Quiet summers can produce a monster hurricane

The forecast for the 2009 hurricane season predicts a calmer summer than we’ve usually had in the past decade or so. But very powerful storms have formed in summers that have been otherwise very quiet.

The forecast for this summer from William Gray and Phil Klotzbach of Colorado State University predicts 11 named tropical storms forming by November 30, when hurricane season ends. Five or so of those storms are expected to strengthen into hurricanes with winds of at least 74 miles an hour. And two of the hurricanes are expected to intensify into major hurricanes with winds exceeding 110 miles an hour.

That’s slightly above the average for hurricane seasons since 1851. The National Oceanic and Atmospheric Administration’s website says that an average of nine tropical storms, five hurricanes and two major hurricanes have formed each summer for the past 158 years.

But a quick look at NOAA’s hurricane archives reveals some worrisome statistics about below-average hurricane seasons.

First, two of the three most powerful hurricanes to strike the United States formed in seasons when there was very little activity otherwise. The Labor Day Hurricane of 1935, which is still the most powerful hurricane to make landfall in the United States, formed in a summer that saw only six total tropical systems – far below the 158-year average. That’s the same number of tropical storms that formed in 1992. But 1992 also produced Hurricane Andrew, the third-most powerful hurricane at landfall.

Only Hurricane Camille, which became the second-most intense storm to make landfall in 1969, came out of a very active season. That year, 18 tropical storms formed.

There’s more unsettling info among the list of other very intense hurricanes that have made landfall in the United States.

· The summer of 1900 produced only seven tropical storms. But one of those storms became the Category 4 killer hurricane that struck Galveston, Texas and killed 6,000 or more people.
· In the summer of 1915, only six tropical storms formed. But one of them intensified into a Category 4 hurricane that struck New Orleans and Galveston.
· Only five tropical storms formed in 1919. But one of them was a Category 4 bruiser that devastated Key West and crossed the Gulf Coast to strike Texas.
· In 1928, six tropical storms formed. But among them was another infamous Category 4 killer, the so-called “Okeechobee hurricane” that came ashore at Palm Beach, roared across the Everglades, and shoved a deadly flood out of Lake Okeechobee. That storm killed perhaps 3,000 in the small lakeside towns.
· In 1960, Category 4 Hurricane Donna followed a track very similar to the Labor Day hurricane of 1935, making landfall in the Florida Keys. Only seven tropical storms formed that summer.

Powerful and deadly hurricanes also formed in seasons that saw exactly the same activity as is predicted for this year.

Hurricane Hazel, the most intense hurricane on record for North Carolina, formed in 1954. Eleven tropical storms formed that year. And Hurricane Hugo, a devastating Category 4 hurricane that made landfall near Charleston, South Carolina, formed in 1989, a summer that also saw 11 total tropical storms.

I don’t know that there’s a correlation between quiet hurricane seasons and very intense storms. But this list of murderous monsters that blew away otherwise quiet summers is a pretty clear indication that residents on the Southeast and Gulf coasts should keep a wary eye on the Atlantic for the next few months.