From the ABC 7 Weather team

Early Season Tropical Scare

May 20, 2012 - 10:32 PM
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Nothing like a quick scare from Mother Nature as the first named storm of the season forms dangerously close to the East Coast two weeks out from the start of the season. Does an early start necessarily mean a busy season ahead?

A low pressure that sat and spun over the Gulf Stream off the South Carolina Coast officially became named Tropical Storm Alberto on Saturday. The storm will start to move away from the Carolina Coast next week, eventually fading into the distance in the cooler water of the North Atlantic by the middle and latter half of the work week. Of course, Alberto formed two weeks before the official June 1 start to the Atlantic hurricane season.

Alberto

Story Image: Visible satellite imagery from Saturday, May 19th showing Tropical Storm Alberto forming off the South Carolina Coast. Courtesy of the Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison.

Prior to Alberto, Tropical Storm Aletta stirred things up in the Eastern Pacific at the beginning of the week....forming just one day shy of the start of the Eastern Pacific’s hurricane season. That storm was hundreds of miles from Mexico and the southern California Baja and posed no threat to land.

What we may think of as an “active” start to the tropics actually awakened a “tropical drought” on Earth! Believe it or not, Aletta broke what had been a 41-day streak with no tropical cyclones on the globe! According to the U.K. Met Office, this was the longest stretch without a tropical cyclone in at least 70 years!

Speaking of tropical withdrawl, a record number of days have passed between major U.S. hurricane landfalls. As a matter of fact, that record was shattered even before Christmas! 2,232 days had passed way back on December 4, 2011 since Hurricane Wilma made landfall along the Gulf Coast as a category 3 storm in 2005. Previously, it was between September 8, 1900 and October 19, 1906 where no major hurricanes made landfall in the U.S.

record

Graph courtesy of Roger Pielke, Jr., professor of environmental studies at the Center for Science and Technology Policy Research at the University of Colorado at Boulder.

So, with two tropical systems kicking things off early this year, should we be extra cautious of how the 2012 Atlantic Hurricane Season might turn out this year? Not necessarily. Let’s look back at two other seasons in recent times where an early start didn’t necessarily equal a busy season.

In 2009, the first tropical depression of the season formed in the same vicinity as Alberto on May 29th. The storm only had a life cycle of one day as a vigorous upper disturbance kicked it off into the cooler water faster than Alberto will be next week. In the 2009 season though only 9 named storms developed. This is two less than the average of 11 for a season.

In 2003, Tropical Storm Ana was the first tropical storm on record in the North Atlantic basin. It became a subtropical storm early on April 20th then later that same day transitioned to a tropical storm as microwave data suggested it had a warm core. Ana formed within 300 miles of Bermuda and then wondered east through the Atlantic, so it posed no threat to land.

An early named storm in that season (2003) lead to an active year with 16 named storms.

The major factor at stake for the upcoming 2012 season is a transition to a weak El Nino which tends to increase upper-level wind shear in the Atlantic, suppressing tropical formation a bit. Therefore, the forecast is for an average to slightly below average season for tropical storm formation. So, while we got an early start, things could level off as the season wears on and El Nino tries to make an appearance.

Of course, stay tuned to the ABC7 Weather Center and WTOP Radio for the latest on any tropical development that may head our way this summer and fall!

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