Experts Upgrade Atlantic Hurricane Forecast

Dan Shapley / News Editor

The country's top hurricane forecaster told reporters this morning that there is an even greater likelihood than previously thought that the Atlantic will see an active hurricane season. The chance of having an active hurricane season has gone up from 75% -- as estimated in May -- to 85% today, according to Gerry Bell, lead seasonal hurricane forecaster at the Climate Prediction Center, part of the National Oceanographic and Atmospheric Administration.

The public perception is that it has been a mild season so far. Not so. For one thing, the August-to-October period is the peak season for hurricanes. And two, the three named storms so far noted is actually more than the two that typically develop in June and July. The apparent dearth of storms so far this season "has no relevance," Bell said. (For more on this, see Chris Mooney's blog, The Storm Pundit.)

However, the National Oceanographic and Atmospheric Administration now expects slightly fewer named storms and hurricanes to form, based on slightly lower sea-surface temperatures and other factors. The latest forecast calls for:

• 13-16 named storms
• 7-9 hurricanes
• 3-5 major hurricanes, rated Category 3 or higher

In May, NOAA expected as many as 17 named storms and 10 hurricanes. A "normal" season -- based on longterm averages -- is 11 named storms, six hurricanes, and two major hurricanes.

It's impossible to predict how many storms might make landfall, Bell said, but past seasons with similar conditions have resulted in 2-4 storms hitting the coastal United States. (Watch The Daily Green's video about the likelihood of a hurricane striking New York City here.) There are three conditions contributing to the new forecast:

• Longterm patterns in hurricane activity that have resulted in 9 above-average hurricane seasons in the past 12 years. "We're in an active hurricane period," Bell said, noting that past active periods have lasted 25-40 years.
• La Nina-like conditions -- lower-than-normal temperatures -- in the Pacific, which influence ocean and air currents. Since the active period started in 1995, the only three years that have not had over-active seasons have had opposite -- El Nino -- conditions, Bell said. Forecasters are already seeing signs of La Nina-like wind patterns that favor tropical storm formation, and expect a better than 50% chance that La Nina conditions will develop.
• Overall warmer temperatures in the Atlantic Ocean and Caribbean Sea, though temperatures are slightly lower than in May. The overall warmer temperatures give energy and moisture to storms, but the slightly lower temperatures recorded since May caused NOAA to downgrade slightly the number of storms it expects to form.

Last year's forecast at this time of year was similar, but the prediction proved inaccurate, as few storms formed. That year, a rapidly and unexpected El Nino pattern -- warmer than usual conditions -- in the Pacific changed conditions, Bell said. Forecasters see no evidence that El Nino conditions might form this year.

He warned coastal communities to resist the sense of complacency that resulted from last year's inaccurate forecast and this year's relatively calm conditions to date. Preparing now can prevent misery and devastation when a storm bears down. Read the forecast here.

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