[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 261142
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED SEP 26 2012

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
VALID THROUGH 1015 UTC.

...SPECIAL FEATURE...

THE CENTER OF TROPICAL STORM NADINE AT 26/0900 UTC IS NEAR
30.9N 30.5W. NADINE IS ABOUT 460 NM/850 KM TO THE
SOUTH-SOUTHWEST OF THE AZORES. NADINE IS MOVING
SOUTH-SOUTHWESTWARD 4 KNOTS. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 998 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE
40 KNOTS WITH GUSTS TO 50 KNOTS. TROPICAL STORM FORCE WINDS
EXTEND OUTWARD UP TO 90 NM IN THE SOUTHEASTERN QUADRANT...
AND TO 100 NM ELSEWHERE AROUND THE CENTER OF NADINE.
PLEASE READ THE FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC...AND THE PUBLIC ADVISORY...
MIATCPAT4/WTNT34 KNHC...FOR MORE DETAILS. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO STRONG FROM
31N TO 32N BETWEEN 28W AND 31W.

...TROPICAL WAVE...

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 18N69W 15N72W...TO
11N73W IN NORTHEASTERN COLOMBIA. THE WAVE IS MOVING WESTWARD
15 KNOTS DURING THE LAST 24 HOURS. THE TROPICAL WAVE IS JUST
TO THE EAST OF AN UPPER LEVEL TROUGH THAT PASSES THROUGH...
CENTRAL HISPANIOLA TO A 14N75W CYCLONIC CIRCULATION CENTER TO
THE GULF OF URABA OF COLOMBIA.  RAINSHOWERS ARE POSSIBLE WITHIN
60 NM ON EITHER SIDE OF THE TROPICAL WAVE. IT IS NOT EASY TO
FIND PRECIPITATION THAT ONLY ACCOMPANIES THE WAVE.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL GUINEA-BISSAU NEAR
12N16W TO 9N20W AND 5N33W. THE ITCZ CONTINUES FROM 5N33W TO
5N35W TO 10N42W AND 12N48W. CONVECTIVE PRECIPITATION...BROKEN
TO OVERCAST MULTILAYERED CLOUDS AND WIDELY SCATTERED MODERATE
TO ISOLATED STRONG WITHIN 300 NM ON EITHER SIDE OF 2N14W
3N32W 10N45W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE
PRECIPITATION IS IN PART OF THE CAPE VERDE ISLANDS FROM
13N TO 16N BETWEEN 19W AND 24W.

...DISCUSSION...

THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH CUTS THROUGH THE
NORTHEASTERN FLORIDA...TO 25N88W IN THE GULF OF MEXICO...
TO 21N91W IN THE SOUTHWESTERN CORNER OF THE AREA. COMPARATIVELY
DRIER AIR IN SUBSIDENCE IS TO THE NORTHWEST AND WEST OF THE LINE
THAT PASSES THROUGH 30N80W IN THE ATLANTIC OCEAN...TO 26N86W...
TO 24N88W TO 21N95W TO 19N96W. BROKEN TO OVERCAST MULTILAYERED
CLOUDS AND POSSIBLE RAINSHOWERS ARE TO THE EAST OF THE AREA
OF COMPARATIVELY DRIER AIR.

A SURFACE RIDGE PASSES THROUGH CENTRAL ALABAMA TO 28N95W
IN THE NORTHWESTERN CORNER OF THE AREA...TO A 1017 MB
COASTAL MEXICO HIGH PRESSURE CENTER THAT IS NEAR 21N98W...
TO THE ISTHMUS OF TEHUANTEPEC OF SOUTHERN MEXICO.

THE CARIBBEAN SEA...

AN UPPER LEVEL TROUGH PASSES THROUGH...CENTRAL HISPANIOLA
TO A 14N75W CYCLONIC CIRCULATION CENTER TO THE GULF OF URABA
OF COLOMBIA. A TROPICAL WAVE IS JUST TO THE EAST OF THE UPPER
LEVEL SYSTEM...ALONG 18N69W 15N72W...TO 11N73W IN NORTHEASTERN
COLOMBIA. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND SCATTERED
MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION IS FROM
THE COLOMBIA COASTAL WATERS TO 23N IN THE ATLANTIC OCEAN BETWEEN
65W AND 75W.

