Tropical Weather Discussion
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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
HTTP://WWW.HURRICANES.GOV/MARINE

$$
NR



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