[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 080550
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE SEP 08 2015

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
0545 UTC.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM GRACE AT 08/0300 UTC IS NEAR 14.0N
39.2W. GRACE IS MOVING TOWARD THE WEST...OR 275 DEGREES...17
KNOTS. THE MINIMUM CENTRAL PRESSURE IS 1006 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 35 KNOTS WITH GUSTS TO 45 KNOTS.
PUBLIC ADVISORIES ABOUT TROPICAL STORM GRACE ARE BEING ISSUED
UNDER THE WMO HEADER WTNT32 KNHC...AND UNDER THE AWIPS HEADER
MIATCPAT2. FORECAST/ADVISORIES ABOUT TROPICAL STORM GRACE ARE
BEING ISSUED UNDER THE WMO HEADER WTNT22 KNHC...AND UNDER THE
AWIPS HEADER MIATCMAT2. CONVECTIVE PRECIPITATION...NUMEROUS
STRONG WITHIN A RADIUS OF 90 NM OF THE CENTER IN THE
SOUTHWESTERN QUADRANT.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 22W/23W FROM 21N
SOUTHWARD...MOVING WESTWARD 10 TO 15 KNOTS. CONVECTIVE
PRECIPITATION...ISOLATED MODERATE FROM 07N TO 23N BETWEEN 10W
AND 28W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 48W/49W FROM 15N
SOUTHWARD...MOVING WESTWARD 15 KNOTS. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG FROM 11N
TO 13N BETWEEN 47W AND 51W...AND FROM 07N TO 09N BETWEEN 50W AND
54W.

AN ATLANTIC OCEAN-TO-CARIBBEAN SEA TROPICAL WAVE IS ALONG
60W/61W FROM 16N SOUTHWARD...MOVING WESTWARD 15 KNOTS.
CONVECTIVE PRECIPITATION...SCATTERED STRONG FROM 11N TO 13N
BETWEEN 63W AND 75W. ISOLATED MODERATE ELSEWHERE FROM 10N TO
14N BETWEEN 58W AND 68W.

A CARIBBEAN SEA TROPICAL WAVE EXTENDS FROM SOUTHEASTERN
CUBA...TO EASTERN JAMAICA...TO 15N77W AND 10N77W. THE WAVE IS
MOVING WESTWARD 10 TO 15 KNOTS. CONVECTIVE PRECIPITATION...
SCATTERED MODERATE TO ISOLATED STRONG IN SOUTHEASTERN CUBA FROM
20N TO 21N BETWEEN 76W AND 78W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH SOUTHERN COASTAL SECTIONS OF
MAURITANIA NEAR 17N16W...TO 12N20W 11N24W AND 13N29W. THE REST
OF THE MONSOON TROUGH...AND THE ITCZ...ARE BROKEN UP BY TROPICAL
STORM GRACE AND THE 48W/49W TROPICAL WAVE. NO SIGNIFICANT DEEP
CONVECTIVE PRECIPITATION.

...DISCUSSION...

THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH SOUTHEASTERN
MISSISSIPPI/SOUTHWESTERN ALABAMA...INTO THE SOUTHWESTERN CORNER
OF THE AREA. A SURFACE TROUGH EXTENDS FROM A 1011 MB LOW
PRESSURE CENTER IS NEAR 28N84W TO 26N84W AND 25N86W. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO STRONG IN THE COASTAL
WATERS OF THE FLORIDA BIG BEND FROM 29N TO 30N BETWEEN 84W AND
85W. ISOLATED MODERATE ELSEWHERE ACROSS THE OPEN WATERS OF THE
GULF OF MEXICO FROM 22N NORTHWARD FROM 94W EASTWARD.

THE CARIBBEAN SEA...

PLEASE REFER TO THE SECTION THAT IS ABOUT HISPANIOLA AND THE
SECTION THAT IS ABOUT TROPICAL WAVES...FOR MORE DETAILS ABOUT
THE CARIBBEAN SEA CUBA-TO-JAMAICA-ALONG 77W TROPICAL WAVE.

UPPER LEVEL ANTICYCLONIC WIND FLOW AND BROKEN TO OVERCAST
MULTILAYERED CLOUDS COVER THE CARIBBEAN SEA FROM 70W WESTWARD. A
RIDGE EXTENDS FROM THE SOUTHWESTERN CORNER OF THE CARIBBEAN
SEA...NORTHWESTWARD...TO THE YUCATAN CHANNEL AND WESTERN CUBA.

THE MONSOON TROUGH IS ALONG 09N76W IN COLOMBIA...TO 10N80W...
BEYOND NORTHERN IN COSTA RICA...INTO THE EASTERN PACIFIC OCEAN.
CONVECTIVE PRECIPITATION...WIDELY SCATTERED TO SCATTERED STRONG
IS IN COLOMBIA FROM 05N TO 10N BETWEEN 72W IN VENEZUELA AND 76W
IN COLOMBIA. ISOLATED MODERATE TO LOCALLY STRONG FROM 05N IN
COLOMBIA TO 12N IN NICARAGUA BETWEEN 76W AND 86W INCLUDING IN
THE GULF OF URABA OF COLOMBIA.

THE 24-HOUR RAINFALL TOTALS IN INCHES FOR THE PERIOD ENDING AT
08/0000 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...ARE 0.02 IN
BERMUDA.

...HISPANIOLA...

