[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU APR 18 2013

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.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL SIERRA LEONE
NEAR 8N13W TO 6N15W. THE ITCZ CONTINUES FROM 6N15W TO
3N22W AND 2N28W. CONVECTIVE PRECIPITATION...SCATTERED
STRONG FROM 2N TO 4N BETWEEN 2W AND 4W...AND FROM 4N
TO 5N BETWEEN 33W AND 42W. SCATTERED MODERATE TO
ISOLATED STRONG FROM 2N TO 4N BETWEEN 23W AND 26W.
ISOLATED MODERATE ELSEWHERE TO THE SOUTH OF 7N TO
THE EAST OF 50W.

...DISCUSSION...

THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL RIDGE EXTENDS FROM THE
SOUTHWESTERN CORNER OF THE AREA TO THE SOUTH CENTRAL
LOUISIANA COASTAL PLAINS. A DEEP LAYER TROUGH STILL
IS IN THE CENTRAL U.S.A. THE DEEP LAYER TROUGH
SUPPORTS A STILL-INLAND COLD FRONT THAT PASSES
THROUGH NORTHEASTERN TEXAS TO SOUTH CENTRAL TEXAS...
BEYOND 28N100W INTO NORTHERN MEXICO. THE 85W-TO
YUCATAN CHANNEL RIDGE FROM 24 HOURS AGO HAS BEEN
PUSHED EASTWARD. THE WIND FLOW THAT WAS MOVING
AROUND THE RIDGE HAS MERGED WITH THE MIDDLE LEVEL
TO UPPER LEVEL NORTHWESTERLY WIND FLOW THAT IS
ON THE WESTERN SIDE OF THE 32N44W TO 16N60W
ATLANTIC OCEAN TROUGH.

SCATTERED LOW CLOUDS COVER THE DEEP SOUTH OF TEXAS.
LIGHT RAIN HAS BEEN REPORTED IN PORT ISABEL FOR THE
LAST FEW HOURS. LOW CLOUD CEILINGS COVER THE U.S.A.
GULF COASTAL PLAINS FROM THE MIDDLE TEXAS COAST TO
THE FLORIDA PANHANDLE. SCATTERED TO BROKEN LOW
CLOUDS WITH MIDDLE LEVEL AND HIGH LEVEL CLOUDS COVER
THE REST OF THE FLORIDA GULF COAST.

FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE
TO THE NORTH OF 27N TO THE WEST OF 88W...

SCATTERED LOW CLOUDS COVER THE OIL PLATFORM
SITES THAT ARE OFFSHORE ALONG THE TEXAS GULF COAST.
VISIBILITIES OF 3 MILES OR LOWER ARE AT THE
ICAO STATIONS...KHQI...KVNP...KATP...KGUL...AND
MYT.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...
AND THE OFFSHORE FORECAST...MIAOFFNT4...FOR MORE
INFORMATION ABOUT THE GALE WARNING. GALE-FORCE
WINDS ARE FORECAST 24 HOURS INTO THE FORECAST
TIME PERIOD. A COLD FRONT WILL BE ALONG 30N88W
24N95W 20.5N97W AT 24 HOURS. EXPECT NORTH TO
NORTHEAST 30 TO 35 KNOT WINDS AND 8 TO 13 FOOT
SEA HEIGHTS TO THE SOUTH OF 27N TO THE WEST OF
THE FRONT. EXPECT 20 TO 30 KNOT NORTH WINDS AND
11 FOOT SEA HEIGHTS ELSEWHERE TO THE WEST OF THE
FRONT. EXPECT NORTHWESTERLY 20 TO 25 KNOT WINDS
AND SEA HEIGHTS LOWER THAN 8 FEET TO THE SOUTH OF
21N TO THE EAST OF THE FRONT TO 95W.

THE CARIBBEAN SEA...

BROAD MIDDLE LEVEL TO UPPER LEVEL NORTHWESTERLY
WIND FLOW COVERS THE CARIBBEAN SEA TO THE NORTH
OF 14N. THE AREA THAT IS TO THE SOUTH 14N IS
COVERED BY THE MIDDLE LEVEL TO UPPER LEVEL
SOUTHWESTERLY-TO-WESTERLY WIND FLOW.
THE NORTHWESTERLY WIND FLOW IS FLOWING TOWARD
THE BASE OF AN ATLANTIC OCEAN-TO-16N60W TROUGH.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES
THROUGH 32N44W IN THE ATLANTIC OCEAN...TO 16N60W
JUST TO THE EAST OF THE EASTERN CARIBBEAN SEA
ISLANDS. RAINSHOWERS ARE POSSIBLE WITHIN 150 NM
ON EITHER SIDE OF 15N61W 19N52W. RAINSHOWERS
ARE POSSIBLE ELSEWHERE TO THE EAST OF 75W.

