[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181144
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU JUL 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 22N29W 16N32W
10N33W...MOVING WESTWARD 15 TO 20 KNOTS. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG IN THE
ITCZ FROM 8N TO 10N BETWEEN 27W AND 33W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 65W/66W TO THE SOUTH OF
22N...MOVING WESTWARD 20 TO 25 KNOTS. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG FROM 14N
TO 22N BETWEEN 60W AND 71W. THE PRECIPITATION THAT IS JUST TO
THE SOUTH OF THE DOMINICAN REPUBLIC IS RACING WESTWARD...MOVING
COMPARATIVELY FASTER THAN THE REST OF THE PRECIPITATION.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 78W/79W TO THE SOUTH OF
18N...MOVING WESTWARD 20 KNOTS. BROAD UPPER LEVEL ANTICYCLONIC
WIND FLOW IS MOVING ACROSS THE WAVE...IN THE SOUTHWESTERN CORNER
OF THE CARIBBEAN SEA. NO SIGNIFICANT DEEP CONVECTIVE
PRECIPITATION IS APPARENT.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH PASSES THROUGH COASTAL MAURITANIA NEAR 19N16W
TO 15N23W 11N27W. THE ITCZ STARTS NEAR 11N27W TO 9N30W 7N40W
6N40W AND 4N50W. CONVECTIVE PRECIPITATION...SCATTERED TO
NUMEROUS STRONG FROM 5N TO 9N BETWEEN 51W AND 57W FROM THE COAST
OF BRAZIL TO THE COASTAL WATERS OF GUYANA. SCATTERED MODERATE TO
ISOLATED STRONG FROM 6N TO 11N TO THE EAST OF 20W... AND WITHIN
90 NM ON EITHER SIDE OF 11N23W 9N30W 7N40W 6N48W.

...DISCUSSION...

FROM THE ATLANTIC OCEAN...INTO THE CARIBBEAN SEA...TO THE NORTH
OF 15N BETWEEN 59W AND 71W...

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC ENVELOPE COVERS THE AREA.
MULTIPLE CYCLONIC CIRCULATION CENTERS ARE PRESENT IN THE
AREA...IN THE ATLANTIC OCEAN. ONE IS NEAR 29N63W. A SECOND
CENTER IS NEAR 28N71W. AN ATLANTIC OCEAN SURFACE TROUGH IS ALONG
71W/72W FROM 26N TO 31N. CONVECTIVE PRECIPITATION...ISOLATED
MODERATE BETWEEN 55W AND 72W TO THE NORTH OF 20N. MIDDLE LEVEL
TO UPPER LEVEL ANTICYCLONIC WIND FLOW FROM A 20N74W 30N80W RIDGE
COVERS THE ATLANTIC OCEAN THAT IS BETWEEN 71W AND 80W. WARMING
CLOUD TOP TEMPERATURES AND WEAKENING CONVECTIVE PRECIPITATION
ARE UNDER THE RIDGE.

GULF OF MEXICO...

ONE MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 28N87W OFF THE COAST OF FLORIDA. SURFACE TROUGHS ARE ALONG
26N87W 28N84W AND 28N87W 31N84W. CONVECTIVE PRECIPITATION...
SCATTERED MODERATE TO ISOLATED STRONG TO THE SOUTH OF 28N TO THE
EAST OF 87W IN THE SOUTHEASTERN CORNER OF THE GULF OF MEXICO.
SCATTERED MODERATE TO THE WEST OF 90W ALSO.

A SECOND CYCLONIC CIRCULATION CENTER APPEARS TO BE WEAKENING AS
ITS CYCLONIC WIND FLOW COVERS THE YUCATAN PENINSULA. BROAD
MULTILAYERED NORTHERLY-TO-NORTHWESTERLY WIND FLOW COVERS THE
REST OF THE GULF OF MEXICO. A SURFACE TROUGH IS ALONG THE
WESTERN SIDE OF THE YUCATAN PENINSULA OF MEXICO.

A MIDDLE LEVEL CLOUD CEILING IS OBSERVED AT BROWNSVILLE TEXAS.
HIGH LEVEL CLOUD CEILINGS ARE REPORTED IN THE NEW ORLEANS
LOUISIANA METROPOLITAN AREA. A HIGH CLOUD CEILING IS IN
VALPARAISO FLORIDA. A LOW CLOUD CEILING COVERS TALLAHASSEE...AND
MARATHON KEY. MIDDLE LEVEL AND HIGH LEVEL CLOUD CEILINGS ARE IN
THE TAMPA METROPOLITAN AREA...AND IN THE FLORIDA KEYS IN
MARATHON AND AT THE KEY WEST NAVAL AIR STATION. 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...

