Delay to the start of the 2018 Wet-Season

Officially, Dominica's wet-season, which coincides with the Atlantic hurricane season, runs from June to November each year. This year, models indicate a delay in the onset of the wet-season.

Less rainfall than normal is expected for the 2018 Wet-Season. A decrease in the frequency of wet days (1.0mm and more) and wet spells (three or more consecutive wet days) is anticipated for the first half of the season. There are no drought concerns for the island at this time for both the short term (March to August 2018) and long term (December 2017 to November 2018). At least one 7-day dry spell is expected for the first half of the season.

Cooler day and night time temperatures are anticipated for the first half of the season with some uncertainties at this time for the second half. Heatwave chances are increasing towards the middle of the wet-season.

Climatologically, Dominica's wet-season accumulates approximately 900 to 1600mm along the western coast, 1200 to 1900mm along the eastern coast with higher amounts in elevated regions. Usually, temperature ranges from 27oC to 28oC during the day with an average maximum of 30oC to 32oC. Night time temperatures usually fall between 24oC to 25oC.

One of the main drivers for the first half of the season is the near average Sea Surface Temperatures (SSTs) around the region and below average SSTs across the eastern Atlantic near west Africa. This normally results in a reduction in evaporation leading to drier air and fewer atmospheric instability which in turn results in a tilt towards slightly drier conditions particularly in the Lesser Antilles.

Dominica's 2017/ 2018 Dry Season accumulated higher rainfall amounts than normal with typical day and night time temperatures. Cooler SSTs in the equatorial eastern Pacific (La Nina) was the main driver for the season resulting in an increase in rainfall activity.

This forecast was issued by the Dominica Meteorological Service in collaboration with the Caribbean Institute for Meteorology and Hydrology on May 24th, 2018. Updates are issued monthly.

Posted: 21/06/2018