Tropical Weather Discussion
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000
AXNT20 KNHC 010005
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON AUG 31 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

THE CENTER OF HURRICANE FRED AT 01/0000 UTC IS NEAR 17.4N
25.0W... OR ABOUT 22 NM TO THE NORTH-NORTHEAST OF SANTO ANTAO IN
THE CAPE VERDE ISLANDS. WIND...STORM SURGE...AND RAINFALL ARE
THE MAIN THREATS TO THE CAPE VERDE ISLANDS. FRED IS MOVING
TOWARD THE NORTHWEST...OR 310 DEGREES...10 KNOTS. THE MINIMUM
CENTRAL PRESSURE IS 992 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 65 KNOTS WITH GUSTS TO 80 KNOTS. PUBLIC ADVISORIES ABOUT
TROPICAL STORM FRED ARE BEING ISSUED UNDER THE WMO HEADER
WTNT31 KNHC...AND UNDER THE AWIPS HEADER MIATCPAT1. FORECAST/
ADVISORIES ABOUT TROPICAL STORM FRED ARE BEING ISSUED UNDER THE
WMO HEADER WTNT21 KNHC...AND UNDER THE AWIPS HEADER MIATCMAT1.
CONVECTIVE PRECIPITATION...SCATTERED TO NUMEROUS STRONG FROM 15N
TO 19N BETWEEN 24W AND 25.5W.

...TROPICAL WAVES...

AN ATLANTIC OCEAN-TO-CARIBBEAN SEA TROPICAL WAVE CURVES FROM
20N59W TO 16N61W AND 11N61W. THE WAVE IS MOVING WESTWARD 15
KNOTS. THIS WAVE IS MOVING THROUGH THE AREA OF AN ATLANTIC OCEAN-
TO-CARIBBEAN SEA MIDDLE LEVEL TO UPPER LEVEL TROUGH THAT REACHES
18N64W. CONVECTIVE PRECIPITATION...ISOLATED MODERATE FROM 10N TO
16N BETWEEN 55W AND 62W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 77W/78W FROM 20N
SOUTHWARD...ACROSS JAMAICA. THE WAVE IS MOVING WESTWARD 20 KNOTS
DURING THE LAST 24 HOURS...THROUGH THE AREA OF AN INVERTED
MIDDLE LEVEL TO UPPER LEVEL TROUGH.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH IS ALONG 11N29W 09N36W...TO A 1012 MB LOW
PRESSURE CENTER THAT IS NEAR 07N40W...TO 07N47W. THE ITCZ IS NOT
PRESENT AT THIS TIME. CONVECTIVE PRECIPITATION...ISOLATED
MODERATE TO LOCALLY STRONG IS WITHIN 60 NM ON EITHER SIDE OF THE
LINE FROM 11N25W TO 09N32W TO 07N39W 06N45W 08N49W 08N52W 11N56W.

...DISCUSSION...

THE GULF OF MEXICO...

UPPER LEVEL SOUTHWESTERLY WIND FLOW SPANS THE GULF OF MEXICO.
THIS WIND FLOW IS ASSOCIATED WITH BROAD UPPER LEVEL CYCLONIC
WIND FLOW...THAT IS CONNECTED WITH A SOUTH TEXAS CYCLONIC
CIRCULATION CENTER THAT IS NEAR 29N98W. CONVECTIVE
PRECIPITATION...WIDELY SCATTERED TO SCATTERED MODERATE AND
ISOLATED STRONG FROM NORTHEASTERN MEXICO NEAR 25N TO 31N BETWEEN
92W AND 100W. SIMILAR CONVECTIVE PRECIPITATION IS UNDER UPPER
LEVEL ANTICYCLONIC WIND FLOW THAT COVERS THE EASTERN AND
SOUTHEASTERN SECTIONS...TO THE EAST OF THE LINE THAT RUNS FROM
29N83W TO 24N89W TO 19N93W...INCLUDING IN THE YUCATAN PENINSULA.

A SURFACE TROUGH IS ALONG THE LINE FROM NORTHEASTERN
FLORIDA...TO A 1015 MB LOW PRESSURE CENTER THAT IS NEAR
26N84W...TO THE NORTHWESTERN CORNER OF THE YUCATAN PENINSULA.
THIS SURFACE TROUGH REPRESENTS THE REMNANTS OF ERIKA.

THE CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL INVERTED TROUGH EXTENDS FROM
SOUTHEASTERN CUBA TO THE EASTERN HALF OF PANAMA. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG ALONG THE
NORTHERN BORDER OF HAITI AND THE DOMINICAN REPUBLIC...IN CENTRAL
CUBA ALONG THE CARIBBEAN SEA COAST. SCATTERED MODERATE TO
ISOLATED FROM 17N TO 21N BETWEEN 80W AND 85W.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH REACHES THE NORTHEASTERN
CORNER OF THE CARIBBEAN SEA NEAR 18N64W. CONVECTIVE
PRECIPITATION...ISOLATED MODERATE FROM 16N TO 20N BETWEEN 60W
AND 65W.

THE MONSOON TROUGH IS ALONG 10N BETWEEN 74W IN COLOMBIA AND 86W
IN COSTA RICA. CONVECTIVE PRECIPITATION...SCATTERED STRONG IN
PANAMA BETWEEN 80W AND 82W.

