Tropical Weather Discussion
Issued by NWS

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000
AXNT20 KNHC 241044
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU JUL 23 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
1015 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IN THE TROPICAL ATLC EXTENDS ALONG 38W FROM 9N-17N
MOVING W 5-10 KT OVER THE PAST 24 HOURS. THE TOTAL PRECIPITABLE
WATER IMAGERY SHOWS THE WAVE IS N OF ANY DEEP MOISTURE. THE
NOAA/NESDIS AEROSOL PRODUCT AND THE FIRST VISIBLE SATELLITE
IMAGERY INDICATES THAT THE WAVE REMAINS EMBEDDED WITHIN A PLUMB
OF AEROSOLS OR SAHARAN DUST LIMITING ANY ASSOCIATED CONVECTION.

TROPICAL WAVE IN THE CENTRAL CARIBBEAN EXTENDS ALONG 78W/79W S
OF 18N TO ACROSS PANAMA MOVING W NEAR 20 KT OVER THE PAST 24
HOURS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS
EMBEDDED WITHIN A BROAD AREA OF MODERATE TO DEEP MOISTURE THAT
COVERS THE CARIBBEAN W OF 74W. NO ASSOCIATED DEEP CONVECTION BUT
IS ENHANCING THE ACTIVITY ASSOCIATED WITH THE UPPER LOW.

TROPICAL WAVE THAT WAS IN THE W CARIBBEAN IS NOW INLAND OVER
CENTRAL AMERICA.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E
TROPICAL ATLC NEAR 21N16W ALONG 11N23W TO 8N30W WHERE THE ITCZ
BEGINS AND CONTINUES ALONG 7N38W 8N51W TO SOUTH AMERICA NEAR
6N58W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
ARE WITHIN 120 NM OF LINE FROM THE COAST OF AFRICA NEAR 12N16W
TO 6N26W AND FROM 8N-11N BETWEEN 46W-53W. CLUSTERS OF SCATTERED
MODERATE CONVECTION ARE WITHIN 120 NM S OF THE ITCZ BETWEEN 31W-
48W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE IS ANCHORED OVER THE FLORIDA PANHANDLE COVERING
THE E GULF WHILE THE UPPER LOW CENTERED IN THE SW GULF NEAR
24N94W COVERS THE REMAINDER OF THE GULF. THE UPPER RIDGE IS
PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED TO NUMEROUS
SHOWERS WITH ISOLATED THUNDERSTORMS ACROSS THE NE GULF N OF 28N
E OF 87W. A WEAK SURFACE RIDGE EXTENDS FROM THE W ATLC THROUGH
THE STRAITS OF FLORIDA TO NE TEXAS WITH A 1018 MB HIGH NEAR
25N84W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 60 NM OF THE W
COAST OF FLORIDA S OF 28N INCLUDING THE FLORIDA KEYS LEAVING THE
REMAINDER OF THE GULF WITH CLEAR SKIES THIS MORNING. SURFACE
RIDGE WILL PERSIST THROUGH SUN. A TROUGH OF LOW PRESSURE MAY
ENTER THE NE GULF SUN NIGHT.

CARIBBEAN SEA...
AN UPPER LOW IS CENTERED JUST W OF HAITI IN THE WINDWARD PASSAGE
WITH AN UPPER TROUGH COVERING THE CARIBBEAN W OF 70W. THIS UPPER
TROUGH COUPLED WITH THE TROPICAL WAVE IS GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF 18N BETWEEN THE WINDWARD
PASSAGE AND 80W AND N OF 21N BETWEEN 80W-84W. AN UPPER RIDGE
ANCHORED IN THE TROPICAL ATLC EXTENDS ACROSS THE E CARIBBEAN.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE SW
CARIBBEAN S OF 12N W OF 73W TO OVER CENTRAL AMERICA LEAVING THE
REMAINDER OF THE CARIBBEAN WITH MOSTLY CLEAR SKIES THIS MORNING.
W ATLC SURFACE RIDGE WILL MAINTAIN MODERATE TO FRESH TRADE WINDS
WITH STRONG TO OCCASIONAL NEAR GALE CONDITIONS OCCURRING OFF THE
COAST OF COLOMBIA AND VENEZUELA THROUGH SUN. THE CENTRAL
CARIBBEAN TROPICAL WAVE WILL MOVE ACROSS THE W CARIBBEAN THROUGH
SAT. A SECOND TROPICAL WAVE WILL ENTER THE E CARIBBEAN SUN.

...HISPANIOLA...
SKIES HAVE CLEARED ACROSS THE ISLAND THIS MORNING WITH SOME
LINGERING SHOWERS/THUNDERSTORMS IN THE WINDWARD PASSAGE. THIS
ACTIVITY IS DUE TO THE UPPER LOW OVER THE WINDWARD PASSAGE AND
THE TROPICAL WAVE MOVING AWAY FROM THE ISLAND. AS THIS UPPER LOW
MOVES W...IT WILL GIVE THE ISLAND SOUTHERLY FLOW ALOFT TODAY AND
SAT WITH AN UPPER RIDGE SETTING UP ON SUN. MOISTURE ASSOCIATED
WITH THE TROPICAL WAVE WILL LINGER THROUGH THIS MORNING. SAT AND
SUN WILL SEE A SLIGHT BREAK IN THE MOISTURE BUT WITH DAYTIME
HEATING COULD STILL PRODUCE A CHANCE OF SHOWERS AND POSSIBLE
THUNDERSTORMS DURING THE AFTERNOON/EVENINGS HOURS.

ATLANTIC OCEAN...
AN E/W ELONGATED UPPER RIDGE IS ANCHORED IN THE W ATLC NEAR
30N68W COVERING THE W ATLC N OF 25N W OF 57W AND IS PROVIDING
DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS WITHIN 75 NM OF LINE FROM 30N73W TO S FLORIDA NEAR
MIAMI INCLUDING THE N BAHAMA ISLANDS. THE UPPER LOW CENTERED
OVER THE WINDWARD PASSAGE COVERS THE W ATLC S OF 25N AND IS
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 23N TO
OVER THE WINDWARD PASSAGE BETWEEN 72W-75W. AN N-NE/S-SW
ELONGATED UPPER LOW IS CENTERED IN THE CENTRAL ATLC NEAR 25N51W
SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 29N47W TO 21N51W
AND GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN
180 NM EITHER SIDE OF THE TROUGH AND FROM 27N-31N BETWEEN 54W-
59W. THE ATLC BASIN IS DOMINATED BY A SURFACE RIDGE ANCHORED BY
A 1028 MB HIGH N OF THE DISCUSSION AREA NEAR 33N36W AND
EXTENDING A RIDGE AXIS THROUGH A 1022 MB HIGH NEAR 26N55W THEN W
THROUGH THE STRAITS OF FLORIDA AND INTO THE GULF OF MEXICO.
SURFACE RIDGE WILL RETREAT EASTWARD AND WEAKEN TONIGHT AND SAT
AS A WEAK LOW MOVES OFF THE SE U.S. COAST. THE LOW WILL THEN
MOVE N OF THE AREA SUN NIGHT.

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

$$
PAW


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