[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 081754 CCA
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN SEP 08 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.

...SPECIAL FEATURES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 18W/19W TO THE SOUTH OF
19N MOVING WESTWARD 10 KNOTS A 1008 MB LOW PRESSURE CENTER IS
ALONG THE WAVE NEAR 13N. CONVECTIVE PRECIPITATION...NUMEROUS
STRONG FROM 12N TO 15N BETWEEN 20W AND 23W...IN COASTAL
MAURITANIA FROM 17N TO 19N...AND FROM THE SOUTHWESTERN CORNER OF
SENEGAL TO 14N INCLUDING IN WESTERN GAMBIA. SCATTERED STRONG
FROM 10N TO 12N BETWEEN 20W AND 30W. THIS SYSTEM HAS A HIGH
CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48
HOURS...AND A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 5 DAYS. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR
FURTHER DEVELOPMENT...AND A TROPICAL DEPRESSION MAY FORM LATER
TODAY OR TOMORROW WHILE THE LOW MOVES WEST-NORTHWESTWARD ABOUT
10 KNOTS. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS...AND A HIGH CHANCE OF BECOMING
A TROPICAL CYCLONE DURING THE NEXT 5 DAYS. INTERESTS IN THE CAPE
VERDE ISLANDS SHOULD MONITOR THE PROGRESS OF THIS SYSTEM...AND
TROPICAL STORM WATCHES OR WARNINGS MAY BE REQUIRED IF A
DEPRESSION FORMS. HEAVY RAINFALL AND GUSTY WINDS ARE POSSIBLE IN
THE CAPE VERDE ISLANDS BY TONIGHT...EVEN IF A TROPICAL CYCLONE
DOES NOT FORM.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 35W/36W TO THE SOUTH OF
21N...MOVING WESTWARD 10 TO 15 KNOTS. A 1010 MB LOW PRESSURE
CENTER IS ALONG THE WAVE NEAR 16.5N. CONVECTIVE PRECIPITATION...
SCATTERED TO NUMEROUS STRONG FROM 18N TO 20N BETWEEN 36W AND
41W. WIDELY SCATTERED MODERATE TO ISOLATED STRONG FROM 15N TO
20N BETWEEN 28W AND 41W.  THIS SYSTEM HAS A LOW CHANCE OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS...AND A LOW
CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS
WHILE IT MOVES TO THE WEST-NORTHWEST ABOUT 9 KNOTS.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 86W TO THE SOUTH
OF 19N...MOVING WESTWARD 10 TO 15 KNOTS. A  MIDDLE LEVEL TO
UPPER LEVEL TROUGH CUTS THROUGH SOUTH FLORIDA...TO WESTERN
CUBA...TO 20N84W IN THE NORTHWESTERN CORNER OF THE CARIBBEAN
SEA...TOWARD WESTERN COASTAL HONDURAS. CONVECTIVE
PRECIPITATION...NUMEROUS STRONG FROM 17N TO 20N BETWEEN 81W AND
84W. WIDELY SCATTERED TO SCATTERED MODERATE TO ISOLATED STRONG
TO THE NORTHWEST OF THE LINE THAT PASSES THROUGH THE WINDWARD
CHANNEL...TO 15N80W...TO NORTHEASTERN COASTAL NICARAGUA/EASTERN
COASTAL HONDURAS.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL SENEGAL NEAR 14N17W TO
THE 1008 MB LOW PRESSURE CENTER THAT IS ALONG THE 18W/19W
TROPICAL WAVE...TO THE 1010 MB LOW PRESSURE CENTER THAT IS ALONG
THE 35W/36W TROPICAL WAVE...TO 12N40W. THE ITCZ CONTINUES FROM
12N40W TO 9N46W. CONVECTIVE PRECIPITATION...SCATTERED MODERATE
TO ISOLATED STRONG FROM 7N TO 10N BETWEEN 42W AND 50W. WIDELY
SCATTERED MODERATE TO ISOLATED STRONG FROM 6N TO 10N TO THE EAST
OF 42W.

...DISCUSSION...

