Wind Forecast Write Up

[dllee]

I took up wingfoiling last year, so am looking for 10-15 mph breezes.
Started sailing Berkeley in '95. Always, most used gear was 100 liter slalom and 6.0.
To use my Crissy and coast gear, I went to PI.....June thru early August.
It's now Sept., well past the peak of PI season. Occasional days for sure, but not like June Gloom.
Berk usually lasts thru into early Oct., but 7.0 and 111 gear is needed....or a semblance of foiling.

[windfind]

Hi Gang,

Thanks for the Feedback! Here are some thoughts about Pt. Isabel and the Napa Valley and why you should watch the Napa Valley satellite imagery and sensors between Pt. Isabel and San Pablo Bay. (see imagery below)

Preamble:
In recent years we have seen an increasing frequency of counter-clockwise eddies between Half Moon Bay and Bodega and also between Stinson Beach and the Golden Gate. These eddies are strongest in the AM and MAY fade in the early afternoon.

If an eddy endures into late afternoon it makes the wind reaching the Golden Gate more southerly than usual which favors Pt. Isabel over Berkeley (even more than usual since we now have the gradient toward Sacramento favoring Pt. Isabel + a more southerly angle to the wind favoring Pt. Isabel.)

Berkeley is more favored than Pt. Isabel when the strongest pressure gradient is towards Stockton since as the wind comes through the Slot it is pulled a bit more towards Berkeley since there are wind gaps in the East Bay hills south of Berkeley leading towards Stockton.

All this is old hat and easy to understand. What is more complex is the pressure gradient towards the Napa Valley.

The eddy is created, in part, by low-pressure that sometimes expands over the Marin Sonoma coast in recent years. That makes fog streaming near Pt. Isabel go up San Pablo Bay, into the Napa Valley and then curve back towards the coast. You can see all this in the images below. When this happens the Pt. Isabel winds become more southerly which makes the winds stronger towards Shimada Park and the Pt. Isabel sensor reads lower while Berkeley has weaker winds.

Unfortunately, the pressure gradient that makes both the eddy and the Napa Valley pressure gradient and SSW winds often fades mid-afternoon. Which makes forecasting all of this very tricky.

How to do your own Pt. Isabel NowCast: Mid-afternoon, Go to the new IW map page and zoom in to the East Bay. Then, watch the direction of winds at the San Pablo Bay sensor and the PD sensors (white) and Tempest sensors (green) in the Richmond area for a hint of what the winds will do later in the afternoon.

https://wx.iwindsurf.com/map#37.926,-122.373,13,19

Mike Godsey
Weatherflow

[windsrf]

Thanks for additional insights Mike.

Years ago used to enjoy watching the hot air balloon fleet sail/drift up the Napa Valley in early October AMs.

David