Special Feature

Caribbean Gale Warning: The subtropical ridge north of the Caribbean will support gale-force winds off the coast of Colombia through near sunrise this morning, and strong to near- gale force easterly trade winds across the much of the central Caribbean into early Mon, before becoming confined to south of 15N through midweek. Winds will pulse to gale force over the waters north of Colombia tonight. Rough to very rough seas, peaking at 12 to 13 ft, will develop during the times of peak winds.

Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details.

NE Gulf of America (Invest AL91): Recent satellite scatterometer wind data and nearby surface observations indicate that an area of low pressure located over the northeastern Gulf of America is slowly becoming better defined. However, its associated shower and thunderstorm activity remains disorganized and displaced well the southwest and west of the low. This activity may produce gusty winds, frequent lightning and rough seas. Mariners should exercise caution across this area. Regardless, gradual development of this system is forecast, and a tropical depression could form over the next couple of days as the system moves slowly northward or northwestward. Interests along the northern Gulf coast from Florida, Alabama, Mississippi, to Louisiana should monitor the progress of this system as it is expected to bring heavy rain to portions of that region during the next several days. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system later today, if necessary. This system has a medium chance for tropical cyclone formation during the next 48 hours.

Please refer to the latest TROPICAL WEATHER OUTLOOK issued by the National Hurricane Center at www.hurricanes.gov for more information.

Tropical Waves

A well-defined tropical wave in the eastern Atlantic is now along 34W, south of 19N, based on recent satellite and scatterometer data. The wave is moving westward at 15 to 20 kt. No significant convection is observed near this wave due to dry Saharan air.

An Atlantic tropical wave is along 60W, south of 18N, moving westward at 15 to 20 kt. Scattered moderate convection is near the wave along the ITCZ, from 10N to 12.5N and between 57W and 62W.

Monsoon Trough/ITCZ

The monsoon trough enters the Atlantic through the coast of Mauritania near 19N16W and continues southwestward through the Cabo Verde Islands to 15N30W and then to 06.5N42.5W. The ITCZ extends from 06.5N42.5W to 07N58W. Scattered moderate to strong convection is moving off the coast of Africa from 07.5N to 14.5N and E of 18W. Scattered moderate convection is found N of the ITCZ from 06.5N to 09.5N between 41W and 57W.

Gulf Of America

Please refer to the Special Features section for information on a broad low pressure over the eastern Gulf that has a medium chance of tropical cyclone formation during the next 48 hours. A 1012 mb low center is analyzed near 27.5N 85.5W and is nearly stationary. Scattered to locally numerous moderate isolated strong convection is occurring in broken bands from 120 to 300 nm around the periphery of this low, except for the N semicircle. Recent satellite scatterometer wind data showed strong gusty winds to near 30 kt in some of these thunderstorms. Seas are estimated at 2 to 5 ft across this area.

Elsewhere, dry air dominates the remainder of the basin suppressing the development of showers and thunderstorms. A 1018 mb high pressure over the NW Gulf waters supports moderate to fresh NE winds and seas of 2-4 ft in the eastern Bay of Campeche, while light to gentle winds and slight seas prevail elsewhere.

For the forecast, the broad area of low pressure over the eastern Gulf is expected to move slowly north to northwestward over the next couple of days, and could become a tropical depression. Regardless, this system will bring thunderstorms with heavy rainfall and strong gusty winds to the NE Gulf and adjacent portions of the Gulf coast through at least Tue. Away from this system, weak high pressure will dominate, producing gentle to moderate winds and slight to moderate seas through the period.

Caribbean Sea

A Gale Warning remains in effect for the south-central Caribbean near the coast of Colombia until near sunrise. Please refer to the Special Features section for more details.

The 1024 mb subtropical ridge centered near 28.5N59W in the central Atlantic and extends westward to the coast of Florida. The pressure gradient to the south of the ridge is forcing strong to near-gale easterly trade winds across the central Caribbean, with the strongest winds occurring off Colombia. Rough to very rough seas are found in these waters. Moderate to fresh NE-E winds and moderate seas are present in the eastern Caribbean and Windward Passage. Elsewhere, light to gentle winds and slight to moderate seas are prevalent. A few showers and isolated thunderstorms that developed over Panama and Costa Rica have shifted inland, while scattered moderate convection associated with a tropical wave is moving into the southern Windward Islands. Generally dry weather conditions are noted elsewhere.

For the forecast, the pressure gradient between the western Atlantic high pressure ridge oriented along 28N, and the Colombian low will support NE winds pulsing to gale-force across the waters N of Colombia through early this morning. Otherwise, strong to near- gale force trade winds and rough seas will prevail across the much of the central Caribbean into Sun night, before contracting to south of 15N Mon through Thu. East winds will pulse fresh to locally strong each evening through Tue in the Windward Passage.

Atlantic Ocean

A couple of weak surface troughs and an upper level low in the north- central tropical Atlantic combine to generate isolated showers north of 23N and between 37W and 53W. Meanwhile, a broad subtropical ridge centered over the central Atlantic forces fresh to locally strong easterly trade winds off northern Hispaniola as shown in a recent satellite scatterometer data. Elsewhere in the central and western Atlantic, moderate to fresh easterly winds and seas of 4-8 ft are occurring south of 24N and west of 45W, with highest seas to 8 ft E of the Windward Islands.

In the far eastern Atlantic, fresh to locally strong N to NE winds and seas of 4-8 ft are present north of the monsoon trough and east of 25W. In the rest of the basin, moderate or weaker winds and moderate seas prevail within the ridge axis.

For the forecast west of 55W, the western Atlantic subtropical ridge along 28N-29N this morning will weaken and drift northward through early next week as a broad surface trough forms E of 50W. This trough will shift westward and reach 65W by Wed, then move W of 70W and weaken quickly Thu. Moderate to fresh trades will prevail S of 24N through Tue, with gentle winds to the N. Pulsing strong winds are expected during the evenings through Tue N of Hispaniola and in the Windward Passage. Expect increasing winds and seas N of 22N and E of 70W Tue through Wed night as the trough approaches.

Posted 29 minutes ago by NHC Forecaster Stripling