[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171615
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON AUG 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1545 UTC.

...SPECIAL FEATURES...
TROPICAL STORM CLAUDETTE MOVED INLAND NEAR FORT WALTON BEACH
AROUND 17/0500 UTC. CLAUDETTE HAS WEAKENED AS IT CONTINUES ITS
MOVEMENT OVER LAND. CLAUDETTE BECAME A TROPICAL DEPRESSION AT
17/1200 UTC. CLAUDETTE AT 17/1500 UTC IS NEAR 31.7N 87.6W...
OR 85 MILES/140 KM TO THE NORTH-NORTHWEST OF PENSACOLA FLORIDA
AND 80 MILES/130 KM TO THE WEST-SOUTHWEST OF MONTGOMERY ALABAMA.
CLAUDETTE WILL CONTINUE DURING ITS TRACK NORTHWESTWARD THROUGH
ALABAMA. THE CENTER OF CLAUDETTE IS EXPECTED TO MOVE OVER
SOUTHWESTERN ALABAMA DURING THE DAY TODAY AND INTO NORTHEASTERN
MISSISSIPPI TONIGHT. THE MAXIMUM SUSTAINED WINDS ARE NEAR
30 MPH/50 KM PER HOUR WITH HIGHER GUSTS. THE MINIMUM CENTRAL
PRESSURE IS 1013 MB/29.92 INCHES. STRONG SHOWERS AND
THUNDERSTORMS COVER THE AREA FROM THE COASTAL WATERS FROM 28N
TO LAND BETWEEN 83W NEAR FLORIDA AND 91W NEAR SOUTHEASTERN
LOUISIANA.

THE CENTER OF TROPICAL DEPRESSION ANA AT 17/1500 UTC IS NEAR
17.3N 66.2W...OR ABOUT 75 MILES/125 KM TO THE SOUTH OF SAN JUAN
PUERTO RICO AND ABOUT 255 MILES/415 KM TO THE EAST-SOUTHEAST OF
SANTO DOMINGO IN THE DOMINICAN REPUBLIC. IT IS MOVING WEST-
NORTHWESTWARD 24 KT. LITTLE CHANGE IN STRENGTH IS FORECAST
DURING THE NEXT 24 HOURS. IT IS POSSIBLE THAT ANA MAY DEGENERATE
INTO A TROPICAL WAVE LATER TODAY. ANA IS EXPECTED TO PRODUCE
RAINFALL AMOUNTS RANGING FROM 2 TO 4 INCHES ACROSS PUERTO
RICO...THE U.S. AND BRITISH VIRGIN ISLANDS...AND THE DOMINICAN
REPUBLIC...WITH ISOLATED MAXIMUM AMOUNTS OF 6 INCHES IN
MOUNTAINOUS TERRAIN. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS
COVER THE AREA FROM 17N TO 20N BETWEEN 65W AND 70W...COVERING
PUERTO RICO...THE EASTERN DOMINICAN REPUBLIC...AND SURROUNDING
WATERS.

THE CENTER OF HURRICANE BILL AT 17/1500 UTC IS NEAR 14.1N
45.2W...OR ABOUT 1080 MILES/1735 KM TO THE EAST OF THE LESSER
ANTILLES. BILL IS MOVING TOWARD THE WEST-NORTHWEST 14 KT. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 977 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 80 KT WITH GUSTS TO 100 KT. SOME
STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS...AND IT
IS POSSIBLE THAT BILL MAY BECOME A MAJOR HURRICANE BY WEDNESDAY.
PLEASE READ THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
TCMAT3/ WTNT23 KNHC FOR MORE DETAILS. STRONG SHOWERS AND
THUNDERSTORMS ARE FROM 12N TO 13N BETWEEN 39W AND 40W...AND
FROM 10N TO 11N BETWEEN 41W AND 42W. HURRICANE FORCE WINDS
EXTEND OUTWARD UP TO 30 MILES/45 KM FROM THE CENTER...AND
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 145 MILES/
230 KM. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM
12N TO 14N BETWEEN 44W AND 47W.

...TROPICAL WAVES...
AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 17N30W 13N28W
10N28W MOVING WESTWARD 10 TO 15 KT. DISORGANIZED ISOLATED
MODERATE SHOWERS COVER THE AREA FROM 12N TO 16N BETWEEN 24W
AND 30W.

A TROPICAL WAVE IS ALONG 93W/94W TO THE SOUTH OF 22N...STRETCHING
FROM THE SOUTHWESTERN GULF OF MEXICO...ACROSS THE ISTHMUS OF
TEHUANTEPEC INTO THE EASTERN PACIFIC OCEAN. THE WAVE IS MOVING
WESTWARD ABOUT 15 KT. THIS WAVE IS MOVING TOWARD THE AREA OF
A MIDDLE LEVEL TO UPPER LEVEL TROUGH THAT IS CONNECTED TO A
CYCLONIC CENTER NEAR 21N98W. ISOLATED MODERATE SHOWERS ARE IN
THE GULF OF MEXICO TO THE SOUTH OF 22N TO THE WEST OF 93W.

