Tropical Waves

A far eastern Atlantic tropical wave has its axis along 37W/38W S of 14N. It is moving westward at 10-15 kt. Isolated showers and thunderstorms are west of the axis to near 42W and from 05N to 06N.

Monsoon Trough/ITCZ

The monsoon trough axis enters the Atlantic through the coast of Africa near 17N16W and continues southwestward to 08N23W, where it transitions to the ITCZ to 05N37W. It resumes to the W of the above described tropical wave near 05N39W to near 03N51W. Scattered moderate convection is within 30 nm of the ITCZ between 33W-37W.

Gulf Of America

Weak high pressure extends from the western Atlantic to the eastern Gulf of America while a trough is analyzed from near 25N92W to 21N95W and to the western Bay of Campeche near 18N95W. The pressure gradient in place is generally allowing for light to moderate S to SW winds over the eastern Gulf, and for mostly gentle to moderate E to SE winds elsewhere, except for fresh E to SE winds S of 25N E of 84W including the Straits of Florida. Good coverage of scatterometer satellite data passes this afternoon captured these winds. Seas are in the range of 3 to 5 ft, except for slightly higher seas of 4 to 6 ft over the central sections of the Gulf and lower seas of 2 to 4 ft over the northern sections.

Satellite imagery shows scattered showers and isolated thunderstorms confined to the eastern Gulf from 25N to 29N between 83W and 85W. This activity is being sustained by a lingering upper-level trough that is over the eastern Gulf. Isolated showers and thunderstorms are along and near the western tip of Cuba. The satellite imagery also reveals that skies are hazy over the Florida peninsula and the eastern Gulf due to the presence of the Saharan Air Layer (SAL).

For the forecast, the weak high pressure that is across the eastern Gulf will build modestly westward into the central Gulf late Sun through early next week. Moderate to fresh E to NE winds are expected each afternoon and evening north of the Yucatan Peninsula and into the eastern Bay of Campeche as a trough develops daily and moves westward. Expect moderate to fresh SE winds across the western and south-central Gulf through Mon between a trough over northern Mexico and Atlantic high pressure.

Caribbean Sea

The pressure gradient between rather weak high pressure over the western Atlantic and relatively lower pressures in the southern Caribbean and in northern S America is allowing for fresh to strong trades to be across the most of the basin, including the Gulf of Honduras. A recent scatterometer satellite data pass highlighted these winds. Seas are in the 7 to 9 ft range over the central section of the basin, 5 to 7 ft in the Gulf of Honduras, also from 18N to 20N between 76W and 80W, and in the approaches to the Windward Passage. Seas are 4 to 6 ft elsewhere. A recent altimeter satellite data pass noted the 7 to 9 ft seas.

Satellite imagery reveals large clusters of numerous moderate to strong convection confined to S of 12N between 76W and 84W due to the eastern extent of the E Pacific monsoon trough that reaches into that part of the sea. Isolated showers and thunderstorms are seen from 19N to 21N between 76W and 85W. Isolated showers are elsewhere primarily W of 76W and E of 70W.

For the forecast, the weak high pressure N of the region that is over the western Atlantic will shift northeastward into the N central Atlantic Fri and through the weekend. The Atlantic ridge will then build southwestward toward the Bahamas and S Florida late Sat through early next week. This pattern will lead to fresh to strong trades and moderate to rough seas across most of the central basin and Gulf of Honduras through Fri evening, diminish slightly on Sat, then increase across most of the basin Sat night into early next week.

Atlantic Ocean

A stationary front extends from near 31N56W southwestward to 28N62W and to 25N67W. Satellite imagery shows isolated small showers and thunderstorms along and near the frontal boundary. A few clusters of scattered moderate convection are evident over the waters E and NE of northern Florida to near 77W. This activity is out ahead of a cold front that is over the southeastern U.S., and a lingering upper-level trough that stretches from eastern Georgia to the eastern Gulf of America. Water vapor imagery depicts broad upper-level troughing that is over the central Atlantic N of about 20N and between 55W and 72W. An area of broken to overcast mostly low and mid-level clouds is noted ahead of this trough to near 54W. Patches of light to moderate rain and isolated showers are possible within this area of clouds. Farther to the E, a trough is analyzed along 32W from 21N to 29N. No significant convection is occurring with this trough. High pressure prevails elsewhere over the tropical and subtropical waters as a 1031 mb high center is well N of the area near 38N41W. The pressure gradient in place is generally supporting moderate to fresh trades and 5 to 7 ft seas over most of Atlantic S of 20N and N of 20N and E of 30W. Lower seas of 2 to 4 ft are N of 29N between between 70W and 74W and from 27N to 29N W of 77W. Seas of 3 to 5 ft are N of 29N between 65W and 70W. Moderate or weaker trades along with seas of 4 to 6 ft remain elsewhere.

Satellite imagery continues to exhibit an extensive outbreak of the Saharan Air Layer (SAL) that covers the vast majority of the eastern Atlantic. A thin swath of this SAL outbreak, has migrated westward to the northern Caribbean and to some areas of the western Atlantic, including to over the Florida peninsula as seen in the GOES-E GeoColor imagery.

For the forecast west of 55W, the aforementioned stationary front will begin to lift back N as a warm front and dissipate through Fri night. Weak high pressure NW of this front will shift NE and into the central Atlantic Fri into Sat. Atlantic high pressure will then build modestly W-SW into the Bahamas and S Florida Sun through Tue. Expect fresh to strong winds to pulse each afternoon and evening offshore of Hispaniola during the period.

Posted 3 hours ago by NHC Forecaster Aguirre