In the winter months the trade winds blow between northeast-by-east and east-southeast at Force 5 to 6. They never blow true northeast or southeast. If reports or models show gradient winds either southeast or northeast, look for a significant feature such as a front or a strong high or low to the north. Fronts may make up every few days in midwinter. By April you may see only one or two all month. A front coming off the U.S. coast may take 3 days to shed swell to Luperón where you will hear it sound in the blowholes at night. The swell at Luperón will veer from N to NE as the low pressure center towing its front makes its way to England.

Banks north of us — Bahamas, Caicos, Turks, Muchoir, Silver and Navidad — reduce and diffract the swell, so it shall differ from the swell in the forecasts. Experienced north coast sailors can use this knowledge to "lengthen" otherwise short windows from port to port along the coast.