avionbianca   Blog for s/v Avion

Synoptic Winds

Return Day 14 8/12/2014 14:00 (250 Miles to Golden Gate Bridge)

Shortly after my last post yesterday after 5:00 P.M. they turned the engine off and it has been off ever since. We have had sustained winds of 15 with occasional gusts to 20 plus. The seas are about the same but shorter in duration so more frequent resulting in a bumpier ride. Just at the end of my shift thee winds clocked about 40 degrees and increased in intensity to sustained over 20. Juan wonders why do all of these changes in conditions seem to happen right at shift changes. We got Nico up and David, Nico and I depowered the boat as best we could without changing sails This is done by flatting the sails which requires all the lines other than the sheets to be tightened.

This increase of wind is a result of the strengthening synoptic winds as we get closer to the coast. I am no weather expert but I have made an asserted effort to learn as much as I can, not just for this adventure but more importantly for when Lindi and I are going cruising. My understanding is that the synoptic winds, that we are currently in, are the result of the compression effect of the easterly winds coming off the north edge of the Pacific High. As they circle clockwise to the south, they are compressed by the mountains along the Mendocino coast north of San Francisco. Without the land mass the winds clocking out of the north would spread out just as they do on for the points of the compass around the High which we have been experiencing as fairly light. Since the winds are being compressed there is a ventura effect just like when you restrict the flow of water there a spray nozzle at the end of a hose, it speeds up. The most resent downloaded weather files shows the wind building slightly for the next 120 miles, so over the next 24 hours, then easing off. Looks like we will have an E-Ticket ride for the next day then the winds should abate some resulting in an easy sail into San Francisco Bay. At least that is Juan’s guess and he is sticking with it.

Everything is still good aboard Avion. We should have a new distance record at the end of the day, my guess is 164 miles which will put us close to 200 NM from Golden Gate. Time to get some sleep, I think I will need it for the wild ride tonight.