[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 060003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON OCT 05 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.

...SPECIAL FEATURE...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 46W/47W TO THE SOUTH
OF 19N MOVING WEST 15 KT. SCATTERED MODERATE SHOWERS TO ISOLATED
STRONG THUNDERSTORMS COVER THE AREA FROM 12N TO 16N BETWEEN
45W AND 48W. THE CHANCE THAT THIS FEATURE MAY DEVELOP INTO
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS IS MEDIUM...
FROM 30 PERCENT TO 50 PERCENT.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 58W/59W TO THE SOUTH
OF 14N MOVING WESTWARD 15 KT. A WEAKENING UPPER LEVEL TROUGH
EXTENDS FROM A CYCLONIC CENTER THAT IS ABOUT 250 NM TO THE
NORTHEAST OF PUERTO RICO TO 12N60W. A SECOND UPPER LEVEL TROUGH
EXTENDS FROM A CYCLONIC CIRCULATION CENTER NEAR 29N47W TO 21N55W
TO 16N60W. ISOLATED MODERATE SHOWERS AND SOME CELLS WITH WARMING
CLOUD TOP TEMPERATURES COVER THE AREA FROM 8N TO 14N BETWEEN
55W AND 61W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG THE HONDURAS/NICARAGUA
COAST ALONG 83W/84W TO THE SOUTH OF 17N MOVING WESTWARD 15 KT.
THIS WAVE IS MOVING THROUGH THE AREA OF AN UPPER LEVEL TROUGH.
NEARBY SHOWERS MAY BE MORE RELATED TO THE UPPER LEVEL TROUGH
THAN TO THE WAVE.

...THE ITCZ...

10N14W 6N31W 13N45W 10N55W 11N58W. STRONG INDIVIDUAL
THUNDERSTORM CELLS WITHIN A 30 NM RADIUS OF 6N12W. WARMING
CLOUD TOP TEMPERATURES AND DISSIPATING PRECIPITATION WITHIN
A 30 NM RADIUS OF 10N17W. ISOLATED MODERATE SHOWERS AND
POSSIBLE THUNDERSTORMS FROM 4N TO 8N BETWEEN 30W AND 40W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL RIDGE EXTENDS FROM WEST CENTRAL MEXICO...INTO
THE CENTRAL GULF OF MEXICO...BEYOND CENTRAL FLORIDA...BEYOND
BERMUDA IN THE WESTERN ATLANTIC OCEAN. DRY AIR IN SUBSIDENCE
COVERS THE AREA TO THE WEST OF 90W. UPPER LEVEL MOISTURE AND
RAINSHOWERS IN A DIFFLUENT FLOW PATTERN COVER THE AREA TO THE
EAST OF 90W. THE SURFACE PRESSURE GRADIENT IS WEAK. A SHALLOW
FRONTAL BOUNDARY PASSES THROUGH SOUTHEASTERN LOUISIANA...BARELY
INTO THE NORTHWESTERN GULF WATERS...TO THE UPPER TEXAS COAST AND
BEYOND AS IT CONTINUES ACROSS CENTRAL TEXAS. ISOLATED MODERATE
SHOWERS ARE IN THE COASTAL WATERS OF LOUISIANA TO THE EAST OF
92W.

THE CARIBBEAN SEA...
UPPER LEVEL ANTICYCLONIC FLOW FROM THE GULF OF MEXICO AND THE
WESTERN ATLANTIC OCEAN STILL SPILLS INTO THE CARIBBEAN SEA...
ACROSS CUBA TOWARD NICARAGUA AND ALL POINTS TO THE NORTHWEST OF
NICARAGUA. AN UPPER LEVEL TROUGH PASSES THROUGH THE WINDWARD
PASSAGE FROM THE ATLANTIC OCEAN...TO JUST EAST OF JAMAICA...
TO A CYCLONIC CIRCULATION CENTER NEAR 15N79W...BEYOND CENTRAL
COSTA RICA INTO THE EASTERN PACIFIC OCEAN. ISOLATED MODERATE
SHOWERS ARE BETWEEN 76W AND 86W. A WEAKENING UPPER LEVEL TROUGH
EXTENDS FROM A CYCLONIC CENTER THAT IS ABOUT 250 NM TO THE
NORTHEAST OF PUERTO RICO TOWARD 12N60W. A SURFACE TROUGH
CURVES THROUGH THE MONA PASSAGE FROM 16N TO 20N ALONG 66W/67W.
THE COMPARATIVELY STRONGEST PRECIPITATION IS IN MONA PASSAGE.
ISOLATED SHOWERS ARE ELSEWHERE FROM 15N TO 20N BETWEEN 66W
AND 71W.

THE ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS ALONG 31N81W BEYOND 32N76W. DEEP LAYER
MOISTURE AND SHOWERS ARE IN AN UPPER LEVEL DIFFLUENT FLOW
PATTERN THAT IS TO THE SOUTHEAST AND SOUTH OF THE TROUGH.
THE MOISTURE AND SHOWERS ARE AT LEAST 420 NM TO THE SOUTHEAST
OF THE TROUGH. A SURFACE TROUGH PASSES THROUGH 32N63W TO 29N67W
TO 28N71W. A CENTRAL ATLANTIC OCEAN UPPER LEVEL TROUGH PASSES
THROUGH 32N55W TO AN UPPER LEVEL CYCLONIC CENTER THAT IS NEAR
27N58W TO 24N61W TO 22N70W BEYOND THE WINDWARD PASSAGE INTO THE
CARIBBEAN SEA. NO DEEP CONVECTIVE PRECIPITATION ACCOMPANIES THIS
TROUGH. A SECOND UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC
CIRCULATION CENTER THAT IS NEAR 29N47W TO 21N55W TO 16N60W.
PRETTY MUCH ALL OF THE EARLIER PRECIPITATION WITH THIS TROUGH
HAS BEEN DISSIPATING DURING THE LAST SIX HOURS. BROAD UPPER
LEVEL CYCLONIC FLOW COVERS THE AREA TO THE NORTH OF 26N BETWEEN
10W AND 40W. AN UPPER LEVEL TROUGH PASSES THROUGH 32N24W TO
26N25W. NO DEEP LAYER PRECIPITATION ACCOMPANIES THIS TROUGH.

$$
MT





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