Dateline: January 13, 2016. Georgetown, Exumas, Bahamas
Interesting Event: January 6, 2016. Black Point Settlement, Exumas, Bahamas
It took me a week to be willing to write this, but it’s time to give it a place in history and sail on.
A New Goal
We owe a lot to people who create musicals. Well, at least I owe something to lyricist/director Martin Charnin, playwright Thomas Meehan and composer Charles Strouse who created the musical ‘Annie’. They created that tune that begins with, “The sun will come out tomorrow”. It’s a good song to chant during the night. I know only the first three lines, but I said them to myself dozens of times the night of January 6th.
The weather report on January 7th begins “Parts of Bahamas experienced an interesting weather event yesterday.” All sailors know that when a meteorologist says “interesting”, it’s time to seek safe harbor and batten down the hatches. However, when they say it the day after, … well, … you know it’s already too late for preventative action.
I have spent a lot of planning-effort over the years to ensure that we could return from this cruising adventure with no interesting stories to tell about surviving storms. I now have to change that goal to “No interesting stories about surviving storms while at sea.”
The Forecast
Forecast: Wind at 6 knots out of the West. Ahhhh… if only.
All of the meteorologists got this one wrong. Check out this grib provided by the United States GFS model. At 6PM on January 6th, it shows winds of 6.6 knots from the west at our location … truly a gentle breeze. It was wrong. We’re accustom to doubling forecasted wind speeds when we do our planning. But that also wasn’t even close.
The event was not expected even as it was about to strike. Chris Parker, the notable and well respected marine weatherman, during his 5 PM forecast an hour before the ‘interesting event’, reportedly told people in the area, “Winds will be in the 20s with possible gusts to 40 around some of the stronger squalls.” That’s higher than the typical, normal forecast. But it is nothing like the 70+ knot winds created along this 200+ mile trough.
The Interesting Event
On his morning Ham/SSB broadcast, Mr. Parker the following day called it a Black Swan event. For those who may not know, “The term Black Swan originates from the (Western) belief that all swans are white because these were the only ones accounted for. However, in 1697 the Dutch explorer Willem de Vlamingh discovered black swans in Australia. This was an unexpected event in (scientific) history and profoundly changed zoology.”[1]
I’m certain that Rose will tell you about the dinghy ride from shore back to the boat as the storm began. Briefly, it was a full-on salt water shower that filled the bottom half of the dinghy and soaked our provisions. Next came boarding the boat. Then attaching and hauling up the dinghy on the davits we installed last summer. If I’d thought it through, I probably should have just gotten on the boat and forgotten about the dinghy at that moment. Given the unfortunate events that happened to many of our friends, I’m glad we got it up.
This is the screen I monitored during the storm. Our boat track is on the left. Those arcs have foci of our anchor location. The wind speed and direction is on the right. Max caught as a picture: 78.1 knots. That’s way too much wind.
The wind speed continued to climb. The rain came. The foul weather gear came out. And I got to have my first experience with pending seasickness while at anchor. We recorded a top wind speed of 78.1 knots. That’s hurricane speed but this wasn’t a cyclonic hurricane.
The boat swept back and forth as shown by the black arc blob of our boat track on the chart. Like Hansel and Gretel’s breadcrumbs, this track is a recording of our boat location every 30 seconds. I’d started tracking the night before when we’d had an ‘un-interesting’ event that brought wind speeds into the 50 knot range. The very good news is that the track swept back and forth during all of these events and the boat did not drag.
The other good news is that there were four other sailboats in the anchorage with us and no one was lined up to drag into anyone. So, rather than having to be at the helm to steer the boat around potential dragging boats, I was able to lay on the floor and monitor our boats position electronically and listen for the anchor watch alarm which fortunately never sounded.
Rose caught Rob ‘resting’ on the floor, arms pushing from each side to keep his body from rolling. Rob’s brain is singing songs from Annie while repeating over and over his step-by-step plan of action should the boat begin to drag.
Without the electronics, it would have been very difficult to monitor our position. It was dark. The rain made it difficult to see any distance. And even if you could see, the lights were knocked out on shore for most of the storm. Sometimes we could see anchor lights of two of the other boats and sometimes we could see car lights from shore. But, since all of those things can move, they’re not good reference points.
