Two major Atlantic hurricanes during a strong El Niño: a first
Strong El Niño conditions currently exist in the Eastern Pacific, where ocean temperatures have warmed to 2.3°C above average in the region 5°N-5°S, 120°W-180°W (called the Niño 3.4 region). Major Atlantic hurricanes are uncommon when ocean temperatures get this warm in the Eastern Pacific, and 2015 is the first strong El Niño year to experience two major Atlantic hurricanes since El Niño records began in 1950. The other four years that had strong El Niño conditions during the peak August-September-October portion of hurricane season have had only one major hurricane each. Those years were 1972, 1982, 1987, and 1997. Joaquin is now the second strongest Atlantic hurricane observed during strong El Niño conditions, behind only Hurricane Debby of 1982, which had 135 mph winds.
Joaquin is an uncommon beast: a major hurricane that did not develop from an African tropical wave. These waves serve as the origin of about 85% of all Atlantic major hurricanes. According to TWC's Stu Ostro, Joaquin's origin can be traced, in part all the way back to a upper-level trough that came off the coast of the Carolinas on September 15 (animation here). This trough became a cold upper low northeast of the Leeward Islands, then warmed and transformed into a warm-cored tropical cyclone. These sorts of systems are usually too far north to have warm enough water temperatures to make it to major hurricane status, but with the waters of Joaquin's birth a record warm 30°C (86°F), this was not a problem for the storm.
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=3136
So now we must add two major hurricanes (111 mph winds or stronger, i.e., categories 3, 4 or 5) during an El Niño event as part of the strangeness of 2015 and the clear and present danger of global warming. Gadzooks! How many major hurricanes would there have been if we had a La Niña or a La Nada instead???
No comments:
Post a Comment