San Juan de Pasto, Colombia

Weather Underground Forecast for Tuesday, June 18, 2013.

Heavy rains and gusty winds are expected for parts of the northwestern Caribbean Sea and parts of northern Central America on Tuesday as a tropical wave in the western Caribbean Sea lifts into the northwestern basin. The wave will extend into Honduras and will bring widespread rain and scattered thunderstorm activity from the Yucatan Peninsula southward through Nicaragua. This system has a low chance, 20 percent, of becoming a tropical cyclone by Tuesday. Meanwhile to the south, expect widely scattered light to moderate showers and thunderstorms to continue in the southwestern corner of the Caribbean basin and from Panama through Nicaragua due to the proximity of the monsoon trough.

Elsewhere, easterly trade winds will increase across the basin due to a strengthening Atlantic high pressure. Expect trades to weaken on Wednesday before increasing again on Thursday.

In South America, onshore flow from the Pacific Ocean and the Caribbean Sea will maintain warm and humid conditions across the north, supporting more shower and thunderstorm activity from Ecuador through Venezuela. To the south, a low pressure system sliding across Paraguay into southeastern Brazil will lead to light to moderate showers with areas of heavy rain and chances of thunderstorms in eastern Paraguay and southeastern Brazil near Santa Catarina. Further south, heavy precipitation will persist across southern Chile and western Argentina as moist onshore flow and low pressure prevail across the region.