...THE ITCZ...
FROM THE AFRICA COAST NEAR 14N17W TO 11N20W 11N26W 11N31W 12N41W
10N49W TO TRINIDAD/VENEZUELA NEAR 10N62W. ISOLATED MODERATE
SHOWERS ARE ELSEWHERE FROM 7N TO 16N BETWEEN AFRICA AND 40W...
AND ELSEWHERE AWAY FROM HURRICANE BILL FROM 3N TO 13N BETWEEN
40W AND 60W.

...DISCUSSION...

THE GULF OF MEXICO...
BROAD MIDDLE LEVEL TO UPPER LEVEL CYCLONIC FLOW COVERS THE AREA
TO THE WEST OF 90W. A TROUGH EXTENDS FROM THE UPPER TEXAS COAST
TO A CYCLONIC CIRCULATION CENTER THAT IS IN EASTERN MEXICO NEAR
21N98W...AND THAT EVENTUALLY REACHES NEAR ACAPULCO. ISOLATED
MODERATE SHOWERS ARE TO THE SOUTH AND SOUTHWEST OF THE LINE
29N95W 25N89W 21N90W. MIDDLE LEVEL TO UPPER LEVEL CYCLONIC FLOW
ALSO HAS WORKED ITS WAY INTO THE EASTERN AND SOUTHEASTERN CORNER
OF THE AREA...THANKS TO AN AREA OF ATLANTIC OCEAN CYCLONIC FLOW
THAT CUTS INTO THE GULF OF MEXICO. TROPICAL STORM CLAUDETTE HAS
MOVED ASHORE IN THE FLORIDA PANHANDLE AND IT HAS WEAKENED INTO
A TROPICAL DEPRESSION.

THE CARIBBEAN SEA...
A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A SMALL GULF
OF HONDURAS CYCLONIC CIRCULATION CENTER TO SOUTHWESTERN HONDURAS.
WEAK UPPER LEVEL CYCLONIC FLOW MOVES FROM THE COASTAL WATERS OF
NICARAGUA TOWARD LAND AND EASTERN HONDURAS. ISOLATED MODERATE
SHOWERS ARE FROM 11N TO 20N TO THE WEST OF 81W. SOME UPPER LEVEL
NORTHWESTERLY FLOW CUTS ACROSS THIS AREA OF PRECIPITATION.
MIDDLE LEVEL TO UPPER LEVEL CYCLONIC FLOW COVERS THE AREA TO THE
NORTH OF 16N BETWEEN 70W AND 84W...ASSOCIATED WITH THE WESTERN
ATLANTIC OCEAN CYCLONIC CENTER NEAR 25N75W. ISOLATED MODERATE
SHOWERS ARE IN THE AREA OF CYCLONIC FLOW.

THE ATLANTIC OCEAN...
A WESTERN ATLANTIC OCEAN MIDDLE LEVEL TO UPPER LEVEL CYCLONIC
CIRCULATION CENTER IS NEAR 25N76W...APPROACHING THE BAHAMA
ISLANDS. CYCLONIC FLOW COVERS THE AREA FROM 16N IN THE CARIBBEAN
SEA TO 31N IN THE ATLANTIC OCEAN BETWEEN 70W AND 84W IN THE GULF
OF MEXICO. SCATTERED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS
ARE MOVING NORTHWESTWARD...FROM 20N/21N TO 25N BETWEEN 67W AND
72W. ISOLATED MODERATE SHOWERS ARE ELSEWHERE FROM 20N TO 32N
BETWEEN 67W AND 78W...CURVING CYCLONICALLY ACROSS THIS AREA.
A CENTRAL ATLANTIC OCEAN MIDDLE LEVEL TO UPPER LEVEL TROUGH GOES
FROM 32N47W TO 27N50W TO 23N53W. ISOLATED MODERATE SHOWERS WITHIN
30 NM ON EITHER SIDE OF 27N BETWEEN 53W AND 60W...AND TO THE
NORTH OF 30N BETWEEN 47W AND 53W. A MIDDLE LEVEL TO UPPER LEVEL
EASTERN ATLANTIC OCEAN TROUGH PASSES THROUGH 32N12W TO 27N21W
TO 20N34W. THIS FEATURE IS SURROUNDED BY DRY AIR/SUBSIDENCE ON
WATER VAPOR IMAGERY.

$$
MT




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