We live on a dynamic, restless planet.
On any given day, there is usually a cyclone, tropical depression, or
extra-tropical storm brewing somewhere on the Earth. But for a brief moment
this week, the skies over all of the oceans were relatively calm.
The image above is a composite of
fourteen polar satellite passes, or swaths, stitched together from September 8,
2013. The natural-color images were acquired by the Visible Infrared Imaging
Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership
(Suomi NPP) satellite.
At the time of those near-midday
passes, there were no hurricanes, cyclones, or tropical storms in the Atlantic,
Pacific, or Indian Ocean basins—a relatively rare occurrence at the height of the
hurricane/cyclone season in the northern hemisphere. There was plenty of cloud
cover, of course, and smaller storm systems. In the eastern Pacific, remnants
of tropical storm Lorena were breaking up near the Baja Peninsula. In the
eastern Atlantic, the pieces of tropical depression #9 were starting to gather
near the islands of Cape Verde; by the next day, tropical storm Humberto would
form.
In its May and August 2013 outlooks,
the National Hurricane Center forecasted a 70 percent chance of a “more active
than normal” season, with 13 to 20 named storms and 7 to 11 hurricanes. A
“normal” season typically produces 12 named storms, including 6 hurricanes.
Through the second week of September (the midpoint of the Atlantic hurricane
season), there have been nine named storms—keeping pace with predictions—but
just one that reached hurricane strength.
The one hurricane, Humberto, was
observed on September 11, 2013, by the Moderate Resolution Imaging
Spectroradiometer (MODIS) on NASA’s Terra satellite. Humberto became a
hurricane around 5 a.m. on September 11, just hours short of becoming the
latest date for the first hurricane in a season. By September 13, Humberto had
weakened to a tropical storm. Forecasts were calling for the northwest-moving
storm to reach hurricane status again by September 19, when it will be in the
middle of the Atlantic Ocean and well away from land.The slow start does not
necessarily mean the hurricane season will be mild. “What happens in the early
part of the season is generally not a good predictor of the second half of the
season, which is when the majority of hurricanes and major hurricanes form,”
said Gerry Bell, lead seasonal hurricane forecaster for the National Oceanic
and Atmospheric Administration. “NOAA’s outlooks are for the season as a whole,
and not for any particular month during the season.”
In the period from 1981 to 2010, the
Atlantic basin has averaged six hurricanes per year, and 61 percent of all
Atlantic named storms form from September through November. “The 2013 hurricane
season was billed as a stud, but up through mid-September, it has been a dud,”
said Bill Patzert, climatologist at NASA’s Jet Propulsion Laboratory. “Stay
vigilant, though. Hurricanes could be late and active. Remember hurricane Sandy
in late October last year.”
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