Storm-watchers this week were tracking a disturbance just off
the coast of Africa that looks like it has the potential to develop
into a tropical storm in the next few days. Dr. Jeff Masters'
Wunderblog has the story
The possible/maybe/someday storm isn't news, however. What is
news is that so far, there's no news in the 2009 hurricane season.
A full month into the official season, no named storm has appeared
in the Atlantic region. Asks a story by Willie Drye in National
Geographic magazine, "Hurricane
Season 2009: Where Are All the Storms?"
As the National Geographic story mentions, there seem to be some
objective forces at work that would tend to limit the incidence of
tropical storm formation. An "El Nino" condition in the southern
Pacific ocean in particular has pulled the Northern Hemisphere's
jet stream south over the Atlantic basin. There, the jet stream
sets up "wind shear" conditions in the upper atmosphere that can
clip the tops off of circulating wind patterns, preventing the
convective currents that engender strong storms.
But a quiet June and July don't necessarily portend a quiet
fall. The National Hurricane Center graphic below shows the
historic pattern of storm incidence through the entire storm
season. As the graph indicates, most storms occur between August
and October, with the peak occurring during mid-September.
The Miami Herald cites the example of 2004, when the first named
storm didn't crank up until the last day of July — but
Florida ended up getting pounded by Hurricanes Charlie, Frances,
Ivan, and Jeanne ("Hurricane
season's been a breeze, but don't breathe easy yet
," by Curtis
Jeff Masters notes, "The first named storm of the year didn't
occur until August in ten of the past fifty years (20%). Only two
of these ten seasons ended up with more hurricanes than average
(seven or greater)." Then, he points out, there's 1992 — a
year that had one, un-named subtropical storm, followed finally by
the first named storm of the year — Hurricane Andrew, which
shattered the previous record for hurricane dollar damage.
In view of current conditions and the quiet early summer,
government officials have scaled back their predictions for the
season. The National Oceanic and Atmospheric Administration (NOAA)
Climate Prediction Center (CPC)
now gives 70% odds that the
Atlantic will see 7 to 11 named storms, with 3 to 6 of those being
hurricanes and 1 or 2 being major hurricanes. That's down from a
May forecast of 9 to 14 named storms, 4 to 7 hurricanes, and 1 to 3
But as NOAA forecaster Gerry Bell said, "It only takes one
strike to make it a bad year."