[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211108
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI AUG 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURES...

THE CENTER OF HURRICANE DANNY AT 21/0900 UTC IS NEAR 13.7N
47.4W...OR 840 NM TO THE EAST OF THE WINDWARD ISLANDS...MOVING
WEST-NORTHWESTWARD...OR 290 DEGREES...09 KNOTS. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 987 MB. THE MAXIMUM SUSTAINED WIND
SPEEDS ARE 75 KNOTS WITH GUSTS TO 90 KNOTS. CONVECTIVE
PRECIPITATION...NUMEROUS STRONG WITHIN A RADIUS OF 60 NM OF THE
CENTER IN THE EASTERN SEMICIRCLE...AND WITHIN A RADIUS OF 30 NM
TO 60 NM OF THE CENTER IN THE WESTERN SEMICIRCLE. ISOLATED
MODERATE ELSEWHERE WITHIN A RADIUS OF 285 NM OF THE CENTER IN
THE EASTERN SEMICIRCLE...AND ELSEWHERE WITHIN A RADIUS OF 180 NM
OF THE CENTER IN THE WESTERN SEMICIRCLE. PUBLIC ADVISORIES ABOUT
HURRICANE DANNY ARE BEING ISSUED UNDER WMO HEADER WTNT34 KNHC
AND UNDER AWIPS HEADER MIATCPAT4. FORECAST/ADVISORIES ABOUT
HURRICANE DANNY ARE BEING ISSUED UNDER WMO HEADER WTNT24 KNHC
AND UNDER AWIPS HEADER MIATCMAT4.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 22N28W 15N30W 06N30W...
MOVING WESTWARD 10 KNOTS. CONVECTIVE PRECIPITATION...RAINSHOWERS
ARE POSSIBLE WITHIN 60 NM ON EITHER SIDE OF THE WAVE.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG THE LINE FROM
19N67W...THROUGH THE MONA PASSAGE...TO 15N68W...TO 10N68W IN
VENEZUELA. THE WAVE IS MOVING WESTWARD 10 TO 15 KNOTS.
CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG
WITHIN A 15 NM TO 30 NM RADIUS OF 16.5N61W NEAR LA DESIRADE/
GUADELOUPE IN THE LEEWARD ISLANDS. RAINSHOWERS ARE POSSIBLE
ELSEWHERE FROM 20N SOUTHWARD BETWEEN 60W AND 74W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL SECTIONS OF SENEGAL
NEAR 14N17W TO 10N22W 08N30W AND 10N38W. NO ITCZ IS PRESENT AT
THIS MOMENT. CONVECTIVE PRECIPITATION...WIDELY SCATTERED
MODERATE TO ISOLATED STRONG FROM 05N TO 16N FROM 30W EASTWARD...
FROM 07N TO 10N BETWEEN 40W AND 50W...AND FROM 11N SOUTHWARD
BETWEEN 50W AND 60W.

...DISCUSSION...

THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS ALONG 99W/100W IN
MEXICO. MOST OF THE CYCLONIC WIND FLOW THAT IS MOVING AROUND THE
TROUGH IS INLAND. CONVECTIVE PRECIPITATION...NUMEROUS STRONG IS
IN THE COASTAL PLAINS/COASTAL WATERS OF SOUTH TEXAS AND EXTREME
NORTHEASTERN MEXICO. SCATTERED MODERATE TO ISOLATED STRONG IS IN
THE COASTAL PLAINS/COASTAL WATERS OF MEXICO FROM 18N TO 24N.

THE UPPER LEVEL ANTICYCLONIC WIND FLOW THAT WAS COVERING THE
ENTIRE GULF OF MEXICO 24 HOURS AGO...NOW...MOSTLY COVERS THE
GULF OF MEXICO JUST FROM 25N NORTHWARD.

COVERING THE SOUTHEASTERN CORNER OF THE GULF OF MEXICO...AND THE
NORTHWESTERN CORNER OF THE CARIBBEAN SEA...

THE SOUTHEASTERN CORNER OF THE GULF OF MEXICO IS BEING INVADED
BY A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
THAT IS NEAR 18N89W IN BELIZE. CYCLONIC WIND FLOW COVERS THE
AREA FROM HONDURAS NEAR 13N TO 24N IN THE GULF OF MEXICO...
BETWEEN 80W AND 94W IN THE GULF OF MEXICO. CONVECTIVE
PRECIPITATION...ISOLATED MODERATE TO LOCALLY STRONG IN THE
COASTAL WATERS AND COASTAL PLAINS OF CUBA ON THE CARIBBEAN SEA
SIDE. BROKEN TO OVERCAST MULTILAYERED CONVECTIVE DEBRIS CLOUDS
REMAIN FROM 15N NORTHWARD FROM 81W WESTWARD.