FROM THE WESTERN ATLANTIC OCEAN...ACROSS FLORIDA...INTO THE
NORTHERN GULF OF MEXICO...TO SOUTH CENTRAL TEXAS...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 35N65W IN
THE ATLANTIC OCEAN...TO 32N74W...TO A CYCLONIC CIRCULATION THAT
IS NEAR 29N79W...ACROSS FLORIDA ALONG 28N/29N...TO 29N86W. A
SHEAR AXIS CONTINUES FROM 29N86W TO THE UPPER TEXAS GULF
COAST...AND A CYCLONIC CIRCULATION CENTER THAT IS NEAR 30N101W
TO THE NORTH OF DEL RIO...THAT IS ALONG THE TEXAS/MEXICO BORDER.
THE SURFACE PRESSURE GRADIENT FOR THE GULF OF MEXICO THAT IS
AWAY FROM THE SOUTHWESTERN CORNER OF THE AREA IS FLAT AND WEAK.
CONVECTIVE PRECIPITATION...SCATTERED TO NUMEROUS STRONG FROM 23N
TO 27N BETWEEN 90W AND 94W. CONVECTIVE PRECIPITATION IN THE
ATLANTIC OCEAN...SCATTERED MODERATE TO ISOLATED STRONG IN THE
BAHAMAS WITHIN A 60 NM RADIUS OF 26N78W. ISOLATED TO WIDELY
SCATTERED MODERATE ELSEWHERE TO THE WEST OF 70W. A STATIONARY
FRONT PASSES THROUGH 32N74W TO 31N76W. THE 24-HOUR RAINFALL
TOTAL IN INCHES FOR THE PERIOD ENDING AT 08/1200 UTC...ACCORDING
TO THE PAN AMERICAN TEMPERATURE AND PRECIPITATION
TABLES...MIATPTPAN...IS 0.13 IN BERMUDA.

THE REST OF THE GULF OF MEXICO...

A SURFACE TROUGH IS IN THE SOUTHWESTERN CORNER OF THE GULF OF
MEXICO...ALONG 23N97W 18N93W. CONVECTIVE PRECIPITATION...
SCATTERED MODERATE TO ISOLATED STRONG FROM THE MEXICO COAST TO
23N BETWEEN 92W AND 97W.

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 COVER THE
ICAO STATION KGBK. FAIR SKIES/CLEAR SKIES AT OR LOWER THAN 12000
FEET ARE BEING REPORTED ELSEWHERE ACROSS THE AREA.

MULTILAYERED CLOUD CEILINGS COVER THE DEEP SOUTH OF TEXAS.
RAINSHOWERS WITH THUNDER ARE IN THE EASTERN/COASTAL AREAS MORE
THAN BEING INLAND. MULTILAYERED CLOUDS AND RAINSHOWERS WITH
THUNDER COVER THE MIDDLE TEXAS GULF COASTAL PLAINS...AND FROM
THE MIDDLE TEXAS GULF COAST TOWARD HOUSTON...GALVESTON...AND
BEAUMONT-PORT ARTHUR. SCATTERED TO BROKEN LOW CLOUDS ARE IN THE
COASTAL AREAS FROM SOUTH CENTRAL LOUISIANA EASTWARD.
MULTILAYERED CLOUD CEILINGS COVER THE AREA THAT IS AROUND LAKE
PONTCHARTRAIN...INCLUDING NEW ORLEANS. SCATTERED TO BROKEN LOW
CLOUDS COVER THE COASTAL AREAS OF MISSISSIPPI AND ALABAMA. HIGH
CLOUD CEILINGS ARE REPORTED AT THE TAMPA INTERNATIONAL AIRPORT
AND AT THE KEY WEST NAVAL AIR STATION. LOW LEVEL CLOUD CEILINGS
COVER THE AREA FROM NAPLES TO PUNTA GORDA. FAIR SKIES/CLEAR
SKIES AT OR LOWER THAN 12000 FEET ARE BEING REPORTED ELSEWHERE
IN THE COASTAL SECTIONS OF THE U.S.A. GULF COAST STATES.

THE REST OF THE CARIBBEAN SEA...

MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE
AREA THAT IS TO THE EAST OF 80W. SOME OF THE WIND FLOW THAT IS
ON THE WESTERN SIDE OF THE AREA OF ANTICYCLONIC WIND FLOW IS
ATTRIBUTABLE TO THE SOUTHWESTERN WIND FLOW THAT IS ON THE
EASTERN SIDE OF THE SOUTH FLORIDA-TO-20N84W TROUGH.

THE 24-HOUR RAINFALL TOTAL IN INCHES FOR THE PERIOD ENDING AT
08/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN...IS 0.40 IN SAN JUAN PUERTO
RICO...AND 1.53 IN TEGUCIGALPA.

