2006 Tropical Storm
Season Now Below
Normal
(21
August 2006)
What a difference a year makes. After
the record-breaking 2005 Atlantic hurricane season, the 2006 season is now below normal.
As of yesterday (20 August) three tropical storms will have formed in the
Atlantic in an "average" year, which is the same number that have
formed this year so far. Because of multi-year averaging, that means that today
(August 21) slightly more than three storms would have formed, making this year
(statistically speaking) just below normal.
In the hurricane category, this year is decidedly below normal, with no
hurricanes so far, while by this date 1.5 hurricanes have formed in the average
of years 1944 though 2005.
Reason for the Season?: Cooler Sea Surface Temperatures
Part of the reason for the slow season is that tropical western Atlantic sea
surface temperatures (SSTs) are running about normal, if not slightly below
normal (see graphic below, which shows SST departures from normal).
In
contrast, at the same time last year SSTs in the same region were running well above
normal.
The cooler SSTs in the Atlantic are not an isolated anomaly. In a research
paper being published next month in Geophysical Research Letters, scientists
will show that between 2003 and 2005, globally averaged temperatures in the
upper ocean cooled rather dramatically, effectively erasing 20% of the warming
that occurred over the previous 48 years.
Global Warming?
The
slow hurricane season and the cooling sea surface temperatures might be
somewhat surprising to the public. Media reports over the last year have
suggested that, since global warming will only get worse, and last year's
hurricane activity was supposedly due to global warming, this season might well
be as bad as last season. But it appears that Mother Nature might have other plans.
The Rest of the Hurricane Season
With
only 3 named storms compared to 9 on this date last year, it is nearly
impossible at this late date to have a season anywhere near as busy as last
season, which totaled 27 by the end of the year. The most recent prediction
from the National Weather Service (see first graphic, above) is for there to be
12 to 15 named storms by December -- only half of last year's total. It now
looks like that prediction might be too generous.
While it is still possible for this hurricane season to end up above normal in
activity and reach that forecast, each day that passes without so much as a
tropical 'depression' makes that target less and less likely.
