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| Another boat barely visable during the storm |
In the morning we were all done with the rolling in the
anchorage. A few boats started to make
their way back to the inside anchorage at Normans Cay. Another boat had gone first and reported back
that, while it was still quite choppy in the anchorage, there wasn’t a
swell. The chop continued until early
afternoon and then everything settled to a quiet and very calm state. It was beautiful. Kerry went to investigate the north beaches
and came back to report that it was gorgeous.
He insisted that we all get ready to head there. We then noticed a large black sky approaching
from the north west. We paused in our
decision to leave the boat to give us a chance to assess this looming
presence. There was no weather
forecasted after yesterday’s storm. We
were a little puzzled. Within 10 minutes
of deciding to wait the storm hit hard.
The wind was between 30-40 knots in the anchorage with 3 foot rolling waves. We had anchored in the shallow area of the
anchorage so, luckily, there was no one in front of us that could drag on us. Rain was coming down hard as well. So much so that we lost sight of all other
boats in the anchorage. At this point we
were feeling secure in our anchor and enjoyed the force of nature that was
impacting us. Connor and I were
collecting water in our little bucket for laundry. During yesterday’s storm we had set up a
collection for fresh rainwater to help us stretch our water supply out. I was, at first, quite pleased at all of the
water we were collecting. We
systematically transferred our little buckets into the larger container. As the rain, plummeted down…I began to
realize that we are going to exceed our need for fresh water. Connor and I had a little water fight and
enjoyed the rain – I was also trying to keep our spirits light in the
situation. Then, as the rain kept coming
and the wind was sustained, the boat was rocking. Our prized bucket of water was sloshing back
and forth and, in the name of safety…I ended up tossing all of our water
overboard. We needed to clear the deck
and hunker down. The wind subsided for
about 30 minutes and we thought that was it.
Without warning and with clear sky, the wind picked up again. Other boats were reporting 50-60 knot winds
and some even reported 106 knots further south.
This had now been going on for several hours. The sun was beginning to set and we knew that
the night would bring a more serious tone.
All boats in the anchorage were now engines one and running lights. We were all trying to keep our anchor. There were a few boats in the anchorage that
were dragging onto other boats. One boat
lost anchor and were just a boat length from another boat we met until his
second anchor caught hold. There was one
boat in the anchorage that dropped and picked up anchor throughout the entire
storm. They must have been exhausted and
we felt form them as they struggled to keep control. Another boat was taking in water through all
their hatches. What a mess that would
have been to dry up after. Our boat was
secure, solid and held in the wind. We
were all safe. The storm finally
subsided completely around 11pm. Running
lights were starting to be turned off and tired sailors were finally getting
rest. It caught everyone off guard.
Chris Parker (weather) gave a report of the event in our daily weather
report. It was called a Derecho. Here is the report for those interested in
weather.
http://www.spc.noaa.gov/misc/AbtDerechos/derechofacts.htm
A Derecho is essentially "a self-sustaining linearly-organized storm". A Derecho often starts as a series of outflow boundaries/gust fronts extending from squalls/T-strms, advancing ahead of a pool of cold air aloft. Over time, these outflow boundaries/gust fronts can merge into a long line, and be self-sustaining.
To meet the definition of a Derecho, the wind event must extend more than 240mi (from end-to-end), include wind gusts of at least 50k, and have several, well-separated 65k gusts. Winds are "straight line" in nature (rather than circular like in a tornado or hurricane), and typically blow perpendicular to the motion of the Derecho. Winds are supported not by the collapse of towering cumulonimbus clouds (as re typical squalls/T-strms), but rather by the inflow of warm air from ahead of the Derecho inward & upward into the pool of cold air aloft behind the Derecho...and fast-moving down-rushing air from the cold pool sustains the progressive gust front with the Derecho.
Derechos are thought to occur less often in moist environments, where inhibiting factors include abundant low-level clouds and less-cool air aloft. Derechos typically form on the equatorial side of the JetStream, with strong wind-shear. The leading edge of a Derecho is often marked by some sort of a shelf cloud.
Our event seems to meet all these criteria...we saw an event:
--over 300mi from end-to-end, and persisted along a path over 400 miles
--widespread wind gusts 50k+ along most of the line, with well-separated areas of 65k+
--straight-line winds, with reports of mostly uniform W-NW wind direction (perpendicular to the squall line)
--pool of cold air aloft located behind the squall line
--relatively-dry (cloud-free) conditions ahead of the squall line (at least in some areas)
--some sort of a shelf cloud was clearly visible in many of the photos I saw taken in Georgetown just before the event
--this occurred along the SE side of sub-Tropical JetStream, in an environment of strong wind shear
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