Warming seas brew stormy season

Another active tropical storm and hurricane season may be just around the meteorological corner. Many forecasters, including myself, are predicting above normal numbers of named storms in Atlantic and Caribbean waters between June 1 and Nov. 30.

Sea-surface temperatures are warming up in these regions, and there currently is no El Nino pattern in the equatorial waters west of South America to alter the upper-level jet stream and decrease tropical storm formation.

With 14 storms, the 2005 tropical storm and hurricane season was the most active in recorded history. Named storms in the Atlantic and Caribbean waters started to be logged in 1851. Up until 2005, the most active hurricane season was in 1933, with 21 storms reaching tropical storm status or greater.

In 1995, there were 19 named storms. Two years ago, we saw a record 28 named storms. Also, for the first time, Greek letters were implemented to name storms.

Of the 14 storms during the 2005 season, seven were considered to be major.

The previous record was 12 hurricanes in 1969, the costliest season ever in terms of damage caused by storms. The overall average is 10 named storms per season with six becoming hurricanes.

Only three Category 5 storms have hit the U.S. mainland over the last 100 years. These were Camille in 1969, Andrew in 1992 and the Labor Day storm (no name) of 1935. In 2005, hurricanes Katrina, Rita and Wilma did reach Category 5 status, but weakened before they made landfall.

The effect of warmer sea-surface temperatures plays a role on hurricane development. According to a recent Time magazine article, between the 1920s and 1970, ocean waters were warmer and hurricane activity was high.

However, as sea-surface temperatures cooled in the 1970s, 1980s and early 1990s, there was a decrease in tropical storms and hurricanes. Since 1995, ocean waters have turned warmer than normal, again leading to above average hurricane seasons, except during the big El Nino years of 1997 and 2002 and 2006.

Last year in 2006, there were only 10 named tropical storms and five hurricanes.

William Gray, a longtime hurricane expert, expects 17 named storms with nine becoming hurricanes during the 2007 season. Out of those nine, five are likely to become major hurricanes, reaching at least a Category 3 status.

I believe that the upcoming 2007 tropical storm and hurricane season will see more named storms than last year, but far from the record number in 2005. I also expect to see approximately 15 to 18 named storms with six to eight becoming hurricanes.

Here in the Inland Northwest, we don’t have to worry about hurricane activity. But, if a major hurricane were to hit in the Gulf of Mexico, it’s quite possible that we would see another jump in oil and gasoline prices, similar to what happened in 2005.

As far as our local weather patterns are concerned, despite occasional showers, most of the rest of April should be a bit milder and drier than usual.

There should be at least eight more sunny days between now and April 30. Some afternoon temperatures will likely soar into the balmy mid-70s later in the period, thanks to a stubborn ridge of high pressure over the Inland Northwest.

The ridge should weaken, though, by early May. Moderate to heavy rains will be likely at times across the Inland Northwest, along with increased thunderstorm activity, into the second week of June.

Then, by mid to late June, like last year, the rains should subside and temperatures will likely rise back to above-normal levels for the late spring/early summer period.