Monsoon Trough Itcz

The monsoon trough axis enters the Atlantic along the coast of Africa near 10N15W to 04N20W and to 01N26. 5W, where it transitions to the ITCZ to south of the Equator near 28W and continues to 04S35W and northwestward to 02S43W to the Equator at 50W. Numerous moderate to strong convection is south of the monsoon trough from 00N to 05N between 10W-19W. Scattered moderate convection is within 30 nm of the trough between 25W-29W.

Gulf Of America

An mid to upper-level trough extends from the southeastern U. S. southwestward to 26N88W and to the Yucatan Peninsula while an amplifying upper-level shortwave trough is moving through its southern portion across the southeastern Gulf. Upper-level dynamics associated with the trough is supporting an area of numerous showers and thunderstorms over the southeastern Gulf south of 26N between 82W and 86W moving generally east-southeastward, and newly developed shower and thunderstorm activity over the south-central Gulf from 23N to 25N between 87W and 90W. This activity is accompanied by heavy rainfall reducing visibility and is attendant by gusty winds producing locally rough seas. The strongest cells appear to be approaching the northwest portion of Cuba. Otherwise, relatively weak high pressure is over the eastern and central Gulf portions. The related gradient is allowing for moderate to fresh southeast winds over the eastern part of the basin, and gentle to moderate southeast winds over the rest of the basin. Seas are 3 to 5 ft over the eastern Gulf and 2 to 4 ft over the remainder of the basin.

For the forecast, high pressure will prevail across the Gulf region, with a relatively weak pressure gradient across the area. This will result in gentle to moderate SE winds and moderate seas basin-wide through the weekend into the early part of next week. The exception will be off the Yucatan Peninsula, where a diurnal trough will pulse moderate winds to fresh during the evenings. The aforementioned area of numerous showers and thunderstorms over the southeastern Gulf will continue east- southeastward through early Fri. The activity over the south- central Gulf will move southeast to south into early Fri.

Caribbean Sea

A surface trough extends southwestward from a tail-end of a stationary front over Hispaniola to near the Nicaragua. Isolated showers are near the trough, however, clusters of moderate convection are north of 20N west of 82W. Moderate to fresh northeast winds and seas at 3 to 5 ft are in the lee of Cuba and near the Windward Passage. Mostly gentle winds and 1 to 3 ft seas prevail elsewhere in the Caribbean Sea.

For the forecast, high pressure located north of the basin will weaken over the next couple of days as the remnants of a frontal boundary, currently located north of Hispaniola and Puerto Rico, lifts northward as a trough during the upcoming weekend. This weather pattern will support a weaker than usual pressure gradient across the Caribbean Sea into the weekend, resulting in mainly gentle to moderate winds and slight to moderate seas across the entire basin.

Atlantic Ocean

A cold front extends southwestward from a 1001 mb low north of the area near 38N40W south-southwestward to 31N45W and to 25N53W, where it transitions to a stationary front to 20N61W and to across north-central Hispaniola and to Haiti. A trough extends from the northern Leeward Islands to near 15N65W. Isolated showers are possible near the trough.

Moderate to fresh northeast winds along with seas of 7 to 10 ft seas are west of the front to near 55W and north of 26N. Moderate to fresh southerly winds and seas of 5 to 7 ft are present north of 26N between 35W and the cold front. Gentle to moderate northeast to southeast winds and seas of 4 to 6 ft prevail for the remainder of the Atlantic Basin west of 35W.

For the forecast west of 55W, the front will remain nearly stationary just north of Hispaniola and Puerto Rico on Fri. The remnant moisture associated with the frontal boundary will lift northward as a trough Sat through Sun. A weak low may develop along the trough axis east of the Bahamas on Sun. This will support gentle to moderate winds with slight to moderate seas across most of the forecast area through the weekend. The exception will be over the northeast waters, where fresh to locally strong westerly winds and rough seas are expected beginning on Fri as another cold front clips the region by late Sat into Sun.

Posted about 3 hours ago by NHC Forecaster Aguirre