HIGH LEVEL NORTHWESTERLY WIND FLOW IS MOVING ON TOP OF 600 MB-TO-
800 MB LEVEL EAST-TO-SOUTHEAST WIND FLOW. CONVECTIVE
PRECIPITATION...ISOLATED MODERATE ALONG THE SOUTHWESTERN COASTAL
WATERS FROM 18N TO 19N BETWEEN 74W AND 75W IN THE WINDWARD
PASSAGE. A CARIBBEAN SEA TROPICAL WAVE EXTENDS FROM SOUTHEASTERN
CUBA...TO EASTERN JAMAICA...TO 15N77W AND 10N77W. THE WAVE IS
MOVING WESTWARD 10 TO 15 KNOTS. CONVECTIVE PRECIPITATION...
SCATTERED MODERATE TO ISOLATED STRONG IN SOUTHEASTERN CUBA FROM
20N TO 21N BETWEEN 76W AND 78W.

CURRENT CONDITIONS...AT PORT-AU-PRINCE IN HAITI...THE LAST
OBSERVATION FOR 08/0100 UTC SHOWED SCATTERED LOW LEVEL CLOUDS.
IN THE DOMINICAN REPUBLIC...RAINSHOWERS WITH THUNDER ARE BEING
OBSERVED IN SANTO DOMINGO. FEW LOW LEVEL CLOUDS ARE IN LA
ROMANA. FEW LOW LEVEL CLOUDS AND SCATTERED HIGH LEVEL CLOUDS ARE
IN PUNTA CANA. SCATTERED LOW LEVEL CLOUDS ARE IN SANTIAGO. FEW
LOW LEVEL CLOUDS ARE IN PUERTO PLATA.

THE GFS MODEL FORECAST FOR 250 MB SHOWS THAT HISPANIOLA FINDS
ITSELF IN THE MIDDLE OF THE FOLLOWING WEATHER FEATURES...A RIDGE
FROM THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA TO
HISPANIOLA...AN INVERTED TROUGH AFFECTING THE SOUTHEASTERN
CORNER OF HISPANIOLA...AN EAST-TO-WEST ORIENTED ATLANTIC OCEAN-
TO-HISPANIOLA RIDGE...AND A TROUGH THAT IS CLOSE TO THE
NORTHEASTERN CORNER OF THE ISLAND. THE RIDGE THAT STRETCHES FROM
THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA TO HISPANIOLA
EVENTUALLY DOMINATES AFTER THE FIRST 12 HOURS OF THE 48-HOUR
FORECAST PERIOD...INTO THE END OF THE FIRST DAY. NORTHERLY WIND
FLOW LASTS DURING ALL OF DAY TWO...AS HISPANIOLA REMAINS ON THE
EASTERN SIDE OF THE SAME SOUTHWESTERN CARIBBEAN SEA RIDGE. A
TROUGH ALSO AFFECTS THE NORTHEASTERN CORNER AND EASTERN SECTIONS
DURING DAY TWO. THE GFS MODEL FORECAST FOR 500 MB SHOWS THAT AN
ANTICYCLONIC CIRCULATION CENTER WILL BE IN THE ATLANTIC OCEAN
ABOUT 120 NM TO THE NORTHEAST OF HISPANIOLA AT THE START OF THE
48-HOUR FORECAST PERIOD. EAST-TO-SOUTHEAST WIND FLOW WILL CROSS
THE ISLAND AT THE START. THE ANTICYCLONIC CENTER WILL MOVE
TOWARD THE TURKS AND CAICOS AND GREAT INAGUA BY THE END OF THE
FIRST 24 HOURS...WITH MORE EAST-TO-SOUTHEAST WIND FLOW. THE
ANTICYCLONIC CENTER EVENTUALLY WILL MOVE TOWARD AND MERGE WITH A
SECOND ANTICYCLONIC CIRCULATION CENTER...AND BE NEAR THE
NORTHERN BAHAMAS BY THE END OF THE 48-HOUR FORECAST PERIOD.
NORTHEASTERLY WIND FLOW WILL CROSS HISPANIOLA DURING DAY TWO.
THE GFS MODEL FOR 700 MB SHOWS THAT EAST-TO-SOUTHEAST WIND FLOW
WILL MOVE ACROSS HISPANIOLA DURING THE NEXT 48 HOURS. A RIDGE
WILL BE ALONG 25N/26N DURING THAT TIME PERIOD.

THE ATLANTIC OCEAN...

PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS
ABOUT TROPICAL STORM GRACE.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N43W TO
26N48W. A STATIONARY FRONT PASSES THROUGH 32N37W TO 29N47W...TO
A 1014 MB LOW PRESSURE CENTER THAT IS NEAR 31N61W...TO 32N68W.
THE LOW PRESSURE CENTER IS FORECAST TO REMAIN STATIONARY FOR THE
NEXT DAY OR SO...AND THEN IT IS FORECAST TO MOVE NORTHWARD 5 TO
10 KNOTS BY WEDNESDAY. THE CHANCE OF FORMATION INTO A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS IS LOW. CONVECTIVE
PRECIPITATION...WIDELY SCATTERED TO SCATTERED STRONG FROM 29N TO
31N BETWEEN 57W AND 62W. ISOLATED MODERATE ELSEWHERE TO THE
NORTH OF THE LINE THAT PASSES THROUGH 32N29W 26N38W 22N55W
20N70W.

A SURFACE RIDGE EXTENDS FROM A 1022 MB HIGH PRESSURE CENTER THAT
IS NEAR 35N17W...THROUGH 32N23W...TO 28N30W...TO 24N38W...TO A
1014 MB HIGH PRESSURE CENTER THAT IS NEAR 25N59W...TO THE
CENTRAL BAHAMAS.

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

$$
MT
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