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2006 hurricane season forecast; severe weather outbreak update

By: Dr. Jeff Masters, 1:56 PM GMT on April 04, 2006

Today marked the release of Dr. Bill Gray's latest 2006 Atlantic hurricane season forecast, and it looks like we are in for another long and busy hurricane season. The team from Colorado State University (CSU), led by Dr. Bill Gray and Philip Klotzbach, predict 17 named storms (average is 9.6), 9 hurricanes (6 is average), and 5 intense hurricanes (average is 2.3). The net activity for the season is expected to be 95% higher than normal. The entire Caribbean and U.S. coast is at above-normal risk for a strike by a major hurricane, with the U.S. East Coast (including the Florida Peninsula) at 64% risk, and the Gulf Coast at 47% risk. There is an 81% chance that at least one major hurricane will strike the U.S. coast. However, it is statistically unlikely that this coming season will have as many major hurricane U.S. landfall events as we saw in 2004-2005.

The forecasters cite three main reasons to expect a very busy season:

1) While the Atlantic Ocean is cooler than it was at this time last year, sea surface temperatures remain warmer than average, and are expected to be warmer than average during the August-October peak of hurricane season.

2) Neutral or weak La Ni�a conditions are likely to be present during August-October 2006. A weak to moderate La Ni�a event is now occurring, with trade winds in the central Pacific anomalously strong and oceanic heat content in the tropical Pacific well below normal. These features will likely keep Eastern Pacific waters from becoming anomalously warm over the next few months and ending the La Ni�a event. In addition, most forecast models call for either neutral or La Ni�a conditions to persist for the next 4-6 months. When the tropical Atlantic is warm, and neutral or La Ni�a conditions are present, Atlantic basin hurricane activity is greatly enhanced.

3) We continue to be in the positive phase of the Atlantic Multidecadal Oscillation (AMO), the decades-long cycle of natural hurricane activity.

Accuracy of last year's April forecast
How did last year's early April hurricane forecast verify? The CSU team did forecast an above-normal year, but did not foresee the extraordinary season that would ultimately unfold. They forecasted 13 named storms (average is 9.6), 7 hurricanes (6 is average), and 3 major hurricanes (2.3 is average. In reality, there were 27 named storms, 14 hurricanes, and 7 major hurricanes. However, they did mention that a continued Atlantic Ocean warming would cause them to raise their forecast numbers for their May 31 and August 5 forecasts, which is what happened.

With this forecast, Dr. Gray hands over leadership of the forecast team to Phil Klotzbach. While Gray, 76, is at the older end of the spectrum of hurricane scientists, Klotzbach, 26, is definitely at the younger end. He earned his Bachelor's degree at age 18 from Bridgewater State College in Massachusetts, then picked up a Masters degree in Atmospheric Science from Colorado State University four years later. He has been a research associate working with Bill Gray since 2001. Dr. Gray will continue to be very involved in working on these forecasts, but prefers to concentrate on researching the connection between hurricane activity and global warming. He is a vocal opponent of theories connecting recent increases in intense hurricane activity with global warming.

Severe weather outbreak of April 2-3
At least 60 tornadoes ripped through Missouri, Arkansas, Illinois, Indiana, Ohio, and Tennessee Sunday, killing 28 people. Hardest hit was northwest Tennessee, where tornadoes claimed at least 12 lives in Dyer County. A preliminary damage survey by the NWS rated this tornado a strong F3, with winds of 200 mph. The tornado that devastated Marmaduke, Arkansas, was also a strong F3, and may have ranked as a violent F4 tornado (207-260 mph winds) on the Fujita scale. More damage surveys are being performed today to determine the exact strength of this tornado. Many other tornadoes from this outbreak also ranked as F3, and the April 2 tornado outbreak may match the March 13 outbreak for number of strong tornadoes. The March 13 outbreak had 11 strong F3 tornadoes among the 84 that touched down.

The last time we had two major tornado outbreaks killing 12 or more people was in 1998. With the peak of tornado season still a month away, we have the potential for the nastiest tornado season seen in a long time--to go along with what could also be a very long and deadly hurricane season.

Jeff Masters
These are two of the hailstones that hit north central Arkansas from a quickly developed thunderstorm that went through Arkansas then through Tennessee causing more damage as it moved eastward
Prelude to April Showers
Prelude to April Showers
Just about ready to cut loose with the season's first major thunderstorm!!


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.