[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181757
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS OVER THE CAPE VERDE ISLANDS WITH AXIS EXTENDING
FROM 17N23W TO 7N23W MOVING W 10 TO 15 KT OVER THE PAST 24
HOURS. THE SOUTHERN PORTION OF THE WAVE IS EMBEDDED IN THE
MONSOON TROUGH WHICH IS SUPPORTING SCATTERED MODERATE CONVECTION
FROM 5N-9N BETWEEN 18W-28W. ELSEWHERE...DRY SAHARAN AIR
INTERACTING WITH THE WAVE HINDERS THE DEVELOPMENT OF CONVECTION.

TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AXIS EXTENDING FROM
12N43W TO 7N45W MOVING W AT 10 KT OVER THE PAST 24 HOURS. THE
LOW-AMPLITUDE WAVE IS EMBEDDED IN THE VERY MOIST ENVIRONMENT OF
THE ITCZ/MONSOON TROUGH WHICH IS SUPPORTING SCATTERED MODERATE
CONVECTION FROM 8N-11N BETWEEN 41W-51W.

TROPICAL WAVE IS MOVING ACROSS THE WINDWARD ISLANDS. ITS AXIS
EXTENDS FROM 14N58W TO 8N61W AND IS MOVING W AT 15-20 KT OVER
THE PAST 24 HOURS. A DEEP LAYER MOIST ENVIRONMENT IS ASSOCIATED
WITH THE WAVE. UPPER-LEVEL DIFFLUENCE ALOFT ENHANCES SCATTERED
MODERATE CONVECTION/ISOLATED TSTMS FROM 9N-14N BETWEEN 58W-65W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC
NEAR 11N16W AND CONTINUES ALONG 7N23W 9N33W TO 9N42W. THE ITCZ
BEGINS NEAR 7N46W AND CONTINUES TO 8N57W. IN ADDITION TO THE
CONVECTION ASSOCIATED WITH THE WAVES...SCATTERED MODERATE
CONVECTION IS FROM 6N-10N BETWEEN 29W-37W.

...DISCUSSION...

GULF OF MEXICO...

A MID-UPPER LEVEL TROUGH EXTENDS FROM THE UPPER GREAT LAKES SW
TO A BASE OVER THE NW GULF AND SUPPORTS A STATIONARY FRONT ALONG
30N85W TO 30N87W THEN ACROSS THEN ACROSS CENTRAL LOUISIANA AND
SE TEXAS. TROUGHINESS ALOFT ALSO SUPPORT A PRE-FRONTAL TROUGH
FROM SE LOUISIANA TO 28N95W TO SOUTHERN TEXAS TO 1011 MB LOW
OVER NE MEXICO. HEAVY SHOWERS AND TSTMS ASSOCIATED TO THESE
FEATURES ARE N OF 26N W OF 86W BEING ENHANCED BY DIFFLUENCE
ALOFT. FAIR WEATHER IS ELSEWHERE BEING SUPPORTED BY DRY AIR
SUBSIDENCE FROM ALOFT. OTHERWISE...RETURN WIND FLOW OF 10-20 KT
DOMINATES ACROSS THE BASIN. SURFACE RIDGING AND RETURN FLOW WILL
DOMINATE ACROSS THE REGION FOR THE NEXT TWO DAYS.

CARIBBEAN SEA...

EXCEPT FOR THE SW AND SE BASIN...THE CARIBBEAN SEA IS UNDER FAIR
WEATHER CONDITIONS BEING SUPPORTED BY DRY AIR SUBSIDENCE FROM
ALOFT. OVER THE SW BASIN...THE MONSOON TROUGH AND A 1010 MB LOW
OVER THE BORDER BETWEEN PANAMA AND COLOMBIA ENHANCE SCATTERED
MODERATE CONVECTION AND TSTMS S OF 11N BETWEEN 75W-84W. A
TROPICAL WAVE IS MOVING ACROSS THE WINDWARD ISLANDS AND SUPPORTS
SCATTERED MODERATE CONVECTION/ISOLATED TSTMS S OF 14N E OF 66W.
HIGH PRESSURE ACROSS THE NORTHERN CARIBBEAN CONTINUE TO SUPPORT
A TIGHTER PRESSURE GRADIENT OVER THE SOUTHERN-CENTRAL BASIN.
THIS IS GENERATING A MODERATE TO FRESH BREEZE S OF 17N BETWEEN
67W-82W. THE WAVE IS FORECAST TO PASS S OF HISPANIOLA SAT NIGHT.
THE NEXT TROPICAL WAVE IS EXPECTED TO ENTER THE E BASIN BY SUN
NIGHT.

...HISPANIOLA...

CURRENTLY FAIR WEATHER IS ACROSS THE ISLAND BEING INFLUENCED BY
DEEP LAYER DRY AIR AND A MID-LEVEL ANTICYCLONE CENTERED N OF THE
MONA PASSAGE. HOWEVER...SHOWERS ARE EXPECTED TO DEVELOP LATER
THIS AFTERNOON ENHANCED BY SOME PATCHES OF LOW LEVEL MOISTURE
AND DAYTIME HEATING. A TROPICAL WAVE IS EXPECTED TO MOVE S OF
THE ISLAND SAT NIGHT ENHANCING SHOWERS/THUNDERSTORMS THROUGH THE
WEEKEND.

ATLANTIC OCEAN...

A MID-LEVEL SHORT-WAVE TROUGH IS OVER THE SW N ATLC AS WELL AS
UPPER-LEVEL DIVERGENCE. THIS ENVIRONMENT ALONG WITH ABUNDANT
MOISTURE IN THE REGION CONTINUE TO SUPPORT SCATTERED SHOWERS AND
TSTMS N OF 22N BETWEEN 67W-77W. FARTHER EAST...A MID-UPPER LEVEL
LOW CENTERED NEAR 27N50W IS SUPPORTING SCATTERED SHOWERS AND
TSTMS FROM 25N-31N BETWEEN 48W-58W. OTHERWISE...THE CENTRAL AND
EASTERN ATLC ARE UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED
BY A 1031 MB HIGH CENTERED NEAR 37N49W. BESIDES SURFACE HIGH
PRESSURE...MOSTLY DRY AIR ACROSS THE REMAINDER BASIN SUPPORTS
FAIR WEATHER.

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

$$
NR

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