THE 24-HOUR RAINFALL TOTALS IN INCHES FOR THE PERIOD ENDING AT
31/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...ARE 0.20 IN
NASSAU IN THE BAHAMAS...0.11 IN FREEPORT IN THE BAHAMAS...0.08
IN GUADELOUPE...0.07 IN TRINIDAD...AND 0.03 IN MONTEGO BAY IN
JAMAICA.

...HISPANIOLA...

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 60W FROM 20N
SOUTHWARD...TOWARD TRINIDAD. IT IS POSSIBLE THAT THIS WAVE MAY
REACH HISPANIOLA DURING THE NEXT 48 HOURS ON WEDNESDAY.

A MIDDLE LEVEL TO UPPER LEVEL INVERTED TROUGH EXTENDS FROM
SOUTHEASTERN CUBA TO THE EASTERN HALF OF PANAMA. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG ALONG THE
NORTHERN BORDER OF HAITI AND THE DOMINICAN REPUBLIC.

OBSERVATIONS...IN HAITI...FEW CUMULONIMBUS CLOUDS AND SCATTERED
HIGH LEVEL CLOUDS ARE BEING OBSERVED IN PORT-AU-PRINCE. FOR THE
DOMINICAN REPUBLIC...FEW CUMULONIMBUS CLOUDS AND SCATTERED HIGH
LEVEL CLOUDS ARE IN BARAHONA. FEW LOW LEVEL CLOUDS AND SCATTERED
HIGH LEVEL CLOUDS ARE IN SANTO DOMINGO. FEW LOW LEVEL CLOUDS ARE
IN LA ROMANA. A LOW LEVEL CLOUD CEILING IS IN PUNTA CANA. FEW
CUMULONIMBUS CLOUDS AND SCATTERED HIGH LEVEL CLOUDS ARE IN
SANTIAGO. FEW CUMULONIMBUS CLOUDS AND A HIGH LEVEL CLOUD
CEILING ARE BEING OBSERVED IN PUERTO PLATA.

THE GFS MODEL FORECAST FOR 250 MB SHOWS THAT CYCLONIC WIND FLOW
WILL CROSS HAITI AT THE START OF THE 48-HOUR FORECAST PERIOD...
AND ANTICYCLONIC WIND FLOW WILL BE MOVING ACROSS THE DOMINICAN
REPUBLIC. THE CYCLONIC CIRCULATION CENTER THAT IS RESPONSIBLE
FOR THE CYCLONIC WIND FLOW IN HAITI EVENTUALLY WILL MOVE TOWARD
SOUTHERN JAMAICA...AND ANTICYCLONIC WIND FLOW WILL COVER THE
ENTIRE AREA FOR AT LEAST THE FIRST 24 HOURS. A NORTHEAST-TO-
SOUTHWEST ORIENTED TROUGH WILL MOVE INTO THE AREA AFTER 24
HOURS...AND IT WILL CONTINUE UNTIL THE END OF THE PERIOD. THE
GFS MODEL FORECAST FOR 500 MB AND FOR 700 MB SHOWS THAT AN
ANTICYCLONIC CIRCULATION CENTER WILL BE IN THE ATLANTIC OCEAN
NEAR 29N67W. LARGE-SCALE EAST-TO-NORTHEAST WIND FLOW WILL MOVE
ACROSS THE AREA. AN INVERTED TROUGH WILL MOVE ACROSS THE AREA
SLOWLY...CAUSING SOME SLIGHT WIND SHIFTS.

THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL INVERTED TROUGH EXTENDS FROM THE
NORTHERN BAHAMAS TO SOUTHEASTERN CUBA. THE TROUGH EVENTUALLY
CONTINUES SOUTHWARD TO PANAMA IN THE SOUTHWESTERN CORNER OF THE
CARIBBEAN SEA. COMPARATIVELY DRIER AIR IN SUBSIDENCE SURROUNDS
THE INVERTED TROUGH AT THIS MOMENT.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N45W TO
27N47W 24N55W 22N60W...INTO THE NORTHEASTERN CARIBBEAN SEA NEAR
18N64W. THIS TROUGH SUPPORTS A 1018 MB LOW PRESSURE CENTER THAT
IS NEAR 33N56W...AND A TROUGH THAT TRAILS THE LOW CENTER TO
29N60W. CONVECTIVE PRECIPITATION...BROKEN MULTILAYERED DEBRIS
CLOUDS AND ISOLATED MODERATE FROM 26N NORTHWARD BETWEEN 50W AND
60W. ISOLATED MODERATE FROM 16N TO 23N BETWEEN 52W AND 62W.
RAINSHOWERS ARE POSSIBLE FROM 24N NORTHWARD BETWEEN 30W AND 50W.

LARGE-SCALE UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE
ATLANTIC OCEAN TO THE NORTH AND NORTHWEST OF THE 32N45W 18N64W
MIDDLE LEVEL TO UPPER LEVEL TROUGH. CONVECTIVE PRECIPITATION...
ISOLATED MODERATE FROM 22N NORTHWARD BETWEEN 60W AND 77W. BROKEN
TO OVERCAST MULTILAYERED DEBRIS CLOUDS AND WARMING CLOUD TOP
TEMPERATURES FROM AREAS OF DISSIPATING PRECIPITATION ARE FROM
30N NORTHWARD BETWEEN 58W AND 66W.

A SURFACE RIDGE IS ALONG 31N14W 26N30W...TO A 1020 MB HIGH
PRESSURE CENTER THAT IS NEAR 25N52W...TO A 1021 MB HIGH PRESSURE
CENTER THAT IS NEAR 31N69W.

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

$$
MT


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