Monday, September 27, 2010

Forecasts, thermals, and inversions

September has been great this years - 12 days of sailing, 10 of them in nice strong winds, so far. That's not bad for someone who (a) should work 40-hour weeks, and (b) has to drive about an hour to get to a nice sailing site.

The forecast for last Saturday looked great - more than 20 mph for the entire day, warm temps, and sun. Last Wednesday, we had windsurfed in Fogland - that turned out to be the wrong choice, since winds were just so-so, while Kalmus had great, steady winds above 30 for the entire afternoon. No big surprise here - in late summer, Kalmus often gets thermals which boost the winds 5-10 miles higher than the forecast (and also higher than other sites on the Cape).

Saturday was just 3 days later, the setup was very similar, so I was really hoping for upper twenties in Kalmus. We decided to book a hotel room so we could start early, and sail until we dropped, without having to drive back to Boston. Since the wind was supposed to pick up early on Saturday, I even thought about going for a 12-hour GPS marathon session. Alas, the wind did not play along.

On Friday afternoon, after visiting the local windsurf stores to pick up warm gear for the fall and winter, the wind readings were much better for West Dennis than for Kalmus, so we windsurfed in West Dennis. I had not sailed there in ages, and Nina had never sailed there. I loved it - the wind was just perfect for my favorite 7.0, the swell nice and gentle, perfect for working on chop hops, and plenty of space for nice long runs. We had dawdled a bit getting there, so we sailed only a couple of hours until the fog got too dense, and the wind line moved out further onto the water.

Saturday morning, I got up at 6, only to see that we wind was not as good as promised. Nevertheless, we had an early breakfast and headed to Kalmus. As we arrived, a couple of guys were out having fun, but then, the long wind tease began. From 10 am to 3 pm, even the gusts refused to go above 20, and averages often sank below 15. Every now and then, a few puffs came through that almost had me planing on my 7.0. I was not the only one attracted by the forecast - a lot of the ABK campers showed, including Ed, Mike, Jonathen, Peter, Cliff, Jeff, Graham, and Martin. When I finally gave up and rigged my 8.5 m V8 to have some fun, the wind finally picked up. So instead of much fun, I was fighting for 20 minutes, before I went back in and got the 7.0.

The wind stayed nice for a couple of hours. The chop was not so nice, though, so I tacked up to the wall that protects Kalmus and went for some flat water speed sailing. With gusts still below 25, I did not get any great speed, but I still had a blast until the wind decided to take another break, and I headed back downwind without getting the great downwind speed runs I had hoped for. Still, first time I made it up to the wall, and I had the entire little harbor to myself. Without the expectations of 12 hours of great wind, that would have been a rather decent day.

So - what had happened? Apparently, we had a mixing problem, also called an inversion. The water is starting to cool down, the winds coming in were very warm, so they did not mix down well. This was worst in Kalmus - West Dennis, Chapin, and even Ned's Point had better winds, unusual for SW. I think this time, the fact that Lewis Bay is exactly in the wind direction increased the mixing problems, instead of helping the wind to be nice and steady. What a difference three days and a few degrees can make.

We had seen some indications of mixing issues the day before in West Dennis, when the wind line moved away from the shore as it got later. Fogland had had similar issues last Wednesday, with gusty & weak winds in the cove, but better winds on the south side and on the far side of the river.

The forecast for Sunday was not great - NE near 20 mph for Chapin and Duxbury for a brief period, below 20 most of the day. Of course, computer models and metereologists often under-predict the N and NE winds in Duxbury, so we stopped by there on the way home. At noon, the wind did not look convincing - some kiters on the ocean side had a hard time to get going. We almost drove home when we saw a brave windsurfer go out on a 7.5 with a 90 cm wide Fanatic board. He said he was working on getting in both straps, but he sure was doing fine. After his first run, he stated that this was the best run he had ever had, so we decided to also go out on our 7.0 and 5.0 sails. Gonzalo, whom we had met at a conference in Hawaii the first time and who had been in Kalmus the day before, also came while we were rigging. He was a bit disappointed that the water was so flat, but went out anyway.

The rest was just great - 3 hours of pure fun. The wind made it up to just above 20, with gusts of 25 - nice & steady. Perfect for long runs, so I worked on improving our mile and one hour postings on the GPS Team Challenge. Here's the GPS tracks:

Nina used the flat water and great wind to work on duck jibes for the first time, and had a lot of fun crashing into the water over and over again (although she did get close on a few). I sailed 86 km in 3 hours, with just a short break to switch boards. But even when I thought I was going fast on Nina's Mistral Screamer 116, Gonzalo passed me all the time. Not a surprise - he was on a Fanatic Ray 125 with a 7.3 m North cambered sail, a much faster than my freeride, camberless setup. And maybe the fact that he once trained to windsurf in the Olympics also had something to do with it :)

While I had a blast in Duxbury, the air temperatures were a bit chilly, and my 3 mm steamer was a bit thin for the weather. Time to get out the warmer gear - I surely would have been sweating in my 5/4 semidry.

So, one good day and two great days of windsurfing - I just love fall windsurfing in New England. South winds now can get a bit gusty with mixing problems, but N and E winds are typically super-steady and make for great flat water sessions in Duxbury. Hope to see more members of the Fogland Speedsurfers there next time!

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