The formation of twin cyclones does occur in both the Indian Ocean as well as the Western Pacific with the Indian Ocean twins being weaker . Schubert et al Symmetric Twin Tropical Cyclones report that the October through May is the period of formation of twin tropical cyclones with December through February being the maximum frequency. The original definition of twin tropical cyclones was provided by Keen in 1982 Cross Equatorial Pairs in the Southern Oscillation. Apart from high SSTs you also need conditions of intense low level vorticity. The convection associated with the eastward propagating Madden Julien Oscillation(MJO) contains cyclonic Rossby gyres that favour tropical cyclogenesis.
If students are wondering what and where are the cyclonic gyres this image may help in that regard- please pay attention to the cyclonic gyres at the 850 hPa level that trail the convection
Lander in Formation of Twin Tropical Cyclone Twins Symmetrical With Respect to the Equator outline the "Keen criteria"
- The northern and southern systems must initially form within 9 days of each other
- Latitudinal separation must not be more than 22 degrees
- The longitudinal difference of the initial disturbances ranged between +9 degrees and -17 degrees
A further strict definition for twins include
They must form simultaneously
They form at low latitudes (5 degrees above and below the equator)
They form along the same longitude
Lander performs case studies for the twin cyclones Lola and Namu in the 1986 Pacific Typhoon season - 1986 Pacific Typhoon Season
A more recent reference Schreck et al. A case study of an outbreak of twin tropical cyclones have performed studies that conclude that a broad and long lasting envelope of warm water, low surface pressure and easterly shear are other conditions that are required for formation of twin cyclones.
Students can watch the video in this URL Cyclone Pam and Bavi and see the twin cyclone activity