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Atlantic Tropical Weather Discussion
NWS National Hurricane Center Miami FL
7:05PM EST (0005 UTC)
Wednesday Apr 21 2021

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 2300 UTC.

Monsoon Trough And Intertropical Convergence Zone - ITCZ
(The ITCZ is also known by sailors as the doldrums)
The monsoon trough passes through the coastal sections of Sierra Leone near 08N13W and continues SW to near 03N24W. The ITCZ continues from 03N24W to 01N40W to the coast of Brazil near 02N51W. Scattered moderate convection is from 00N-03N between 26W-31W. Similar convection is within about 45 nm S of the monsoon trough between 17W-19W.

Discussion: Gulf Of Mexico
A stationary front extends from near Sarasota, Florida to 24N90W to a 1014 mb low pressure at 21N95W. The low is well defined on satellite imagery, and an area of showers and thunderstorms is just S of the front over the SE Gulf. The stationary front will transition back to a cold front reaching the far southeastern Gulf Wednesday night. The low is forecast to lose its identity along the front by early Wed. Scattered showers and thunderstorms will be focused along and near the front tonight into Wednesday morning. Some of this activity may produce strong gusty winds and rough seas. Another cold front is forecast to reach the coast of Texas this evening and gradually weaken on Wed. Reinforcing cold air behind the front will support the movement of the aforementioned stationary front.

High pressure in the wake of the primary front will shift eastward through Saturday night as a cold front reaches eastern Texas. Fresh to strong southerly return flow will develop over the NW Gulf Fri, shift to the central Gulf early Saturday and diminish by late Saturday as the cold front moves across the NW Gulf and central Gulf waters. This front will become stationary across the central Gulf Sunday and Sunday night as a weak gradient sets up over the area.

Discussion: Caribbean Sea
The most recent scatterometer data provided observations of fresh to strong winds across the south-central Caribbean, including the Gulf of Venezuela. Seas are in the 7-10 ft range. This area is cloud free. Elsewhere, mainly moderate E-SE winds are noted with seas of 4-7 ft across the eastern Caribbean, and 4-6 ft over the NW Caribbean. Visible satellite imagery shows narrow lines of clouds forming parallel to the E-SE winds. Currently, convection is flaring up over the NE Yucatan peninsula. Scattered showers and thunderstorms are also noted over parts of Central America.

Fresh to strong trade winds over the central Caribbean will diminish by late in the week as high pressure over the central Atlantic shifts eastward, except near the coast of Colombia where these winds will persist through the week.

Discussion: Atlantic Ocean
As of 1800 UTC and W of 65W, a weak cold front extends from near Bermuda to 27N76W, where it transitions to a stationary front to Melbourne, Florida. The cold front will become stationary near 30N tonight, while the stationary portion of the front will begin to slowly move southward as a cold front. By late Wed, the stationary front will have lifted back to the N as a warm front, while the cold front will have reached from near 31N69W to the central Bahamas and to west-central Cuba as yet another cold front moves over the NW waters. By late Thu, both fronts will be weakening NE of the Bahamas as high pressure builds in over the area. The high pressure will shift eastward through Saturday night as a stronger cold front approaches the southeastern U.S. coast. This front is expected to move across the NW and north-central waters Sunday and Sunday night preceded by fresh to strong southerly winds and possible scattered showers and thunderstorms.

E of 65W, high pressure of 1024 mb located near 27N38W dominates the remainder of the Atlantic forecast waters. Moderate to fresh trades are noted per scatterometer data from 10N-20N between the coast of west Africa and the Lesser Antilles. The high pressure will weaken by late Wed, and will be replaced by another high pressure system located over the central Atlantic by Wednesday night.

Forecaster: Gladys Rubio, National Hurricane Center

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