Instability with cloudiness should be increasing across St.Vincent and the Grenadines (SVG) with showers and isolated thunderstorms overnight. Gusty winds nearing 46 km/h (25 knots) could accompany thunderstorm activity during Wednesday. See image compliments METEOFRANCE...at 6:20pm. However, the presence of dry air surrounding the tropical wave should limit the
convective/shower activity, with instability now expected to decrease early Thursday as the Atlantic High Pressure System builds quickly across the islands with dry stable air at mid to upper levels. A thick plume of dust behind the tropical wave, is approaching the island chain, caught in the High Pressure clockwise circulation, this plume could significantly reduce visibility and air quality. Although the High Pressure System should dominate, sufficient lower level moisture could result in few showers late Thursday and a lower level trough associated with ITCZ activity could move northward during Friday to reach the island chain with showers.
Expect east north- easterly breeze to veer south-easterly moderate to fresh (20 - 40km/h) breeze by Wednesday morning, becoming temporarily strong (up to 45km/h) by evening. Direction should be backing to east north-easterly during Thursday. Wind speeds should generally be reduced during Friday.
Barometric Pressure readings are ranging 1011mb - 1013 mb and should rise again by Thursday as the Atlantic High Pressure System builds across the islands.
Sea swells are originating from the east due north and rising, to peak near 1.8m on the west coasts and up to 2.5m on east coasts on Wednesday. Small craft operators and sea bathers should exercise caution for above normal swells.... Wave heights should be decreasing by Friday.
Visibility across our area should be decreasing with increased hazy conditions by late Wednesday as a thick plume of dust approaches the islands. During Thursday visibility and air quality could be significantly reduced. Small craft operators and persons with respiratory concerns should be alert as PM 2.5 levels could peak near 68 µg/m**3 and PM10 levels could peak near 95 µg/m**3 by evening.
NOTES:
- A tropical wave is approaching the Lesser Antilles with axis along 57W/58W from Suriname to 18N, moving west at 20-25 kt. Model guidance indicates the wave is associated with a 700 mb trough and is well-defined on the TPW product. It is near the leading edge of an extensive area of dry Saharan air from 12N-24N between 37W-57W. Only isolated showers are near the wave axis at this time. Moisture associated with the tropical wave is expected to mainly affect the Windward Islands later today into early Wednesday.…. about 180 nmiles away
- ITCZ extends from 10N20W to 07N30W to near the coast of Suriname. Scattered to numerous moderate and isolated strong convection is within 300 nm south of the ITCZ from 20W-42W. Scattered moderate convection extends to within 60 nm south and 300 nm north of the ITCZ, between 42W-50W. The ITCZ is much more convectively active than 24 hours ago, especially between 37W-43W
- A new tropical wave moved off the coast of Africa this afternoon