Tropical Weather Discussion
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000
AXNT20 KNHC 270005
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN JUL 26 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
2345 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE CAME OFF THE WEST AFRICAN COAST EARLIER THIS
AFTERNOON. ITS AXIS IS ALONG 19W...MOVING W AT APPROXIMATELY 10
TO 15 KT. SSMI TPW IMAGERY SHOW THE WAVE IS MAINLY ASSOCIATED
WITH A MODERATE AIRMASS THAT ALONG WITH A MIDDLE TO UPPER LEVEL
DIFFLUENT WIND ENVIRONMENT SUPPORT A CLUSTER OF MODERATE
CONVECTION FROM 10N TO 14N BETWEEN 18W AND 22W AND SCATTERED
MODERATE CONVECTION FROM 08N TO 12N E OF 19W. THE REMAINDER WAVE
ENVIRONMENT IS UNDER THE INFLUENCE OF SAHARAN DRY AIR AND
DUST...WHICH IS HINDERING CONVECTION.

A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AXIS ALONG
32W...MOVING W AT APPROXIMATELY 15 KT. SHALLOW MOISTURE IS AHEAD
OF THE WAVE AXIS WHILE A SURGE OF MODERATE TO DEEP MOISTURE IS
BEHIND IT. UPPER-LEVEL WIND DIFFLUENCE SUPPORT SCATTERED
MODERATE CONVECTION SE OF THE WAVE AXIS FROM 06N TO 10N BETWEEN
25W AND 34W. SAHARAN DRY AIR AND DUST COVER THE NORTHERN WAVE
ENVIRONMENT...THUS HINDERING CONVECTION.

A TROPICAL WAVE IS WITHIN 360 NM E OF THE LESSER ANTILLES WITH
AXIS NEAR 54W...MOVING W AT 20 KT. SSMI TPW IMAGERY AND ENHANCED
METEOSAT IMAGERY SHOW DRY AIR AND DUST OVER THE ENTIRE WAVE
ENVIRONMENT...THUS SUPPORTING LACK OF CONVECTION.

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS NEAR 73W
...MOVING W AT APPROXIMATELY 20 KT. SSMI TPW IMAGERY SHOW DRY
AIR AHEAD OF THE WAVE AXIS AND A MODERATE TO DEEP MOIST AIRMASS
BEHIND IT...WHICH IS ENHANCING ISOLATED SHOWERS AND TSTMS OVER
HISPANIOLA AND SOUTHERN ADJACENT WATERS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM THE WEST AFRICAN COAST NEAR
10N15W TO 08N30W TO 07N42W. THE ITCZ BEGINS NEAR 07N42W AND
CONTINUES TO THE COAST OF GUYANA. FOR CONVECTION
INFORMATION...SEE THE TROPICAL WAVES SECTION.

...DISCUSSION...

GULF OF MEXICO...

SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS COVERS THE
EASTERN GULF S OF 29N AND EXTENDS W-NW TO INLAND SOUTHERN
LOUISIANA AND FAR EASTERN TEXAS. THIS CONVECTION IS ASSOCIATED
WITH A 1010 MB LOW PRESSURE CENTER W OF TAMPA NEAR 27N83W FROM
WHICH A SURFACE TROUGH EXTENDS FROM 30N82W TO THE LOW TO 25N85W.
THIS LOW PRESSURE SYSTEM IS BEING SUPPORTED BY A MIDDLE LEVEL
LOW CENTERED NEAR 26N84W. AT THE UPPER-LEVELS...THE SOUTHERN
PERIPHERY OF A BROAD RIDGE CENTERED OVER SOUTHERN MISSISSIPPI
COVERS THE GULF OF MEXICO AND SUPPORT AT 1014 MB HIGH NEAR
24N89W. VARIABLE WIND IN THE RANGE OF 5 TO 10 KT DOMINATES THE
BASIN...EXCEPT OVER THE SE GULF WHERE SW TO W FLOW OF 15 KT IS
OBSERVED. SHOWERS AND TSTMS ACROSS THE E GULF WILL CONTINUE
THROUGH TUESDAY NIGHT...RIDGING WILL PREVAIL ELSEWHERE.

CARIBBEAN SEA...

AN ELONGATED UPPER-LEVEL LOW CONTINUES TO DOMINATE ACROSS
WESTERN CARIBBEAN WATERS WHILE A WEAK RIDGE COVERS THE REMAINDER
BASIN. THE UPPER LOW ALONG SHALLOW MOISTURE OVER THE NW BASIN
SUPPORT SCATTERED SHOWERS AND TSTMS ALONG CUBA. A TROPICAL WAVE IS
MOVING ACROSS THE CENTRAL BASIN WITH A SURGE OF MOISTURE E OF
ITS AXIS THAT SUPPORTS SCATTERED TO ISOLATED SHOWERS AND TSTMS
ACROSS HISPANIOLA AND ADJACENT SOUTHERN WATERS. DEEP LAYER DRY
AIR DOMINATES ELSEWHERE...THUS SUPPORTING FAIR WEATHER. A TIGHT
PRESSURE GRADIENT IS EXPECTED TO BUILD OVER THE S-SW CARIBBEAN
DURING THE NEXT 24 HOURS AND GALE-FORCE WINDS ARE FORECAST TO
DEVELOP TUESDAY MORNING. THE TROPICAL WAVE WILL MOVE OVER THE W
BASIN BRINGING SHOWERS TO JAMAICA MONDAY...AND THE CAYMAN
ISLANDS MONDAY NIGHT. THE NEXT TROPICAL WAVE WILL ENTER THE E
CARIBBEAN MONDAY EVENING.

...HISPANIOLA...

A TROPICAL WAVE IS MOVING ACROSS THE CENTRAL CARIBBEAN ASSOCIATED
WITH A MODERATE MOIST AIRMASS E OF ITS AXIS THAT ENHANCES
SCATTERED TO ISOLATED SHOWERS ACROSS THE ISLAND AND SOUTHERN
ADJACENT WATERS. THE WAVE WILL BE WEST OF THE ISLAND BY MONDAY
AND DRY AIR TRAILING THE WAVE WILL MOVE ACROSS THE ISLAND...THUS
SUPPRESSING SHOWERS THROUGH TUESDAY MORNING.

ATLANTIC OCEAN...

A DIFFLUENT WIND ENVIRONMENT AT THE MIDDLE-LEVELS COVER THE FAR
SW N ATLC BASIN AND ALONG WITH DEEP MOISTURE IN THIS REGION
SUPPORT SCATTERED TO ISOLATED SHOWERS AND TSTMS W OF
72W...INCLUDING THE NORTHERN BAHAMAS. ANOTHER REGION OF
DIFFLUENCE IN THE UPPER-LEVELS SUPPORT SIMILAR CONVECTION N OF
25N BETWEEN 53W AND 60W. THE REMAINDER BASIN N OF 16N CONTINUES
UNDER THE INFLUENCE OF A BROAD SURFACE RIDGE...WHICH SUPPORT
FAIR WEATHER. FOR TROPICAL WAVES INFORMATION...SEE SECTION AT THE
TOP OF THE DISCUSSION.

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

$$
NR



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