AXNT20 KNHC 272336

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
736 PM EDT Thu Jul 27 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 1800 UTC surface analysis and satellite imagery through 2330 UTC.


An eastern Atlantic tropical wave extends its axis from 18N33W to 07N33W, moving west at 10 kt. Scattered moderate convection is noted from 09N-12N between 32W-38W. Satellite imagery shows Saharan dust in the northern portion of the wave wrapping into the northern side of an elongated circulation, currently centered east of the wave's axis near 12N31W.

A central Atlantic tropical wave extends its axis from 18N43W to 04N44W, moving west at 10 to 15 kt. No significant convection is associated with this tropical wave other than a few showers where it intersects the monsoon trough near 09N44W. This is due in part to remnant dry Saharan air with the tropical wave, but also due to subsident dry air in northerly flow aloft.

A tropical wave extends its axis across the Lesser Antilles from 22N61W to 11N61W, moving west at 15-20 kt. The northern portion of the wave is interacting with an upper-level low centered near 26N58W. The only convection is noted closer to the upper low mainly north of 20N.

A Caribbean tropical wave extends south of Hispaniola with axis from 18N73W to 07N73W,moving west at 15 to 20 kt. The wave is moving toward an upper-level low centered over central Cuba, and will start interacting with it through tonight, complicating precise position analysis. No significant convection is associated to the tropical wave at this time, but its presence has allowed the pressure gradient to relax and subsequently diminished the area of strong trade winds across the central Caribbean. This wave will move across the western Caribbean on Friday through Saturday.


The monsoon trough axis extends from 16N17W to a 1012 surface low near 12N30W to 09N46W. The ITCZ continues from that point to 08N60W. No significant convection is noted other than what was already mentioned in the Tropical Waves section above.



Weak ridging extends across the basin anchored by a 1019 mb high centered near 28N93W. A 1014 mb surface low was analyzed over northern Florida near 30N83W with a trough extending to 28N87W. Scattered showers and thunderstorms are observed along and in the vicinity of the low/trough affecting the Florida Peninsula and adjacent waters east of 86W. over the Big Bend area this morning. Another area of showers and thunderstorms is observed off Veracruz in the southwest Gulf attributed to divergent flow aloft between an upper-level low over central Cuba and an upper-level anticyclone farther north. The light to gentle winds across the region are maintaining slight seas overall. Little change is expected through Saturday for the majority of the Gulf. On Saturday, a weak front is forecast to drop south over the southeastern United States to near the Florida panhandle by late Saturday may bring an increase of moisture along with an increase in shower and thunderstorm activity to the NE Gulf at that time.


Two tropical waves are moving across the basin. Refer to the section above for details. Scattered showers and thunderstorms continue over the western Caribbean west of 73W on the periphery of an upper-level low centered over central Cuba. Most of the activity is affecting land areas over Cuba, Central America and western Hispaniola. Ridging north of the area continues to support fresh to locally strong trade across the Caribbean to the S of 17N and E of 82W, with the strongest winds along the coasts of northwest Venezuela and northeast Colombia.


Daytime heating is supporting scattered showers and thunderstorms starting to form over the higher terrain of the island, on the eastern edge of an upper-level low centered over central Cuba. Moisture is expected to decrease on Friday, then increase on Saturday as a tropical wave passes through the central Caribbean.


An upper-level low centered near 26N58W. This low is reflected at the surface as a trough that extends from 28N57W to 24N59W. Isolated showers are noted along the trough. The upper-level low centered over Cuba is also enhancing convection across the western Atlantic, mainly over the Bahamas area. Weak surface ridging along 28N is supporting light to gentle breezes and slight seas. Farther east, high pressure over the central Atlantic is maintaining gentle to moderate trade winds, with Saharan dust dominating east of 40W.

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