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Atlantic Tropical Weather Discussion (Text)

000
AXNT20 KNHC 291026
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE JUL 29 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1030 UTC.

...SPECIAL FEATURE...                                   

A DISTURBANCE OVER THE CENTRAL TROPICAL ATLANTIC HAS BECOME 
BETTER ORGANIZED DURING THE PAST SEVERAL HOURS. THE SYSTEM IS 
ASSOCIATED WITH A 1010 MB LOW EMBEDDED IN THE MONSOON TROUGH 
NEAR 9N37W. A CLUSTER OF MODERATE CONVECTION IS FROM 8N-11N 
BETWEEN 36W-40W. RAINBANDS OF MODERATE CONVECTION ARE ELSEWHERE 
FROM 4N-14N BETWEEN 33W-42W. THERE IS A HIGH CHANCE OF FURTHER 
DEVELOPMENT OF THIS DISTURBANCE WITHIN 48 HOURS. SEE THE LATEST 
NHC TROPICAL WEATHER OUTLOOK UNDER AWIPS/WMO HEADERS 
MIATWOAT/ABNT20 KNHC FOR MORE DETAILS.

...TROPICAL WAVES... 

A TROPICAL WAVE IS OVER THE EASTERN ATLC WITH AXIS EXTENDING 
FROM 15N19W TO 5N20W MOVING W AT 10 KT. THE NORTHERN ENVIRONMENT 
OF THE WAVE IS EMBEDDED IN THE DRY SAHARAN AIR LAYER WHILE S OF 
11N THE WAVE IS ASSOCIATED WITH DEEP LAYER MOISTURE. SCATTERED 
MODERATE CONVECTION IS IN THE SOUTHERN WAVE ENVIRONMENT FROM 6N-
10N BETWEEN 15W-28W.

A TROPICAL WAVE IS W-NW OF AN AREA OF DISTURBED WEATHER OVER THE 
CENTRAL ATLC. THE AXIS OF THE WAVE EXTENDS FROM 18N42W TO 9N40W 
MOVING W AT 10 KT DURING THE PAST 24 HOURS. MOST OF THE WAVE 
ENVIRONMENT IS IN THE DRY SAHARAN AIR LAYER WHICH IS HINDERING 
THE DEVELOPMENT OF DEEP CONVECTION. 

...ITCZ/MONSOON TROUGH...                                     

MONSOON TROUGH EXTENDS FROM THE COAST OF WEST AFRICA NEAR 11N16W 
TO 7N28W TO A 1010 MB LOW NEAR 9N37W TO 7N41W. THE INTERTROPICAL 
CONVERGENCE ZONE AXIS EXTENDS FROM 7N42W TO 7N54W. AREAS OF 
CONVECTION ARE ASSOCIATED WITH TROPICAL WAVES. SEE THE SECTIONS 
ON TROPICAL WAVES AND SPECIAL FEATURES FOR DETAILS.

...DISCUSSION...

GULF OF MEXICO...                                               

A BROAD MID-UPPER LEVEL TROUGH EXTENDS ACROSS THE EASTERN CONUS 
SUPPORTING A COLD FRONT ANALYZED FROM 30N84W TO 30N87W THEN 
ACROSS LOUISIANA TO TEXAS. A PRE-FRONTAL TROUGH IS ALONG THE 
NORTHERN GULF EXTENDING FROM 30N84W 28N90W TO 28N95W AND 
SUPPORTING SCATTERED SHOWERS AND TSTMS N OF 27N E OF 94W. OVER 
THE SW GULF...SCATTERED MODERATE CONVECTION AND TSTMS ARE S OF 
20N E OF 96W ASSOCIATED WITH THE NORTHERN PORTION OF A TROPICAL 
WAVE MOVING INTO E PACIFIC WATERS. THE REST OF THE GULF IS BEING 
INFLUENCED BY RIDGING ALOFT WHICH IS SUPPORTING A 1017 MB HIGH 
NEAR 25N89W. DRY AIR SUBSIDENCE FROM ALOFT ALONG WITH SURFACE 
HIGH PRESSURE PROVIDE A GENERAL STABLE ENVIRONMENT THAT SUPPORT 
FAIR WEATHER ELSEWHERE IN THE GULF. VARIABLE WINDS OF 5-15 KT 
PREVAILS ACROSS THE GULF. THE FRONT WILL MOVE INTO THE NE GULF 
LATER TODAY WHERE IT IS EXPECTED TO TRANSITION BACK INTO A 
STATIONARY FRONT LATER DURING THE DAY. SURFACE RIDGING WILL 
PREVAIL ELSEWHERE DURING THIS PERIOD.