RAINSHOWERS ARE POSSIBLE TO THE NORTH OF 13N TO THE WEST OF 76W
IN SURFACE EASTERLY WIND FLOW AND POSSIBLE LINES OF SURFACE
CONFLUENT WIND FLOW. SCATTERED MODERATE TO ISOLATED STRONG
CONVECTIVE PRECIPITATION IS TO THE NORTH OF 15N TO THE WEST
OF 82W. THIS PRECIPITATION IS RELATED TO THE UPPER LEVEL
DIFFLUENT WIND FLOW FROM THE GULF OF MEXICO MIDDLE TO UPPER
LEVEL TROUGH. PASSES THROUGH

THE MONSOON TROUGH IS ALONG 9N73W IN COLOMBIA...THROUGH
8N81W IN PANAMA...BEYOND 9N83W IN SOUTHERN COSTA RICA.
CONVECTIVE  PRECIPITATION...WIDELY SCATTERED MODERATE TO
ISOLATED STRONG TO THE SOUTH OF 12N TO THE WEST OF 76W
IN THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA.

PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT3...FOR DETAILS ABOUT 20 TO 25 KNOT
WINDS AND 9 FOOT SEA HEIGHTS FROM 12N TO 16N BETWEEN 69W AND 79W
FOR AT LEAST THE FIRST 12 HOURS OF THE FORECAST PERIOD.

THE ATLANTIC OCEAN...

A STATIONARY FRONT PASSES ON TOP OF BERMUDA...TO 29N71W...
ACROSS ELEUTHERA ISLAND AND NEW PROVIDENCE ISLAND AND ANDROS
ISLAND IN THE BAHAMAS...TO 23N82W IN THE FLORIDA STRAITS.
BROKEN TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE CONVECTIVE
PRECIPITATION ARE WITHIN 120 TO 240 NM ON EITHER SIDE OF THE
LINE THAT PASSES THROUGH 34N64W TO 26N77W...TO 23N85W IN THE
SOUTHEASTERN CORNER OF THE GULF OF MEXICO.

AN UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 30N45W.
CYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN TO THE NORTH OF
23N BETWEEN 40W AND 57W. A SEPARATE CYCLONIC CIRCULATION CENTER
IS NEAR 23N57W. CYCLONIC WIND FLOW THAT IS MOVING AROUND THIS
CENTER COVERS THE ATLANTIC OCEAN FROM 18N TO 25N BETWEEN 50W
AND 65W. A SURFACE TROUGH IS ALONG 23N49W 19N52W. CONVECTIVE
PRECIPITATION...SCATTERED STRONG FROM 20N TO 22N BETWEEN 50W
AND 52W...SCATTERED MODERATE TO ISOLATED STRONG ELSEWHERE
FROM 20N TO 23N BETWEEN 49W AND 57W.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A 25N34W
CYCLONIC CIRCULATION CENTER TO 19N35W AND 16N38W 15N46W.
COMPARATIVELY DRIER AIR IN SUBSIDENCE IS WITHIN 120 NM ON
EITHER SIDE OF THE LINE THAT STARTS NEAR 30N20W 25N27W
18N38W...AND TO THE NORTH OF 30N TO THE EAST OF 20W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION
IS FROM 24N TO 25N BETWEEN 36W AND 40W...RAINSHOWERS ARE POSSIBLE
FROM 20N TO 22N BETWEEN 40W AND 43W.

A SURFACE TROUGH IS ALONG 58W/59W FROM 11N TO 16N. RAINSHOWERS
ARE POSSIBLE WITHIN 30 TO 60 NM ON EITHER SIDE OF THE TROUGH.

A SECOND SURFACE TROUGH IS ALONG 26N39W 22N41W.

SURFACE ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN FROM
13N TO 26N BETWEEN AFRICA AND 36W. THE ANTICYCLONIC WIND FLOW
MOVES AROUND A 1016 MB HIGH PRESSURE CENTER THAT IS NEAR 23N29W.

A SURFACE RIDGE PASSES THROUGH 35N53W TO 29N57W AND 21N67W.

PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...
FOR DETAILS ABOUT TROPICAL STORM NADINE.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
MT





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