Tropical Storm Or Typhoon
Friday, May 12, 2006
May 12, 2006
That Chanchu has cut through the heart of the Philippines is beyond dispute--it landed from the east late Thursday, local time, over northern Samar Island. It has since winged westwards reaching the area of Mindora as I write. But there is a lack of consensus as to whether Chanchu was--and, indeed, is--a typhoon. A scan of local government advisories is consistent in showing the status of strong tropical storm whereas the Joint Typhoon Warning Center (JTWC) has reckoned upon typhoon status since landfall for Chanchu. Having look, albeit not exhaustively, at some synoptic and METAR data, I found no reason to believe that the storm was a typhoon as of late Friday, Philippines time.
Whatever the latest status of Chanchu, it strikes me as a given that it will be a typhoon within 12 to at most 24 hours. The South China Sea, which lies in the direct path of Chanchu, hosts sea-surface temperatures at/near 30 degrees Celsius to about the 20th parallel. From satellite imagery, Chanchu has good, concentric outflow, so it should deepen once its breaks free of the topographic hobbles posed by the rugged Philippines.
It is the conscensus of model output that Chanchu will swing northwards Sunday and Monday. Approach to South China--potentially Hong Kong--is indicated for late Wednesday and early Thursday, local time. One thing I have seen today is that the trend in all models is westward with bias towards landfall in South China and thus away from a path into the Formosa Strait and Taiwan. Early this week, there were hints of Chanchu cutting east of the Philippines and Taiwan. If I were on Hainan Island or even Vietnam, I would be loathe to see this trend persist, as it looks as though Chanchu has room to breach the category-3 (equivalent) threshold over the South China Sea.