24 FEBRUARY 1998. TROPICS: OCEANOGRAPHY (ITCZ)

"Why have the Trade Winds slackened? Why is it overcast here in Panama, Why is it suddenly raining in Mauritania and Senegal? Why have the rains returned to the Guianas?

Because of a major low pressure area now passing east of North America. The one that cause all those tornadoes in Florida. Oh yeah, how do you figure that? simple. That low is at 992 mb. We here in Panama are at 1012 mb. The Huge Atlantic High is at 1024 mb. This is the mass of dry air that sits on top of Central America, Northwestern South America and West Africa at this time of the year ("Our Dry Season") Air Pressure "flows downhill" (wind). Thus the Atlantic High becomes distorted and the normal flow The trade winds!!) from it to the Intertropical Convergence Zone (low pressure) slacken and go north. So?

The ITCZ then reforms between the bulge of South America and the bulge of Africa. It"moves up". Thus rain returns to almost 6 degrees north and clouds to 9 degrees north (Panama). The drought in west Africa gets a break and it rains in Eastern Venezuela and Surinam. But no such distortion is occuring over the Indian sub continent nor over the Indian Ocean so All is DRY down until good old Madagascar where the ITCZ is pouring it on. Aussies will rejoice with the reformation of the low pressure over Indonesia. Darwin is wet....!!!!"--Neal Smith <SMITHN@tivoli.si.edu>

Back to The 1997 El Niño/Southern Oscillation (ENSO 97-98)