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The Secrets of Tropical Waves
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The northern
part of the Atlantic Ocean is a naughty sail area. North
of 40 degrees North averages three depressions a week
from the American coast to Europe. South of 30 degrees
North the phenomena 'tropical wave' are troubling and
Caribbean islands like Cuba, the Bahamas, the coast
of Florida and Bermuda are regularly visited by hurricanes.
Furthermore it is hard to cross the ITCZ to southern
latitudes due to its frequent calms. Dutch born journalist,
author and ocean sailor Peter Stuivenberg makes some
notes.
The bright blue painted sky atproduces fluffy
clouds thline up like parading soldiers.  The
patterns look alike converging lines on a dartboard.
One path shows the blue sky. In another path fluffs
lined up. Than, the next one, a blue sky appears again.
All lined up, all converging to a center. Maaike visions
a beauty beyond imagination. Words are improper; silence
takes over. What is the message of this unexpected thrill
of nature? |
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Maaike
watches almost in trance the heavenly gallery
of paintings, makes some photographs and writes
later on the remembrance of the past in the ships logbook.
Position 8 degrees North and 28 degrees West. Course
200 degrees true, heading for Natal in Brazil. Date
the fourth of June 2002, the official beginning of the
cyclone season. "To the south we face the doldrums
and a bit to the east on 15 degrees North and 25 degrees
West we passed the Cape Verde Islands. There is no wind.
The humidity is 96 percent. It is sweating hot and I
feel like entering a sauna. To the west I see a lot
of convection activity and the seawater temperature
shows 27 to 28 degrees Celsius".
Troubling by a lack of answers on the
Why, What, When, Who and What questions
she studies some meteorological books. Finally she finds
what she is looking for and yells: "Peter listen,
you everlasting snoring beast!
It has something to do with hurricanes!"
It refers to the converging stripes of clouds
and blue sky. I open my eyes with the knowledge that
I have to absorb some information: "Here, it is
all written". Maaike taps the book. " The
day before a tropical cyclone is born will be hot and
humid. The atmosphere is depressing. Quite unexpected
cirrus clouds will invade the hemisphere and these clouds
will converge to a point on the horizon that directs
the center of the storm".
Maaike is enthusiastic, while I still try to get the
picture. I feel in the middle of awakening. The thrill
of Maaikes voice confuses. A tropical cyclone?
No, impossible. True the ocean is steaming and true
she watches radiant cirrus. Nevertheless, it is too
early in the season. Besides that I did not intercept
meteorological warnings over the Inmarsat-C and there
does not exist a low depression cell in this area or
any another tropical disturbance. Nature is just mistaken.
That is it. I feel satisfied that there is nothing to
worry about. Even if nature should be right a stormy
problem will lie to the West of our position and we
are heading South. You see?! Point taken. No worries.
We discuss the situation and Maaike, disappointed, bakes
pancakes while I check the Inmarsat-C for the latest
meteorological warnings.
While Maaike explains why the pancakes this time are
not soaked with vegetable oil, I reread the messages
issued for Navarea ll, an area that is controlled by
Meteo-France in Toulouse (France).
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3 June 2002, 08:54:14
ITCZ along 3N 1W, 4N 10W, 5N 20W and 5N 45W.
Nothing wrong, ahh?!
3 June 2002, 21:09:22
ITCZ along 4N 2W, 2N 17W, 5N 26W and 6N 48W.
Still everything ok.
4 June 2002, 08:54:13
ITCZ along 5N 1W and 5N 40W. Low 1007 15N 12W, deepening, expected 1003 HPA(mbar) at 4 June, 18.00 UTC.
A deepening low 7 degrees North of our position and 16 degrees to the West. So what? I wait half an hour and pick up the latest forecast:
4 June 2002, 20:54:14
ITCZ along 5N 1W and 5N 40W. Tropical wave nears 26W
south of 11N moving west 10/15 knots. Low 1012 08N 15W
moving west, expected 1012 HPA 5N 27W by 5 June, 12.00
UTC.
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What?!! A low-pressure
area speeds up from the African continent to a spot
just 2 degrees to the South of our position! In addition,
2 degrees to the West a tropical wave has been born.
My goodness! Nature just fills in the two missing ingredients
for a tropical party. Within a minute the yacht points
180 degrees into another direction: Northeast. If that
low will merge with the southern top of the tropical
wave, close to the ITCZ, we are getting closer
and closer to the ideal breeding ground of a tropical
storm or even a tropical cyclone. |
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