Overnight into Thursday, the Western Atlantic High Pressure System should build while pushing instability (shearline/ pre-frontal boundary) southward across the island chain. As moisture levels increase, some showers can be expected. Instability associated with the shearline is expected to dip southward and eventually weaken the High Pressure System, resulting in marginal reduction of wind speeds.
At mid levels, increased moisture due to troughing should contribute to cloudy skies and shower activity increasing late Friday. Elevated moisture levels are expected to linger into Saturday, with upper levels enhancing shower activity.
Fresh to occasionally strong breeze (29-49km/h) should generally decrease, becoming moderate to fresh (20-38km/h) by Saturday as the shearline affects the islands.
Harmless clusters and streaks of Sargassum seaweed are present along coastal waters. Moderate seas up to 2.0m on the west and moderate to rough (2.0m to 3.0m) on the east should increase with north north-easterly swells by late Thursday into Friday. Swells are expected to peak near 3.5m (11.5ft) on the east retreating by Saturday afternoon. Therefore, a HIGH-SURF ADVISORY will accompany the SMALL-CRAFT WARNING and these will be in effect for St Vincent and the Grenadines from 6:00p.m today Wednesday 21st February until 12:00 noon Saturday 24th February, 2018.