A LOW CLOUD CEILING AND A MIDDLE LEVEL CLOUD CEILING ARE
REPORTED AT THE ICAO STATION KMZG OFF THE TEXAS COAST. A LOW
CLOUD CEILINGS IS OBSERVED AT THE ICAO STATION KBBF. FAIR
SKIES/CLEAR SKIES AT OR LOWER THAN 12000 FEET ARE BEING REPORTED
ELSEWHERE.

CARIBBEAN SEA...

UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE AREA THAT IS TO
THE SOUTH OF THE LINE THAT RUNS FROM THE YUCATAN PENINSULA OF
MEXICO...TO 15N75W...AND TO THE PENINSULA DE LA GUAJIRA OF
NORTHERN COLOMBIA.

A MIDDLE LEVEL TO UPPER LEVEL INVERTED TROUGH IS ALONG 19N63W
15N61W 9N59W.

WIDELY SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE
PRECIPITATION IS IN THE NORTHWESTERN CORNER OF THE AREA...IN AN
AREA OF DIFFLUENT WIND FLOW...TO THE NORTH OF 18N TO THE WEST OF
80W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 65W/66W TO THE SOUTH OF
22N...MOVING WESTWARD 20 TO 25 KNOTS. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG FROM 14N
TO 22N BETWEEN 60W AND 71W. THE PRECIPITATION THAT IS JUST TO
THE SOUTH OF THE DOMINICAN REPUBLIC IS RACING WESTWARD...MOVING
COMPARATIVELY FASTER THAN THE REST OF THE PRECIPITATION. THE
WAVE SHOULD BE AFFECTING HISPANIOLA TODAY.

THE MONSOON TROUGH IS ALONG 9N BETWEEN 73W IN COLOMBIA...AND
BEYOND 83W IN SOUTHERN COSTA RICA. CONVECTIVE PRECIPITATION...
NUMEROUS STRONG IN THE EASTERN PACIFIC OCEAN COASTAL WATERS OF
COLOMBIA AND PANAMA FROM 4N TO 9N TO THE EAST OF 80W. SCATTERED
STRONG IN THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA TO THE
SOUTH OF 12N84W 10N77W. SCATTERED MODERATE TO STRONG ALONG THE
COAST OF NICARAGUA FROM 13N TO 14N BETWEEN 82W AND 84W.

HISPANIOLA...

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 65W/66W TO THE SOUTH OF
22N...MOVING WESTWARD 20 TO 25 KNOTS. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG FROM 14N
TO 22N BETWEEN 60W AND 71W. THE PRECIPITATION THAT IS JUST TO
THE SOUTH OF THE DOMINICAN REPUBLIC IS RACING WESTWARD...MOVING
COMPARATIVELY FASTER THAN THE REST OF THE PRECIPITATION. THE
WAVE SHOULD BE AFFECTING HISPANIOLA TODAY.

THE GFS FORECAST FOR 700 MB SHOWS EASTERLY WIND FLOW ACROSS THE
AREA FOR THE FIRST 30 HOURS OR SO... FOLLOWED BY SOUTHEASTERLY
WIND FLOW ACROSS THE AREA. THE GFS FORECAST FOR 500 MB STARTS
WITH HISPANIOLA IN A RIDGE FOR MOST OF THE FIRST 24 HOURS...
FOLLOWED BY AN INVERTED TROUGH MOVING WESTWARD ACROSS THE AREA.
THE 250 MB GFS SHOWS THAT A TROUGH WILL START ON TOP OF THE
AREA...FOLLOWED BY THE TRANSITION TO NORTHERLY WIND FLOW...
FOLLOWED BY AN INVERTED TROUGH ACROSS THE AREA FOR THE REST OF
THE 48 HOURS.

THE REST OF THE ATLANTIC OCEAN...

A SURFACE RIDGE EXTENDS FROM A 1024 MB HIGH PRESSURE CENTER THAT
IS NEAR 32N23W TO 28N35W...TO A 1024 MB HIGH PRESSURE CENTER
THAT IS NEAR 27N47W...TO 29N67W.

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

$$
MT


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