[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 121145
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON AUG 12 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 30W TO THE SOUTH OF 19N.
A 1010 MB LOW PRESSURE CENTER IS ALONG THE TROPICAL WAVE NEAR
12N. THE WAVE IS MOVING WESTWARD 15 KNOTS. A MIDDLE LEVEL TO
UPPER LEVEL TROUGH IS ALONG 23N33W 16N41W 10N42W. CONVECTIVE
PRECIPITATION...RAINSHOWERS ARE POSSIBLE FROM 10N TO 20N BETWEEN
26W AND 40W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 50W/51W TO THE SOUTH OF
20N. THE WAVE IS MOVING WESTWARD 15 TO 20 KNOTS. THE WAVE IS
MOVING INTO THE AREA WHERE A MIDDLE LEVEL TO UPPER LEVEL TROUGH
ALREADY HAS BEEN IN PLACE. CONVECTIVE PRECIPITATION...
RAINSHOWERS ARE POSSIBLE FROM 10N TO 20N BETWEEN 50W AND 56W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH PASSES THROUGH COASTAL SENEGAL NEAR 19N16W TO
16N20W 11N30W AND 8N39W. THE ITCZ CONTINUES FROM 8N39W TO 5N47W.
CONVECTIVE PRECIPITATION...SCATTERED STRONG WITHIN 90 NM ON
EITHER SIDE OF 14N17W 9N25W 8N30W...FROM 8N TO 10N BETWEEN 30W
AND 39W...AND FROM 6N TO 8N BETWEEN 53W AND 59W. RAINSHOWERS ARE
POSSIBLE ELSEWHERE TO THE SOUTH OF 10N TO THE EAST OF 60W.

...DISCUSSION...

FROM THE ATLANTIC OCEAN...ACROSS THE BAHAMAS...TO CUBA AND THE
NORTHWESTERN CORNER OF THE CARIBBEAN SEA...INCLUDING IN THE
EASTERN GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 21N82W...JUST OFF THE COAST OF CUBA. CYCLONIC WIND FLOW
COVERS THE ATLANTIC OCEAN...CUBA AND THE CARIBBEAN SEA...AND THE
EASTERN GULF OF MEXICO...FROM 18N TO 30N BETWEEN 74W AND 90W.
CONVECTIVE PRECIPITATION...SCATTERED STRONG FROM 19N TO THE
YUCATAN CHANNEL NEAR 22N BETWEEN 79W AND 86W. WIDELY SCATTERED
MODERATE TO THE NORTH OF 15N TO THE WEST OF 80W. ISOLATED
MODERATE ELSEWHERE TO THE NORTH OF 18N TO THE WEST OF THE MONA
PASSAGE...INCLUDING THE COASTAL WATERS OF HISPANIOLA.

THE REST OF THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 21N97W. CYCLONIC WIND FLOW COVERS THE GULF OF MEXICO TO THE
SOUTH OF 26N TO THE WEST OF 90W. A SURFACE TROUGH IS ALONG
23N97W 19N96W NEAR SOUTHERN MEXICO. CONVECTIVE PRECIPITATION...
SCATTERED STRONG TO THE SOUTH OF 22N TO THE WEST OF 93W.

A SURFACE RIDGE EXTENDS FROM AN ATLANTIC OCEAN 1022 MB HIGH
PRESSURE CENTER THAT IS NEAR 30N77W...INTO THE FLORIDA
PANHANDLE. BROAD SURFACE ANTICYCLONIC WIND FLOW COVERS THE GULF
OF MEXICO TO THE EAST OF 94W. THE SURFACE PRESSURE GRADIENT IS
COMPARATIVELY WEAK.

LOW LEVEL AND MIDDLE LEVEL CLOUD CEILING AND RAINSHOWERS WITH
THUNDER ARE REPORTED IN GULFPORT MISSISSIPPI. PERRY FLORIDA IS
REPORTING 2 MILES VISIBILITY WITH FOG. BROKEN LOW LEVEL TO
MIDDLE LEVEL CLOUDS ARE IN MARATHON IN THE FLORIDA KEYS. FAIR
SKIES/CLEAR SKIES AT OR LOWER THAN 12000 FEET ARE BEING REPORTED
ELSEWHERE.

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

LOW CLOUD CEILINGS ARE OBSERVED AT THE ICAO STATIONS KEIR AND AT
KCRH. MULTILAYERED CLOUD CEILINGS ARE REPORTED AT THE ICAO
STATION KDLP AT THE SOUTHEASTERN COAST OF LOUISIANA. FAIR SKIES/
CLEAR SKIES AT OR LOWER THAN 12000 FEET ARE BEING REPORTED
ELSEWHERE ACROSS THE AREA.

THE REST OF THE CARIBBEAN SEA...

BROAD MIDDLE LEVEL TO UPPER LEVEL SOUTHERLY WIND FLOW COVERS THE
ATLANTIC OCEAN AND THE CARIBBEAN SEA IN THE AREA THAT IS BOUNDED
BY THE POINTS 10N60W 22N53W 20N70W 10N60W.

