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000
AXNT20 KNHC 290908
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
508 AM EDT Sat Jul 29 2017

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 0900 UTC.


...TROPICAL WAVES...

A tropical wave is in the E Atlc with axis extending from 16N22W to 05N22W. The wave is in a region of low vertical wind shear and is being engulfed by Saharan dry air and dust. Abundant low level moisture along with middle to upper level diffluence support scattered moderate convection from 06N to 13N E of 30W.

A tropical wave is in the central Atlc with axis extending from 18N40W to 07N41W, moving W at 10 kt within the last 24 hours. The wave is in a region of low vertical wind shear, however is being severely affected by Saharan dry air and dust intrusion to its environment, which is hindering convection.

A tropical wave is in the central Atlc with axis extending from 22N52W to 09N53W, moving west at 20 kt within the last 24 hours. The wave is in a moderate to strong vertical wind shear environment and continues to be severely affected by Saharan dry air and dust intrusion to its environment, which is inhibiting the development of convection.

A tropical wave is in the central Caribbean with axis extending from 20N68W to 10N68W, moving W at 10 kt within the last 24 hours. Water vapor imagery depict dry subsident air over the wave also noticed in the CIRA LPW imagery. Besides dry air, strong vertical wind shear is in the central Caribbean, which is influencing the lack of deep convection at this time.

A tropical wave is in the W Caribbean with axis extending from 21N81W to 09N82W, moving W at 15 kt within the last 24 hours. Isolated showers and tstms are within 90 nm off the coast of Costa Rica and northern Panama being also supported by the E extension of the EPAC monsoon trough. Otherwise, strong vertical wind shear is in the W Caribbean, which is influencing the lack of deep convection elsewhere. The wave will move across inland over central America today.


...ITCZ/MONSOON TROUGH...

The monsoon trough extends from 11N15W to 08N24W to 10N32W to 08N43W. The ITCZ extends from 08N43W to 08N58W. Aside from convection related to the tropical wave described above, scattered moderate isolated strong convection is from 05N to 11N between 31W and 38W and from 06N to 10N between 44W and 53W.


...DISCUSSION...

GULF OF MEXICO...

A surface ridge prevails across the basin. Water vapor imagery and satellite derived winds indicate anticyclonic flow aloft covering most of the Gulf, which is centered in northern Texas. Deep layered subsidence accompany the flow over the Gulf west of 90W while upper level moisture prevails east of 90W. Scatterometer and surface observational data depict light to gentle winds across the basin. A mid to upper level trough will push a cold front southward to the deep south by late today with an increase in showers and thunderstorms along the Gulf coast. The front itself will enter the northern Gulf on Sun with winds shifting to the north. Increasing SW to W winds will develop south of the front over the Gulf to 25N.

CARIBBEAN SEA...

Two tropical waves are moving across the basin. Refer to the section above for details on these features. Showers over S Cuba adjacent waters have ceased, however the middle to upper-level low centered over the Island formerly supporting the shower activity will stay nearly stationary through early next week. With shallow moisture in the region, local orography effects and daytime heating, showers are expected to resume during the afternoon/evening hours today. Diffluent flow to the E of the low aloft along with the passage of a tropical wave across the central Caribbean will support showers across Hispaniola through late Sunday. Scatterometer data indicated fresh to strong trades over the south-central Caribbean with generally light winds over the western portion of the basin. Little change in the overall conditions is expected through the weekend.


...HISPANIOLA...

Diffluent flow to the E of an upper-level low situated near central Cuba along with the passage of a tropical wave across the central Caribbean today will support scattered to isolated showers across the Island later today through Sunday. Some pockets of dry air will follow in behind the wave.

ATLANTIC OCEAN...

Three tropical waves are moving across the basin. Refer to the section above for details. Diffluent flow E of an upper level-low centered over Cuba continue to support scattered heavy showers and tstms in the Great Bahama Bank and the central Bahamas. This activity is expected to lift northward today in response to a frontal boundary that will push off the southeastern United States and move to the northwest portion of the basin late today through Sunday. The remainder of the basin is under the influence of a surface ridge anchored by a 1025 mb high centered near 30N39W.

For additional information please visit http://www.hurricanes.gov/marine

$$ Ramos

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