This article is from the Storms FAQ, by Chris Landsea firstname.lastname@example.org with numerous contributions by others.
The effect of El Nino-Southern Oscillation (ENSO) on Atlantic tropical
cyclones is described in subject F2).
The Australian/Southwest Pacific shows a pronounced shift back and
forth of tropical cyclone activity with fewer tropical cyclones between
145 and 165E and more from 165E eastward across the South Pacific during
El Nino (warm ENSO) events. There is also a smaller tendency to have the
tropical cyclones originate a bit closer to the equator. The opposite
would be true in La Nina (cold ENSO) events. See papers by Nicholls (1979),
Revell and Goulter (1986), Dong (1988), and Nicholls (1992).
The western portion of the Northeast Pacific basin (140W to the
dateline) has been suggested to experience more tropical cyclone genesis
during the El Nino year and more tropical cyclones tracking into the
sub-region in the year following an El Nino (Schroeder and Yu 1995), but
this has not been completely documented yet.
The Northwest Pacific basin, similar to the Australian/Southwest
Pacific basin, experiences a change in location of tropical cyclones
without a total change in frequency. Pan (1981), Chan (1985), and Lander
(1994) detailed that west of 160E there were reduced numbers of tropical
cyclone genesis with increased formations from 160E to the dateline during
El Nino events. The opposite occurred during La Nina events. Again there
is also the tendency for the tropical cyclones to also form closer to the
equator during El Nino events than average.
The eastern portion of the Northeast Pacific, the Southwest Indian,
the Southeast Indian/Australian, and the North Indian basins have either
shown little or a conflicting ENSO relationship and/or have not been looked
at yet in sufficient detail.