Barbados Meteorological Services
Initial to 4 days discussion based on Satellite imagery,BMS Radar composite,S.P.I.E products,GEM, GFS, WW3, UKMET and BMS WRF modeling, surface and upper air observations, Satellite derived products.
DATE: 20170529 PERIOD: Evening
A weak easterly wave was near 61W south of 11N at 18Z moving west near 20 knots. All associated deep convection well south of 12N. Some moderate to strong convection brought some showers to Trinidad as well as the coastal areas of Guianas.
NHC tropical wave was near 20W has been rebranded as an easterly wave. This feature was induced by divergent south western flow just off the coast of Africa. This wave is now along 24W but will lose its identity over the next few days.
A tropical wave was near 33/34W at 18Z moving westward near 20 knots.
A surface to low level Atlantic high pressure system dominated weather conditions across Barbados, the central and southern Windward islands throughout the day. Fair to occasionally cloudy skies with a few scattered showers were reported over these islands. On the other hand, lingering moisture and instability associated with the tropical wave near 69W, resulted in occasionally cloudy skies with scattered showers mainly over the Leewards and northern Windward islands. Furthermore, St. Maarten also reported thunderstorm activity with a heavy shower and gusty winds at 1100Z(7:00am local time). This thunderstorm activity and gusty winds persisted into 1400Z(10:00am local time) with fluctuations in shower intensity. Subsequently, the highest recorded rainfall total between 8am and 2pm was 4mm at Juliana Airport, St. Maarten. Other lesser totals were 3mm in Le Lamentin, Martinique, 0.5mm at Canefield Airport, Dominica and 0.3mm in Vigie, St. Lucia. However, as the day progressed, conditions over some of these islands began to improve as the surface to low level Atlantic high pressure system began to exert its dominance.
Wind speeds across the region generally ranged from 12 to 24 knots with some higher gusts near showers reported. The highest gust reported was 35 knots in St. Maarten at 1100Z(7:00am local time). Seas remained slight to moderate in open water with swells peaking near 2.5m.
Over the Guianas, the combination of the ITCZ and an easterly wave with axis now along 61W generated some moderate to strong convection mainly along the coastline of the Guianas.
A weak tropical wave was near 69W at 18Z, moving westward near 20 knots.
Over in the Western Caribbean, mostly fair conditions prevailed for most of the day as a surface to low level Atlantic high pressure system dominated weather conditions over the area. Despite this, sufficient moisture and instability allowed for some localized activity to develop over some of the Bahamas, sections of Cuba and Jamaica by mid to late afternoon. A weak low to mid level trough extending from north of Hispaniola south westward over the Central Caribbean in conjunction with the tropical wave near 69W, generated some showers and thunderstorm activity over Hispaniola and Puerto Rico mainly during the afternoon.
The surface to low level Atlantic high pressure system will continue to dominate weather conditions across Barbados and most of the Eastern Caribbean tonight into early Thursday. Nevetheless, mid level moisture across the area will generate some shallow mid level clouds. Meanwhile, a developing upper level low to the north of Puerto Rico, is expected to produce a diffluent upper level pattern over the northern sections of the eastern Caribbean over the next few days. This may result in a few enhanced convective showers during that time. On Friday afternoon, the tropical wave now along 33/34W is expected to begin affecting Barbados and by Friday night the rest of the Windward islands. Along with this, will be a favourable upper level pattern which may provide enhancement of the convective development over the area. However, preceeding this wave on Thursday will be a weak low level trough which may trigger a few scattered showers over some islands.
A ridge pattern will generally persist over the western Caribbean over the next few days however, some afternoon localized convection can still be anticipated. The tropical wave near 69W will begin to affect Jamaica by tomorrow afternoon while an upper level trough lingers in the vicinity of Hispaniola and Puerto Rico triggering some convective showers. By Wednesday, the tropical wave will begin to affect some sections of Cuba while the upper level trough lingers over the Central Caribbean. Shower activity should spread across a wider area with greater accumulations in the vicinity of Puerto Rico.