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Marine surge Fri-Sun in one animation then NPH.

 
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windfind



Joined: 18 Mar 1997
Posts: 1453

PostPosted: Sun Jul 01, 2018 10:48 am    Post subject: Marine surge Fri-Sun in one animation then NPH. Reply with quote

Hi Gang,

That sure was one of the more difficult marine surge forecasts. Hard to believe I called it last Tuesday. Probably more luck than skill.

The first animation shows how abruptly the marine surge arrives at the Golden Gate.

The 2nd. animation below follows the marine surge from its start in Southern California predawn Friday to its current Sherman Island build this Sunday morning.

Lastly a time lapse video from the East Bay showing what a similar marine surge looks like: https://windnotes.smugmug.com/1-Videos-WindsurfKite/1-Gorge-Videos/i-w8Gt9Lv/A

It looks like SW flow will linger several days as a combo of factors batter the North Pacific High. Right now it looks like the North Pacific High's surface NW winds appear weakly during mid weak then return with strength on Friday.

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



Marine surgeArrivesGGmarin.gif
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Marine surgeArrivesGGmarin.gif



MARINE SURGEsc2Sherman.gif
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MARINE SURGEsc2Sherman.gif


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windsrf



Joined: 01 May 1998
Posts: 351

PostPosted: Sun Jul 01, 2018 12:33 pm    Post subject: Reply with quote

Mike,

Some perhaps interesting observations at Pt. Isabel yesterday/Saturday PM.

I chose to launch there vs. His Lords at 4PM for several reasons (already too tired from tennis for dealing with 26+ avg, etc). The wind/flow from Gate was obvious from clouds/fog streamer heading straight to Berkeley, but south of PI. Result of constrained flow was that wind was quite strong south of launch, especially between radio towers and Bulb, then nice 5.6 conditions between towers and launch down to near The Structure, then almost glass north of The Structure. Since the new sensor position is at the radio station, PI read quite high, but only if you sailed south of the launch. Strong die-off occurred about an hour later at PI vs. Berkeley.

David
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windfind



Joined: 18 Mar 1997
Posts: 1453

PostPosted: Sun Jul 01, 2018 12:51 pm    Post subject: Reply with quote

Hi David,

Thanks for the Pt. Isabel report. Information really helps me learn patterns.

Reports from Berkeley said it faded fast around 4PM as I forecast. But Pt. Isabel faded later than expected. Here is what I suspect was going on...

The pressure gradients were actually stronger to Stockton than Sacrament yesterday which would the wind curve less than normal towards Pt. Isabel. Hence the wind flow S. of Pt. Isabel and towards Berkeley you saw. The problem is that there is no direct pathway for this wind to the Central Valley. So part of it hits the Berkeley hills and turn S. to the Altamont Pass and part of it turns N. towards Sherman Island. This makes both the wind strength and the fade time hard to forecast.

If there had been more fog yesterday you would have seen the famous Berkeley T in the fog. Like you see in the time lapse:
https://windnotes.smugmug.com/1-Videos-WindsurfKite/1-Gorge-Videos/i-w8Gt9Lv/A

Mike
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WNDZRFR



Joined: 28 Mar 2000
Posts: 59
Location: Greater East Bay Area

PostPosted: Sun Jul 01, 2018 1:18 pm    Post subject: Reply with quote

Arriving at HLS at noon yesterday the HLS iwind sensor was reading 16 but since it looked much stronger I pulled out my Weatherflow phone sensor and got readings of 21 avg. -24 mph gusts.

Considering your forecast of "mid teens" I figured this must be the peak!

Luckily I rigged a sail size smaller than normal for my readings because while I was out the wind kept climbing and climbing into the mid 20's avg and gusts to 30! After an hour of now being way op’ed I called it quits.

Everyone on shore was pulling out the smallest sails they had on them.

So although you get kudos for calling the fall after 4 pm you totally missed the Most Important part of the forecast - the wind in the mid-20's average with gust to 30!

