Tropical Weather Discussion
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000
AXNT20 KNHC 012354
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT AUG 01 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-FORCE WINDS ARE FORECAST ALONG THE COAST OF COLOMBIA
STARTING AT 0600 UTC TONIGHT...FROM 11N TO 13N BETWEEN 74W AND
76W. THE GALE-FORCE WINDS ARE FORECAST TO LAST FOR ABOUT 12
HOURS. PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2/ FZNT02
KNHC...AND THE OFFSHORE FORECAST...MIAOFFNT3/FZNT23 KNHC...FOR
MORE DETAILS.

...TROPICAL WAVES...

AN EASTERN ATLC TROPICAL WAVE HAS AN AXIS FROM 08N27W TO
18N26W...MOVING W AT AROUND 10 TO 15 KT OVER THE PAST 24 HOURS.
THIS WAVE COINCIDES WITH A SHARP INVERTED 700 MB TROUGH BETWEEN
25W AND 29W. THE LEADING EDGE OF A MODERATE POLEWARD SURGE IS
NOTED IN SSMI TPW IMAGERY ALONG THE WAVE. CLUSTERS OF MODERATE
CONVECTION ARE FROM 08N TO 13N BETWEEN 23W AND 31W.

A CENTRAL ATLC TROPICAL WAVE HAS AN AXIS FROM 10N56W TO
22N58W...MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. THIS
WAVE COINCIDES WITH A BROAD 700 MB INVERTED TROUGH FROM 55W TO
63W WITH SSMI TPW IMAGERY SHOWING A POLEWARD SURGE OF MODERATE
MOISTURE ALONG THE WAVE. ISOLATED MODERATE CONVECTION IS FROM
19N TO 23N BETWEEN 56W AND 60W.

A WESTERN CARIBBEAN TROPICAL WAVE HAS AN AXIS FROM 08N84W TO
17N84W...MOVING W AT 10 TO 15 KT OVER THE PAST 24 HOURS. HIGH
DEEP LAYER MOISTURE IS NOTED WITH THIS WAVE. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 09N TO 18N BETWEEN 80W AND 87W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL SECTIONS OF AFRICA
NEAR 17N16W AND CONTINUES TO 12N25W...THEN RESUMES W OF A
TROPICAL WAVE NEAR 11N28W TO A 1011 MB LOW NEAR 12N39W TO
08N52W. OTHER THAN CONVECTION ASSOCIATED WITH THE TROPICAL
WAVE...SCATTERED MODERATE CONVECTION IS WITHIN 200 NM OF THE
MONSOON TROUGH AXIS BETWEEN 38W AND 52W...WITH ISOLATED MODERATE
CONVECTION ELSEWHERE WITHIN 200 NM OF THE MONSOON TROUGH AXIS.

...DISCUSSION...

...THE GULF OF MEXICO...
A BROAD UPPER LEVEL ANTICYCLONE CENTERED OVER TX HAS AN AXIS
THAT EXTENDS E ACROSS THE NORTHERN GULF. UPPER LEVEL DIFFLUENCE
IS OCCURRING WITH THIS AXIS. AN UPPER TROUGH OVER THE NE US
SUPPORTS A FRONTAL SYSTEM WITH A 1011 MB LOW CENTERED NEAR
30N85W AND STATIONARY FRONT FROM THIS LOW ACROSS THE NORTHERN
GULF...TO A DISSIPATING 1013 MB LOW NEAR 28N94W. A COLD FRONT
EXTENDS FROM THE 1013 MB LOW TO NEAR THE TX/MEXICO BORDER NEAR
26N97W. THE COMBINATION OF FORCING FROM THE EASTERNMOST LOW AND
THE FRONT...AND UPPER LEVEL DIFFLUENCE...SUPPORTS SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION FROM 26N TO 31N BETWEEN
THE FL W COAST AND 91W. SCATTERED SHOWERS AND THUNDERSTORMS ARE
ELSEWHERE WITHIN 50 NM OF THE FRONTAL BOUNDARIES. E TO NE WINDS
OF 10 TO 15 KT ARE N OF THE FRONTS. SW WINDS OF 15 TO 20 KT ARE
WITHIN 125 NM S OF THE FRONTS. SE TO SW WINDS OF 10 TO 15 KT ARE
S OF 24 N ACROSS THE REMAINDER OF THE GULF. THE SURFACE LOWS
WILL DISSIPATE OVER THE NEXT 24 HOURS. THE STATIONARY FRONT WILL
REMAIN IN TACT WITH ONGOING CONVECTION EXPECTED ACROSS THE
NORTHERN GULF THROUGH SUNDAY.

