Tropical Waves

An eastern Atlantic tropical wave has its axis along 38W from 01N to 15N, moving westward at about 15 to 20 kt. This wave remains embedded in a dry Saharan airmass that is suppressing deep convection from forming near it. Only isolated showers are within 120 nm west of the wave from 05N to 08N and within 120 nm east of the wave from 07N to 09N.

A central Atlantic tropical wave has its axis along 50W from 01N to 13N, moving westward at 10 to 15 kt. Isolated showers and thunderstorms are seen south of 06N between 49W and 51W.

A central Caribbean tropical wave has its axis along 76W south of 15N. It is moving westward at 10 to 15 kt. Isolated showers and thunderstorms are near the wave axis south of 14N.

Monsoon Trough/ITCZ

The monsoon trough axis enters the Atlantic through the coast of Guinea-Bissau near 12N16W and continues southwestward to 06N21W, where it transitions to the ITCZ to 05N30W, then briefly pauses at 04N38W. It resumes at 04N39W to 02N49W. Scattered moderate convection within 120 nm north of the trough between 19W-21W. Similar convection is southeast of the trough from 03N to 09N between 10W-17W.

Gulf Of America

The upper-level flow pattern attributed to a rather robust upper-level trough that is over the west-central Gulf is drawing abundant deep tropical moisture northward from the Caribbean and into the eastern and central Gulf. This is resulting in scattered to numerous showers and thunderstorms, some strong, primarily over the NW and NE Gulf waters. A squall line moving quickly east-southeastward across the NW Gulf waters is analyzed from south- central Louisiana to 27N93W and to the coast of Mexico at 25N98W. Scattered showers and thunderstorms are over the western half of the Yucatan Peninsula and its interior portions. Otherwise, the pressure gradient related to the western extension of weak Atlantic ridging is maintaining moderate or weaker winds. Seas are of moderate state with these winds.

For the forecast, the aforementioned squall line of active thunderstorms will continue to move across the NW Gulf tonight. Expect periods of heavy rainfall, frequent lightning, wind gusts to gale-force and locally rough seas with this activity. Otherwise, the Atlantic ridge extends westward across north Florida and the northern Gulf coasts, and will sustain moderate to locally fresh SE to S winds through Fri, then diminish to gentle to moderate over the weekend. The exception will be evening pulses of fresh to strong winds off the northern Yucatan this evening and again Thu. The energetic upper-level trough that is over the west-central Gulf should continue to combine with abundant tropical moisture to produce scattered showers and strong thunderstorms over the central and eastern Gulf through Thu. Mariners are urged to keep up to date with the latest forecasts.

Caribbean Sea

The interaction between high pressure of 1023 mb centered over the western Atlantic with relatively lower pressure to the south over the Caribbean and in northern South America is bringing fresh to near gale-force trades along with rough to locally very rough seas over the central Caribbean. Seas are peaking up to 13 ft off northwest Colombia as revealed by an earlier altimeter satellite data pass. Moderate to fresh trades and mostly moderate seas are present elsewhere. The southeastern periphery of a rather robust upper-level trough is supporting scattered to numerous showers and thunderstorms over and near western Cuba, and over some areas of the northwestern Caribbean. Similar convection is just offshore eastern Honduras, Nicaragua and Costa Rica. Scattered showers and thunderstorms are also over the interior sections of central Cuba and Hispaniola as well as over northern and southern Panama. Isolated showers are elsewhere west of 79W.

For the forecast, a tight pressure gradient between 1023 mb high pressure in the western Atlantic and a 1007 mb Colombian low will continue to support fresh to strong trades and rough seas across the central Caribbean through Thu morning before gradually diminishing in areal coverage Thu evening through Fri. Winds are expected to pulse to near-gale force off northwest Colombia tonight through Thu morning. Trades in the Gulf of Honduras and just north of Jamaica will reach fresh to strong speeds this evening through early Thu morning. The high pressure will shift eastward Thu night through the weekend, leaving a weakened Atlantic ridge north of the Caribbean. This will yield moderate to locally fresh winds and moderate seas across most of the basin through the weekend, except in the south-central basin, where fresh to strong winds and rough seas will remain.

Atlantic Ocean

High pressure of 1023 mb is located near 29N68W, with a ridge stretching westward across northern Florida and to the north- central Gulf of America. To the east, a 1024 mb high center is near 30N31W. A weak stationary front is analyzed from near 31N23W to 27N30W, where it transitions to a weak trough to 25N40W and to 24N49W. Another weak trough extends from near 31N46W to 25N60W and northwestward to 27N68W. No significant convection is occurring with these features. High pressure is present over the rest of the basin north of about 15N anchored by the two previously mentioned high centers. Moderate to fresh trades along with moderate to locally rough seas are south of 20N and east of 35W, also south of about 25N and east of 35W, and south of a line from northeast Florida to the northern Leeward Islands. Elsewhere, light to gentle winds are noted. Seas with these winds are of moderate state.

For the forecast west of 55W, the present pattern is expected to produce fresh to strong winds with moderate to rough seas south of 24N and west of 65W through tonight, including the Great Bahama Bank, as the high begins to shift eastward. The ridge will remain in place, but weaken as this occurs, allowing winds and seas to begin to diminish. Looking ahead, two cold fronts will sweep eastward across the north Atlantic are expected to produce increasing winds and seas north of 28N and east of 70W from Thu night through Fri evening, then again from Sat night through Sun night.

Posted 14 minutes ago by NHC Forecaster Aguirre