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windfind



Joined: 18 Mar 1997
Posts: 1453

PostPosted: Sun Jul 01, 2018 1:56 pm    Post subject: Reply with quote

Hi WNDZRFR,

I had been forecasting a strong marine surge to hit sometime this weekend since last Tuesday. As you know a marine surge typically means strong winds for the Berkeley and Pt. Isabel.

The forecast I published at 11:30 AM Saturday sald:

North and East Bay: "Berkeley best early with mid to maybe weak upper-teens inside then building to low 20's outside ... BUT likely to FADE fast towards 4-5 PM." ...

The same forecast said: "Low to mid 20's for the Olympic Circle."

My reasoning was that since S. Olympic Circle is a short distance from Berkeley people would realize that there was potential for very strong wind Berkeley wind.

Still, I clearly under forecast the Berkeley launch site winds.

But I did it for a simple reason. There was a very good chance that the marine surge would not arrive at all yesterday. And to forecast mid to upper 20's and have only weak wind would piss people off more than under forecasting winds mid to upper teens inside and low to mid 20' outside.

At the time I was working on the 11:30 update yesterday the marine surge was still stalled near Waddell. And the NWS had the marine surge arriving Saturday night. And the great SFO meteorology team did not even mention the marine surge. So I was taking a gamble even forecasting the marine surge to even arrive at Berkeley yesterday.

When you can't see all the cards you have 2 choices: bet wildly or hedge your bet. I hedged for Berkeley but tried to give hints that things could be wild.

Mike
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WNDZRFR



Joined: 28 Mar 2000
Posts: 59
Location: Greater East Bay Area

PostPosted: Sun Jul 01, 2018 2:12 pm    Post subject: Reply with quote

Mike,

After reading your response I think I figured out the disconnect here.

The largest contingent of sailors that launch at HLS, rig per HLS winds as we are not likely to slog westward towards Olympic circle in search of wind.

Sure there are those that don't care what the wind is at HLS as long as the know they can reach the wind in Olympic circle but for the rest of us we will either rig big for the HLS conditions or head over to PI to sail rather than take a chance on not being able to get back to the launch!

And when you say Olympic Circle do you mean through the gap in the pier or just that far west from HLS?

Thanks

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dllee



Joined: 03 Jul 2009
Posts: 3974
Location: East Bay

PostPosted: Sun Jul 01, 2018 2:33 pm    Post subject: Reply with quote

Some very good high wind sailiors rigged and sailed from the East dock with 85 liters and 3.7's and were very happy.
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rigatoni



Joined: 25 Feb 1999
Posts: 413

PostPosted: Sun Jul 01, 2018 2:56 pm    Post subject: Reply with quote

I drove back into SF from Marin around 1:30 and there was not a stitch of fog. By the time I got to Crissy 2 hrs later, there was a streamer of fog running all the way thru the gate to the East Bay Hills. There was no fog over SF proper. Wind on the water was all over the place switching directions with big huge gusts and massive lulls. At around 5pm with the ebb kicking in, the fog started to pull back a bit and the wind steadied for some really fantastic sailing. Wind direction was very west.

This morning my car was covered in ash from the fire up north.
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windfind



Joined: 18 Mar 1997
Posts: 1453

PostPosted: Sun Jul 01, 2018 7:18 pm    Post subject: Reply with quote

rigatoni wrote:
I drove back into SF from Marin around 1:30 and there was not a stitch of fog. By the time I got to Crissy 2 hrs later, there was a streamer of fog running all the way thru the gate to the East Bay Hills. There was no fog over SF proper. Wind on the water was all over the place switching directions with big huge gusts and massive lulls. At around 5pm with the ebb kicking in, the fog started to pull back a bit and the wind steadied for some really fantastic sailing. Wind direction was very west.


Thanks rigatoni,

Your description, especially about the lack of fog even at 1:30 PM, helps people understand why I hedged on the forecast marine surge winds. Whoever heard of a marine surge with no fog at 1:30 PM. By that time I was getting prepared to be razzed not by pissed customers who were already very skeptical of my surge forecast but also by all the other Weatherflow meteorologist, NWS etc. etc.

Mike
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