[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 130625
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON OCT 13 2008

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 0545 UTC.

...SPECIAL FEATURES...
THE CENTER OF TROPICAL STORM NANA AT 13/0300 UTC IS NEAR
16.6N 38.8W...MOVING WEST-NORTHWEST OR 285 DEGREES 7 KT.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 35 KT WITH GUSTS TO 45 KT. PLEASE
READ THE LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 85 NM FROM
THE CENTER IN THE EASTERN SEMICIRCLE. NUMEROUS STRONG SHOWERS
AND THUNDERSTORMS ARE FROM 15N TO 17N BETWEEN 35W AND 37W.
NANA IS EXPECTED TO WEAKEN DURING THE NEXT DAY OR SO...
AND FORECAST TO BECOME A TROPICAL DEPRESSION LATER TODAY.

A 1008 MB CARIBBEAN SEA LOW PRESSURE CENTER IS NEAR 16N69W.
IT IS POSSIBLE THAT THIS LOW CENTER MAY BECOME A TROPICAL
CYCLONE DURING THE NEXT 24 HOURS OR SO. NUMEROUS STRONG
SHOWERS AND THUNDERSTORMS ARE FROM 14N TO 16N BETWEEN 63W
AND 68W. THIS SYSTEM IS EXPECTED TO RESULT IN HEAVY RAINS
IN PUERTO RICO AND PARTS OF THE LEEWARD ISLANDS DURING THE
NEXT FEW DAYS. THESE RAINS MAY CAUSE FLASH FLOODS IN SOME AREAS.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 20N46W 10N44W MOVING
WEST 10 TO 15 KT. IT IS NOT READILY APPARENT THAT ANY CONVECTIVE
PRECIPITATION IS ACCOMPANYING THIS WAVE.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 56W/57W SOUTH OF 20N
MOVING WEST 10 KT. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS
ARE FROM 18N TO 22N BETWEEN 55W AND 60W. A MIDDLE TO UPPER LEVEL
IS NEAR 21N62W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 70W/71W SOUTH OF 20N
MOVING WEST 10 KT. THE WAVE EXTENDS FROM THE WESTERN DOMINICAN
REPUBLIC TO NORTHWESTERN VENEZUELA. UPPER LEVEL SOUTHWESTERLY
WIND FLOW IS MOVING ON TOP OF THE AREA OF THIS WAVE. MODERATE
SHOWERS AT THE NORTHERN COAST OF COLOMBIA BETWEEN 73W AND 74W...
AND STRONG THUNDERSTORMS WITHIN A 15 NM RADIUS OF 8N72.5W
NEAR THE COLOMBIA/VENEZUELA BORDER MAY HAVE BEEN ASSOCIATED
WITH THIS WAVE. THOSE AREAS OF CONVECTIVE PRECIPITATION HAVE
DISSIPATED DURING THE LAST 2 TO 3 HOURS.

...THE ITCZ...
12N16W 5N31W 9N43W 10N47W 10N60W. SCATTERED MODERATE SHOWERS
TO ISOLATED STRONG THUNDERSTORMS ARE SOUTH OF 7N BETWEEN 29W
AND 37W. ISOLATED MODERATE SHOWERS TO POSSIBLE THUNDERSTORMS
ELSEWHERE FROM 3N TO 10N BETWEEN 10W AND 29W. ISOLATED MODERATE
SHOWERS TO LOCALLY STRONG THUNDERSTORMS ELSEWHERE FROM 6N TO
15N BETWEEN 38W AND 60W. A 1010 MB LOW PRESSURE CENTER IS NEAR
12N42W. SCATTERED STRONG THUNDERSTORMS IN SOME CELLS ARE FROM
12N TO 13N BETWEEN 41W AND 42W.

...DISCUSSION...

THE GULF OF MEXICO...
MIDDLE TO UPPER LEVEL NORTHERLY FLOW AND DRY AIR IN SUBSIDENCE
ON THE WESTERN SIDE OF A TROUGH. THE TROUGH RUNS FROM
NORTHEASTERN FLORIDA TO A CYCLONIC CIRCULATION CENTER ALONG
THE NORTHWESTERN CORNER OF THE YUCATAN PENINSULA...TO THE
NORTHEASTERN COAST OF THE ISTHMUS OF TEHUANTEPEC. ISOLATED
MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE ON THE EASTERN
SIDE OF THE TROUGH.

THE CARIBBEAN SEA...
A SPECIAL FEATURE 1008 MB LOW PRESSURE CENTER IS NEAR 16N69W.
MIDDLE TO UPPER LEVEL SOUTHWESTERLY WIND FLOW COVERS THE AREA
WEST OF A LINE FROM SOUTHEASTERN CUBA TO THE HONDURAS COAST.
THIS FLOW IS DUE TO THE CYCLONIC FLOW WITH THE NORTHEASTERN
FLORIDA-TO-NORTHWESTERN YUCATAN PENINSULA MIDDLE TO UPPER LEVEL
TROUGH. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS ARE WEST OF THE LINE FROM CUBA TO HONDURAS.
BROAD UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE AREA
TO THE EAST OF THE CUBA-TO-HONDURAS LINE.

THE ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH PASSES THROUGH 33N14W TO 30N20W 32N24W.
UPPER LEVEL ANTICYCLONIC FLOW...THAT IS NORTH OF 22N17W 22N30W
BEYOND 32N38W...IS MOVING ON TOP OF THIS TROUGH. A MIDDLE TO
UPPER LEVEL TROUGH PASSES THROUGH 33N40W TO 24N42W. A STATIONARY
FRONT PASSES THROUGH 32N43W TO 27N50W. ISOLATED MODERATE SHOWERS
TO POSSIBLE THUNDERSTORMS ARE NORTH OF 26N BETWEEN 40W AND 50W.
ONE MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR
24N57W. A SECOND MIDDLE TO UPPER LEVEL CYCLONIC CENTER IS NEAR
24N64W. UPPER LEVEL ANTICYCLONIC FLOW IS MOVING ON TOP OF THE
AREA OF THESE TWO CYCLONIC CENTERS. ISOLATED MODERATE SHOWERS
TO POSSIBLE THUNDERSTORMS ARE FROM 24N TO 26N BETWEEN 57W AND
61W...SOME PRECIPITATION HAS BEEN DISSIPATING DURING THE LAST
TWO TO THREE HOURS. SCATTERED MODERATE SHOWERS AND THUNDERSTORMS
ARE WITHIN A 15 TO 30 NM RADIUS OF 27N76W...ASSOCIATED WITH
A COMPARATIVELY FAST-MOVING LOW TO MIDDLE LEVEL CYCLONIC
CIRCULATION CENTER. THIS PRECIPITATION MAY PASS OVER THE
NORTHERN BAHAMAS DURING THE NEXT FEW HOURS AND IT MAY REACH
THE FLORIDA COAST EVEN...IF IT REMAINS INTACT.

$$
MT




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