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: 20180718 PERIOD: Morning
****** TROPICAL WAVES******(0900 UTC)
TW #27 extends from 19°N21°W through 10°N23°W moving westward near 15 knots.
TW #26 extends from 17°N56W through 10°N58°W moving westward near 15 knots.
Moisture ahead of an approaching tropical wave began to produce cloudy skies with a few scattered showers during the early part of the night across the Windward islands. However, after midnight, an increase in cloudiness and shower activity was observed across the Windward islands with the activity spreading over the extreme southern Leeward islands. Trinidad and Tobago experienced more convective activity due to a combination of a surface to low level confluent pattern and the approaching tropical wave.
Further south, over the Guianas, mostly fair to partly cloudy skies were observed which aided in early morning fog being observed, however little shower activity was reported over these parts.
Calm winds were observed over the Guianas, while wind speeds across the island chain ranged between 5 to 17 knots. Seas remained moderate in open waters with swells peaking at near 2.5m.
The combination of surface to low level convergence on the southwestern periphery of the Atlantic surface to mid level high pressure system and a surface to low level trough over eastern Cuba, was responsible for cloudy skies, scattered showers and isolated thunderstorm activity over Hispaniola, eastern Cuba, Jamaica and southern Bahamas during the early part of the night. As the early morning progressed, this activity migrated across central Bahamas. Elsewhere across the central Caribbean fair weather conditions prevailed. While over southwestern and western Caribbean similar conditions were encountered due to similar features which were experience over the aforementioned area.
Today: The axis of TW #26 will drift across the island chain during the morning session. As a result, cloudy skies, scattered showers and the possibility of a few periods of rain can be expected across the entire eastern Caribbean and this is likely to remain into the night as moisture trailing the axis of this wave will persist. Model data is indicating an upper level low centered just to the east of the northern Leeward islands with a trough emanating over the Windward islands. However, little support at this time is anticipated from this upper level feature.
Thursday: TW #26 aforementioned by this time would have drifted westward across the Caribbean Sea. Moisture trailing this wave will continue to spread a few brief early morning showers across the island chain. However, around midday, as this moisture moves away, a surface to mid level Atlantic high pressure system will rebuild behind this wave allowing for a relatively dry and stable atmosphere. Mostly fair weather, breezy and hazy conditions will be anticipated after midday. The upper level low is expected to weaken, however a few brief scattered showers can be expected over the Leeward islands.
Friday: The surface to mid level Atlantic high pressure system will maintain full dominance across the eastern Caribbean. Mostly fair weather, breezy and hazy conditions can be expected as model data is indicating relatively very dry and stable mid levels.
Saturday: Model data is indicating a surface to low level trough in conjunction with a surface to low level convergence pattern will be approaching and affecting the area producing partly cloudy skies and spreading a few scattered showers by late afternoon.
Today: The surface to mid level Atlantic high pressure will become the dominant feature across the basin allowing for mostly fair weather conditions. Surface to mid level trough positioned over Panama will maintain cloudy skies, scattered showers and possible thunderstorms over the south western Caribbean. TW #26 is anticipated to move over the eastern Caribbean Sea by nightfall.
Thursday: TW #26 will progress westward over the Virgin Island, Puerto Rico and eventually Hispaniola by evening. Partly cloudy to occasionally cloudy skies and scattered showers are expected over the aforementioned areas. While instability remains over southwestern Caribbean spreading cloudy skies with scattered showers and possible thunderstorms.
Friday: TW #26 progresses further westward over the south western Caribbean and is expected to generate cloudy skies, scattered showers, periods of rain and thunderstorms across southwestern and western Caribbean area. Meanwhile, a building surface to mid level high pressure system is expected to dominate conditions across the central Caribbean. A few brief scattered showers afternoon showers can still be expected.
Saturday: Similar conditions from previous day will prevail across the southwestern and western Caribbean. While the surface to mid level high pressure system is expected to strengthen producing fair weather across the Greater Antilles.