THE MONSOON TROUGH IS ALONG 10N73W IN COLOMBIA...11N80W IN THE
SOUTHWESTERN CORNER OF THE CARIBBEAN SEA...BEYOND WESTERN/
NORTHWESTERN NICARAGUA. CONVECTIVE PRECIPITATION...ISOLATED
MODERATE TO THE SOUTH OF 15N TO THE WEST OF 79W IN THE
SOUTHWESTERN CORNER OF THE CARIBBEAN SEA.

HISPANIOLA...

A SURFACE TROUGH EXTENDS FROM THE 1008 MB LOW PRESSURE CENTER
REMNANT OF GABRIELLE THAT IS NEAR 25N68.5W...TO 22N70W AND
18N72W IN SOUTHEASTERN HAITI. CONVECTIVE PRECIPITATION...
NUMEROUS STRONG FROM 14N TO 18N BETWEEN 70W AND 74W TO THE SOUTH
OF HISPANIOLA. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND WIDELY
SCATTERED TO SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE
PRECIPITATION ARE WITHIN 240 NM ON EITHER SIDE OF THE LINE THAT
PASSES THROUGH 32N58W TO 28N60W 20N66W 15N73W.

MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS
HISPANIOLA.

THE GFS FORECAST FOR 700 MB SHOWS THAT AN EAST-TO-
WEST ORIENTED RIDGE WILL COVER THE AREA FOR AT LEAST THE FIRST
24 TO 30 HOURS OF THE FORECAST. AN INVERTED TROUGH WILL COVER
HISPANIOLA FOR THE REST OF THE TIME PERIOD. THE GFS FORECAST FOR
500 MB AND FOR 250 MB SHOWS THAT A NORTHEAST-TO-SOUTHWEST
ORIENTED RIDGE WILL COVER THE AREA FOR THE ENTIRE TIME.

THE REST OF THE ATLANTIC OCEAN...

A SURFACE TROUGH IS ALONG 30N67W 27N68W...TO THE 1008 MB LOW
PRESSURE CENTER REMNANT OF GABRIELLE THAT IS NEAR 25N68.5W...TO
22N70W AND 18N72W IN SOUTHEASTERN HAITI. CONVECTIVE
PRECIPITATION...NUMEROUS STRONG FROM 22N TO 25N BETWEEN 65W AND
70W. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND WIDELY SCATTERED
TO SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE
PRECIPITATION ARE WITHIN 240 NM ON EITHER SIDE OF THE LINE THAT
PASSES THROUGH 32N58W TO 28N60W 20N66W 15N73W. AN UPPER LEVEL
RIDGE IS ON TOP OF THE AREA OF THE TROUGH AND LOW CENTER. THE
CIRCULATION ASSOCIATED WITH THE LOW IS NOT WELL ORGANIZED...AND
THE SHOWER AND THUNDERSTORM ACTIVITY IS DISPLACED TO THE EAST OF
THE CENTER. UPPER LEVEL WINDS ARE EXPECTED TO BECOME EVEN LESS
CONDUCIVE FOR DEVELOPMENT DURING THE NEXT FEW DAYS WHILE THE LOW
MOVES NORTHEASTWARD AND THEN NORTH-NORTHEASTWARD ABOUT 10 KNOTS.
THIS SYSTEM HAS A LOW CHANCE OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS...AND A MEDIUM CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 5 DAYS.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A 28N43W
CYCLONIC CIRCULATION CENTER TO 23N47W...TO AN 18N53W CYCLONIC
CIRCULATION CENTER TO 11N53W. RAINSHOWERS ARE POSSIBLE FROM 16N
TO 20N BETWEEN 51W AND 54W.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N10W IN
THE EASTERN ATLANTIC OCEAN...TO 28N18W TO 22N24W. NO SIGNIFICANT
DEEP CONVECTIVE PRECIPITATION IS APPARENT.

A SURFACE RIDGE PASSES THROUGH 32N43W TO 28N51W TO 20N60W.
SURFACE ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN TO THE
NORTH OF 20N TO THE EAST OF 60W...AND AWAY FROM THE 35W/36W
TROPICAL WAVE.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE
DETAILS ABOUT 1009 MB LOW CENTER REMNANTS OF GABRIELLE NEAR
25N69W. EXPECT 20 TO 25 KNOT WINDS AND SEA HEIGHTS TO 8 FEET
FROM 22N TO 26N BETWEEN 65W AND 69W. A SECOND LOW CENTER IS A
1011 MB CENTER THAT IS NEAR 17N37W. EXPECT NORTHEAST TO EAST 20
TO 25 KNOT WINDS AND SEA HEIGHTS TO 9 FEET FROM 17N TO 25N TO
THE EAST OF 40W.

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

$$
MT


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