[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 241755 CCA
TWDAT

TROPICAL WEATHER DISCUSSION...COR
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU SEP 24 2009

CLARIFYING THE WEATHER FEATURES AND RELATED PRECIPITATION
THAT JUST PERTAIN TO THE UPPER LEVEL ELONGATED TROUGH
THAT EXTENDS FROM THE NORTHERN BAHAMAS INTO THE
SOUTHWESTERN GULF OF MEXICO SECTION...

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...

AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS MOVING ACROSS THE
CAPE VERDE ISLANDS ALONG 24W/25W TO THE SOUTH OF 18N...MOVING
WEST ABOUT 15 KT. A 1010 MB LOW PRESSURE CENTER IS ALONG THE
WAVE NEAR 14N. THIS FEATURE SHOWS UP WELL IN THE VISIBLE
SATELLITE IMAGERY. SCATTERED STRONG SHOWERS AND THUNDERSTORMS
COVER THE AREA FROM 12N TO 16N BETWEEN 27W AND 30W. OTHER
SHOWERS AND THUNDERSTORMS COVER THE REST OF THE AREA FROM
12N TO 17N BETWEEN 23W AND 30W.

AN ATLANTIC OCEAN TROPICAL WAVE HAS BEEN MOVED TO 54W/55W
TO THE SOUTH OF 19N...MOVING WEST 15 KT. ITS CURRENT POSITION
AGREES WITH SURFACE OBSERVATIONS AND MODEL INFORMATION.
THE WAVE HAS BEEN MOVED AT LEAST A FEW DEGREES OF LONGITUDE
MORE TO THE WEST THAN MAY BE EXPECTED BASED ON ITS 24/0600 UTC
POSITION. IT IS POSSIBLE THAT STRONG ITCZ PRECIPITATION FROM
9N TO 12N BETWEEN 52W AND 55W IS BEING ENHANCED BY THE WAVE.

...THE ITCZ...
FROM NORTHERN SENEGAL TOWARD THE 1010 MB LOW CENTER THAT IS
ALONG THE 24W/25W TROPICAL WAVE...TO 9N26W TO 7N35W TO 11N53W...
INTO NORTHEASTERN VENEZUELA NEAR 10N62W. SCATTERED MODERATE
SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE WITHIN 120 NM ON
EITHER SIDE OF 9N22W 6N31W 6N36W 9N45W TO 10N60W AND 9N62W.

...DISCUSSION...

FROM THE ATLANTIC OCEAN NEAR THE NORTHERN BAHAMAS..TO THE
STRAITS OF FLORIDA...TO THE WATERS JUST TO THE NORTH OF THE
YUCATAN PENINSULA...INTO THE SOUTHWESTERN CORNER OF THE GULF
OF MEXICO AND THE ISTHMUS OF TEHUANTEPEC...
AN ELONGATED UPPER LEVEL TROUGH COVERS THE AREA FROM THE
NORTHERN BAHAMAS...THROUGH THE STRAITS OF FLORIDA...TO THE
WATERS JUST TO THE NORTH OF THE YUCATAN PENINSULA...INTO THE
SOUTHWESTERN CORNER OF THE GULF OF MEXICO AND THE ISTHMUS OF
TEHUANTEPEC. ISOLATED MODERATE SHOWERS ARE ALONG THE NORTHERN
EDGE OF THE CYCLONIC FLOW OF THE ELONGATED TROUGH...FROM THE
BAHAMAS TO THE ISTHMUS OF TEHUANTEPEC.

THE REST OF THE GULF OF MEXICO...
A STATIONARY FRONT PASSES THROUGH SOUTHERN LOUISIANA INTO THE
WESTERN GULF OF MEXICO...THE COASTAL WATERS OF TEXAS AND MEXICO
TO THE MEXICO COAST NEAR 18N94W...IN THE NORTHERN ISTHMUS OF
TEHUANTEPEC. ISOLATED MODERATE SHOWERS AND POSSIBLE
THUNDERSTORMS ARE IN A 60 NM WIDE LINE THAT IS ON THE WESTERN
SIDE OF THE STATIONARY FRONT. A SURFACE TROUGH IS ALONG 85W/86W
FROM 23N TO 31N. ISOLATED MODERATE SHOWERS FROM 24N TO 26N
BETWEEN 84W AND 88W.

THE REST OF THE CARIBBEAN SEA...
UPPER LEVEL CYCLONIC FLOW...FROM THE NORTHEAST-TO-SOUTHWEST
ORIENTED UPPER LEVEL TROUGH THAT STRETCHES FROM THE NORTHERN
BAHAMAS TO THE YUCATAN PENINSULA TO THE SOUTHWESTERN GULF OF
MEXICO...COVERS THE CARIBBEAN SEA TO THE WEST OF 82W/83W TO THE
NORTH OF NICARAGUA. STRONG SHOWERS AND THUNDERSTORMS ARE FROM
13N TO 15N BETWEEN 81W AND 82W...AND FROM 11N TO 13N BETWEEN 82W
AND 84W...IN UPPER LEVEL DIFFLUENT WIND FLOW. OTHER SHOWERS AND
THUNDERSTORMS ARE FROM 16N TO 18N BETWEEN 82W AND 86W IN THE SAME
DIFFLUENT FLOW. A SURFACE TROUGH EXTENDS FROM JUST TO THE NORTH
OF THE YUCATAN PENINSULA TO THE NORTHWESTERN CORNER OF THE
PENINSULA TO NORTHWESTERN GUATEMALA. SCATTERED MODERATE SHOWERS
TO ISOLATED STRONG THUNDERSTORMS EXTEND FROM THE GULF OF
HONDURAS TO THE NORTHEASTERN YUCATAN PENINSULA. WARMING CLOUD
TOP TEMPERATURES AND WEAKENING CONVECTIVE PRECIPITATION COVERS
THE NORTHWESTERN CORNER OF THE AREA TO THE NORTH OF 18N BETWEEN
JAMAICA AND THE WESTERN TIP OF CUBA. BROAD UPPER LEVEL CYCLONIC
FLOW COVERS THE AREA TO THE EAST OF 71W. THIS CYCLONIC FLOW IS
AT THE BASE OF A TROUGH THAT ORIGINATES FROM A 28N66W CYCLONIC
CIRCULATION CENTER.

THE REST OF THE ATLANTIC OCEAN...
A WELL-ESTABLISHED UPPER LEVEL CYCLONIC CIRCULATION CENTER AND
TROUGH EXTEND FROM 28N66W TO 20N67W TO 12N65W IN THE
SOUTHEASTERN CARIBBEAN SEA. WIDELY SCATTERED MODERATE SHOWERS
ARE TO THE NORTH OF 27N BETWEEN 60W AND 70W. SCATTERED MODERATE
TO STRONG SHOWERS AND POSSIBLE THUNDERSTORMS COVER THE AREA FROM
24N TO 27N BETWEEN 52W AND 55W...AND FROM 30N TO 32N BETWEEN 57W
AND 61W...IN AN AREA OF UPPER LEVEL DIFFLUENT FLOW THAT IS TO THE
EAST OF THE 28N66W 20N67W TROUGH. A SURFACE TROUGH IS ALONG
24N52W 20N54W. EARLIER SHOWERS NEAR THE TROUGH HAVE DISSIPATED
AND/OR HAVE BEEN DISSIPATING DURING THE LAST SIX HOURS. AN UPPER
LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 34N17W. CYCLONIC FLOW
COVERS THE AREA TO THE NORTH OF 27N TO THE EAST OF 24W.

$$
MT



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