Tropical Waves

A central Atlantic tropical wave IS 46W from 11N southward, and moving westward at 10 to 15 kt. Scattered showers are seen from 04N to 06N between 45W and 48W.

A central Caribbean tropical wave is near 75W from 15N southward across western Colombia. It is moving westward at 10 to 15 kt. It is enhancing convection near the East Pacific monsoon trough.

Monsoon Trough Itcz

A monsoon trough enters the Atlantic near the coastal border of Mauritania and Senegal, then runs southwestward to 10N25W. An ITCZ continues from 10N25W to 03N43W. Numerous moderate to isolated strong convection is occurring south of the monsoon trough from 02N to 09N east of 19W. Widely scattered moderate convection is seen up to 100 nm along either side of the ITCZ.

The eastern end of the East Pacific monsoon trough is triggering numerous heavy showers and isolated strong thunderstorms across the Caribbean waters near eastern Panama and northwestern Colombia.

Gulf Of America

Divergent flow aloft attributed to a deep upper-level trough, combined with abundant tropical moisture pulled northward from the Caribbean, results in numerous showers and thunderstorms south of 28N and E of 91W. Moderate to fresh SE winds prevail across the basin, with moderate seas.

For the forecast, a squall line is going to produce heavy showers, dangerous lightning and strong to near-gale W winds along with locally rough seas for the northwestern Gulf this morning. Otherwise, the Atlantic ridge extending west-southwestward across Florida into the central Gulf will sustain gentle to moderate with locally fresh SE to S winds through the weekend. The exception will be evening pulses of fresh winds off the northern Yucatan through Thu night. An upper- level trough across the central Gulf should continue to couple with abundant tropical moisture to produce scattered heavy showers and strong thunderstorms over the central and eastern Gulf through Thu. These thunderstorms are capable of producing gusty winds, frequent lightning, limited visibility, and locally rough seas. Mariners are urged to keep up to date with the latest forecast.

Caribbean Sea

The interaction between strong high pressure over the central Atlantic and lower pressure to its south related to low pressure over northern S America has created a tight pressure gradient over the central part of the basin. This is inducing strong to near- gale trade winds along with rough seas across the central Caribbean. Moderate to fresh trade winds along with moderate seas are over the eastern Caribbean and Gulf of Honduras. Long-period E swell is creating rough seas in the Atlantic water passages of the Lesser Antilles. Elsewhere, moderate or lighter winds and moderate seas are prevalent.

The southeastern periphery of a well pronounced upper-level trough is supporting scattered showers and thunderstorms over the Yucatan Channel and waters adjacent to the northeast portion of the Yucatan Peninsula and the western tip of Cuba. Similar activity is inland over some sections of Cuba, and over the southwestern Caribbean S of 14N and W of 78W. This activity extends to inland Central America.

For the forecast, tight pressure gradient between high pressure in the western Atlantic and the Colombian low will continue to support fresh to strong trades across the central Caribbean with rough seas through Thu. These winds are expected to pulse to near- gale force off Barranquilla, Colombia tonight through Thu morning. Trades in the Gulf of Honduras and just north of Jamaica will reach fresh to strong this evening through early Thu morning. By Fri night, most of the basin should experience moderate with locally fresh winds and moderate seas, except the south-central basin in which fresh to strong winds and rough seas will remain through the weekend.

Atlantic Ocean

A weak cold front is analyzed from near 31N28W southwestward to 28N30W, where it transitions to a stationary front to 25N37W. To the W of the front, a 1023 mb low pres is analyzed near 26N55W. The remainder of the basin is under the influence of a broad and strong area of high pressure centered over the central Atlantic. The pressure gradient between the high pressure and relatively lower pressure in the deep tropics is sustaining fresh to strong E to SE winds and rough seas south S of 25N between 67W-74W. Elsewhere, moderate to fresh easterly winds along with seas of about 6-8 ft are south of 20N and west of 30W, and moderate or weaker winds and moderate are over the remainder of the basin.

For the forecast west of 55W, fresh to strong winds with moderate to rough seas are anticipated across waters south of 25N and west of 68W through this afternoon, including the Great Bahama Bank, as the Atlantic high pressure shifts southeastward, tightening the pressure gradient. This high is going to weaken tonight, allowing winds and seas to diminish. A dissipating stationary front from 25N35W to 24N40W will be gone later this morning. In the longer term, two cold fronts passing across the north Atlantic might cause increasing winds and seas north of 28N and east of 70W from Thu night through Fri, and again from Sat night through Sun.

Chan Posted about 4 hours ago by NHC Forecaster