[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE SEP 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...SPECIAL FEATURE...

THE CENTER OF TROPICAL STORM NADINE AT 18/1800 UTC IS NEAR
34.8N 32.7W. NADINE IS MOVING NORTHEASTWARD 7 KT.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 983 MB.
THE MAXIMUM SUSTAINED WIND SPEEDS ARE 50 KNOTS WITH GUSTS
TO 60 KNOTS. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP
TO 200 NM/370 KM. 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 35N TO 36N
BETWEEN 32W AND 33W.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 41W/42W TO THE SOUTH
OF 17N...MOVING WESTWARD 15 KNOTS DURING THE LAST 24 HOURS.
CONVECTIVE PRECIPITATION...ISOLATED MODERATE TO LOCALLY
STRONG FROM 11N TO 17N BETWEEN 41W AND 47W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 17N59W 15N62W 12N63W...
MOVING WESTWARD 5 TO 10 KNOTS DURING THE LAST 24 HOURS.
CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 15N TO 17N
BETWEEN 67W AND 70W...SCATTERED MODERATE TO ISOLATED STRONG
FROM 16N TO 19N BETWEEN 62W AND 68W IN INCLUDING PUERTO RICO
AND THE VIRGIN ISLANDS...ISOLATED TO WIDELY SCATTERED MODERATE
FROM 14N TO 17N BETWEEN 60W AND 62W.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL MAURITANIA NEAR 19N16W
TO 13N20W 6N29W 8N41W. THE ITCZ IS NOT PRESENT AT THIS TIME.
CONVECTIVE PRECIPITATION...ISOLATED TO WIDELY SCATTERED MODERATE
TO LOCALLY STRONG WITHIN 150 NM ON EITHER SIDE OF 11N15W 7N24W
6N34W 7N40W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE
PRECIPITATION IS FROM 6N TO 10N BETWEEN 49W AND 54W...TO THE
SOUTH OF AN AREA OF MIDDLE LEVEL TO UPPER LEVEL CYCLONIC WIND
FLOW THAT COVERS THE ATLANTIC OCEAN FROM 9N TO 20N BETWEEN 49W
AND 57W.

...DISCUSSION...

THE GULF OF MEXICO...

A DEEP LAYER TROUGH IS MOVING THROUGH THE CENTRAL U.S.A.
THIS TROUGH SUPPORTS A COLD FRONT THAT PASSES THROUGH THE
FLORIDA PANHANDLE ALONG 87W...INTO THE NORTH CENTRAL GULF
OF MEXICO...TO 26N93W. CONVECTIVE PRECIPITATION...SCATTERED
MODERATE TO STRONG IS IN FLORIDA TO THE NORTH OF 28N TO THE
EAST OF 83W...SCATTERED MODERATE TO ISOLATED STRONG WITHIN
100 NM TO THE EAST AND SOUTHEAST OF 30N85W 25N90W AND FROM
24N TO 25N BETWEEN 90W AND 94W AND IN THE ATLANTIC OCEAN
TO THE NORTH OF 27N TO THE WEST OF 76W.

A SURFACE RIDGE PASSES THROUGH WESTERN CUBA...INTO THE
SOUTHWESTERN CORNER OF THE AREA ALONG THE MEXICO GULF COAST
ALONG 21N/22N.

PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT4...FOR DETAILS ABOUT A COLD FRONT
30N87W 26N94W...FOR THE NEXT 12 HOURS OR SO...TO THE NORTH OF
27N TO THE EAST OF THE FRONT TO 84W...SW WINDS 20 TO 25 KT
AND SEAS LESS THAN 8 FT.

THE CARIBBEAN SEA...

MIDDLE LEVEL TO UPPER LEVEL CYCLONIC WIND FLOW COVERS THE
CARIBBEAN SEA BETWEEN 75W AND 84W. UPPER LEVEL MOISTURE IS
MOVING NORTHWARD ON THE EASTERN SIDE OF THE AREA OF CYCLONIC
WIND FLOW. CONVECTIVE PRECIPITATION THAT IS RELATED TO THE
MONSOON TROUGH IS ALONG THE SOUTHERN SIDE OF THE CYCLONIC FLOW.
PRECIPITATION FROM THE EASTERN CARIBBEAN SEA TROPICAL WAVE
STILL IS TO THE EAST OF THE AREA OF CYCLONIC WIND FLOW.

THE MONSOON TROUGH IS ALONG 9N73W IN COLOMBIA...TO 9N81W IN
PANAMA...BEYOND NORTHWESTERN COSTA RICA. CONVECTIVE
PRECIPITATION...SCATTERED STRONG FROM PANAMA TO 11N BETWEEN
80W AND 82W...SCATTERED MODERATE TO ISOLATED STRONG ALONG THE
SOUTHEASTERN COAST OF NICARAGUA.

THE ATLANTIC OCEAN...

A DEEP LAYER TROUGH IS IN THE CENTRAL ATLANTIC OCEAN...PASSING
THROUGH 32N53W 27N54W 25N61W. THE TROUGH SUPPORTS A STATIONARY
FRONT THAT PASSES THROUGH 32N52W TO 31N53W. A SURFACE TROUGH
CONTINUES FROM 31N53W TO 29N56W AND 27N59W. ISOLATED MODERATE
TO LOCALLY STRONG CONVECTIVE PRECIPITATION IS TO THE NORTH OF
25N BETWEEN 48W AND 55W.

AN UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 35N32W.
A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS ALONG 32N39W TO 28N40W
24N42W AND 22N45W. THIS TROUGH IS SURROUNDED BY COMPARATIVELY
DRIER AIR IN SUBSIDENCE.

A BROAD UPPER LEVEL RIDGE COVERS THE ATLANTIC OCEAN AND THE
CARIBBEAN SEA...ALONG 16N61W 19N66W 23N72W 27N74W BEYOND 32N74W.
ISOLATED MODERATE TO LOCALLY STRONG CONVECTIVE PRECIPITATION
IS FROM 20N TO 23N BETWEEN 60W AND 75W.

A SURFACE RIDGE PASSES ON TOP OF BERMUDA TO 26N70W...ACROSS
CUBA TO 22N82W IN THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA.

PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...FOR DETAILS
ABOUT TROPICAL STORM NADINE...AND 20 TO 25 KNOT WINDS AND 8 FOOT
SEA HEIGHTS TO THE NORTH OF 28N TO THE WEST OF 72W. A COLD FRONT
APPROACHES THE AREA FROM THE NORTHWEST AT 24 HOURS. WINDS 20 KT
OR LESS. SEAS LESS THAN 8 FT.

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

$$
MT




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