Tropical Weather Discussion
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000
AXNT20 KNHC 292355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUL 29 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...
GALE WARNING...
A GALE WARNING WILL GO INTO EFFECT OVERNIGHT TONIGHT AND END THU
AFTERNOON FOR THE AREA FROM 11N-14N BETWEEN 74W-78W IN THE SW
CARIBBEAN. THESE GALE FORCE WINDS ARE THE RESULT OF A STRONG
PRESSURE GRADIENT BETWEEN W ATLC HIGH PRESSURE AND LOWER
PRESSURE OVER THE SW CARIBBEAN AND SOUTH AMERICA. SEE LATEST NWS
HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC
FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IN THE E TROPICAL ATLC EXTENDS ALONG 29W FROM 8N-
17N MOVING W-SW 10-15 KT OVER THE PAST 12 HOURS. THE TOTAL
PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS EMBEDDED WITHIN A
SURGE OF DEEP MOISTURE. THE NOAA/NESDIS AEROSOL PRODUCT AND THE
LAST VISIBLE SATELLITE IMAGERY INDICATES THAT THE WAVE REMAINS
WITHIN A PLUMB OF AEROSOLS OR SAHARAN DUST LIMITING ANY
ASSOCIATED CONVECTION.

TROPICAL WAVE IN THE CENTRAL TROPICAL ATLC EXTENDS ALONG 44W
FROM 9N-16N MOVING W-SW NEAR 30 KT OVER THE PAST 24 HOURS. THE
TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS EMBEDDED
WITHIN A LOW AMPLITUDE SURGE OF MODERATE TO DEEP MOISTURE. THE
NOAA/NESDIS AEROSOL PRODUCT AND THE LAST VISIBLE SATELLITE
IMAGERY INDICATES THAT THE WAVE REMAINS WITHIN A PLUMB OF
AEROSOLS OR SAHARAN DUST LIMITING ANY ASSOCIATED CONVECTION.

TROPICAL WAVE IS IN THE W TROPICAL ATLC IS MOVING INTO THE E
CARIBBEAN ALONG 61W FROM 9N-18N IS MOVING W NEAR 20 KT OVER THE
PAST 24 HOURS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE
WAVE IS ALONG THE LEADING EDGE OF A SURGE OF MODERATE TO DEEP
MOISTURE. THE NOAA/NESDIS AEROSOL PRODUCT AND THE 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 W CARIBBEAN EXTENDS ALONG 84W S OF 20N TO
OVER CENTRAL AMERICA MOVING W NEAR 20 KT OVER THE PAST 24 HOURS.
THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS EMBEDDED
WITHIN A SURGE OF MODERATE MOISTURE. THE NOAA/NESDIS AEROSOL
PRODUCT AND THE VISIBLE SATELLITE IMAGERY INDICATES THAT THE
WAVE IS EMBEDDED WITHIN A PLUMB OF AEROSOLS OR SAHARAN DUST
LIMITING ANY ASSOCIATED CONVECTION. THE ACTIVITY W OF THE WAVE
IS ASSOCIATED WITH UPPER LEVEL FEATURES.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E
TROPICAL ATLC NEAR 20N16W ALONG 16N20W TO A 1010 MB LOW NEAR
12N23W THEN TO E OF THE EASTERN MOST TROPICAL WAVE NEAR 11N27W
THEN RESUMES W OF THE WAVE NEAR 10N30W ALONG 9N34W TO 10N39W
WHERE THE ITCZ BEGINS AND CONTINUES TO E OF THE NEXT TROPICAL
WAVE NEAR 11N43W THEN RESUMES W OF THE WAVE NEAR 11N46W TO E OF
THE NEXT WAVE NEAR 11N59W. SCATTERED MODERATE/STRONG CONVECTION
IS ASSOCIATED WITH THE 1010 MB LOW WITHIN 90 NM OF THE CENTER
OVER THE S QUADRANT AND WITHIN 60 NM OF 12N BETWEEN 22W-28W.
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 90 NM ALONG
THE COAST OF AFRICA BETWEEN 11N-14N.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE REMAINS OVER THE GULF OF MEXICO AND THE E
CONUS INTO THE W ATLC ANCHORED OVER THE LOWER MISSISSIPPI VALLEY
AND THE MOUNTAINS OF NORTH CAROLINA. A 1013 MB LOW IS IN THE W
ATLC WITH A SURFACE TROUGH EXTENDING ACROSS FLORIDA BETWEEN VERO
BEACH AND FORT MYERS THEN TO 26N86W IN THE GULF WATERS.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 25N-28N E OF
88W TO OVER FLORIDA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
ARE MOVING S INTO THE NE GULF N OF LINE FROM TAMPA BAY FLORIDA
TO 29N86W TO THE LOUISIANA COAST NEAR SLIDELL. A WEAK SURFACE
RIDGE EXTENDS FROM THE W ATLC OVER S FLORIDA/STRAITS OF FLORIDA
TO A 1018 MB HIGH NEAR 26N92W TO OVER THE SE CONUS NEAR THE
LOUISIANA/TEXAS BORDER. THE UPPER TROUGH OVER THE NW CARIBBEAN
IS GENERATING SCATTERED SHOWERS/THUNDERSTORMS INLAND AND ALONG
THE IMMEDIATE COAST OF CUBA W OF 81W. ISOLATED SHOWERS/
THUNDERSTORMS ARE POSSIBLE WITHIN 120 NM OF LINE FROM 23N86W TO
28N92W LEAVING THE REMAINDER OF THE GULF WITH CLEAR SKIES THIS
EVENING. THE SURFACE RIDGE WILL PERSIST THROUGH THU THEN SHIFT S
ON FRI AS A WEAK COLD FRONT MOVES INTO THE N/CENTRAL GULF.

