From 5 to 70 knots in less than 60 seconds

[GordMay]

Predicting Weather ~ United States Search and Rescue Task Force
Predicting Weather

[ssullivan]

We just had the same thing happen last night.

We were in bed at 9:00 or so (yeah... it was still light out.. ha ha) in one of the most calm nights you'd ever see. The water was like glass (with 2-3 miles of fetch, if there was a wind direction). There would be no hope of sailing. The wind was basically non-existant. Not even a breeze.

As we turned out the lights, all of a sudden we heard wind in the rigging like you'd hear in a tropical storm! No rain, no odd clouds, nothing. Just a gust of wind I estimate to be in the 40-50 knot range.

I was a little worried about our anchor holding since in the calm, there is a great deal of slack in the chain, which would be taken up rather violently by the instant 40-50 knots we got.

As the wind started up, the boat was turned beam into the wind, since the slack in the anchor chain had not all been taken up yet by the great push. As the wind increasted, we heeled maybe 10 degrees under bare poles (it's a big, strong boat). Once the anchor chain slack was taken up, the bow again comfortably pointed into the wind.

I got up to turn on my Palm Treo to check the weather. By the time I could turn it on, the wind had already returned to calm.

We could make out some very strange, thin cloud or layer or something (it was dark) that passed us at about the time of the burst and stretched from horizon to horizon, moving in the same direction the wind came from.

We are about the same lattitude as Raven now, and in a similar body of water to him (excet that it's salty). I wonder if there is some connection with that and these bursts. I had never experienced them before in my 20+ years at sea.

[Labatt]

Raven - We had a similar issue last year in June on Lake Champlain. We were coming out of Mallett's Bay and were just north of Stave Island. The wind had been blowing about 15kts from the south with predictions 10-15kts for the day. We left the protection of the island and went out about another 1/2 mile when we got hit with 48kts on the beam. We were having some issues so we were bare poled (thank God). The wind waves rapidly increased to about 5 feet on our beam, and without our sails up we were getting close to broaching. We were on our old boat - a light displacement 23' trailersailor - with our kids. It certainly didn't like square 5 foot wind waves. When the waves hit, we went nose to them in order to stay upright. We knew we had to turn and run in order to be OK, but in order to do that we'd have to be beam to the waves for a very short period. With only a single reef available to us on the main we couldn't put the sails up to stabilize us. We called to the Coast Guard to let them know where we were and what we were doing. They sounded surprised, thinking the winds were only around 20 - not gale force plus. Anyway, with my wife holding the outboard and with me holding the tiller, we were able to push both over simultaneously and execute a quick turn between waves. We were then able to run and get back in the lee of Stave Island. Within minutes, the wind had died down. Shortly afterward, a Sheriff's patrol boat stopped by to make sure we were OK. According to them, after checking the radar (doppler I'm assuming) they realized we were in a small microburst. There was NO time to react between regular wind and when the wind rose. It was near instantaneous.