Moisture in the flow behind a recent tropical wave is bringing some rainy periods across parts of the Lesser Antilles. There are a few showers also. A high pressure ridge is gradually pushing in with some drier air with breezy conditions so things should improve late today to evening except for isolated light to moderate showers in most of the Lesser Antilles.
Exceptions are in Virgin Islands where chances continue for light to heavy showers and Trinidad and Tobago where convergence within the ITCZ will bring some light to heavy showers and some periods of rain late today to Monday. Localized flooding and mudslides are still possible. Gusty winds can be expected as a modest surge in trade winds is ahead of the next tropical wave now entering French Guiana.
The ITCZ ahead of this tropical wave will bring scattered showers and thunderstorms to Guyana and Suriname as well. The tropical wave will maintain daily chances Mon-Wed… it then affects the Windwards from early Tuesday to Wednesday.
South American/Andean Cold Surge
The upper trough and source of Antarctic cold air is already pushing north into the Pampas plains of Argentina with showers and thunderstorms (some severe likely in Argentina up to SW to W Amazon regions) and this will rapidly move into the Amazon regions in 24 hours and sweep north to affect south/central Guianas late Wednesday.
By early Thursday morning showers and thunderstorms will near coastal South America including NE Venezuela and Guianas. Later in the day convergence with showers and thunderstorms should push in to the Caribbean Sea, ABC Islands, Trinidad and Windwards continuing into Friday.
The GFS has shown circulations forming from the large areas of convergence that will be pushing north and NE into the Caribbean and SW Atlantic… they then move in the unusual ENE to NE direction given the dramatic disturbance of low to mid-level steering. We’ll need to monitor this since in medium to long range (5-10 days) other models are showing general supportive environment for possible cyclone formation in the basin.
These cold surges occur sometimes crossing the Equator but it’s rare to see such a strong one and at the start of summer in the southern hemisphere. By the time the airmass reaches the islands it will have been modified by the warm waters so very marginal cooling is possible and may not be noticed.
Furthermore, the slight cooling shown on islands is more attributable to rain cooled air which is normal. The cold is more effective over the larger landmasses of Venezuela and maybe inland Trinidad for 1 or 2 nights.
