Monday, July 21, 2014

Insurers May Not Get Hurricane Benefit From El Niño This Year: "High chance of cyclone near Lesser Antilles" Within 48 Hours

As the hype-n-tout about this season's El Nino begins to fade* the hurricane forecasts are going to have to be changed to reflect the increased risk of cyclone formation.
(see NOAA)

The largest change is in decreased wind shear which allows more storms to spin up. There are additional teleconnections that affect steering winds and even some hypothesized changes in sea surface temps. See below.
And today's blurb, from Reuters:
An area of low pressure located east of the Lesser Antilles now has a high, or 70 percent, chance of becoming a tropical cyclone during the next 48 hours, the U.S. National Hurricane Center (NHC) said in its latest advisory on Monday.

"Only a small increase in organization of shower activity would result in the formation of a tropical depression as the system moves westward to west-northwestward at 15 to 20 miles per hour during the next day or two," the Miami-based weather forecasters said.
*NOAA Changes El Niño Forecast From "We're All Gonna Die" to "Weak to Moderate"

From the University of Illinois:

AtlanticEastern Pacific

Average El Niño Avg. Average El Niño Avg.
Named storms 9.4 7.1 16,7 17.6
Hurricanes 5.8 4.0 9.8 10.0
Intense Hurricanes 2.5 1.5 4.8 5.5
The primary explanation for the decline in hurricane frequency during El Niño years is due to the increased wind shear in the environment.
In El Niño years, the wind patterns are aligned in such a way that the vertical wind shear is increased over the Caribbean and Atlantic. The increased wind shear helps to prevent tropical disturbances from developing into hurricanes. In the eastern Pacific, the wind patterns are altered in such a way to reduce the wind shear in the atmosphere, contributing to more storms.