Sea Conditions Guide: Gulf of Guinea www.dtn.com © 2019 DTN, LLC, all rights reserved. “DTN” and the degree symbol logo are trademarks of DTN, LLC. Climate key features but over the ocean the ITCZ causes convergence at the surface and possible Region is delimited by the International squall formations as weather along the Hydrographic Organization between Cape Zone is driven by thunderstorms. Lopez, Gabon and Cape Palmas, Liberia. DTN uses near-real time products to Gulf of Guinea’s climate pattern is warn clients when thunderstorms and driven by the seasonal variation of the squall lines are moving towards the local Intertropical Convergence Zone (ITCZ) or port operations or vessels with harsh doldrums as frequently named by mariners. weather and sea conditions which can disrupt operations and prove dangerous Intertropical for safety onboard. convergence zone – Harmattan winds – squalls, thunderstorms dry conditions but and weather pattern dangerous for harbour The ITCZ subtle variation Northerly- Southerly (Summer-Winter) over the and offshore operations region throughout the year, brings one During the dry season when the drier season (November-March) and one northeasterly trade winds are located rainy season (March-July) with another closer to the Gulf and the ITCZ over smaller drier and rainy seasons in it, dangerous conditions could develop between like a well-known called August following the continental African Break period which starts a sudden dry Harmattan winds. period right after the main wet season. Harmattan conditions develop with Note the term applied was drier and not specific synoptic scale pressure dry, because across the Gulf itself squalls distribution across the Western Sahara. with stormy weather and abundant rain The general distribution is associated can develop throughout the year. with the Azores High subtropical ridge advecting a high amount of dust During the summer season over the southwards from the and Sahel area. Northern Hemisphere the ITCZ is positioned more northwards therefore This airmass is often characterized by the southwestern monsoon is more poor visibilities, low relative humidity active along the Gulf and squalls and generally colder temperatures can develop frequently and daily over the disrupt port and vessel operations and is area. In the winter season the ITCZ is dangerous for helicopter operations which positioned roughly over the Gulf and rely often on visual flight rules, therefore the northeasterly trade winds bring dry visual meteorological conditions to operate. conditions across the continental shelf .