The Western Atlantic High Pressure system is building across the islands with cloudiness continually decreasing today, yet a few isolated showers are possible. The sub-Tropical Storm Leslie in the northern Atlantic Ocean is expected to move south-westward causing a weakening effect of the pressure gradient across our area by Sunday. Meanwhile, an approaching tropical wave could be squeezed between
the sub-Tropical Storm Leslie and the Atlantic High Pressure System as it approaches the islands. Lower level moisture could increase early Monday resulting in scattered showers as the backward tilting axis of the tropical wave crosses the southern portion of the Eastern Caribbean. Favourable mid to upper level conditions on Tuesday could increase the chance of isolated thunderstorms with the northern portion of the axis moving through the central and Northern Windward Islands.
Expect east-south easterly moderate to fresh (20- 35 km/h) breeze this afternoon, backing to easterly by nightfall. Wind speeds should become gentle to moderate (15-25km/h) with direction varying between east south-east and east north-east by Monday afternoon with the crossing of the tropical wave. A south-easterly flow can be expected by Tuesday afternoon with gentle (10 – 20km/h) breeze.
Barometric Pressure readings should slightly fall to range 1010 mb - 1012 mb this afternoon, gently rising on Sunday to range 1011 mb – 1013 mb.
Visibility on the horizon is reduced due to haze due to a combination of sea spray and suspended Saharan dust across our area. Visibility should be generally improving by Monday, but to be reduced again late Tuesday behind the next tropical wave.
Northerly swells generated by Post-Tropical cyclone Leslie, are propagating southwards across the Lesser Antilles and eastern Caribbean Islands, including St.Vincent and the Grenadines (SVG). Expect northerly swells to impact eastern and western coastlines of SVG later today (peaking tonight) and continuing on Sunday. Wave heights on the western coasts could peak near 2.0 m while on the eastern coasts, near 3.0m.
These large waves and dangerous rip-tides can create unsafe conditions for small-craft operators, and these conditions may become even more adverse at times of high tide. High Tide times are expected around: 10:29 pm on Saturday; 9:35 am and 11:08 pm on Sunday. Sea-bathers and other users of the sea are being warned to stay out of the water.
The High-Surf Advisory and Small-Craft Warning remain in effect until 6:00 am Monday, 1st October, and may be extended based on conditions.
Although northerly swells should continue, a reduction in wave heights can be expected by late Sunday with heights on the west reducing to 1.0m and on the east near 1.5m by Monday night.
NOTES: Post-Tropical Cyclone Leslie has been moving toward the southwest and probably continue on the same general track for the next 3 to 4 days with some strengthening Forecast. Large swells generated by Leslie will soon reach the Lesser and Greater Antilles. These northerly swells will affect the tropical Atlantic waters tonight through Sunday, building seas to 10 or 11 ft and could cause life-threatening surf and rip currents.
· Tropical wave along 25W from 03N-18N, moving W at 15 kt. Scattered moderate convection within 180 nm east of the wave axis south of 10N. This system shows up well in the Total Precipitable Water animation, with a sharp trough at the surface seen by the latest ASCAT scatterometer pass. .…. about 2160 nmiles away… vicinity around Thursday afternoon
· Tropical wave along 48W from 02N-17N, moving W at 15 kt. Scattered showers are developing within 75 nm to the east of the wave's axis between 10N-13N..…. about 780 nmiles away… vicinity SE .Caribbean Monday (backward tilt)