Animated blog: Autopsy of a East Bay wind crash!

windfind · Joined: 18 Mar 1997 Posts: 1902

Hi Gang,

If you were on the water near Pt. Isabel on May 28 or 29th at 3:30PM you remember those days well since the winds went from fairly strong to almost nothing in minutes. Take a look at this wind graph below and imagine what it was like on the water.

This type of event happened 2 day in a row and even though the overall the winds were in our forecast range that does not matter to someone bobbing about in the Bay waters.

So I have prepared a blog with a very detailed animated autopsy of those 2 days. And this autopsy was make possible by useful comments from customers. It is important to send us feedback about what you see on days when the forecast fails. That is the main way we can learn to improve the forecasts.

http://blog.weatherflow.com/west-coast-wind-blog-sudden-mystery-larkspur-eddy-leads-to/

Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com

dllee · Joined: 03 Jul 2009 Posts: 5329 Location: East Bay

Sun, we arrived around 3:30, a couple sailors getting out of the water at Marina Bay, none from PtIsabelle that we could see, proceeded to rig our big gear, 5.8 and 100 liters, and had a great time for over an hour fully powered mostly heading towards Pt. Portrero, past the old Ford plant.
Same thing Sat., but with 5.2 and 84 liters.
Same thing Wed yesterday, but at around 4:30.
It seems to love to die almost completely right when the wind should peak, the come back for a couple of hours to reward the late day sailors.

windsrf · Joined: 01 May 1998 Posts: 464

Mike,

Since you asked....

I've had several bad experiences at Pt. Isabel this year, including one long walk back to PI from Shimada (4/4) and a long swim back to PI launch (4/30). The latter was an exceptionally steep dropoff (I'll try to attach screenshot below).

Those two events as I recall involved sunny days and windline simply receding quickly back towards GG and/or Brooks.

Then yesterday (6/7) another near-miss around 3 PM. However, in this instance it was overcast and no obvious reason for drop - local temp changes, etc. I've learned to wait, and eventually with lowered boom clamp caught a puff and slogged back. Saw a CG heli later that might have been looking for me, but WSers keeping an eye on me didn't notify.

Starting to feel like we can't trust wind at all this season.

Do appreciate the additional "sudden drop" warnings though.

Cheers, David

windfind · Joined: 18 Mar 1997 Posts: 1902

Hi Gang,

Starting today I am going to set the time resolution for Berkeley and Pt. Isabel to 1 hour in the 3-5PM time slot.

My reasoning is that since the NAM3 model caught the sudden heat up towards Larkspur the high res. models might pick up an early hint of a die off if we avoid the averaging of the wind velocity that happens with a 3 hour time slot.

This makes forecasting more time consuming but I will try it on the days I forecast: Th, Fri, Sat. and Sun.

Mike
iwindsurf.com/ikitesurf.com
Weatheflow.com