50 November 2017When he was 20, Mark A Michaelsen, a meteorologist and
lifelong sailor, was caught in a ferocious storm that wasn’t
forecast while sailing his catamaran off Malibu. It almost
cost him his life. He vowed never to be caught out at sea
again and began the study of microclimate forecasting.
His company WxRouting now provides weather routing for
professional racing teams and for yacht deliveries from the
Caribbean prior to the start of the hurricane season.n the humid Mississippi night air, I stood in front
of the nose of the Hercules C130 as the first two
engines started. The 53rd Weather Reconnaissance
Squadron was ready for action.
We boarded the plane where our dropsonde operator
(who releases the digital transponders that are dropped
from the plane to measure the air mass below), Master
Sergeant Bussil, ran through the safety checks and handed
me a set of ear plugs.
“You wanna make sure you wear these all the time,” he
said. “We got four big fans turnin’ and a burnin’ out there
and 110 decibels in here.”
We strapped ourselves in. Bizarrely, I felt at home. From
the basic canvas, cushionless seats, to the utilitarian inner
skin and frames of the plane’s structure, it felt much like
the inside of an offshore racing boat.
At 0111 we thundered down the 7,000ft runway and
rotated into the night sky. Shortly after take off I was
invited up to the flight deck. Our mission was to make
contact with Hurricane Irene, measure her characteristics
and mark her centre.
With the storm capable of inflicting damage along
America’s eastern seaboard, it was important to let the
National Hurricane Center know what was developing and
quickly. The NHC needed to know whether to alter Irene’sSaharan air to the north. The massive annular cyclone was
nearly bulletproof from the effects of shear which would,
in most years, have at least reduced the storm’s intensity.
Then the almost unthinkable happened: yet another
tropical cyclone developed. Maria formed to the east of
the Lesser Antilles on 16 September, south of Irma’s track.
Warm waters were abundant with no dry air that might
inhibit her intensification, and almost no shear.
On 18 September Maria morphed into a catastrophic
Category 5 hurricane and began a slow turn to the
west-north-west. It ravaged Dominica with 175mph winds.
Crossing the island caused slight weakening and the
storm was downgraded to Category 4 status. But back out
over hospitable waters Maria ramped back up to a 175mph
monster and a recon mission over the island of Western St
Croix found a central pressure of 908mb, lower even than
Irma the previous week.
Just how unusual were these two devastating storms so
close together, both in geography and in time? The answer
is highly. This was the first time in ten years that two
Category 5 systems were generated out of the Atlantic
basin in the same season, let alone just weeks apart. The
regions hit were far enough apart that the cold water wake
left in Irma’s path did little if anything to reduce Maria’s
intensity or speed of development. That’s more unlucky
than anything else. Puerto Rico absorbed a devastating
direct hit.
What can we expect from the rest of this hurricane
season? The answer is that we don’t really know.
Statistically the secondary peak of hurricane season falls
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