[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181804
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI OCT 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.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 18W/19W TO THE SOUTH OF
19N MOVING WESTWARD 10 TO 15 KNOTS. CONVECTIVE PRECIPITATION...
NUMEROUS STRONG FROM 11N TO 14N BETWEEN 19W AND 24W. PART OF THE
PRECIPITATION IS RELATED TO THE ITCZ ALSO.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 49W/50W TO THE SOUTH OF
15N. THE WAVE IS MOVING WESTWARD 10 TO 15 KNOTS. CONVECTIVE
PRECIPITATION...SCATTERED STRONG FROM 8N TO 13N BETWEEN
46W AND 51W.

A WEAKENING ATLANTIC OCEAN TROPICAL WAVE IS ALONG 21N61W 13N60W.
THE WAVE IS MOVING WESTWARD 10 TO 15 KNOTS. IT IS NOT EASY TO
RELATE ANY DEEP CONVECTIVE PRECIPITATION TO THIS TROPICAL WAVE.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL SENEGAL AND GUINEA-
BISSAU TO 11N18W. THE ITCZ CONTINUES FROM 10N21W 8N30W 8N40W
8N43W. CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 11N TO
14N BETWEEN 19W AND 24W. PART OF THE PRECIPITATION IS RELATED TO
THE ITCZ ALSO. SCATTERED MODERATE TO ISOLATED STRONG FROM 5N TO
7N BETWEEN 17W AND 20W...AND ELSEWHERE FROM 5N TO 13N BETWEEN
30W AND 60W.

...DISCUSSION...

FROM THE GULF OF MEXICO...INTO THE ATLANTIC OCEAN...AND
INCLUDING IN THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA...

UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE GULF OF MEXICO...
THE ATLANTIC OCEAN TO THE WEST OF 70W...AND THE CARIBBEAN SEA TO
THE NORTH OF 16N TO THE WEST OF THE WINDWARD PASSAGE. THE MEAN
ANTICYCLONIC CIRCULATION CENTER IS IN THE FLORIDA STRAITS.
COMPARATIVELY DRIER AIR IN SUBSIDENCE...AS SEEN IN WATER VAPOR
IMAGERY...COVERS THE MOST OF THE AREA. THE ONLY EXCEPTION IS TO
THE NORTHWEST OF THE LINE THAT RUNS FROM THE WESTERN FLORIDA
PANHANDLE TO 22N97W ALONG THE MEXICO GULF COAST. BROKEN TO
OVERCAST MULTILAYERED CLOUDS AND ISOLATED MODERATE CONVECTIVE
PRECIPITATION ARE TO THE NORTHWEST OF THE LINE.

A STATIONARY FRONT PASSES THROUGH FLORIDA JUST TO THE WEST OF
APALACHEE BAY...TO THE NORTH CENTRAL GULF OF MEXICO NEAR
27N90W...TO 26N96W...INTO THE SOUTHWESTERN CORNER OF THE GULF OF
MEXICO NEAR 19N96W.

A 1016 MB HIGH PRESSURE CENTER IS NEAR 25N88W. SURFACE
ANTICYCLONIC WIND FLOW COVERS THE GULF OF MEXICO...AROUND THE
1016 MB HIGH CENTER...BETWEEN FLORIDA AND THE STATIONARY FRONT.

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

LOW CLOUD CEILINGS AND FOG AND VISIBILITIES LESS THAN THREE
MILES ARE OBSERVED AT THE STATIONS THAT ARE TO THE WEST OF 94W.
LOW CLOUD CEILINGS...AND SOME MIDDLE LEVEL CLOUD
CEILINGS...COVER MANY OF THE REST OF THE ICAO STATIONS/PLATFORM
SITES.

FAIR SKIES COVER THE DEEP SOUTH OF TEXAS. MULTILAYERED CLOUD
CEILINGS AND PRECIPITATION COVER THE REST OF THE TEXAS COASTAL
PLAINS. LOW CLOUD CEILINGS COVER SOUTHEASTERN COASTAL LOUISIANA.
MULTILAYERED CLOUD CEILINGS ARE AROUND THE SOUTHERN SIDE OF LAKE
PONTCHARTRAIN. MULTILAYERED CLOUD CEILINGS AND PRECIPITATION
COVER THE FLORIDA PANHANDLE TO THE WEST OF PERRY...WITH THE
STATIONARY FRONT.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT4...FOR MORE DETAILS ABOUT THE 30-
HOUR FORECAST COLD FRONT 30N85W 22N92W 18N94W. EXPECT NORTH TO
NORTHEAST WINDS 20 TO 25 KNOTS AND SEA HEIGHTS TO 8 FEET TO THE
WEST OF THE FRONT TO THE NORTH OF 22N.

