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AXNT20 KNHC 171755
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
155 PM EDT Thu Aug 17 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 1200 UTC surface analysis and satellite imagery through 1715 UTC.


...SPECIAL FEATURES...

Hurricane Gert is centered near 43.2N 50.0W at 17/1500 UTC or about 248 nm SSE of Cape Race Newfoundland moving ENE at 35 kt. Estimated minimum central pressure is 975 mb. Maximum sustained wind speed is 70 kt with gusts to 85 kt. Scattered moderate to isolated strong convection is from 43N-48N between 43W-49W. See latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC for more details.

Potential Tropical Cyclone Nine is centered near 13.1N 54.1W at 17/1500 UTC or about 317 nm E of Barbados moving W at 15 kt. Estimated minimum central pressure is 1008 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. The disturbance is expected to become a tropical cyclone later today or tonight, and it could become a tropical storm before reaching the Windward islands. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the disturbance this afternoon. The disturbance is expected to produce rainfall totals of 2 to 4 inches across portions of the Windward Islands from Martinique southward to Grenada. These rains could cause life- threatening flash floods and mudslides. See see the latest NHC Intermediate Public Advisory under AWIPS/WMO headers MIATCPAT4/WTNT34 KNHC, and the full Forecast/Advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC for more details.

A tropical wave is in the central Atlc associated with a 1009 mb low pressure located near 15N42W. The wave axis extends from 20N42W to the low to 10N43W moving W at 15 kt. The system has become a little better organized during the past 24 hours. Continued gradual development of this system is possible during the next couple of days. Upper-level winds are expected to become less conducive for tropical cyclone formation when the disturbance moves north of the Leeward Islands this weekend. This system has a medium chance of becoming a tropical cyclone within the next two days.


...TROPICAL WAVES...

A tropical wave is in the E Atlc associated with a 1010 mb low near 09N24W. The wave axis extends from 19N22W to the low center to 05N24W. This wave in a very moist area based on SSMI TPW imagery and has a well pronounced 700 mb trough. Widely scattered moderate convection is over a large area from 06N-13N between 20W-30W. Environmental conditions are forecast to become more conducive for development over the weekend while the system moves WNW.

A tropical wave is in the E Caribbean with axis extending from 24N66W to E Hispaniola to 10N71W, moving W at 15-20 kt. This wave in a moist area based on SSMI TPW imagery and has a well pronounced 700 mb trough. Scattered moderate to isolated strong convection is over a large area from 15N-26N between 65W-71W to include Puerto Rico and E Hispaniola.

A tropical wave is in the Yucatan Peninsula with axis extending from 21N89W across Guatemala to 06N90W, moving W at 20 kt. Dry air subsidence continues to limit convection over land. The E Pacific in contrast has a moist SSMI TPW area, and a 700 mb trough, that is producing widely scattered moderate convection.


...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 15N17W to 09N24W to 08N34W. To the west, the monsoon trough and ITCZ is disrupted due to the tropical lows and tropical waves mentioned above. Otherwise, scattered moderate convection is from 05N-08N between 33W-39W.


...DISCUSSION...

GULF OF MEXICO...

A 1019 mb high is centered over the NE Gulf of Mexico near 28N87W with mostly fair weather. 5-10 kt anticyclonic winds are noted around the high. 10-15 kt SE surface winds are over the W Gulf W of 90W. Radar imagery shows scattered showers over the E Gulf, Florida, and the Straits of Florida, E of 84W. Airmass thunderstorms are over Louisiana. Similar thunderstorms are over NE Florida. In the upper levels, an upper level low is centered over the W Gulf near 22N97W producing scattered showers along the coast of Mexico from 18N-24N between 95W-98W. An upper level high is centered over the Florida Panhandle near 30N86W. Expect the surface high to remain quasi- stationary over the Gulf for the next 24 hours. Expect more airmass thunderstorms Friday during maximum heating over Louisiana, Florida, W Cuba, S Mexico, and the Bay of Campeche.

CARIBBEAN SEA...

A tropical wave is over the E Caribbean, and another wave is over the Yucatan Peninsula. See above. The eastern extent of the Pacific monsoon trough is producing scattered moderate convection over Costa Rica and Panama. Expect the E Caribbean tropical wave to move W with convection over the next 24 hours. Also expect continued convection the SW Caribbean.


...HISPANIOLA...

Presently E Hispaniola has scattered moderate to isolated strong convection spreading W. More convection is N of the island. Expect the convection to persist beyond the next 24 hours.

ATLANTIC OCEAN...

Except for the SW N Atlc waters that are being impacted by the tropical wave moving to central Caribbean waters, the Atlantic basin N of 20N is under the influence of the mid-Atlantic subtropical high near 32N38W with mostly fair weather. For the tropical Atlantic S of 20N, see the special features and tropical waves sections above.

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

$$ Formosa

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