THE REST OF THE CARIBBEAN SEA...

A SURFACE TROUGH EXTENDS FROM A 1008 MB LOW PRESSURE CENTER THAT
IS NEAR 10N74W IN COLOMBIA...TO 05N77W ALONG THE EASTERN PACIFIC
OCEAN COAST OF COLOMBIA...AND TO 03N81W. CONVECTIVE
PRECIPITATION...NUMEROUS STRONG IN COLOMBIA FROM 07N TO 10N
BETWEEN 75W AND 78W...AND IN COASTAL AREAS OF COLOMBIA AND
PANAMA FROM 02N TO 08N BETWEEN 76W AND 81W. OTHER SCATTERED
MODERATE TO ISOLATED STRONG PRECIPITATION IS IN LAKE MARACAIBO
IN NORTHWESTERN VENEZUELA.

UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE CARIBBEAN SEA FROM
17N SOUTHWARD FROM 80W EASTWARD.

...HISPANIOLA...

OBSERVATIONS...IN HAITI...THE EARLIER NUMEROUS STRONG CONVECTIVE
PRECIPITATION FOR PORT-AU-PRINCE HAS ENDED. SCATTERED LOW LEVEL
CLOUDS AND A MIDDLE LEVEL CLOUD CEILING REMAIN. FOR THE
DOMINICAN REPUBLIC...FEW LOW LEVEL CLOUDS AND SCATTERED HIGH
LEVEL CLOUDS ARE IN SANTO DOMINGO. FEW LOW LEVEL CLOUDS ARE IN
PUNTA CANA. FEW CUMULONIMBUS CLOUDS AND A MIDDLE LEVEL CLOUD
CEILING ARE BEING OBSERVED IN SANTIAGO. FEW LOW LEVEL CLOUDS ARE
IN PUERTO PLATA.

THE GFS MODEL FORECAST FOR 250 MB SHOWS THAT NORTHERLY WIND FLOW
WILL MOVE ACROSS THE AREA WITH A NORTHEAST-TO-SOUTHWEST ORIENTED
TROUGH. THE GFS MODEL FORECAST FOR 500 MB SHOWS THAT NORTHEAST
WIND FLOW WILL PASS ACROSS THE AREA FOR THE FIRST 24 HOURS.
INVERTED TROUGHS WILL PASS THROUGH THE AREA FROM 24 HOURS UNTIL
48 HOURS. THE GFS MODEL FORECAST FOR 700 MB SHOWS THAT
NORTHEASTERLY WIND FLOW WILL MOVE ACROSS THE AREA.

THE ATLANTIC OCEAN...

HURRICANE DANNY IS IN THE ATLANTIC OCEAN. PLEASE READ THE
SPECIAL FEATURES SECTION FOR MORE DETAILS ABOUT THE
HURRICANE.

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 34N65W. A SECOND MIDDLE LEVEL TO UPPER LEVEL CYCLONIC
CIRCULATION CENTER IS NEAR 33N46W. CYCLONIC WIND FLOW COVERS THE
AREA THAT IS TO THE NORTHWEST OF THE LINE 30N18W 24N40W 22N60W
22N66W 24N72W 30N80W. A 1012 MB LOW PRESSURE CENTER IS NEAR
30N66W. A SURFACE TROUGH EXTENDS FROM THE LOW CENTER TO 27N61W.
A SECOND SURFACE TROUGH EXTENDS FROM THE LOW CENTER TO 27N69W
AND 28N74W. A 1016 MB LOW PRESSURE CENTER IS NEAR 29N44W. ONE
SURFACE TROUGH EXTENDS FROM THE LOW CENTER BEYOND 32N44W. A
SECOND SURFACE TROUGH EXTENDS FROM THE LOW CENTER TO 26N46W AND
26N49W. CONVECTIVE PRECIPITATION...WIDELY SCATTERED TO SCATTERED
MODERATE AND ISOLATED STRONG FROM 24N NORTHWARD BETWEEN 54W AND
81W. WIDELY SCATTERED TO SCATTERED MODERATE AND ISOLATED STRONG
FROM 30N BETWEEN 38W AND 43W. ISOLATED MODERATE ELSEWHERE FROM
25N NORTHWARD BETWEEN 38W AND 52W.

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

$$
MT
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