Tropical Waves

A far eastern Atlantic tropical wave has its axis near 24W from 01N to 13N. It is moving westward at about 10 kt. The wave is in a very dry surrounding environment marked by a dense area of Saharan Air Layer (SAL) as seen in the GOES-E dust and GEO color imagery. Isolated showers are near and along the wave axis from 02N to 05N.

A central Atlantic tropical wave has its axis near 44W from 01N to 14N, moving westward at 10-15 kt. See the Monsoon Trough/ITCZ section below for convection near the southern portion of this wave.

Monsoon Trough Itcz

The monsoon trough axis enters the Atlantic Ocean through the coast of Guinea-Bissau near 12N16W and continues southwestward to 06N20W, where it transitions to the ITCZ to 04N23W, then breaks due to the tropical wave near 24W, and continues at 04N25W to 01N34W to just west of the other wave near 01N45W and to just inland Brazil near 02N51W. Numerous moderate to isolated strong convection within 240 nm north of the ITCZ between 44W-51W and within 180 nm north of the ITCZ between 36W-44W.

Gulf Of America

A weak stationary front extends southwestward from low pressure of 1008 mb that is located east of central Florida near 29N80W to southwest Florida, and continues to just northeast of the Yucatan Peninsula. Isolated showers are southeast of the frontal boundary. The activity becomes scattered in coverage across the Straits of Florida. The remainder of the basin is under a weak high pressure system and a continental dry airmass. The related weak pressure gradient supports moderate or weaker winds and slight to moderate seas.

For the forecast, the entire frontal boundary will slowly move southeastward and stall over the Straits of Florida today and lose definition through Fri. Otherwise, weak high pressure over the basin will maintain rather quiet conditions throughout today. Another weak cold front is forecast to enter the NE Gulf tonight and dissipate over the eastern Gulf on Fri. Southeast winds are forecast to reach moderate to fresh speeds over the western half of the basin this weekend and into early next week as the pressure gradient tightens between the western extension of Atlantic high pressure and relatively lower pressures in west Texas.

Caribbean Sea

The interaction between strong high pressure centered well north of the basin over the central Atlantic, with relatively lower pressures in northern South America is supporting a pressure gradient that is sustaining fresh to strong trades in the south- central Caribbean, including the Gulf of Venezuela. Seas of 6 to 8 ft are outside the Gulf of Venezuela per an overnight altimeter satellite data pass. Overnight scatterometer satellite data indicates moderate to fresh trades across north-central, eastern and southwestern portions of the sea while light to gentle winds and slight seas are elsewhere in the basin.

For the forecast, the pressure gradient in place will support fresh to strong trades across the central Caribbean, with the strongest winds offshore Colombia and in the Gulf of Venezuela. Moderate to fresh trades are expected across the remainder of the forecast waters, pulsing to strong in the Gulf of Honduras at night Sat through Tue. Large E swell resulting in rough seas will impact the tropical N Atlantic waters through late Sun, then begin to subside on Mon.

Atlantic Ocean

A weak stationary front extends southwestward from a 1007 mb low that is centered near 32N75W to a 1008 mb low at 29N80W, and continues southwestward to inland Florida near Vero Beach. Water vapor imagery shows a broad mid to upper-level trough across the same area as the front. Very dry sinking air with northwest flow aloft is moving across most of the western half of the basin as the trough advances eastward. To the east of trough, an area of numerous moderate to strong convection is evident north of 27N between 65W and 71W. Scattered showers and isolated thunderstorms are from 22N to 27N between 65W and 73W, and also from 22N to 27N between 73W and 80W. Isolated showers and thunderstorms are noted elsewhere south of 30N and west of about 58W. Fresh to strong southerly winds are north of about 27N between 63W and 73W. Seas with these winds are 5 to 7 ft as noted by Sofar Ocean Spotter buoys in the described area, and by an overnight altimeter satellite pass. A portion of a stationary front is along 31N between 51W and 56W. Isolated showers are possible along and near the frontal boundary.

The remainder of the SW North Atlantic west of 55W is dominated by a rather broad high pressure ridge axis. Moderate to fresh southeast to south winds and seas of 4 to 7 ft are south of 28N and between 55W and 75W, with the exception of higher seas of 6 to 8 ft in long- period east swell south of 16N between 55W and 60W.

The pressure gradient between a strong 1034 mb high pressure center centered well north of the Azores and lower pressures in western Africa support fresh to strong northerly winds and rough seas roughly from 13N to 26N and east of 30W. Over the rest of the central and eastern tropical Atlantic, mainly south of 28N and between 30W and 55W, moderate to fresh easterly winds and rough seas prevail. Elsewhere, moderate or lighter winds and moderate seas are noted.

For the forecast west of 55W, the stationary front off northeastern Florida will merge with a weak cold front that will move off the northeast Florida coast today. The cold front will extend from near 31N69W to 26N72W and as a weakening stationary front to near the northern Bahamas Fri afternoon, from near 31N62W to 26N70W early on Sat, then become a weakening stationary front from near 31N60W to 27N69W by late Sat night as high pressure N of the area shifts eastward while it strengthens some. Fresh to strong southerly winds are expected over the central and eastern waters N of about 27N through Fri while gradually lifting N of the area.

Posted 40 minutes ago by NHC Forecaster Aguirre