The prospect of an El Niño event is now looking likely, a meteorologist told insurance professionals last month, pointing to computer models signaling at least a weak event coming in late spring or early summer.
El Niño can reducethe number and intensity of hurricanes in the Atlantic, said Ray Hawthorne, who is also Product Manager for Insurance Products at WSI Corporation, a member of The Weather Company, during a March 18, 2014 webinar.
“Hurricane season starts in June [and] some forecast models suggest that an El Niño could start to develop just as we move into hurricane season,” Hawthorne said, noting that while there are uncertainties about how strong it will be, and exactly when it will start, the models forecasting the warmer waters over the Eastern Pacific that characterize an El Niño are lining up to favor lower amounts of tropical cyclone activity in the summer months.
Overall for the year, “our confidence level is above average this year that we will have a below-average severe weather season,” Hawthorne said, referring to hurricanes, thunderstorms, and tornadoes across the nation generally.
WSI is assigning a 70 percent probability to the scenario of severe weather reports of tornadoes, hail and wind damage falling below the five-year average for 2014, he said.
Hawthorne prefaced WSI’s summer and 2014 forecasts with a description of this year’s late-arriving spring and signals for wetter conditions in the North-Central states during the next few months, which in turn could produce increased flooding and ice jams in the region. He also described the opposite problem on the West Coast—dry conditions sparking wildfires.
Cold temperatures, which were well below average throughout the winter, continued into the month of March—a situation that has an impact on thunderstorm formations, he said.
Hawthorne started his explanation of why it has been tougher for thunderstorms to going within the United States by noting that there has been a lot of thunderstorm activity over western Pacific near China and Vietnam. “That basically pumps up a big ridge of high pressure that out of the Pacific waters [and] on the other side of that [high pressure ridge], a lot of cold air gets pushed southward.”
Displaying temperature maps for North America coming from European and U.S forecasts models, the U.S. model showed white and blue areas indicating at or below-average temperatures for much of the United States, with the only regions colored orange—indicating above-average temperatures—shown over Alaska and western Canada. This continued pattern of colder than normal temperatures “tends to suppress warm moist and unstable air” in the Gulf of Mexico, which is required for Gulf storms, Hawthorne said.
Throughout the presentation, Hawthorne stressed that while WSI is forecasting the number of severe weather episodes to come in below the averages of the last four or five years, “that’s not to say there won’t be severe weather.”
“There will probably still be brief bursts of very active weather,” he said. “It only takes one storm to hit a very populated area to cause a lot of insured losses.”
Facing the opposite problem on the West coast are states like Oregon, Washington, California and Arizona, where dry patterns are continuing to exacerbate the threat of drought “at least for next couple of months,” he said. Conditions will also be favorable for wildfires this spring, he said, noting that the El Niño in the second half of the year could bring some relief.
El Niño is a warming of the waters that happens every two-to-seven years over the Central and Eastern parts of Pacific Ocean.
Displaying El Niño conditions on a map, Hawthorne pointed to a red area off the coast of Peru in South America signifying a large area of warm water.
El Niño warming changes the location of the jet stream, usually moving it farther South. “That actually tends to limit the amount of severe weather in the favorite areas of Tornado Alley. But it can increase the amount of severe weather in Florida and the Southeastern U.S.— but that’s typically later on in the year,” he said.
“Also, El Niño can actually reduce the number and intensity of hurricanes in the Atlantic,” he added.
Hawthorne reported that El Niño’s “are notoriously difficult to predict,” adding that the science is very young on forecasting them. Still, “we certainly feel there is an increased risk for at least a weak El Niño to develop starting later on in the spring, but particularly in the summer, starting in June July and August.
“At present, water temps are below average in the main development region—off the coast of Africa. So that would also tend to move us in the direction of below-average [Atlantic hurricane] activity in 2014.”
Working against this development to threaten a busy season, however, is the fact that “we are still in an active multi-decadal cycle,” Hawthorne said, explaining that every 20-30 years, there are periods of increased or decreased hurricane activity. There was an inactive cycle throughout the 1970s, 80s and early 90s, but increased activity started around 1995 and continues, he said.
“The location of the El Niño is also going to be critical,” Hawthorne said, noting that if it forms into the eastern part of the Pacific Ocean—just off the South American coastline—rather than farther West in the Central Pacific, “that would really cap the number of storms this year [and] cause below-average activity in parts of the Atlantic basin.”
Hawthorne ended the session with a recap of WSI forecasts for each region of the United States: