The Boquete Weather site has an excellent list of links on many topics, including books, software, climate, and weather. There is no need to duplicate it here - go straight there for as complete a reference as you're likely to want.

Here's a short list of links, several of which are on the Boquete Weather list, that may be of interest to you.

Weather Services Some Personal Weather Stations in Panama Climate and Weather

El Niño

Inter Tropical Convergence Zone (ITCZ):