CARIBBEAN SEA...                                               

WITH THE EXCEPTION TO THE FAR WESTERN AND SW CARIBBEAN...LOWER 
TO MIDDLE LEVEL DRY AIR DOMINATES ACROSS THE REGION ALONG WITH 
STRONG DEEP LAYER ENVIRONMENTAL WIND SHEAR. THESE TWO FACTORS 
PROVIDE OVERALL STABILITY...THUS SUPPORTING CLEAR SKIES. AN 
UPPER-LEVEL TROUGH BETWEEN CUBA AND HISPANIOLA SUPPORTS 
CLOUDINESS AND POSSIBLE ISOLATED SHOWERS ON THE WINDWARD 
PASSAGE...HAITI AND WESTERN DOMINICAN REPUBLIC. CLOUDINESS AS 
WELL AS ISOLATED SHOWERS AND TSTMS ASSOCIATED WITH THE PASSAGE 
OF A TROPICAL WAVE ARE ALONG CENTRAL AMERICA COASTAL WATERS N OF 
14N W OF 81W. OVER THE SW BASIN...THE MONSOON TROUGH ENHANCES 
SHOWERS AND TSTMS S OF 11N W OF 77W. OTHERWISE...A CONTINUAL 
TIGHT PRESSURE GRADIENT BETWEEN A LOW OVER NORTHERN COLOMBIA AND 
HIGH PRESSURE FROM THE ATLC EXTENDING INTO THE CARIBBEAN SUPPORT 
TRADES OF 20-25 KT S OF 17N BETWEEN 66W-83W WITH NEAR GALE FORCE 
WINDS ALONG THE COAST OF COLOMBIA. A TROPICAL WAVE IS EXPECTED 
TO ENTER THE EASTERN CARIBBEAN THU MORNING AHEAD OF A POSSIBLE 
TROPICAL CYCLONE. SEE THE SPECIAL FEATURES SECTION FOR MORE 
DETAILS.

...HISPANIOLA...                                                 

CURRENTLY...A TROUGH ALOFT SUPPORTS CLOUDINESS AND POSSIBLE 
ISOLATED SHOWERS ACROSS HAITI AND WESTERN DOMINICAN REPUBLIC. 
MOSTLY FAIR WEATHER IS FORECAST FOR TODAY...HOWEVER MODEL 
GUIDANCE INDICATES SHOWERS ACROSS PORTIONS OF THE ISLAND MOST OF 
THE DAY WEDNESDAY.

ATLANTIC OCEAN...                                               

A MID-UPPER LEVEL TROUGH OVER THE EASTERN CONUS ALONG WITH THE 
SE PERIPHERY OF A RIDGE GENERATE A DIFFLUENT ENVIRONMENT ALOFT 
OVER THE SW N ATLC WATERS WHICH ALONG MODERATE DEEP LAYER 
MOISTURE IN THE REGION SUPPORT HEAVY SHOWERS AND TSTMS FROM 25N-
29N BETWEEN 75W-79W. THE REMAINDER BASIN IS FAIRLY DRY AND UNDER 
THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1026 MB HIGH NEAR 
34N52W. THESE TWO FACTORS SUPPORTS FAIR WEATHER ELSEWHERE IN THE 
BASIN. OTHERWISE...SEE ABOVE THE SPECIAL FEATURES AND TROPICAL 
WAVES SECTIONS. SURFACE RIDGING WILL DOMINATE ACROSS THE CENTRAL 
AND EASTERN ATLC THE TUE AND WED. A FRONTAL BOUNDARY IS EXPECTED 
TO MOVE ACROSS THE SW N ATLC TODAY THROUGH THU MORNING. ANOTHER 
FRONTAL SYSTEM IS EXPECTED TO SINK INTO THE NORTHERN CENTRAL 
ATLC BY EARLY THU.

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

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NR