Monsoon Trough/ITCZ

The monsoon trough axis enters the Atlantic through the coast of Guinea-Bissau near 12N16W and continues southwestward to 04N24W, where it transitions to the ITCZ to 02N30W to 02N40W and to 02N50W. Scattered moderate convection is seen within 60 nm northwest of the ITCZ between 21W-24W. Similar activity is south of the trough from the Equator to 07N between 10W-19W.

Gulf Of America

High pressure dominates the Gulf of America maintaining generally dry conditions. High mostly thin debris cirrus clouds are moving eastward over the north-central and NE Gulf sections. Isolated showers and thunderstorms are just inland the coast of southeastern Mississippi while scattered to numerous showers and thunderstorms moving eastward are over northern and central Louisiana

The gradient between the high pressure and low pressure in Mexico and southern Texas is allowing for generally fresh to locally strong east to southeast winds to exist over the southern Gulf, including the Straits of Florida as depicted in an overnight ASCAT pass. Seas over these waters are 3 to 6 ft, except for higher seas of 6 to 8 ft over the Straits of Florida and 5 to 7 ft seas over the central Gulf. Seas of 3 to 5 ft are over the SW Gulf.

For the forecast, high pressure will be main feature controlling the weather pattern across the Gulf through late Fri. Its associated pressure gradient will maintain moderate to fresh east to southeast winds over the basin through Sat morning. East winds will pulse to strong speeds north of the Yucatan peninsula and over the Bay of Campeche nightly through Fri in association with a diurnal trough. Fresh to strong east winds across the Straits of Florida will diminish to moderate to fresh speeds this morning, change little through Sat night, then diminish to light to gentle speeds into early next week. Moderate seas in the Straits of Florida will subside today. Elsewhere, winds will diminish Fri into Sat for most of the zones. Looking ahead, a weak cold front may reach the NE Gulf Sat night before shifting east of the basin Sun. High pressure will then build southward across the Gulf leading to mostly fresh easterly winds over most of the forecast zones through early next week.

Caribbean Sea

A broad upper-level trough that is over the central Atlantic stretching southwestward to the Greater Antilles along with a surface trough that extends from a weak central Atlantic low to the eastern Caribbean is resulting in plenty of atmospheric instability over the eastern section of the sea. Satellite imagery shows ample cloudiness over this part of the sea along with scattered showers and isolated thunderstorms. Some of this activity is affecting the nearby islands. Clusters of scattered showers and isolated thunderstorms are also evident over the southwestern Caribbean, affecting Costa Rica, Panama and Colombia. No deep convection is evident across the remainder of the basin.

The gradient that is in place is sustaining fresh to locally strong trades over the north-central Caribbean, through the Windward Passage and in the lee of Cuba. Seas over these waters are 4 to 7 ft. Elsewhere, moderate or lighter winds and slight to moderate seas prevail.

For the forecast, the combination of high pressure over the western Atlantic with relatively lower pressures in South America will maintain a gradient that will support fresh to strong northeast winds tonight through the Windward Passage and in the lee of Cuba. At the same time, fresh to strong northeast winds are expected south of the Dominican Republic, mainly near Cabo Beata. Fresh to strong northeast winds will materialize through the Windward Passage Fri night. Otherwise, rather quiet conditions are expected over the basin into early next week.

Atlantic Ocean

A stationary front enters the basin near 31N48W and continues southwestward to 26N59W. To its southeast, a trough extends from 29N49W to low pressure of 1013 mb near 23N53W, and continues southwestward to vicinity of Antigua and Barbuda. Numerous showers and thunderstorms are seen east of the trough from 23N to 29N between 46W and 51W. Scattered showers and thunderstorms are along and near the stationary front. Ample cloudiness is also noted from the Leeward Islands and eastern Greater Antilles to the north-central Atlantic due to a broad upper-level trough. Moderate to locally fresh northeast to east winds, as noted in overnight ASCAT satellite data passes, are to the west of the aforementioned boundaries. Moderate seas are with these winds.

A large and strong extratropical cyclone centered north of Madeira Island supports fresh to strong westerly winds north of 28N and east of 29W. Seas over these waters are 10-15 ft. Fresh to locally strong north winds are from 14N to 23N and east of 25W, along with seas of 7 to 10 ft. The rest of the basin is under the influence of a broad subtropical ridge that is maintaining moderate to locally fresh easterly winds and moderate seas east of 55W. Elsewhere, moderate or lighter winds and moderate seas prevail.

For the forecast west of 55W, high pressure west of the aforementioned front and low pressure will remain about stationary through Fri, then begin to shift eastward into the weekend. The pressure gradient between the low and high pressure to its NW will induce fresh northeast winds north of 25N and east of 65W from Fri morning into the weekend. The low is forecast to slowly lift north-northeastward through Fri night, then weaken into a broad trough on Sat. Looking ahead, a weak cold front will emerge off the northeast Florida coast late Sat night into Sun.

Posted 0 minutes ago by NHC Forecaster Aguirre