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windfind
Joined: 18 Mar 1997
Posts: 1902
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 Posted: Tue Jun 13, 2023 9:47 am Post subject: June 15 NEW Blog: June 18 then NW wind returns: WHY? |
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Hi Gang,
NEW BLOG: https://blog.weatherflow.com/west-coast-wind-blog-san-francisco-eddy-dies-june-18-why/
By now, you're likely curious about the underlying factors responsible for the persistent occurrence of eddies and southerly winds along the coast
Actually, if you play north of the Bay Bridge, you have probably been too busy enjoying the WSW eddy wind to give it a thought.
But if you ply the waters of the Peninsula or coast, you may have given the eddy some thought.
In the satellite animation below, notice how huge and "ugly" yesterday's all-day eddy looks. This "Big Eddy" is very unlike our normal small and infrequent eddies that look more like tiny hurricanes that politely die mid-afternoon.
The next two animations show how upper-level winds ≈18,000 feet set the stage for the eddy's birth, life and death.
Mid-week I will publish a blog explaining all this in more detail. Then we can all await the death of the eddy this coming weekend.
Mike Godsey
weatherflow.com
iwindsurf.com
ikitesurf.com
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ctuna
Joined: 27 Jun 1995
Posts: 1126
Location: Santa Cruz Ca
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| Posted: Fri Jun 16, 2023 5:14 am Post subject: I have noticed the charts don't seem as reliable |
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I have noticed the charts don't seem as reliable
I am talking about the charts under the complete
prediction option . iW-WRF , IW-HRRR and NAM3KM
Seems to have been getting worse with the increasing
amount of eddy's
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windfind
Joined: 18 Mar 1997
Posts: 1902
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| Posted: Fri Jun 16, 2023 9:47 am Post subject: |
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| ctuna wrote: | I have noticed the charts don't seem as reliable
I am talking about the charts under the complete
prediction option . iW-WRF , IW-HRRR and NAM3KM
Seems to have been getting worse with the increasing
amount of eddy's |
Hi ctuna,
You are right! Have you ever watched a dust devil's erratic movement and fast changes in size? If not, take a look at this video:
https://www.youtube.com/watch?v=Mo8561rS13E
The eddies we see off the Bay Area are larger and slower moving but just as erratic. So during the day, they change in size and location. This changes the strength of the eddy winds and the direction of their southerly winds from WSW to SW to S to even SSE.
This, in turn, changes the strength of the wind at different sites and even which gaps in the Coast Range the winds flow through.
The models cannot reliably forecast all of this. And even a human forecaster looking at the satellite animations and sensors at 11:30 AM can not always forecast where the eddy winds will focus at 4 PM.
Yesterday is a great example. Look at this satellite animation of the radical shift in the eddy's position from dawn to noon. I caught the eddy's trajectory mid-morning on this particular day, so my forecast was decent.
https://blog.weatherflow.com/west-coast-wind-blog-abnormal-sse-winds-blow-san-francisco-fog-out-to-sea/
Mike Godsey
iwindsurf.com
Last edited by windfind on Fri Jun 16, 2023 3:13 pm; edited 1 time in total |
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ctuna
Joined: 27 Jun 1995
Posts: 1126
Location: Santa Cruz Ca
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| Posted: Fri Jun 16, 2023 11:47 am Post subject: Went to San Luis yesterday chart forecast 25 by 3 pm |
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Went to San Luis yesterday chart forecast 25 by 3 pm
Actual wind in the morning was ahead of those model's
Got there a 1pm and it dropped .
Model had it hitting 25 by 3 pm instead it was a slow
crawl back up to 19 by around 6pm .
I have had mostly days like this at San Luis this year.
Also no typical Central Valley Heating to drive the thermal winds
yet it has blown there quit a bit but Gusty most of the time
and up and down.
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