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AXNT20 KNHC 161053
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
653 AM EDT Mon Sep 16 2019

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 1040 UTC.


...SPECIAL FEATURES...

Hurricane Humberto is near 29.7N 77.3W at 16/0900 UTC or 660 nm W of Bermuda moving NE at 4 kt. Estimated minimum central pressure is 980 mb. Maximum sustained wind speed is 75 kt with gusts to 90 kt. Numerous moderate to scattered strong convection extends outward from the center 270 nm NE quad, 180 nm SE quad, 90 nm SW quad and 120 nm NW quad. A trailing rainband affecting portions of the NW Bahamas with heavy rain is not as strong as it was several hours ago, but is still producing convection in the area south of Great Abaco, west of Eleuthera and north of Nassau. An ENE motion with a gradual increase in forward speed is expected tonight through early Thursday. The center of Humberto is forecast to approach Bermuda late Wed or Wed night. Additional strengthening is expected during the next couple of days along with an expansion of the wind radii. Please read the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC, or at the website hurricanes.gov for more details.

Showers and thunderstorms have increased in association with an area of low pressure along a tropical wave in the central tropical Atlantic. A 1008 mb surface low is centered near 09N41W along a wave that extends along 41W from 04N-16N. The low and wave are moving W at 5-10 kt. Scattered moderate convection is seen from 06N-13N between 38W-46W. Environmental conditions are forecast to be conducive for gradual development, and a tropical depression is likely to form within the next two to three days while the system moves slowly west-northwestward to northwestward.


...TROPICAL WAVES...

An eastern Atlantic tropical wave has an axis along 28W S of 19N, moving W around 20 kt. The wave shows up well in model diagnostics and TPW imagery. Scattered moderate convection is from 10N-15N between 26W-33W.

See section above for information on the tropical wave along 41W.

A tropical wave moving through the Lesser Antilles today has its axis along 58/59W from 06N-22N, moving W around 15 kt. Scattered to numerous moderate with embedded isolated strong convection is from 12N-17N between 57W-63W, affecting islands from St. Vincent to Guadeloupe. Barbados recently recorded sustained winds of 31 kt at 0800 UTC. Scattered showers are over the Lesser Antilles elsewhere from 11N-19N. This wave is well depicted in model guidance and TPW imagery. The wave will continue to bring enhanced rain to the Lesser Antilles and eastern Caribbean today.

An eastern Caribbean tropical wave extends its axis along 68/69W from 19N southward, moving west around 15 kt. This wave is well depicted in TPW imagery. Scattered showers are within 60 nm of the wave axis from 15N-18N and also inland over Venezuela.


...MONSOON TROUGH/ITCZ...

The monsoon trough extends from northern Mauritania near 21N16W to 13N24W to 09N48. The ITCZ continues from 09N48W to 10N57W. Aside from the convection already discussed in the Tropical Waves section above, scattered moderate with embedded isolated strong convection is noted from 03N-15N between the coast of Africa and 22W.

GULF OF MEXICO...

The weather over the Gulf of Mexico is dominated by a large mid to upper-level low that is centered over the western portion of the basin, as well as a surface trough. The low is closed down to 850 mb, according to the GFS model. The surface trough is analyzed from 26N86W to 26N92W to 22.5N96.5W. Scattered moderate convection is seen north of the surface trough from 27N-29N between 89W-95W. In the eastern Bay of Campeche, upper-level diffluence has induced an area of scattered moderate convection from 18N-21N between 90W-93W. The latest ASCAT pass from late Sunday evening shows fresh to strong E winds from 27N-29.5N between 89W-94W. Light winds are over the south-central Gulf. A 1016 mb high is over western Cuba near 23N83W.

An elongated trough extending across the central and western Gulf will become a broad low pressure center over the northwest Gulf later today, before moving inland over Texas tonight. Weak high pressure will build over the north central Gulf through mid week, before dissipating later in the week ahead of a weak cold front moving across the eastern Gulf.

CARIBBEAN SEA...

Refer to the Tropical Waves section above for details on the two tropical waves currently impacting the eastern Caribbean.

Relatively dry air covers the central and NW Caribbean. Deep- layered ridging is over Cuba. A 1016 mb surface high is analyzed near 23N83W. Scattered showers and tstorms cover portions of the SW Caribbean and Central America, including the waters near eastern Honduras and northern Nicaragua as well as the waters north of western Colombia and eastern Panama. The latest ASCAT pass from Sunday evening depicts moderate to fresh trades in the south-central Caribbean.

Moderate to fresh trade winds will dominate much of the basin. Long period northerly swell will starting pushing through Atlantic passages by early Tue. A tropical wave entering the central Caribbean will move through the western Caribbean by late Tue, and west of the basin by mid week. Scattered thunderstorms and gusty winds accompany another tropical wave currently impacting the Lesser Antilles. This wave will move through the eastern Caribbean today, across the central Caribbean through mid week, and into the western Caribbean by late week. Looking ahead, low pressure developing east of the area will move toward the Atlantic offshore waters of the Leeward Islands by late Fri, possibly as a tropical cyclone.

ATLANTIC OCEAN...

Refer to the sections above for details on Hurricane Humberto and the tropical waves moving across the basin.

A cold front enters the discussion area near 32N35W to 27N43W to 26N49W to 26N52W. It continues as a stationary front from that point to 29N60W to Bermuda. A pre-frontal trough is analyzed from 30N35W to 26N40W to 24N45W with scattered showers. Scattered showers are also seen within 180 nm of the stationary front from 23.5N-29N between 49W-62W.

Hurricane Humberto will strengthen as it moves to near 30.5N 74W Tue afternoon, and the wind radii will expand as it moves to near 33N 66.5W late Wed night or early Thu morning. Northerly swell will follow across the open waters in the wake of Humberto.

$$ Hagen

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