Tropical Waves

A central Atlantic tropical wave has its axis along 45W from 02N to 16N, moving westward at 15 to 20 kt. Scattered moderate convection is west of the wave from 04N to 07N between 46W and 48W. Scattered showers and thunderstorms are near the southern part of the wave.

Another central Atlantic tropical wave has its axis near 60W south of 14N to inland South America. It is moving westward at 10 to 15 kt. Isolated showers are near the wave axis over water while scattered moderate to isolated strong convection is noted over South America on either side of the wave axis.

The previous southwestern Caribbean tropical wave has moved inland Central America, with its axis near 85W south of 15N to the eastern Pacific Ocean near 06N. It is moving westward near 10 kt. This wave has become more embedded in southeasterly mid-level flow that is across the northwestern Caribbean as well as with the monsoonal flow that is over the eastern Pacific. Deep convection attributed to this wave is occurring over the Pacific waters to the south of Costa Rica and northern Panama. In addition to that convection, there is numerous strong convection active over eastern Nicaragua and eastern Honduras. Scattered showers and thunderstorms are east of the wave over the southwestern Caribbean south of 13N and west of 77W to inland Costa Rica and Panama.

Monsoon Trough Itcz

The monsoon trough axis enters the Atlantic near 16N17W, then curves south then southwestward to near 06N23W, where it transitions to the ITCZ to 06N30W to 06N35W and to near 07N45W. Scattered moderate convection is within 180 nm south of the ITCZ between 39W-43W and within 60 nm north of the ITCZ between 36W-40W.

Gulf Of America

A very pronounced and sharp deep layer trough extends across eastern Texas then southward across the western Gulf. This feature is combining with very deep tropical moisture resulting in scattered moderate to isolated strong convection over most of the western and central Gulf waters, namely over the waters south of 28N and between 87W and 95W. A couple of surface troughs over the western Gulf are further aiding the convective activity. A squall line that extends from near 29N88W to 25N89W has weakened some during the past few hours. Scattered moderate to isolated strong convection is over the eastern Bay of Campeche and along the northern coast of the Yucatan Peninsula. Scattered showers and thunderstorms are also south of 26N between 82. 5W and 87W, including the waters adjacent to western Cuba and the northern Yucatan Channel. Otherwise, Atlantic high pressure along 65W extends a broad and weak ridge westward across Florida and the northeastern Gulf. The associated pressure pattern is generally supporting light to gentle winds across the basin, with the exception of moderate to fresh east to southeast winds south of 23N between 85W and 88W. Seas are 2 to 4 ft over the basin, except for slightly higher seas of 3 to 5 ft over the central and eastern Gulf.

For the forecast, the Atlantic ridge extends across Florida into the Gulf region. This system will sustain gentle to moderate E to SE winds over the weekend into early next week. The exception will be evening pulses of fresh winds off the northern Yucatan through early next week. A pronounced deep-layered upper- level trough across the western Gulf combined with a very warm, humid and unstable airmass will continue to support scattered to numerous showers and thunderstorms over parts of the Gulf waters likely 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

Instability associated to the Gulf of America deep layer trough is sustaining scattered showers and isolated thunderstorms over the northeast portion of the Yucatan Peninsula and over the northern portion of the Yucatan Channel. The induced pressure gradient between central Atlantic high pressure, and relatively lower pressure over the Caribbean and in northern South America is bringing fresh to strong trade winds to the south-central section of the basin. Mostly moderate to fresh trade winds are elsewhere across the sea, except for gentle to moderate east to southeast winds winds in the lee of Cuba, reaching southward to near 18N between 78W and 83W. Seas are 7 to 10 ft in the south-central portion and about 4 to 6 ft elsewhere, except for seas of 6-9 ft in east swell in the north- central waters.

Satellite imagery also 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 lower pressure to its south will continue to allow for fresh to strong trades and rough seas across the central Caribbean through tonight before gradually diminishing in areal coverage on Fri. Winds are expected to pulse to near-gale force offshore Colombia tonight. Fresh east to southeast winds are expected in the Gulf of Honduras through early next week. The aforementioned high is going to weaken and open up into a ridge near 24N by Fri. This will yield moderate to locally fresh winds and moderate seas across most of the basin through the weekend, 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, possibly leading to increased shower activity.

Atlantic Ocean

A ridge stretching from a 1026 mb high near Madeira west- southwestward across 30N30W to a 1018 mb high center near 26N63W, then to northern Florida 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 scatterometer satellite and altimeter data passes during the day.

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 30W to the coast of Africa. Fresh to locally strong northeast trade winds along with seas of 6 to 8 ft remain over these same waters.

For the forecast west of 55W, the aforementioned ridge over the western Atlantic will support gentle to moderate winds with moderate seas south of 28N into nearly next week. For the waters north of 28N 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 tonight through Fri night, then again from Sat night through Sun night.

Posted 8 minutes ago by NHC Forecaster Aguirre