CONCENTRATED AREA OF 850 MB RELATIVE
VORTICITY CENTERED ALONG THE WAVE AXIS FROM 10N-17N. THIS
LOW-LEVEL VORTICITY COUPLED WITH AN UPPER LEVEL DIFFLUENT
PATTERN ALOFT IS GENERATING SCATTERED MODERATE CONVECTION FROM
10N-12N BETWEEN 48W-50W...AND FROM 15N-18N BETWEEN 43W-49W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 8N13W 10N30W 8N34W 11N48W 9N61W.
BESIDES THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION...
SCATTERED MODERATE TO STRONG CONVECTION IS ALONG THE W AFRICA
COAST FROM 7N-11N BETWEEN 10W-15W. SCATTERED MODERATE CONVECTION
IS FROM 11N-13N BETWEEN 20W-23W...AND FROM 9N-11N BETWEEN
36W-39W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...AN COLD FRONT EXTENDS FROM S FLORIDA TO THE
SOUTH CENTRAL GULF OF MEXICO ALONG 26N80W 23N90W. WIDELY
SCATTERED MODERATE CONVECTION IS MOSTLY S OF THE FRONT OVER THE
YUCATAN CHANNEL AND ALONG THE COAST OF W CUBA FROM 21N-24N
BETWEEN 81W-86W. SCATTERED SHOWERS ARE OVER THE FLORIDA KEYS.
OUTSIDE OF THE SE GULF...MOSTLY FAIR WEATHER PREVAILS. 5-10 KT
NORTHERLY WINDS ARE OVER THE E GULF N OF THE FRONT. IN THE UPPER
LEVELS...AN UPPER LEVEL TROUGH IS OVER THE E GULF E OF 90W
SUPPORTING THE COLD FRONT. A RIDGE IS OVER THE W GULF PRODUCING
NW UPPER LEVEL FLOW. CONSIDERABLE UPPER LEVEL MOISTURE IS OVER
THE SE GULF...CENTRAL AND SOUTHERN FLORIDA...AND CUBA. STRONG
SUBSIDENCE IS OVER THE REMAINDER OF THE GULF. EXPECT...THE COLD
FRONT TO MOVE INTO THE W ATLANTIC OVER THE NEXT 24 HOURS WITH
CONTINUED CONVECTION OVER THE STRAITS OF FLORIDA. ALSO EXPECT A
NEW FRONTAL SYSTEM TO PRODUCE CONVECTION OVER E TEXAS AND
LOUISIANA OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
FRESH TO STRONG TRADEWINDS ARE OVER THE CARIBBEAN SEA AND
CENTRAL AMERICA. CLUSTERS OF SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS OVER PANAMA FROM 6N-10N BETWEEN 77W-83W.
WIDELY SCATTERED MODERATE CONVECTION IS OVER HISPANIOLA FROM
18N-20N BETWEEN 68W-72W. ISOLATED MODERATE CONVECTION IS INLAND
OVER CENTRAL AMERICA N OF HONDURAS. SIMILAR CONVECTION IS OVER
CUBA. IN THE UPPER LEVELS...AN UPPER LEVEL TROUGH IS OVER THE
WESTERN AND CENTRAL CARIBBEAN. DIFFLUENCE E OF THE TROUGH IS
ENHANCING SHOWERS OVER THE LEEWARD ISLANDS. AN UPPER LEVEL RIDGE
IS OVER THE E CARIBBEAN AND E OF 65W. STRONG SUBSIDENCE IS OVER
THE CENTRAL AND NW CARIBBEAN. EXPECT...CONTINUED SHOWERS AND
THUNDERSTORMS OVER CENTRAL AMERICA AND THE W CARIBBEAN OVER THE
NEXT 24 HOURS.

ATLANTIC OCEAN...
A COLD FRONT IS OVER THE W ATLANTIC EXTENDING SW TO S FLORIDA
ALONG 32N68W 26N80W. ISOLATED MODERATE CONVECTION IS OVER THE N
BAHAMAS FROM 24N-27N BETWEEN 73W-79W. A 1017 MB HIGH IS OVER THE
W ATLANTIC NEAR 24N61W. A SURFACE TROUGH...THE REMNANTS OF T.D.
EIGHT IS OVER THE TROPICAL CENTRAL ATLANTIC ALONG 22N55W 16N56W.
WIDELY SCATTERED MODERATE CONVECTION IS FROM 20N-22N BETWEEN
50W-56W.  A COLD FRONT IS OVER THE CENTRAL ATLANTIC ALONG 32N18W
28N24W 28N40W 29N47W. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE
FRONT. A 1019 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR 22N39W.
ANOTHER 1018 MB HIGH IS OVER THE E ATLANTIC NEAR 25N20W. IN THE
UPPER LEVELS...AN UPPER LEVEL TROUGH IS N OF 20N W OF 70W. AN
UPPER LEVEL RIDGE IS N OF 20N BETWEEN 60W-70W. AN UPPER LEVEL
LOW IS OVER THE CENTRAL ATLANTIC NEAR 26N51W. UPPER LEVEL
DIFFLUENCE N OF THE CENTER IS PRODUCING WIDELY SCATTERED
MODERATE CONVECTION FROM 27N-30N BETWEEN 45W-50W. AN UPPER LEVEL
TROUGH IS OVER THE E ATLANTIC N OF 20N AND E OF 50W. AN UPPER
LEVEL HIGH IS OVER THE TROPICAL ATLANTIC NEAR 13N50W. ANOTHER
UPPER LEVEL HIGH IS OVER W AFRICA NEAR 12N9W WITH RIDGING
EXTENDING W OVER THE TROPICAL E ATLANTIC TO 25W.

$$
FORMOSA




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