THE SOUTHWESTERLY WIND FLOW FROM SOUTH AMERICA
AND CENTRAL AMERICA HAS BEEN PUSHING HIGH CLOUDS
INTO THE CARIBBEAN SEA...TO THE SOUTH OF 17N
TO THE EAST OF 83W.

THE TOTAL PRECIPITATION AMOUNT FOR THE 24-HOUR
TIME PERIOD ENDING AT 18/1200 UTC IS 0.30 OF
AN INCH FOR SAN JUAN PUERTO RICO...ACCORDING
TO THE PAN AMERICAN TEMPERTATURE AND
PRECIPITATION TABLE...MIATPTPAN.

THE MONSOON TROUGH IS ALONG 7N73W IN COLOMBIA...
TO 7N71W IN COLOMBIA...TO 8N80W IN PANAMA...
AND BEYOND 9N84W IN SOUTHERN COSTA RICA...
INTO THE EASTERN PACIFIC OCEAN. CONVECTIVE
PRECIPITATION...SCATTERED TO NUMEROUS STRONG
FROM 3N TO 6N BETWEEN 80W AND 84W. NUMEROUS
STRONG FROM 6N TO 9N BETWEEN 82W AND 87W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...
AND THE OFFSHORE FORECAST...MIAOFFNT3...FOR MORE
DETAILS ABOUT THE NORTHEAST TO EAST 20 TO 25 KNOT
WINDS AND SEA HEIGHTS REACHING 9 FEET FROM 11N
TO 13N BETWEEN 70W AND 78W. ALSO EXPECT EAST TO
SOUTHEAST 20 TO 25 KNOT WINDS AND SEA HEIGHTS
REACHING 8 FEET TO THE SOUTH OF 19N TO THE WEST
OF 84.5W INCLUDING IN THE GULF OF HONDURAS.

THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES
THROUGH 32N44W AND 28N48W...TO A CYCLONIC
CIRCULATION CENTER THAT IS NEAR 26N50W...
TO 24N54W AND 20N60W...TO 16N60W JUST TO
THE EAST OF THE EASTERN CARIBBEAN SEA ISLANDS.
RAINSHOWERS ARE POSSIBLE WITHIN 150 NM ON
EITHER SIDE OF 15N61W 19N52W 23N45W 25N41W.
A SEPARATE CYCLONIC CIRCULATION CENTER IS NEAR
27N69W. THAT CENTER HAS A RADIUS OF 60 NM OR
SO. MIDDLE LEVEL TO UPPER LEVEL NORTHWESTERLY
WIND FLOW COVERS THE ATLANTIC OCEAN TO THE
WEST OF THE TROUGH. BROAD MIDDLE LEVEL TO
UPPER LEVEL SOUTHWESTERLY WIND FLOW COVERS
THE ATLANTIC OCEAN TO THE EAST OF THE TROUGH.
A DISSIPATING STATIONARY FRONT TRAILS FROM
A 1022 MB LOW PRESSURE CENTER THAT IS NEAR
33N40W...TO 29N45W AND 26N53W. RAINSHOWERS
ARE POSSIBLE TO THE NORTH OF 25N BETWEEN
40W AND 60W...AND TO THE NORTH OF 30N
BETWEEN 38W AND 41W.

A SURFACE TROUGH IS ALONG 33N71W 30N72W.
THIS FEATURE REMAINS FROM THE TWO WESTERN
ATLANTIC OCEAN LOW PRESSURE CENTERS OF THE
LAST FEW DAYS. RAINSHOWERS ARE POSSIBLE WITH
THE REMNANT CLOUDINESS THAT IS TO THE NORTH
AND NORTHWEST OF THE LINE THAT PASSES THROUGH
32N64W 26N67W 26N74W 25N80W.

A SURFACE RIDGE IS ALONG 32N31W 27N35W 25N40W
AND 23N50W ON THE EASTERN SIDE OF THE
DISSIPATING STATIONARY FRONT.

A SURFACE RIDGE EXTENDS FROM A 1027 MB HIGH
PRESSURE CENTER THAT IS NEAR 34N53W TO 28N61W
AND 22N67W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...
FOR MORE DETAILS ABOUT THE WINDS 20 KNOTS OR LESS
AND THE 10 FOOT SEA HEIGHTS TO THE NORTH OF 26N
BETWEEN 40W AND 59W. ALSO EXPECT WINDS 20 KNOTS
OR LESS AND 8 FOOT SEA HEIGHTS FROM 18.5N TO 23N
BETWEEN 53W AND 66W.

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

$$
MT

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