WACE pattern-Cyclones

1. Cyclogenesis is an indicator that denotes the chance of a cyclone forming.
2. It depends on parameters such as  
   1. Sea surface temperature
   2. The ocean heat content
   3. Change in winds from the surface into the upper atmosphere (or the vertical shear)
   4. Rotation of winds near the surface.
3. A rapid increase in the cyclogenesis potential over the Arabian Sea in 1990s coincided with a shift in the so-called ‘Warm Arctic, Cold Eurasian’, or WACE, pattern.
4. WACE is a pattern of warm surface temperatures over the Arctic and a large cold surface temperatures over Eurasia. 
5. This pattern is associated with upper-level circulation changes that reach into the Indian Ocean sector.