CARIBBEAN SEA...
AN UPPER TROUGH EXTENDS FROM AN UPPER LOW IN THE SW ATLC ACROSS
HISPANIOLA THEN W ALONG 17N80W TO THE GULF OF HONDURAS
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS INLAND AND
ALONG THE IMMEDIATE COAST OF CUBA W OF 81W AND FROM 18N-20N
BETWEEN 84W-87W. A SECOND UPPER TROUGH EXTENDS FROM HISPANIOLA
TO THE ABC ISLANDS. AFTERNOON ISOLATED SHOWERS/THUNDERSTORMS
HAVE DEVELOPED INLAND OVER PUERTO RICO AND S HAITI. THE
NOAA/NESDIS AEROSOL PRODUCT AND THE VISIBLE SATELLITE IMAGERY
INDICATES THE CARIBBEAN IS COVERED A PLUMB OF AEROSOLS OR
SAHARAN DUST LEAVING THE REMAINDER OF THE CARIBBEAN WITH MOSTLY
CLEAR SKIES THIS EVENING. W ATLC SURFACE RIDGE WILL MAINTAIN
STRONG TO NEAR GALE TRADE WINDS THROUGH FRI INCREASING TO GALE
FORCE OVERNIGHT TONIGHT THROUGH THU AFTERNOON ALONG THE COAST OF
COLOMBIA. W CARIBBEAN TROPICAL WAVE WILL MOVE OVER THE YUCATAN
PENINSULA THU. TROPICAL WAVE MOVING INTO THE E CARIBBEAN WILL
MOVE ACROSS THE E CARIBBEAN THROUGH THU REACHING THE W CARIBBEAN
FRI NIGHT.

...HISPANIOLA...
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS HAVE DEVELOPED OVER S
HAITI THIS EVENING. THE UPPER LOW OVER THE SW ATLC WILL KEEP AN
UPPER TROUGH OVER THE ISLAND THROUGH FRI. MOISTURE WILL INCREASE
AGAIN THU NIGHT AHEAD OF THE NEXT TROPICAL WAVE. HOWEVER DAYTIME
HEATING COULD STILL PRODUCE A CHANCE OF OF ISOLATED SHOWERS AND
POSSIBLE THUNDERSTORMS DURING THE AFTERNOON/EVENINGS HOURS
THROUGH THU WITH AN INCREASE CHANCE OF OF SHOWERS AND
THUNDERSTORMS ON FRI.

ATLANTIC OCEAN...
THE UPPER RIDGE OVER THE E CONUS AND GULF OF MEXICO EXTENDS OVER
THE FAR W ATLC W OF 76W. A WEAK 1013 MB LOW IS CENTERED NEAR
31N77W WITH A SURFACE TROUGH EXTENDING OVER FLORIDA INTO THE
GULF OF MEXICO NEAR VERO BEACH. THIS IS GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 200 NM SE OF THE SURFACE
TROUGH. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 28N
BETWEEN 63W-73W ASSOCIATED WITH A FRONTAL SYSTEM N OF THE
DISCUSSION AREA. AN UPPER LOW IS CENTERED IN THE SW ATLC NEAR
21N68W EXTENDING AN UPPER TROUGH AXIS OVER HISPANIOLA AND IS
GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
FROM 20N-23N BETWEEN 65W-69W. A SURFACE RIDGE COVERS THE E ATLC
ANCHORED BY A 1027 MB HIGH ABOUT 350 NM SW OF THE AZORES WITH A
NARROWING RIDGE AXIS S OF THE W ATLC FRONTAL SYSTEM AND EXTENDS
THROUGH 32N39W ALONG 27N60W THEN ACROSS S FLORIDA/STRAITS OF
FLORIDA INTO THE GULF OF MEXICO. THE W ATLC 1013 MB LOW AND
SURFACE TROUGH WILL MOVE N OF THE AREA BY THU. THE SURFACE RIDGE
WILL DOMINATE THE REMAINDER THE ATLC SHIFTING N AND
STRENGTHENING BY FRI.

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

$$
PAW



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