Blog: possible marine surge Friday.

[windfind]

Hi Gang,

Since Sunday I have been watching conditions set up for another marine surge. Not positive yet but I there is enough evidence to make a blog worthwhile.

http://blog.weatherflow.com/bay-area-weather-blog-atypical-marine-surge/

This is another atypical very early season marine surge and is very tricky to forecast since it has a cause quite different than out typical post heat wave marine surge.

Mike Godsey
iwindsurf.com

[windsrf]

Mike,

I'm curious if the Daily Briefing for Pt. Isabel is based on sensor expected readings or instead on what sailors might expect out on the water there? For example, is an allowance made for wind direction effect on sensor reliability? By that I mean what we would experience sailing vs. what the sensor experiences and reports.

For example, today's 7 AM update reads as follows:

East and North Bay: Berkeley WSW peaks around 20, but may fade fast. Pt. Isabel faint upper teens.

Depending on wind direction, the PI sensor can read "faint upper teens" (i.e. 16 mph from the south) while we are being blown off the water using 5.5 and 6.3 sails - exactly what happened this past Monday (you can see the graph drop each time the wind shifts to the south). Meanwhile, 20 avg at Berkeley/His Lords is barely 6.3 conditions.

Thanks, David

[windfind]

Hi David,

For most sites we try to forecast for the wind in the main sailing area.

The issue is that for most sites in the Bay Area the wind is much lighter at or near shore. So if we just forecast for the winds outside there would be days when you could not get to the forecast winds.

On those day we try to modify the forecast by compromising between the weak winds near shore and the stronger wind outside. Our reasoning is the most people are not going to complain if they find stronger wind than forecast but they do complain if they cannot even get to the forecast wind. Crissy is the best example of that situation.

I also try to add text below a sites wind graph to describe what might happen to the winds. Like "wind might fade after 4PM or "Forecast winds towards Brook's Island" or "Weak inside"

The sensor at Pt. Isabel has many issues and I have long wanted to put it out on the radio antenna pier that extends into the bay just south of the launch site. But there are lots of issues to resolve before we can do that.

Mike

[windsrf]

Thanks Mike. Usually more wind out in the middle, vs. near launch or over in shadow of Brooks Island. Sometimes the wind "band" is even narrower, plus moving east or west (i.e. towards launch or towards Brooks). On the days when it is unexpectedly strong in middle those less windier ends/borders are more appreciated.

[veterduet]

The last two days the wind has been really strong and on shore. Yesterday it even had an easterly slant. Maybe the City of Richmond will give you permission to mount a sensor on the rest room near the beach launch. It's opposite Brooks Island and about half-way between the dog park launch sensor and the Potrero sensor. I often look at both of those existing ones to get an idea of what's going on in the main sailing area, but it doesn't always help.

[victor]

if you go to windalert or ikite maps there are 3 public sensors at marina bay that aren't on iwindsurf.

one is back in the corner of the marina, another on a building next to the liberty ship that's docked across the way and another at pt. potrero.

with those and pt. isabel and potrero reach sensors you can get a better idea of what's happening at marina bay.

[windfind]

Thanks Victor.

Actually you can find all those sensors and more at the new iwindsurf.com:

http://wx.iwindsurf.com/map#37.907,-122.361,14,1

Mike

[windsrf]

Good info - thanks.

The sensor at the dry docks just behind/north of the Brooks Jetty should be particularly helpful in evaluating what's actually happening in the middle of Marina Bay.

At the same time, I don't think trying to mount a sensor on the concrete restrooms just south of the Dog Shop would be a good idea - too shadowed by trees and too inland from sailing area (if that was the location being suggested). The existing PI sensor location at the Sewage Plant suffers from similar siting problems.

Also, there's a near-ideal, existing, and unused pole within the Clear Channel compound just to the south of the PI launch (photo below). Just need to make the location move happen.

David

[windsrf]

Ah, sorry. You meant the restrooms at Marina Bay launch, not at PI launch. That would definitely be good spot, but without as much equipment security as the Clear Channel location would provide.

[SwellRipper]

Hi Mike, thanks for keeping wind-addled minds informed and entertained. I know on a marine surge Waddell and other nearby coast spots get shutdown on southerly winds. But what about Natural Bridges, if you had to guess, how often does it blow there under the SW wind marine surge scenario? Thanks.