...THE CARIBBEAN SEA...

DIFFLUENCE BETWEEN AN UPPER LOW OVER GUATEMALA AND ANOTHER
UPPER LOW NEAR THE BAHAMAS SUPPORTS ISOLATED MODERATE CONVECTION
OVER THE NW CARIBBEAN MAINLY NEAR THE GREATER ANTILLES. A
TROPICAL WAVE IS PRODUCING CONVECTION OVER THE W CARIBBEAN.
PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. A
TIGHT PRESSURE GRADIENT BETWEEN W ATLC HIGH PRESSURE AND LOWER
PRESSURES OVER S AMERICA IS PRODUCING STRONG TRADE WINDS OVER
THE S CENTRAL CARIBBEAN THIS EVENING. THESE WINDS WILL
STRENGTHEN FURTHER TONIGHT WHICH WILL RESULT IN GALE-FORCE WINDS
STARTING AT 0600 UTC. PLEASE REFER TO THE SPECIAL FEATURES
SECTION FOR MORE DETAILS. MODERATE TO FRESH TRADE WINDS COVER
THE REMAINDER OF THE CARIBBEAN BASIN. EXPECT A GENERAL DECREASE
IN CONVECTION OVER THE CENTRAL AND WESTERN CARIBBEAN OVER THE
NEXT 24 HOURS. SHOWERS WILL INCREASE OVER THE EASTERN CARIBBEAN
AS A TROPICAL WAVE CROSSES THE LESSER ANTILLES LATER TONIGHT.

...HISPANIOLA...

DEEP MOISTURE OVER THE WESTERN PORTION OF THE ISLAND SUPPORTS
SCATTERED THUNDERSTORMS OVER HAITI THIS EVENING. THESE STORMS
SHOULD WEAKEN LATER THIS EVENING. ADDITIONAL SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE SUNDAY AFTERNOON AND EVENING AS A
TROPICAL WAVE APPROACHES THE ISLAND FROM THE EAST.


THE ATLANTIC OCEAN...

THE EASTERN FRINGE OF AN UPPER LEVEL RIDGE AXIS EXTENDS ACROSS N
FL AND OVER THE W ATLC TO NEAR 78W. HIGH DEEP LAYER TROPICAL
MOISTURE IS INTERACTING WITH THE DIFFLUENCE UNDER THE RIDGE AXIS
TO SUPPORT SCATTERED MODERATE CONVECTION FROM 26N TO 31N W OF
78W. AN UPPER LOW IS CENTERED OVER THE CENTRAL BAHAMAS NEAR
24N75W...SUPPORTING CLUSTERS OF MODERATE CONVECTION FROM 21N TO
24N BETWEEN 72W AND 76W...AND SCATTERED THUNDERSTORMS FROM 24N
TO 28N BETWEEN 71W AND 77W. FARTHER EAST...A 1023 MB HIGH
CENTERED NEAR 30N52W DOMINATES MUCH OF THE CENTRAL AND EASTERN
SUBTROPICAL ATLC WITH FAIR WEATHER. TWO TROPICAL WAVES ARE OVER
THE TROPICAL ATLC. PLEASE SEE THE TROPICAL WAVES SECTION FOR
MORE DETAILS. A 1011 MB LOW IS ALSO OVER THE TROPICAL ATLC.
PLEASE SEE THE ITCZ/MONSOON TROUGH SECTION FOR MORE DETAILS.
CONVECTION WILL CONTINUE W OF 72W OVER THE NEXT 24 HOURS.

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

$$
LATTO



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