The Annual Hurricane Prediction

It's going to be another busy, above average hurricane season, meteorologists say

After a nightmarish 2017 hurricane season featuring monsters such as Harvey, Irma and Maria, many in the U.S. are hoping for a quieter year. A top forecasting group says that won't be the case.

Meteorologist Phil Klotzbach and other experts from Colorado State University — regarded as the nation's top seasonal hurricane forecasters — predict 14 named tropical storms, of which seven will become hurricanes. Both numbers are above the average of 12 and six, respectively.

A tropical storm becomes a hurricane when its wind speed reaches 74 mph.

Of the seven predicted hurricanes, three are expected to spin into major hurricanes — category 3, 4 or 5 — with sustained wind speeds of 111 mph or greater. The group said there's a slightly above-average chance for major hurricanes to make landfall along the U.S. coastline. Klotzbach put the chance of a major hurricane strike at 63%.

The Atlantic hurricane season runs from June 1 to Nov. 30, though storms sometimes form outside those dates.

Colorado State's prediction in 2017 was low: Last year, the team predicted 11 tropical storms would form, of which 4 would become hurricanes. In all, 17 tropical storms developed and 10 strengthened into hurricanes.

Yes, but just how good are those predictions. Shockingly, the article actually presents the predicted vs. actual hurricanes since 2000  However, I found this slightly longer record:

Bottom numbers indicate how many hurricanes were forecast for each year.
Red icons above the line indicate how many more hurricanes occurred than predicted.
Blue icons below the line indicate how many fewer hurricanes occurred than predicted.

You can add 2017 in your head from the first source, 4 predicted, 9 actual.

Without extracting the data off the chart and doing real math and statistics, it looks like the average prediction is wrong by about 3 hurricanes, and when the actual forecast is 3-9 hurricanes, but the average prediction is not terribly biased (that is consistently over-predicting or under-predicting hurricanes.

One of the major determining factors in hurricane forecasting is whether the U.S. is in an El Niño or La Niña climate pattern, he said.

El Niño is a natural warming of tropical Pacific Ocean water, which tends to suppress the development of Atlantic hurricanes. Its opposite, La Niña, marked by cooler ocean water, tends to increase hurricanes in the Atlantic.

Klotzbach said we're now in a weak La Niña event, which appears likely to diminish over the next several months. At this point, a significant El Niño is not anticipated for the summer or fall, he added.

I've seen predictions for an El Niño event forming this year: Will There Be A 2018/19 El Niño? Looks like one may be forming right now. If it happens, it might be too late to affect this hurricane season much.