Damages
I don’t believe anyone knows the total damage, but there are reports of several boats driven onto rocky shores and serious damage from boats dragging into each other. One boat was ‘harpooned’ by the bow sprint and pulpit of another in Georgetown. They required a saw to cut the metal pulpit to separate them the next day. Another boat started to drag, caught another boat’s chain with its anchor. By the time the first boat finished dragging they had collected five boats together in total. About a dozen dinghies that we know of were lost or flipped. And we only have heard reports from a small fraction of the storm zone. Unbelievably, we’ve heard of no loss of life or serious injury.
Here’s a few examples of damages from friends close to us.
Neko
Our good friends, Pete and Mary on s/v Neko have quite a tale to tell. Read their story here. In summary, Pete was driving his boat while on anchor to avoid other boats that were dragging by. Their dinghy flipped, submerging the engine in salt water. But that’s not all. In the middle of all of the chaos, a line from the dinghy wrapped around the starboard prop of their catamaran, stopping the engine. Pete jumped into the water to free it. He was successful and able to return to his position at the helm. I feel very fortunate that our story is much less interesting. They’ve been working diligently to get the outboard engine running again, but so far, it appears to be terminal.
Sasha and Odin
Where we were anchored at Black Point Settlement, four fellow cruisers from two sailboats, s/v Sasha and s/v Odin, were just minutes behind us in leaving the restaurant to return to their boats. They were unable to do so until two and a half hours later after the main portion of the storm had passed. They had planned on returning to their boats before dark and had not turned on any lights. As darkness fell, they were able to sit safely on shore, but they were looking out at a very dark bay wondering if they would have anything left to which they could return. I’m sure it felt worse when the power on shore got knocked out and they were completely surrounded by darkness.
As they waited it out, their dinghies were tied at the dock. Unfortunately, the waves and surge from the storm was so large that it pushed their dinghies up to and under the dock. That destroyed one of the boats of one of the dinghies and the engine on the other. After the storm, they put the working motor on the working dinghy to get back to where they had left their boats. Fortunately, the big boats were still there.
Wayward Sun
Amazingly, they had no damage. But read their story about dragging here: http://www.sailblogs.com/member/wayward_sun. See their article, “The Perfect Storm – Bahamas Style”. It’s amazing.
R&R Kedger
We were very lucky. We received only insignificant damage.
Our bridle uses two anchor lines. One of them broke and shred. Fortunately, the other held. How? I have no idea. But it did. We had out 260’ of chain. It was pulled completely straight all the way back to the anchor. For reference, holding here in the Bahamas is good. People rarely put out more than 100’. In fact, a few weeks back, I had a Charter Captain laughing at me for my ‘excessive’ use of chain. He said that 50’ was plenty and even 100’ was excessive. He may be laughing, but today I’m smiling.
When we decided to head south and pulled up the chain 36 hours after the storm, the last 80 feet was buried under the sand and the anchor was also nowhere to be seen having burrowed itself down. That’s a good thing. With patience, we were able to pull it up.
We tore a UV cover that provides shade in our cockpit. Nothing that a little time with a sewing machine in a calm anchorage could not repair.
As the boat rolled from side to side, water came up through the open thru-hulls of the bathroom sinks and spilled onto the floor. But again, no damage.
Oh, and naturally, we ‘rearranged’ the items in the interior of our boat. But nothing broke inside.
We were extremely fortunate. Much more fortunate than many of our friends. There are many, many stories like those above repeated over and over along this section of the Bahamas. When you meet new cruisers this week, it’s like the John F. Kennedy assassination. “Where were you when…?”
Local Support
During the storm, the people at Black Point Settlement came to the shoreline with their cars and swept the anchorage with their headlights trying to provide some light to see what was going on. They also called on the VHF radio asking if anyone needed help. We know it was unsettling to them that no one answered their hail. But everyone on their boat was very busy doing everything they could to ensure that they didn’t need any help.
Local Boats
All of sailboats held fast in our anchorage at Black Point. But several of the locals’ boats ended up on shore and one flipped and sank. Being smaller boats and in very shallow water, there were no significant damage except possibly to the motor of the boat that flipped. We saw several people out with flashlights in the middle of the storm. They were moving boats to which they could get to whatever protection they could find. We learned later that several of those boats were owned by absent owners but the locals risked their lives to preserve that property. I’m not certain I would be so brave. Actually, now that I reflect on it, having ridden out the storm on a ‘big’ 46 foot boat, I’m pretty positive I would not.
