[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 070556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0515 UTC.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 32W/33W TO THE SOUTH OF
16N MOVING WESTWARD 10 TO 15 KT. NEARBY ITCZ PRECIPITATION.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 50W TO THE SOUTH OF 15N
MOVING WESTWARD 15 TO 20 KT. NEARBY ITCZ PRECIPITATION.

AN EASTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 67W FROM 20N
SOUTHWARD ACROSS WESTERN PUERTO RICO INTO NORTH CENTRAL 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 THAT JUST ACCOMPANIES ONLY THE TROPICAL WAVE.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 83W/84W FROM
WESTERN CUBA SOUTHWARD 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 BETWEEN JAMAICA AND CUBA...AND IN THE SOUTHWESTERN CORNER
OF THE CARIBBEAN SEA...IN DIFFERENT AREAS OF DIFFLUENT WIND FLOW.

...THE ITCZ...

FROM THE AFRICA COAST NEAR 11N15W TO 14N32W 12N42W 11N55W. 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 11N55W LINE...GIVING
THE IMPRESSION THAT THE NORTHERN-MORE LINE IS THE ITCZ. STRONG
SHOWERS AND THUNDERSTORMS ARE IN CLUSTERS NEAR 14N34W...AND
WITHIN 15 NM TO 30 NM ON EITHER SIDE OF 11N BETWEEN 43W AND 55W.
SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE
NEAR 6N42W...AND FROM 6N TO 8N BETWEEN 46W AND 54W. ISOLATED
MODERATE SHOWERS ARE WITHIN 30 NM TO 60 NM ON EITHER SIDE OF
THE 10N14W 7N34W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL TROUGH EXTENDS FROM A 24N93W 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.
ISOLATED MODERATE SHOWERS ARE TO THE SOUTH OF 28N TO THE EAST
OF 86W. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS ARE IN MEXICO BETWEEN THE ISTHMUS OF TEHUANTEPEC
AND THE BORDER WITH GUATEMALA...ENHANCED BY UPPER LEVEL
DIFFLUENT WIND FLOW...ON THE SOUTHERN SIDE OF THE CYCLONIC FLOW
AROUND THE UPPER LEVEL TROUGH.

THE CARIBBEAN SEA...
STRONG MODERATE TO STRONG SHOWERS AND THUNDERSTORMS ARE IN
EASTERN EL SALVADOR AND ITS COASTAL WATERS...IN BROAD SURFACE
LOW PRESSURE AND UPPER LEVEL DIFFLUENT FLOW. ONE TROPICAL WAVE
IS ALONG 67W...AND A SECOND ONE IS ALONG 83W/84W. IT DOES NOT
APPEAR THAT EITHER WAVE IS ACCOMPANIED BY MUCH PRECIPITATION.
ONE UPPER LEVEL TROUGH IS ALONG 16N77W TO NORTHERN COASTAL
COLOMBIA. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE IN
COLOMBIA AND VENEZUELA FROM 6N TO 11N BETWEEN 71W WITH LAKE
MARACAIBO AND 77W. THE BASE OF A PERSISTENT UPPER LEVEL TROUGH
PASSES THROUGH 25N67W OF THE ATLANTIC OCEAN TO EASTERN SECTIONS
OF THE DOMINICAN REPUBLIC. ISOLATED MODERATE SHOWERS AND LOCALLY
STRONG THUNDERSTORMS ARE FROM 19N TO 20N BETWEEN 68W AND 69W
JUST OFF THE EASTERN COAST OF THE DOMINICAN REPUBLIC.

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. ISOLATED MODERATE
SHOWERS ARE FROM 20N TO 32N BETWEEN 60W AND 73W. A SURFACE
TROUGH IS ALONG 29N72W 22N74W. THIS TROUGH USED TO BE THE
NORTHERN EXTENSION OF THE EASTERN 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. SHOWERS ARE POSSIBLE FROM 24N TO 30N
BETWEEN 40W AND 50W.

$$
MT





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