Squalls seemed to be on the mind of a lot of the cruisers with whom we chatted in Las Palmas. As we have had two sets of line squalls in the last 18 hours, we thought a few comments might be of interest.
To begin with, in light airs, like we have had so far, the increased wind pressure that comes with a squall can provide a welcome boost in boat speed, as well as a cool rinse. The key is to play the squall so as not to be left bobbing in the vacuum which often follows. The strongest winds are downwind on the equator side. Conversely, weaker winds are on the pole side and upwind (there is a detailed chapter on this subject in our Mariner's Weather Handbook).
Our experience over the years has been that squalls rarely exceed 1.5 to twice wind speed. Early this morning, with a large line squall system, we saw 18 to 20 knots of breeze. A 90 degree shift (or more) is not unusual.
Radar is an excellent tool for squall analysis. When we used to see isolated squalls of small stature we didn't worry, and often positioned ourselves in front for an extra push. But if there is a large line of squalls, or the isolated cells begin to emerge, it is time to get the light sails furled.
Other signs are a growing anvil top, and cool tickle of breeze just before the big gust hits.
Once the squall has passed there is often a vacuum, and it can take an hour or more for the gradient breeze to resume. This period of light airs is usually less on the equator side of the system when you are in the trade winds.
This morning our squall activity gave rise to a 180 degree double rainbow, something we have never experienced before. There were wonderful clouds in the early sunlight, and by 0900 we had a clear blue sky, and barely rippled sea. Perfect FPB weather (except we'd rather have big seas from behind to surf). It looks like we will have a few hours of brisk headwinds over the next two days, or maybe not if the wind gods smile on us.
We have averaged a hair over eleven knots for the first 48 hours. Once we get through this area of low pressure we should make contact with the expanding high and its tradewind flow. We'll be lighter by then and the combination of wind, waves, and a few less tons of fuel and water should make for good surfing. Late this evening we shall resume our partying with a one quarter of the way there soiree. In preparation thereof a bath for Linda and shower for Steve are on the todo list. Our two little John Deere diesels continue to purr, and all are content on Wind Horse.
ARC-2010-Passage-4-258-2194