Bottom Line
Underway two days later. How could this possibly be the same place? Swells: one to two … inches?
We were lucky. Some of that ‘luck’ we had ‘made’ through prior preparation. But we were not prepared for this interesting event. No one was. It was a Black Swan. The good news for us, Annie was right. The sun did come out the next day.
Bonus: Chris Parker’s ‘Day After’ Discussion:
This came out the next morning. I thought you might find it interesting due to the unusual nature of this weather event. The places he mentions, Staniel Cay, Cambridge Cay, Great Exumas, etc., are all places we have recently visited or passed in the last few weeks. We were at Black Point Settlement, about 7 miles south of Staniel Cay when the storm hit. Here’s the discussion:
SYNOPSIS:
Parts of Bahamas experienced an interesting weather event yesterday.
StanielCay reported (confirmed independently from multiple sources) W-NW@45-50 with gusts at least into the 60s from about 6pm-7:30pm EST.
CambridgeCay (about 20mi N of StanielCay) recorded a gust which registered 106.2k on an anemometer. Even if not precisely correct, there were almost certainly Hurricane Force wind gusts.
Most reports were a bit less…mostly W-NW winds in 30-40k range, gusting 50k+ persisting about an hour+/- generally between the hours of 5pm-8pm in RoyalIsland & RockSound Eluthera, various locations near GreatExuma/LittleExuma.
Vessel overnight near 24N/73W reported an hour of S-W@35.
Our forecasts the past couple days were for squalls to 40-50k generally predicted for Wed6 afternoon-evening in C Bahamas. In the 1pm Wed6 forecast I refined that to say squall risk would end in most of C Bahamas Wed6 evening, and that areas which had been seeing mild wind S of TROF Wed6 still had chance of squalls until FRONT passed and we saw steadier WNW wind establish N of TROF in the evening.
While our forecasts missed the intensity of squalls (some of which were 50-70k, possibly a bit higher especially in gusts…versus the 40-50k we predicted for this event over the previous several days)…did capture the timing, with activity not ending in C Bahamas until sometime in the evening / I think activity weakened some as it swept thru SE Bahamas later in the evening and overnight.
In 13 years, I don’t think I’ve seen an event like this in the Bahamas. Although there was some fairly strong convection (Lifted Index -4 to -6, and CAPE 1000 to just under 2000), there were no very tall (cold) cloud tops. Infrared Satellite cloud top temps were only about -20C TO -30C, suggesting cloud tops probably in the range of 20,000′ to 25,000′ or maybe a bit higher. In order to generate observed winds, I would expect cloud top temps below -50C, and cloud tops well above 40,000′.
UofWisc analysis shows a large pool of cold air aloft near & W of the squall event.
Yesterday we discussed the 10am Wed6 ASCAT: TROF lies from 20mi S of Nassau-N BightAndros-N side of CaySalBk-Veradero, with SW-WSW@20-45 (sustained) within 120mi SE of TROF / NE-ENE@25-45 (sustained) within 120mi NW of TROF. Lightning strike data shows a band of intense lightning was along TROF.
So here’s my ANALYSIS: I believe the same TROF/convergence persisted from before 10am Wed6 morning until well after 10pm Wed6 evening, (at 10pm Wed6 it was along 25N/73W-Acklins-21N/75W, with one of the most intense bands of lightning strikes I’ve seen)…and it is this line that swept thru much of C Bahamas just before Sunset Wed6.
If we pick a point along TROF W of Andros (24N/80W) at 10am…and follow TROF E thru Bahamas (to 24N/73W) at 10pm, it covered about 400 miles in 12 hours, moving about 35k. As TROF began rotating around the LO which was developing just NE of Eluthera, the S portion of TROF/convergence moved more rapidly than the N part (closer to the developing LO)…and TROF/convergence gradually became more NNE-to-SSW-oriented. But throughout the day our TROF/convergence spanned about 300-400 miles from NE-to-SW (or NNE-to-SSW).
One unusual wind event which can persist for a long interval of time and move across many hundreds of miles, and lies along an axis hundreds of miles long is a Derecho.
Here’s a pretty good discussion of Derecho:
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
I can’t be sure what we saw was a Derecho, but it was certainly (thankfully) a rare event.
[1] http://blackswanevents.org/?page_id=26