A SURFACE TROUGH IS ALONG 69W FROM THE COASTAL WATERS OF THE
SOUTHEASTERN PART OF THE DOMINICAN REPUBLIC TO COASTAL
VENEZUELA. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO
ISOLATED STRONG TO THE SOUTH OF 18N BETWEEN 63W AND 70W. THE
24-HOUR RAINFALL TOTAL IN INCHES...FOR THE PERIOD ENDING AT
12/0000 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLE...MIATPTPAN...IS 0.61 FOR CURACAO...AND
0.53 FOR GUADELOUPE. ISOLATED MODERATE ELSEWHERE TO THE NORTH
OF 18N TO THE WEST OF THE MONA PASSAGE...INCLUDING THE COASTAL
WATERS OF HISPANIOLA.

BROAD MIDDLE LEVEL TO UPPER LEVEL CYCLONIC WIND FLOW SURROUNDS
HISPANIOLA.

UPPER LEVEL CYCLONIC WIND FLOW COVERS THE SOUTHWESTERN CORNER OF
THE AREA...TO THE SOUTH OF 12N TO THE WEST OF 76W. UPPER LEVEL
SOUTHWESTERLY WIND FLOW IS TO THE SOUTH OF 16N TO THE EAST OF
80W. UPPER LEVEL NORTHWESTERLY-TO-WESTERLY WIND FLOW THAT IS
MOVING THROUGH THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA
EVENTUALLY MERGES WITH THE SOUTHWESTERLY WIND FLOW.

THE MONSOON TROUGH IS ALONG 10N/11N BETWEEN 74W IN COLOMBIA...
BEYOND 86W IN COSTA RICA...INTO THE EASTERN PACIFIC OCEAN.
CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 10N TO 13N
BETWEEN 73W AND 79W. SCATTERED MODERATE TO ISOLATED STRONG
ELSEWHERE TO THE SOUTH OF 15N TO THE WEST OF 73W.

HISPANIOLA...

A SURFACE TROUGH IS ALONG 69W FROM THE COASTAL WATERS OF THE
SOUTHEASTERN PART OF THE DOMINICAN REPUBLIC TO COASTAL
VENEZUELA. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO
ISOLATED STRONG TO THE SOUTH OF 18N BETWEEN 63W AND 70W.
ISOLATED MODERATE ELSEWHERE TO THE NORTH OF 18N TO THE WEST OF
THE MONA PASSAGE...INCLUDING THE COASTAL WATERS OF HISPANIOLA.
THE 24-HOUR RAINFALL TOTAL IN INCHES...FOR THE PERIOD ENDING AT
12/0000 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLE...MIATPTPAN...IS 0.61 FOR CURACAO...AND
0.53 FOR GUADELOUPE. BROAD MIDDLE LEVEL TO UPPER LEVEL CYCLONIC
WIND FLOW SURROUNDS HISPANIOLA. CONVECTIVE PRECIPITATION...
ISOLATED MODERATE IN THE COASTAL WATERS...MAINLY ON THE SOUTHERN
SIDE OF THE ISLAND.

THE 700 MB GFS FORECAST SHOWS THAT HISPANIOLA WILL BE ON THE
EASTERN SIDE OF AN AREA OF BROAD CYCLONIC WIND FLOW. THE TROUGH
ACTUALLY STARTS ON TOP OF HISPANIOLA...AND IT EVENTUALLY SHIFTS
WESTWARD IN ORDER TO BE ON TOP OF CUBA FOR MUCH OF THE REST OF
THE FORECAST PERIOD. THE 500 MB GFS FORECAST SHOWS THAT
HISPANIOLA WILL BE ON THE WESTERN SIDE OF A TROUGH. THE TROUGH
EVENTUALLY SHIFTS WESTWARD...TO BE ON TOP OF CUBA...AND THEN TO
REMAIN IN THE WESTERNMOST PART OF THE CARIBBEAN SEA. THE GFS
FORECAST FOR 250 MB STARTS WITH AN EAST-TO-WEST TROUGH ACROSS
THE AREA FOR MUCH OF THE FIRST 24 HOURS. A RIDGE FOLLOWS THE
TROUGH. THE RIDGE SHIFTS WESTWARD AND A SECOND TROUGH STARTS TO
INFLUENCE THE AREA BY THE END OF THE 48 HOUR PERIOD.

THE REST OF THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A 30N55W
CYCLONIC CIRCULATION CENTER TO 26N55W...TO 25N60W...TO A 24N72W
CYCLONIC CIRCULATION CENTER...ACROSS THE BAHAMAS...TO A 21N82W
CYCLONIC CIRCULATION CENTER THAT IS JUST TO THE SOUTH OF CUBA.
A SURFACE TROUGH IS ALONG 50W/51W FROM 22N TO 29N. CONVECTIVE
PRECIPITATION...WIDELY SCATTERED TO SCATTERED MODERATE TO
ISOLATED STRONG TO THE NORTH OF 24N BETWEEN 50W AND 54W.
RAINSHOWERS ARE POSSIBLE TO THE SOUTH OF 27N TO THE WEST OF 70W.

BROAD SURFACE ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN
TO THE NORTH OF 20W TO THE EAST OF 46W. A 1025 MB HIGH PRESSURE
CENTER IS NEAR 34N42W. BROAD SURFACE ANTICYCLONIC WIND FLOW
COVERS THE ATLANTIC OCEAN TO THE WEST OF 52W. A 1022 MB HIGH
PRESSURE CENTER IS NEAR 30N77W.

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

$$
MT


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