[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 300604
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI AUG 30 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

A TROPICAL WAVE STILL IS MOVING THROUGH AFRICA...FROM MAURITANIA
TO SENEGAL AND GUINEA-BISSAU. IT IS ALONG 15W/16W TO THE SOUTH
OF 20N. CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 12N TO
15N BETWEEN 16W AND 18W. SCATTERED MODERATE TO STRONG FROM 8N TO
10N BETWEEN 13W AND 16W. ENVIRONMENTAL CONDITIONS APPEAR TO BE
CONDUCIVE FOR DEVELOPMENT...AND A TROPICAL DEPRESSION MAY FORM
DURING THE NEXT COUPLE OF DAYS. LOCALLY HEAVY RAINS AND GUSTY
WINDS ARE LIKELY IN THE CAPE VERDE ISLANDS AS THE WAVE NEARS
THAT AREA LATE SATURDAY. THIS SYSTEM HAS A MEDIUM CHANCE OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
ENVIRONMENTAL CONDITIONS SHOULD SUPPORT SOME DEVELOPMENT WHILE
THE LOW MOVES ACROSS THE EASTERN ATLANTIC OCEAN...TOWARD THE
WEST-NORTHWEST...AFTER THAT TIME. THE SYSTEM HAS A HIGH CHANCE
OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 46W/47W TO THE SOUTH OF
20N MOVING WESTWARD 10 TO 15 KNOTS. CONVECTIVE PRECIPITATION...
WIDELY SCATTERED MODERATE TO ISOLATED STRONG FROM 14N TO 20N
BETWEEN 40W AND 47W. RAINSHOWERS ARE POSSIBLE ELSEWHERE FROM 13N
TO 22N BETWEEN 40W AND 55W. THIS WAVE IS FORECAST TO MOVE
WESTWARD...INTO A REGION WHERE THE UPPER LEVEL WINDS ARE NOT
FAVORABLE FOR DEVELOPMENT.

AN ATLANTIC OCEAN SURFACE TROUGH IS ALONG 16N59W 12N58W.
CONVECTIVE PRECIPITATION...ISOLATED MODERATE FROM 13N TO 18N
BETWEEN 56W AND 63W...FROM THE ATLANTIC OCEAN INTO THE CARIBBEAN
SEA.

AN ATLANTIC OCEAN-TO-CARIBBEAN SEA TROPICAL WAVE IS ALONG
23N64W...TO THE EASTERN COAST OF PUERTO RICO...TO 15N66W IN THE
CARIBBEAN SEA. IT IS MOVING WESTWARD 15 TO 20 KNOTS. THE WAVE IS
MOVING THROUGH THE AREA OF AN ALREADY-EXISTING MIDDLE LEVEL TO
UPPER LEVEL TROUGH. THE TROUGH EXTENDS FROM A 26N57W CYCLONIC
CIRCULATION CENTER...TO 20N65W TO 16N66W IN THE CARIBBEAN SEA.
CONVECTIVE PRECIPITATION...NUMEROUS STRONG IN SOUTHERN HAITI.
RAINSHOWERS ARE POSSIBLE FROM 17N TO 20N BETWEEN 64W AND THE
WINDWARD PASSAGE. SCATTERED MODERATE TO STRONG IN THE ATLANTIC
OCEAN TO THE NORTH OF 26N BETWEEN 60W AND 67W. SCATTERED
MODERATE FROM 20N TO 25N BETWEEN 55W AND 70W.

AN INLAND TROPICAL WAVE IS MOVING THROUGH THE ISTHMUS OF
TEHUANTEPEC OF SOUTHERN MEXICO...ALONG 94W/95W TO THE SOUTH OF
17N. IT IS MOVING WESTWARD 10 TO 15 KNOTS. NO SIGNIFICANT DEEP
CONVECTIVE PRECIPITATION IS APPARENT IN SATELLITE IMAGERY ONLY.

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

THE MONSOON TROUGH PASSES THROUGH THE COASTAL SENEGAL NEAR
14N17W TO 11N28W 9N36W 10N46W AND 9N50W. CONVECTIVE
PRECIPITATION...SCATTERED TO NUMEROUS STRONG FROM 9N TO 10N
BETWEEN 24W AND 26W...AND FROM 12N TO 15N BETWEEN 32W AND 37W.
SCATTERED MODERATE TO ISOLATED STRONG FROM 4N TO 8N BETWEEN 32W
AND 36W. ISOLATED MODERATE FROM 4N TO 12N BETWEEN 44W AND 57W.

...DISCUSSION...

THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS IN
THE SOUTHERNMOST PART OF FLORIDA/THE FLORIDA KEYS/THE FLORIDA
STRAITS. THIS CYCLONIC CENTER HAS BEEN IN THIS GENERAL AREA FOR
THE LAST FEW DAYS. CYCLONIC WIND FLOW COVERS THE GULF OF
MEXICO...FLORIDA...THE FLORIDA STRAITS...THE BAHAMAS...THE
ATLANTIC OCEAN...CUBA...AND THE NORTHWESTERN PART OF THE
CARIBBEAN SEA FROM 21N TO 29N BETWEEN 76W AND 90W. CONVECTIVE
PRECIPITATION...ISOLATED MODERATE IN THE AREAS THAT ARE COVERED
BY THE CYCLONIC WIND FLOW AROUND THE CENTER.

