Wednesday, June 01, 2011

A dry June and the start of hurricane season

Just when out weather is starting to dry out after more than 14 inches or rain since April 1st, the start of hurricane season is now taking center stage with the talk of an above year for tropical storms and hurricanes. 

Why the increase this year?

Let look at the total amount of available moisture in the atmosphere in the tropics courtesy of Dr. Jeff Masters at the

Now take a look at the water temperatures in the same spots compared to the averages and last year. Notice the warm pockets in the Caribbean, Gulf of Mexico and along the eastern US coast. Last year, most of the warmth was located in the central Atlantic.  This year, its all over the place. Click on each image to make it larger.

Last year in late May

Late this May

The latest satellite image shows clusters of storms in these spots as of May 31st.  So look for the first tropical storms to develop in these spots in June and July.

The major hurricanes that make landfall in the US originate in the locations that are the warmest this year. We will need to watch these areas VERY carefully in the months ahead.

La Nina, the temporary cooling trend in the Pacific Ocean is weakening to neutral conditions this summer and early fall.  This allows the winds aloft to weaken allowing tropical storms to develop further without being sheared apart. 

These factors are why the National Hurricane Center is calling for an active hurricane season. Here is their link with the details

One other thing to remember in the next several years:

We are in a period of higher hurricane activity mostly due to the Atlantic Ocean entering a "warm mode" in the mid 1990s.  These warm modes typically last 25-35 years.  We can trace these warm/cold modes back into the 1800s.  These warm modes are directly related to higher hurricane activity.  We can expect a greater than normal number of hurricanes that make landfall in the US in these "warm modes".  This also increases the likelihood of a hurricane making landfall in New England. This is a REAL threat; one that's been a reality in the past and one--according to many forecasters-- will likely occur in the next 5 to 10 years.

If you vacation along the east coast in late August or early September, stay updated on the tropics. The right side of the following graph might be our reality in the future.