Tropical Weather Discussion
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000
AXNT20 KNHC 220008
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU AUG 21 2014

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
2345 UTC.

...SPECIAL FEATURES...

A 1009 MB LOW IS LOCATED 230 NM MILES EAST OF GUADELOUPE
NEAR 16N58W...MOVING W AT 15-20 KT. A TROPICAL WAVE EXTENDS N
FROM THE LOW CENTER TO 24N56W. HEAVY SHOWERS AND TSTMS ARE NW
FROM THE LOW FROM 17N-21N BETWEEN 62W-64W. SCATTERED MODERATE
CONVECTION IS FROM 14N-18N BETWEEN 56-60W AND ELSEWHERE FROM 14N-
23N BETWEEN 60W-67W. THIS AFTERNOON...HURRICANE HUNTER AIRCRAFT
FOUND GALE FORCE WINDS IN THE NORTHERN SEMICIRCLE OF THE LOW
EXPECTED TO LAST FOR THE NEXT 48 HOURS. GRADUAL DEVELOPMENT OF
THE LOW IS POSSIBLE DURING THE NEXT FEW DAYS AS IT MOVES ACROSS
THE LEEWARD ISLANDS...PUERTO RICO...AND THE BAHAMAS. INTERESTS
DOWNSTREAM OF THE LOW SHOULD MONITOR CLOSELY THE PROGRESS OF
THIS SYSTEM. CHANCES FOR DEVELOPMENT INTO A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS IS HIGH.

...TROPICAL WAVES...

A TROPICAL WAVE IS WEST OF THE CAPE VERDE ISLANDS WITH AXIS
EXTENDING FROM 23N26W TO 12N26W MOVING W AT 10 KT. NO CONVECTION
IS OCCURRING AT THIS TIME AS DRY SAHARAN AIR AND DUST ARE IN ITS
ENVIRONMENT.

A TROPICAL WAVE IS EAST OF THE LEEWARD ISLANDS. SEE SPECIAL
FEATURES SECTION.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 11N16W
AND CONTINUES ALONG 13N26W 8N33W TO 7N40W. AN ITCZ EXTENDS FROM
7N40W TO 10N50W. SCATTERED MODERATE CONVECTION IS FROM 5N-14N E
OF 22W AND FROM 5N-10N BETWEEN 44W-51W.

...DISCUSSION...

GULF OF MEXICO...

A 1019 MB HIGH IS CENTERED ON THE NE GULF NEAR 29N86W. A
SCATTEROMETER PASS SHOWS ANTICYCLONIC WINDS MAINLY BETWEEN 5-15
KT WITH SW WINDS UP TO 20 KT ACROSS THE BAY OF CAMPECHE. UPPER
LEVEL DIFFLUENCE AND LOW LEVEL MOISTURE ARE SUPPORTING SCATTERED
SHOWERS AND HEAVY THUNDERSTORMS ON THE SE GULF S OF 25N E OF
89W. ISOLATED SHOWERS AND THUNDERSTORMS ARE LOCATED NEAR THE
LOUISIANA COAST AND OVER THE YUCATAN. DURING THE NEXT 24 HOURS
EXPECT SCATTERED SHOWERS AND THUNDERSTORMS MAINLY OVER THE
SOUTHERN HALF OF THE BASIN.

CARIBBEAN SEA...

AN AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE IS EAST OF
THE LEEWARD ISLANDS. THIS SYSTEM IS BRINGING HIGH MOISTURE INTO
THE EASTERN CARIBBEAN AND ADJACENT WATERS. MIDDLE LEVEL
DIVERGENCE ALONG WITH DEEP LAYER MOISTURE ASSOCIATED WITH THIS
SYSTEM IS SUPPORTING THE CONVECTION DESCRIBED IN THE SPECIAL
FEATURES SECTION. SEE ABOVE. AN ELONGATED UPPER LEVEL LOW
EXTENDS ACROSS THE CENTRAL AND SW CARIBBEAN ENHANCING SHOWERS
AND ISOLATED TSTMS ON JAMAICA AS WELL AS S OF 13N BETWEEN 73W-
83W. UPPER LEVEL DIFFLUENCE ACROSS THE NW BASIN ENHANCES HEAVY
SHOWERS AND TSTMS ALONG SOUTHERN CUBA AND ADJACENT WATERS.
SCATTERED HEAVY SHOWERS AND TSTMS ARE ALSO NOTED OVER HAITI.
FAIR WEATHER IS ELSEWHERE ACROSS THE BASIN BEING SUPPORTED BY
DEEP LAYER DRY AIR AND/OR STRONG ENVIRONMENTAL SHEAR ON THE
CENTER CARIBBEAN. TRADE WINDS OF 10-15 KT ARE ACROSS THE
REGION...EXCEPT ALONG COLOMBIA WHERE WINDS INCREASE UP TO 20 KT.
RAINSHOWERS ASSOCIATED WITH THE SYSTEM ON THE SPECIAL FEATURES
WILL BE AFFECTING THE GREATER ANTILLES OVER THE WEEKEND.

...HISPANIOLA...

LINGERING MOISTURE ASSOCIATED WITH THE PASSAGE OF A SURFACE
TROUGH ALONG WITH A REGION OF UPPER LEVEL DIFFLUENCE IS
SUPPORTING SCATTERED SHOWERS AND TSTMS OVER CENTRAL HAITI.
RAINSHOWER ACTIVITY WILL INCREASE OVER THE WEEKEND...PEAKING
EARLY ON SATURDAY AS THE SYSTEM ON SPECIAL FEATURES MOVES
ACROSS/NEAR THE ISLAND.

ATLANTIC OCEAN...

MAINLY MIDDLE TO UPPER LEVEL RIDGING IS ACROSS THE BASIN N OF
24N WHICH IS SUPPORTING SURFACE RIDGING. GALE FORCE WINDS ARE
CLOSE TO THE LEEWARD ISLANDS ASSOCIATED WITH THE SYSTEM IN THE
SPECIAL FEATURES. SEE ABOVE.

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

$$
NAR/ASL



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