FROM THE WESTERN ATLANTIC OCEAN INTO THE CARIBBEAN SEA...
INCLUDING ACROSS HISPANIOLA...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH THE WESTERN
ATLANTIC OCEAN NEAR 32N62W..TO 26N65W...ACROSS HISPANIOLA...TO
16N76W IN THE CARIBBEAN SEA...ACROSS NORTHERN NICARAGUA...AND
THROUGH SOUTHERN HONDURAS...AND BEYOND EL SALVADOR. A SURFACE
TROUGH IS IN THE ATLANTIC OCEAN ALONG 30N69W...TO A 1012 MB LOW
PRESSURE CENTER THAT IS NEAR 28N71W...CROSSING THE BAHAMAS/TURKS
AND CAICOS ISLANDS NEAR 22N73W...INTO THE WINDWARD PASSAGE.
CONVECTIVE PRECIPITATION...IN THE CARIBBEAN SEA...BROKEN TO
OVERCAST MULTILAYERED CLOUDS AND WIDELY SCATTERED TO SCATTERED
MODERATE TO ISOLATED STRONG FROM 12N TO 18N BETWEEN 63W AND 73W.
CONVECTIVE PRECIPITATION IN THE ATLANTIC OCEAN...SCATTERED
MODERATE TO ISOLATED STRONG FROM 21N TO 25N BETWEEN 69W AND
71W...AND FROM 20N TO 29N BETWEEN 60W AND 63W.

THE GFS FORECAST FOR 700 MB SHOWS THAT ANTICYCLONIC WIND FLOW...
FROM AN EAST-TO-WEST ORIENTED RIDGE...WILL COVER THE AREA FOR
MOST OF THE FIRST 24 HOURS OF THE FORECAST PERIOD. AN INVERTED
TROUGH AND/OR CYCLONIC WIND FLOW FROM AN INVERTED TROUGH...WILL
COVER THE AREA FOR THE REST OF THE 48 HOUR FORECAST PERIOD. THE
GFS FORECASTS FOR 500 MB AND FOR 250 MB SHOW THAT CYCLONIC WIND
FLOW FROM THE CURRENT ATLANTIC OCEAN-TO-CARIBBEAN SEA TROUGH
WILL COVER THE AREA FOR THE NEXT 48 HOURS OR SO.

THE REST OF THE CARIBBEAN SEA...

THE 24-HOUR RAINFALL TOTAL IN INCHES FOR THE PERIOD ENDING AT
18/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES... MIATPTPAN...IS 0.96 IN GUADELOUPE.

THE MONSOON TROUGH IS ALONG 9N BETWEEN 74W IN COLOMBIA AND
BEYOND 85W INTO THE EASTERN PACIFIC OCEAN. CONVECTIVE
PRECIPITATION...WIDELY SCATTERED TO SCATTERED MODERATE TO
ISOLATED STRONG WITHIN 30 NM TO 60 NM ON EITHER SIDE OF 9N77W
10N80W 12N84W 14N84W.

THE REST OF THE ATLANTIC OCEAN...

A WEAKENING MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION
CENTER IS NEAR 24N53W. THE ASSOCIATED TROUGH FROM 24 HOURS AGO
ALSO APPEARS TO HAVE DISSIPATED. A SURFACE TROUGH IS ALONG 55W
FROM 18N TO 24N. A SECOND SURFACE TROUGH IS ALONG 19N52W 14N54W.
CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 20N TO 22N
BETWEEN 46W AND 48W. WIDELY SCATTERED TO SCATTERED MODERATE TO
ISOLATED STRONG ELSEWHERE FROM 19N TO 29N BETWEEN 44W AND 56W.

A FAR EASTERN ATLANTIC OCEAN MIDDLE LEVEL TO UPPER LEVEL TROUGH
SUPPORTS A COLD FRONT THAT PASSES THROUGH 32N18W NEAR THE
MADEIRA ARCHIPELAGO...TO 28N23W AND 27N30W. BROKEN TO OVERCAST
MULTILAYERED CLOUDS AND ISOLATED MODERATE CONVECTIVE
PRECIPITATION ARE WITHIN 60 NM TO 120 NM ON EITHER SIDE OF THE
LINE THAT PASSES THROUGH 32N12W 28N16W 25N22W 25N30W.

A 1023 MB HIGH PRESSURE CENTER IS NEAR 33N44W. A 1018 MB HIGH
PRESSURE CENTER IS NEAR 30N57W. SURFACE ANTICYCLONIC WIND FLOW
COVERS THE ATLANTIC OCEAN TO THE NORTH OF 25N BETWEEN 33W AND
65W.

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

$$
MT


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