[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131211
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN JUL 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1045 UTC.

...SPECIAL FEATURE....

BERTHA HAS WEAKENED TO A TROPICAL STORM AND A TROPICAL STORM
WARNING REMAINS IN EFFECT FOR BERMUDA. AT 13/1200 UTC BERTHA WAS
CENTERED NEAR 29.8N 62.5W...AND IT IS NEARLY STATIONARY. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 988 MB. THE MAXIMUM
SUSTAINED WIND SPEED HAS DECREASED TO 60 KT WITH GUSTS TO 75 KT.
THIS POSITION ALSO IS 189 NM/350 KM SOUTHEAST OF BERMUDA. PLEASE
READ THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER
MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. BERTHA IS CURRENTLY
NEARLY STATIONARY. A DRIFT TOWARD THE NORTHWEST IS EXPECTED TO
BEGIN LATER TODAY AND CONTINUE INTO MONDAY. THE CENTER OF BERTHA
IS EXPECTED TO PASS SLOWLY AND NOT FAR TO THE SOUTHEAST AND EAST
OF BERMUDA DURING THE NEXT COUPLE OF DAYS. THE MOTION MAY BE
ERRATIC AT TIMES AND IT MAY BRING THE CENTER OF BERTHA CLOSER TO
BERMUDA THAN THE FORECAST TRACK INDICATES. A SLIGHT WEAKENING IS
EXPECTED DURING THE NEXT COUPLE OF DAYS. TROPICAL STORM FORCE
WINDS EXTEND OUTWARD UP TO 120 NM/220 KM FROM THE CENTER.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 32W/33W SOUTH OF 15N
MOVING 10 TO 15 KT. A 1009 MB LOW PRESSURE CENTER IS NEAR 10N
ALONG THE WAVE. ITCZ PRECIPITATION IS AND HAS BEEN TO THE WEST
OF THE WAVE BETWEEN 36W AND 43W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 53W/54W SOUTH OF 16N
MOVING WEST 15 KT. ISOLATED MODERATE SHOWERS TO LOCALLY STRONG
THUNDERSTORMS FROM 10N TO 13N BETWEEN 48W AND 57W.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 80W/81W SOUTH OF
19N MOVING WEST 15 KT. THIS WAVE STRETCHES FROM WEST OF JAMAICA
TO CENTRAL PANAMA. STRONG SHOWERS AND THUNDERSTORMS FROM 10N TO
12N BETWEEN 78W AND 80W MAY OR MAY NOT HAVE ANYTHING TO DO WITH
THIS WAVE.

...THE ITCZ...
12N16W 12N24W 9N39W 11N50W 7N60W IN NORTHERN GUYANA. SCATTERED
STRONG SHOWERS AND THUNDERSTORMS FROM 5N TO 6N BETWEEN 39W AND
43W...AND FROM 7N TO 9N BETWEEN 59W AND 60W IN NORTHWESTERN
GUYANA. SCATTERED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS
FROM 7N TO 9N BETWEEN 15W AND 23W. ISOLATED MODERATE SHOWERS TO
LOCALLY STRONG THUNDERSTORMS ELSEWHERE FROM 2N TO 12N BETWEEN
35W AND 45W.

...DISCUSSION...

THE GULF OF MEXICO...AND THE ATLANTIC OCEAN WEST OF 70W...

A MIDDLE TO UPPER LEVEL TROUGH IS FORMING FROM THE ATLANTIC
OCEAN NEAR 32N78W TO NORTHERN FLORIDA INTO THE EASTERN AND
SOUTHEASTERN GULF OF MEXICO. SHOWERS AND THUNDERSTORMS ARE
NORTH OF 27N EAST OF 86W TO THE FLORIDA WEST COAST. A MIDDLE
TO UPPER LEVEL TROUGH RUNS FROM EASTERN CUBA ACROSS THE BAHAMAS
TO 32N75W IN THE ATLANTIC OCEAN. SHOWERS AND THUNDERSTORMS COVER
THE WATERS FROM CUBA TO 27N BETWEEN 74W AND 78W OVER THE
BAHAMAS. A SMALL MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION
CENTER HAS MOVED INTO THE CENTRAL PART OF THE SOUTHWESTERN
CORNER OF THE AREA...NORTH OF THE ISTHMUS OF TEHUANTEPEC.
A MIDDLE TO UPPER LEVEL TROUGH COVERS INTERIOR MEXICO WEST OF
100W PRODUCING WIDESPREAD PRECIPITATION WEST OF 30N104W 24N107W.

THE CARIBBEAN SEA...

THE TAIL END OF A MIDDLE TO UPPER LEVEL TROUGH THAT STARTS
NEAR 32N75W IN THE ATLANTIC OCEAN TO EASTERN CUBA REACHES THE
NORTHWESTERN CORNER OF THE AREA. SOME MIDDLE TO UPPER LEVEL
CYCLONIC FLOW FROM THE SOUTHWESTERN GULF OF MEXICO CYCLONIC
CIRCULATION CENTER REMAINS IN THE WATERS EAST OF THE YUCATAN
PENINSULA/NORTH OF HONDURAS. STRONG SHOWERS AND THUNDERSTORMS
PERSIST UNDER EXTENSIVE UPPER LEVEL ANTICYCLONIC OUTFLOW WITH
AN UPPER LEVEL RIDGE AND A MIDDLE LEVEL TROUGH IN THE
SOUTHWESTERN CORNER OF THE AREA. THE STRONG SHOWERS AND
THUNDERSTORMS ARE FROM 12N TO 14N BETWEEN 80W AND 86W INCLUDING
IN EASTERN AND NORTHEASTERN NICARAGUA. MIDDLE TO UPPER LEVEL
DRY AIR IN SUBSIDENCE IS EAST OF 70W AND EAST OF 72W SOUTH OF
HISPANIOLA. BROAD MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW IS
NORTH OF 16N BETWEEN 60W AND 70W. A MIDDLE LEVEL CYCLONIC
CIRCULATION IN THE DRY AIR/SUBSIDENCE IS NEAR 14N64W.

THE REST OF THE ATLANTIC OCEAN EAST OF 70W...

A MIDDLE TO UPPER LEVEL TROUGH REMAINS ABOUT 900 NM EAST OF
HURRICANE BERTHA...THROUGH 33N46W TO 23N46W. A SURFACE TROUGH IS
ALONG 46W/47W NORTH OF 32N. ISOLATED MODERATE SHOWERS ARE
NORTH OF 29N BETWEEN 43W AND 47W. BROAD MIDDLE TO UPPER LEVEL
CYCLONIC FLOW FROM 10N TO 20N BETWEEN 30W AND 34W IS AROUND
A WEAK AND POSSIBLY STILL-FORMING CYCLONIC CENTER NEAR 14N35W.

$$

MT


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