DISCUSSION: As cyclonic activity in the Eastern Pacific develops, it has become a concern for the Hawaiian Islands yet has brought some unconventional interest in the Californian coast. The concern regarding California and this activity is the Fujiwhara effect.
The National Hurricane Center in conjunction with the Central Pacific Hurricane Center are currently reporting Tropical Storm Irwin and Hurricane Hilary in the Eastern North Pacific and Tropical Depression Greg in the Central Pacific. In particular, Tropical Storm Irwin and Hurricane Hilary are storms to monitor as they could bring dangerous surf to locations in Southern California.
The Fujiwhara Effect according to the American Meteorological Society (AMS) is, ”the tendency of two nearby tropical cyclones to rotate cyclonically about each other as a result of their circulations’ mutual advection.” However rare, the AMS notes that this frequently may occur in the northwestern Pacific basin, while increasingly rare in other oceanic basins. The Fujiwhara Effect is currently being seen with Kulap and Noru in the Western Pacific.
Irwin and Hilary’s close proximity could showcase this rare possibility that Irwin may be absorbed into Hilary. If Hilary interacts with Irwin the hurricane is expected to weaken as it moves into cooler waters in the next few days. Current intensity of hurricane Hilary indicates a strong Category 2 with max winds around 90 knots with minimal changes in the short-term with overall weakening in the near future. Model guidance indicating that merging of these two storms could potentially happen by the end of the work week. The probability would bring large swaths of moisture into Southern California with an onslaught of rough conditions for the state including heavy rain, high surf and flash flooding.
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© Meteorologist Jessica Olsen