A SECOND MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
IS INLAND IN THE SOUTHWESTERN SECTIONS OF MEXICO NEAR 21N105W.
CYCLONIC WIND FLOW COVERS MEXICO AND THE GULF OF MEXICO TO THE
SOUTH OF 28N TO THE WEST OF 93W.

COMPARATIVELY DRIER AIR IN SUBSIDENCE SHOWS UP IN WATER VAPOR
IMAGERY.

A SURFACE 1017 MB HIGH PRESSURE CENTER IS NEAR 29N88W.

A SURFACE TROUGH IS ALONG 90W/91W FROM 24N TO 28N MOVING
WESTWARD 10 KNOTS. RAINSHOWERS ARE POSSIBLE BETWEEN 87W AND
92W...AND TO THE SOUTH OF 24N TO THE WEST OF 90W.

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

LOW LEVEL CLOUD CEILINGS ARE AT THE FOLLOWING ICAO
STATIONS...KCRH AND KHQI. ICAO STATION KEMK IS REPORTING A
VISIBILITY OF LESS THAN ONE MILE WITH HAZE. FAIR SKIES/CLEAR
SKIES AT OR LOWER THAN 12000 FEET ARE BEING REPORTED ELSEWHERE
ACROSS THE AREA.

BROKEN MIDDLE LEVEL CLOUDS COVER THE FLORIDA COASTAL AREAS FROM
BROOKSVILLE TO TAMPA TO SARASOTA AND FORT MYERS. FAIR SKIES/
CLEAR SKIES AT OR LOWER THAN 12000 FEET ARE BEING REPORTED
ELSEWHERE IN THE COASTAL STATIONS OF THE U.S.A. GULF COAST
STATES.

THE CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL INVERTED TROUGH IS ALONG 17N74W TO
14N77W TO 10N77W. CYCLONIC WIND FLOW IS TO THE SOUTH OF 17N
BETWEEN 70W AND 80W. THE TROUGH IS SURROUNDED BY COMPARATIVELY
DRIER AIR IN SUBSIDENCE AS SEEN ON WATER VAPOR IMAGERY. A MIDDLE
LEVEL TO UPPER LEVEL TROUGH CUTS ACROSS THE AREA THAT RUNS FROM
FROM PUERTO RICO TO HISPANIOLA.

BROAD MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS
THE CARIBBEAN SEA TO THE WEST OF THE WINDWARD PASSAGE.
CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG
IN THE CARIBBEAN SEA TO THE NORTH OF 16N TO THE WEST OF THE
WINDWARD PASSAGE.

THE MONSOON TROUGH IS ALONG 10N BETWEEN 73W IN COLOMBIA BEYOND
85W IN COSTA RICA. CONVECTIVE PRECIPITATION...NUMEROUS STRONG IN
COLOMBIA FROM 7N TO 9N BETWEEN 74W AND 76W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT3...FOR MORE DETAILS ABOUT THE 6-
HOUR FORECAST OF NORTHEAST TO EAST WINDS 20 TO 25 KNOTS AND SEA
HEIGHTS LOWER THAN 8 FEET FROM 11N TO 13N BETWEEN 69W AND 72W.

HISPANIOLA...

AN ATLANTIC OCEAN-TO-CARIBBEAN SEA TROPICAL WAVE IS ALONG
23N64W...TO THE EASTERN COAST OF PUERTO RICO...TO 15N66W IN THE
CARIBBEAN SEA. IT IS MOVING WESTWARD 15 TO 20 KNOTS. THE WAVE IS
MOVING THROUGH THE AREA OF AN ALREADY-EXISTING MIDDLE LEVEL TO
UPPER LEVEL TROUGH. THE TROUGH EXTENDS FROM A 26N57W CYCLONIC
CIRCULATION CENTER...TO 20N65W TO 16N66W IN THE CARIBBEAN SEA.
CONVECTIVE PRECIPITATION...NUMEROUS STRONG IN SOUTHERN HAITI.
RAINSHOWERS ARE POSSIBLE FROM 17N TO 20N BETWEEN 64W AND THE
WINDWARD PASSAGE. SCATTERED MODERATE TO STRONG IN THE ATLANTIC
OCEAN TO THE NORTH OF 26N BETWEEN 60W AND 67W. SCATTERED
MODERATE FROM 20N TO 25N BETWEEN 55W AND 70W.

THE GFS FORECASTS FOR 700 MB AND 500 MB...SHOW THAT ANTICYCLONIC
WIND FLOW WILL BE MOVING ACROSS HISPANIOLA FOR THE NEXT 48
HOURS...WITH AN EAST-TO-WEST ORIENTED RIDGE. THE GFS FORECAST
FOR 250 MB SHOWS THAT A RIDGE WILL COVER HISPANIOLA FOR THE
FIRST 24 HOURS OF THE FORECAST PERIOD. A TROUGH WILL REPLACE THE
RIDGE FOR THE REST OF THE FORECAST PERIOD.

THE ATLANTIC OCEAN...

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR DETAILS
ABOUT THE 6 HOUR FORECAST FOR NORTHEAST TO EAST WINDS 20 TO 25
KNOTS AND SEA HEIGHTS TO 8 FEET FROM 17N TO 19N BETWEEN 45W AND
49W.

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

$$
MT


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