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Tropical Waves

A central Atlantic tropical wave has its axis along 51W south of 15N, moving westward at 15 to 20 kt. Associated convection is described below in the ITCZ/Monsoon trough section.

An eastern Caribbean tropical wave has its axis near 70W south of 15N to inland central Venezuela. It is moving westward at 15 to 20 kt. No significant convection is associated with this tropical wave over the Caribbean.

Monsoon Trough/ITCZ

The monsoon trough axis enters the Atlantic near 16N17W, then curves south then southwestward to near 10N23W. The ITCZ extends from 10N23W to 03N40W to 05N50W. Scattered moderate convection is from 05N to 07N between 18W and 21W, and from 05N to 07N between 37W and 43W.

Gulf Of America

An upper low is centered over the Bay of Campeche near 21N95W. An associated 1011 mb surface low is centered Ciudad del Carmen in the Bay of Campeche. Clusters of showers and thunderstorms are active near the surface low and over the south- central Gulf north of the Yucatan Peninsula, and Yucatan Channel. Elsewhere, 1016 mb high pressure is centered over the eastern Gulf near 27N85W. This pattern is supporting gentle to moderate breezes across the Gulf, except over the far southwest Gulf where gusty outflows are possible near the thunderstorms. Seas are mostly 2-4 ft across the basin.

For the forecast, the pattern will sustain gentle to moderate E to SE winds through Tue. The exception will be evening pulses of fresh winds off the northern Yucatan and in the central Gulf through the same period. A pronounced deep-layered upper-level trough across the western Gulf combined with a very warm, humid and unstable airmass will continue to support periodic showers and thunderstorms, across the central and eastern Gulf through Sun. Frequent lightning, with gusty winds and locally rough seas are expected in strong thunderstorms. Mariners are urged to keep up to date with the latest forecasts.

Caribbean Sea

A generally drier, subsident pattern is in place across the central and eastern Caribbean, suppressing shower and thunderstorm activity. Over the northwest Caribbean, divergent southerly flow in the mid to upper levels of the atmosphere along with abundant deep layer moisture is supporting late evening, sea-breeze generated showers and thunderstorms across Belize, with a larger cluster of thunderstorms off Costa Rica and southeast Nicaragua, responding to drainage off the land. Broad ridging north of the basin across the western Atlantic, along with lower pressure over northern South America is supporting fresh to strong tradewinds across mainly the central Caribbean, and combined seas of 7-10 ft. Moderate to fresh E to SE winds and 5-7 ft seas are noted elsewhere. Satellite imagery shows a plume of Saharan dust across the tropical Atlantic that extends westward to the eastern Caribbean. The dust is expected to increase late in the weekend and into early next week.

For the forecast, the pressure gradient between high pressure north of the area and the Colombian low will sustain fresh to strong trades and rough seas across the central Caribbean through this morning before gradually diminishing in areal coverage this afternoon and evening. Moderate E to SE winds in the Gulf of Honduras are going to pulse to fresh during the night through Tue night. The aforementioned high is going to weaken and open up into a ridge near 24N later today. This will yield moderate to locally fresh winds and moderate seas across most of the basin through Tue, except the south-central Caribbean, where fresh to strong winds and rough seas will persist. Looking ahead, a tropical wave is forecast to reach the Windward Islands late on Sat, leading to increased shower activity.

Atlantic Ocean

A ridge stretches west- southwestward from a 1026 mb high between the eastern Azores and Madeira to the northern Bahamas and off eastern Florida. This pattern is promoting gentle to moderate anticyclonic winds along with 4 to 6 ft seas in mixed moderate swell north of 22N between 35W and the central Bahamas/Florida coast. Across the tropical Atlantic south of 22N between 35W and the southeast Bahamas/Lesser Antilles, moderate to locally fresh northeast to east winds and seas in the range of 6 to 8 ft are present there as depicted in recent scatterometer and altimeter satellite passes. A Saharan dust plume is observed over this area roughly from 08N and 20N, with a dense plume of dust over the waters east of 40W to the coast of Africa.

For the forecast west of 55W, a ridge over the western Atlantic will support gentle to moderate winds with moderate seas south of 26N through Tue. For the waters north of 26N and east of 70W, two cold fronts migrating eastward across the north Atlantic are going to bring fresh to strong winds along with rough seas through this evening, then again from Sat night through Sun night. Winds related to the second cold front might peak at near-gale force from Sat night through Sun.

Posted 5 hours ago by NHC Forecaster Christensen