El Nino Watch
A pulse of tropical clouds and rain that travels east around the equator every 30-60 days.
Indices
NOAA PSL's real-time OLR MJO index (ROMI), daily: two components (mjo_romi_pc1, mjo_romi_pc2) and their combined strength mjo_romi_amplitude.
Limits. Published with a delay of about 5 days. The MJO is a short-term signal and does not change the season's overall El Nino tendency.
Amplitude above 1 = an active MJO, below 1 = weak or absent. The two components together say where the active phase is (Indian Ocean, Maritime Continent, western Pacific, ...). We store the numbers; the phase diagram is on the source page.
When the active MJO passes over the Indian Ocean and Maritime Continent, southern Thailand often gets a wetter 1-3 week spell, even during El Nino; its westerly wind bursts over the Pacific can also strengthen El Nino and help tropical storms form.