Jun 28, 2016

A Gallery of Tropical Influences: MJO, CCKW, TIW, and La Niña

Atlantic Ocean
by
Bob Henson
,
Weather Underground
Schematic cross section through a convectively coupled Kelvin wave (CCKW). Image: Michael Ventrice
Schematic cross section through a convectively coupled Kelvin wave (CCKW). Image: Michael Ventrice

Given the quick start we’ve seen to the 2016 Atlantic hurricane season--with Tropical Storms Danielle and Colin the earliest third and fourth named storms on record--the Atlantic may not need much help working its way well through the alphabet. Even so, this moment of relative quiet is a good time to look at some factors that could help move the process along. One player now approaching is a strong convectively coupled Kelvin wave (CCKW) located near the International Date Line. CCKWs are large but subtle atmospheric impulses, centered on the equator, that roll eastward at 30-40 mph, with showers and thunderstorms typically along their forward flank. When an eastward-moving CCKW encounters a tropical wave in the Atlantic, the enhanced moisture and upward motion may give it a boost and help it consolidate into a tropical cyclone