[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071044
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI AUG 07 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 34W TO THE SOUTH OF
17N MOVING WESTWARD 10 TO 15 KT. LINGERING ISOLATED SHOWERS
FROM 13N TO 15N BETWEEN 34W AND 38W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 51W/52W TO THE SOUTH
OF 15N MOVING WESTWARD 15 TO 20 KT. NEARBY ITCZ PRECIPITATION.

AN EASTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 68W/69W FROM 20N
SOUTHWARD THROUGH THE MONA PASSAGE INTO NORTHWESTERN COASTAL
VENEZUELA...MOVING WESTWARD ABOUT 15 KT. THIS WAVE IS MOVING
TOWARD THE AREA THAT ALREADY IS COVERED BY AN UPPER LEVEL TROUGH
WHOSE BASE REACHES NORTHERN COASTAL COLOMBIA...AND THE BASE OF
A DIFFERENT UPPER LEVEL TROUGH THAT REACHES THE EASTERN SECTIONS
OF THE DOMINICAN REPUBLIC. NO SIGNIFICANT DEEP CONVECTIVE
PRECIPITATION JUST ACCOMPANIES ONLY THE TROPICAL WAVE.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 85W/86W FROM THE
YUCATAN CHANNEL SOUTHWARD INTO NICARAGUA...MOVING WESTWARD ABOUT
15 KT. IT IS NOT EASY TO FIND SIGNIFICANT DEEP CONVECTIVE
PRECIPITATION THAT JUST ACCOMPANIES ONLY THE TROPICAL WAVE.
SOME PRECIPITATION IS IN THE SOUTHWESTERN CORNER OF THE
CARIBBEAN SEA...IN UPPER LEVEL DIFFLUENT WIND FLOW.

...THE ITCZ...

FROM THE AFRICA COAST NEAR 11N15W TO 15N38W 11N56W. WHAT APPEARS
TO BE A SECOND ITCZ...AND/OR A SECOND OF LINE OF SURFACE
CONFLUENT WIND FLOW...IS TO THE SOUTH OF THE FIRST ONE ALONG
10N14W 9N23W 7N34W 7N41W 7N50W 6N56W. IT IS INTERESTING TO NOTE
THAT THE LAST VISIBLE SATELLITE IMAGES FROM YESTERDAY CLEARLY
SHOW THAT THE WIND FLOW FROM THE EQUATOR NORTHWARD BLOWS RIGHT
PAST THE 10N14W 6N56W LINE TOWARD THE 11N15W 11N56W LINE...GIVING
THE IMPRESSION THAT THE NORTHERN-MORE LINE IS THE ITCZ. STRONG
SHOWERS AND THUNDERSTORMS ARE IN CLUSTERS FROM 10N TO 13N
BETWEEN 44W AND 57W. SCATTERED MODERATE SHOWERS TO ISOLATED
STRONG THUNDERSTORMS ARE FROM 6N TO 8N BETWEEN 48W AND 53W.
ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE
ELSEWHERE FROM 6N TO 11N BETWEEN AFRICA AND 44W. STRONG SHOWERS
AND THUNDERSTORMS ARE IN THE COASTAL WATERS OF AFRICA FROM
13N TO 17N...POSSIBLY/PROBABLY WITH THE NEXT TROPICAL WAVE.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL TROUGH EXTENDS FROM A 24N92W TO 19N99W INLAND
IN SOUTH CENTRAL MEXICO. SHOWERS ARE WITHIN 60 NM TO 120 NM ON
EITHER SIDE OF THE TROUGH. THIS TROUGH IS IN THE MIDDLE OF TWO
SEPARATE AREAS OF UPPER LEVEL ANTICYCLONIC FLOW. A SURFACE
TROUGH PASSES THROUGH NORTH CENTRAL FLORIDA TO 28N85W TO 24N87W
INTO THE NORTHERN YUCATAN PENINSULA. ISOLATED MODERATE SHOWERS
ARE TO THE SOUTH OF 29N TO THE EAST OF 86W. EARLIER PRECIPITATION
IN INTERIOR MEXICO HAS BEEN DISSIPATING DURING THE LAST SIX
HOURS.

THE CARIBBEAN SEA...
THE MODERATE TO STRONG SHOWERS AND THUNDERSTORMS IN EL SALVADOR
SIX HOURS NOW ONLY ARE IN ITS COASTAL WATERS...IN BROAD SURFACE
LOW PRESSURE AND UPPER LEVEL DIFFLUENT FLOW. ONE TROPICAL WAVE
IS ALONG 68W/69W...AND A SECOND ONE IS ALONG 85W/86W. IT DOES
NOT APPEAR THAT EITHER WAVE IS ACCOMPANIED BY MUCH
PRECIPITATION. ONE UPPER LEVEL TROUGH RUNS FROM 16N77W
TO NORTHERN COASTAL COLOMBIA. NUMEROUS STRONG SHOWERS AND
THUNDERSTORMS ARE IN NORTHERN COLOMBIA AND THE GULF OF URABA
FROM 7N TO 10N BETWEEN 75W AND 79W. THE LAKE MARACAIBO
PRECIPITATION FROM SIX HOURS AGO HAS DISSIPATED. A PERSISTENT
UPPER LEVEL TROUGH PASSES THROUGH 25N67W OF THE ATLANTIC OCEAN
TO EASTERN SECTIONS OF THE DOMINICAN REPUBLIC. SHOWERS ARE
POSSIBLE FROM THE NORTHEASTERN ISLANDS TO 20N BETWEEN 60W AND
70W...UNDER THE PERSISTENT UPPER LEVEL CYCLONIC FLOW AROUND THE
TROUGH.

FROM THE WESTERN ATLANTIC OCEAN INTO THE EASTERN CARIBBEAN SEA..
A PERSISTENT UPPER LEVEL TROUGH GOES BERMUDA TO 25N67W TO
EASTERN SECTIONS OF THE DOMINICAN REPUBLIC. SHOWERS AND POSSIBLE
THUNDERSTORMS WILL CONTINUE TO BE POSSIBILITY TO THE NORTH OF
20N BETWEEN 60W AND 73W. A SURFACE TROUGH IS ALONG 29N72W
22N74W. THIS TROUGH USED TO BE THE NORTHERN EXTENSION OF THE
MONA PASSAGE/CARIBBEAN SEA TROPICAL WAVE.

THE REST OF THE ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE GOES FROM SOUTHEASTERN CUBA TO 26N78W
IN THE PROVIDENCE CHANNEL...IN BETWEEN ANDROS ISLAND AND GRAND
BAHAMA AND ABACO ISLAND OF THE BAHAMAS...BEYOND 32N79W. AN UPPER
LEVEL TROUGH EXTENDS FROM A CYCLONIC CIRCULATION CENTER THAT IS
NEAR 28N39W TO 19N48W. ISOLATED MODERATE SHOWERS FROM 25N TO 31N
BETWEEN 41W AND 46W.

$$
MT




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