[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181741
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1730 UTC.

...SPECIAL FEATURES...

AS OF 1500 UTC...TROPICAL DEPRESSION FOUR HAS
DEVELOPED...CURRENTLY CENTERED NEAR 10.6N AND 36.5W. THE
DEPRESSION IS MOVING W AT ABOUT 12 KT AND HAS MAXIMUM SUSTAINED
WINDS NEAR 30 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009
MB. NUMEROUS SHOWERS AND THUNDERSTORMS PREVAILS FROM 06N-13N
BETWEEN 32W-42W. GRADUAL STRENGTHENING IS FORECAST OVER THE NEXT
48 HOURS. PLEASE SEE LATEST PUBLIC ADVISORY UNDER THE AWIPS/WMO
HEADERS MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE HAS MOVED OFF THE AFRICAN COAST ALONG A 1009 MB
LOW CENTERED NEAR 15N18W. THE TROPICAL WAVE AXIS EXTENDS FROM
20N18W TO 11N17W...MOVING W AT ABOUT 05-10 KT. TPW IMAGERY
DEPICTS A MOISTURE MAXIMA SURROUNDING THIS WAVE AND LOW AND A
700 MB TROUGH IS OBSERVED ALONG 18W. SCATTERED MODERATE
CONVECTION PREVAILS FROM 10N-18N BETWEEN 17W-22W.

A TROPICAL WAVE IS AT ABOUT 500 NM E OF THE WINDWARD ISLANDS
WITH AXIS EXTENDING FROM 14N53W TO 05N53W. THIS WAVE HAS MOVED W
AT 10-15 KT OVER THE PAST 24 HOURS. TPW IMAGERY SHOWS A MODERATE
MOIST ENVIRONMENT SURROUNDING THE SOUTHERN PORTION OF THE WAVE
MAINLY S OF 12N. SCATTERED MODERATE CONVECTION IS FROM 07N-11N
BETWEEN 49W-57W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 16N17W TO
THE 1009 MB LOW NEAR 15N18W TO 13N30W. THE ITCZ EXTENDS FROM
THAT POINT TO THE SPECIAL FEATURE LOW NEAR 11N36W TO 07N52W.
ASIDE FROM CONVECTION ASSOCIATED WITH THE LOW
CENTERS...SCATTERED MODERATE CONVECTION IS FROM 10N-13N BETWEEN
23W-28W.

...DISCUSSION...

GULF OF MEXICO...

AN UPPER-LEVEL ANTICYCLONE CENTERED OVER THE SW GULF NEAR 22N90W
EXTENDS ACROSS THE WHOLE BASIN. AT THE SURFACE...A SURFACE
TROUGH EXTENDS ACROSS THE GULF OF CAMPECHE FROM 23N92W TO
19N93W. A CLUSTER OF MODERATE CONVECTION IS W OF THE TROUGH AXIS
FROM 19N-25N BETWEEN 93W-96W. AN AREA OF SCATTERED MODERATE
CONVECTION PREVAILS ALONG THE COAST OF LOUISIANA...MISSISSIPPI
AND THE FLORIDA PANHANDLE AFFECTING THE GULF WATERS N OF 28N AND
E OF 94W. UPPER-LEVEL DIFFLUENCE IS SUPPORTING ISOLATED
CONVECTION ACROSS THE SE GULF MAINLY E OF 85W INCLUDING THE
STRAITS OF FLORIDA. THE REMAINDER OF THE AREA IS UNDER A FAIR
WEATHER REGIME WITH THE ATLANTIC RIDGE EXTENDING W ACROSS THE E
GULF. SCATTEROMETER DATA DEPICTS A LIGHT TO GENTLE ANTICYCLONIC
FLOW ACROSS THE AREA. OVER THE NEXT 24 HOURS...AN AREA OF LOW
PRESSURE WILL DEVELOP OVER TEXAS/MEXICO AND APPROACH THE W GULF
INCREASING WIND SPEED ACROSS THE AREA AND SUPPORTING CONVECTION.

CARIBBEAN SEA...

THE BROAD AREA OF SURFACE HIGH PRESSURE THAT PREVAILS ACROSS THE
ATLANTIC EXTENDS S REACHING THE CARIBBEAN WATERS. AN UPPER-LEVEL
LOW IS CENTERED OVER W JAMAICA NEAR 18N78W SUPPORTING ISOLATED
CONVECTION ACROSS THE NW CARIBBEAN MAINLY N OF 16N AND W OF 74W.
LOOKING S...AN AREA OF UPPER-LEVEL DIFFLUENCE IS SUPPORTING
ISOLATED CONVECTION S OF 14N BETWEEN 74W-82W. FAIR WEATHER
PREVAILS ACROSS THE REMAINDER OF THE BASIN. SCATTEROMETER DATA
DEPICTS A GENTLE TO MODERATE NE FLOW PREVAILING ACROSS THE BASIN
EXCEPT S OF 13N BETWEEN 72W-77W WHERE A MODERATE TO FRESH FLOW
IS OBSERVED. OVER THE NEXT 24 HOURS...EXPECT FOR A TROPICAL WAVE
TOO APPROACH THE LESSER ANTILLES SUPPORTING CONVECTION.

...HISPANIOLA...

FAIR WEATHER PREVAILS ACROSS THE ISLAND AS THE UPPER-LEVEL LOW
CONTINUES MOVING AWAY FROM THIS AREA. EXPECT THESE DRY
CONDITIONS TO PREVAIL OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...

TWO TROPICAL WAVES AND A TROPICAL DEPRESSION ARE MOVING ACROSS
THE TROPICAL ATLANTIC. PLEASE REFER TO THE SECTIONS ABOVE FOR
MORE DETAILS. AN AREA OF UPPER-LEVEL DIFFLUENCE IS SUPPORTING
SCATTERED MODERATE CONVECTION ACROSS THE W ATLANTIC MAINLY N OF
29N AND W OF 65W. S OF THIS ACTIVITY...A 1019 MB SURFACE HIGH IS
CENTERED NEAR 30N73W. TO THE E...A 1023 MB SURFACE HIGH PREVAILS
ACROSS THE CENTRAL ATLANTIC CENTERED NEAR 30N45W AND EXTENDING E
ACROSS THE REMAINDER OF THE BASIN WITH FAIR WEATHER. A SIMILAR
WEATHER REGIME WILL CONTINUE ACROSS THE BASIN OVER THE NEXT 24
HOURS.

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

$$

ERA
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