Special Features

Atlantic Gale Warning: A cold front will move across the Southwest North Atlantic waters Sat night into early next week. A tight pressure gradient will support gale force winds on either side of the cold front Sat night through Sun night, north of 30N and between 55W and 70W. Rough to locally very rough seas are expected with these winds. Conditions will improve Mon.

Please read the latest High Seas and Offshore Waters Forecast issued by the National Hurricane Center at websites - https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and https://www.nhc.noaa.gov/marine/offshores.php for more details.

Tropical Waves

A new tropical wave has been introduced in the eastern Atlantic along 14W, south of 15N based on recent satellite imagery, total precipitable water and tropical wave guidance. The wave is moving westward at 10 to 15 kt. Scattered moderate convection is noted south of 12N and east of 27W.

A central Atlantic tropical wave is along 57W, south of 18N, moving westward at 15 to 20 kt. Scattered moderate to isolated strong convection is observed south of 11N and between 45W and 65W.

A Caribbean tropical wave is analyzed along 73W, south of 16N, moving westward at 10 to 15 kt. No significant convection is associated with this tropical wave over the Caribbean waters. However, scattered moderate to strong convection is inland across Colombia and far western Venezuela on either side of the wave.

Monsoon Trough/ITCZ

The monsoon trough enters the Atlantic through the coast of Guinea-Bissau near 11N15W, continues southwestward to 06N21W. The ITCZ extends from 06N21W to 05N35W and then to 03N51W. Scattered moderate convection is present near the ITCZ between 30W and 45W.

Gulf Of America

Divergence aloft associated with a sharp upper level trough over the western Gulf and a broad surface trough over the central Gulf combine to produce scattered showers and isolated thunderstorms over a good portion of the eastern half of the basin. Heavy rainfall is also affecting parts of Yucatan, Central America and Florida. At the surface, a weak pressure gradient results in moderate or lighter winds and slight to locally moderate seas. However, stronger winds and higher seas can occur near the strongest storms.

For the forecast, the Atlantic ridge extends across Florida into the Gulf region. This system 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

Divergence aloft and diurnal heating combine to produce scattered showers and isolated thunderstorms across Cuba, Hispaniola, Yucatan and Central America. A strong subtropical ridge over the central Atlantic extends southwestward into the Caribbean Sea supporting fresh to strong easterly trade winds and seas of 5-8 ft in the south-central Caribbean. Moderate to fresh breezes and moderate seas are found in the rest of the central and eastern Caribbean and NW Caribbean, mainly south of 20N. Elsewhere, light to gentle winds and slight to moderate seas prevail.

For the forecast, the pressure gradient between the Atlantic ridge and the Colombian low will sustain fresh to strong trades and rough seas across the central Caribbean through tonight before gradually diminishing in areal coverage on Sat. Moderate E to SE winds in the Gulf of Honduras are going to pulse to fresh speeds during the night through Mon night, then to strong speeds Tue night and again Wed night. The aforementioned ridge is going to weaken as a couple of frontal boundaries move across the western Atlantic. 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 by Sat afternoon, leading to increased shower activity.

Atlantic Ocean

A cold front extends from 31N61W to 29N72W, followed by a stationary front to the Georgia coast. Scattered showers are seen near these boundaries. A recent scatterometer satellite pass indicate that moderate to locally strong SW winds are occurring ahead of the fronts to 40W and north of 27N. Seas in these waters are 5-10 ft, with the highest seas near 31N54W.

The rest of the tropical Atlantic are dominated by a broad subtropical ridge anchored by a 1029 mb high pressure system centered between the Azores and Madeira Island. The pressure gradient between this ridge and lower pressures in western Africa sustain fresh to locally strong N-NE winds and rough seas from 17N to 29N and east of 30W. Moderate to fresh easterly winds and moderate seas are present south of 20N and between the Lesser Antilles and 30W. Elsewhere, moderate or weaker winds and moderate seas prevail.

For the forecast west of 55W, the 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 tonight, then again from Sat night through Sun night. Winds are forecast to reach minimal gale force on either side of the second cold front Sat night through Sun night. As a result, a Gale Warning has been issued. Rough to very rough seas could accompany the strongest winds.

Posted 20 minutes ago by NHC Forecaster Delgado