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Blog: Gorge, S. F. Bay Area and Southern California get HOT

 
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windfind



Joined: 18 Mar 1997
Posts: 1453

PostPosted: Tue Jul 24, 2018 3:54 pm    Post subject: Blog: Gorge, S. F. Bay Area and Southern California get HOT Reply with quote

Hi Gang,

A huge upper high pressure area at ≈ 18,000 ft. is baking the Gorge, Southern California and the interior of the San Francisco Bay Area.

This blog uses photos, satellite imagery and animations to show why such events occur and how they impact our wind and marine layer clouds:

http://blog.weatherflow.com/west-coast-wind-blog-gorge-s-f-bay-area-and-southern-california-get-hot-as/

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



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sorenson



Joined: 04 Jul 1999
Posts: 45

PostPosted: Tue Jul 24, 2018 10:02 pm    Post subject: Delta blows during heat wave Reply with quote

Mike, this has been a very strange July since these crushing high pressure ridges have not seemed to affect the Delta Wind; there's no doldrums that you typically get followed by a Marine Surge. I have never seen a pattern before where it has been Windy at the Delta with 96-100 degree highs in Fairfield! Is this a new norm? It just seems counterintuitive to have 105 degrees in Sacramento with a strong Delta breeze!
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windfind



Joined: 18 Mar 1997
Posts: 1453

PostPosted: Wed Jul 25, 2018 9:17 am    Post subject: Re: Delta blows during heat wave Reply with quote

sorenson wrote:
Mike, this has been a very strange July since these crushing high pressure ridges have not seemed to affect the Delta Wind; there's no doldrums that you typically get followed by a Marine Surge. I have never seen a pattern before where it has been Windy at the Delta with 96-100 degree highs in Fairfield! Is this a new norm? It just seems counterintuitive to have 105 degrees in Sacramento with a strong Delta breeze!


Hi Sorenson,

I agree it has been a weird July. Waddell has seen more strong winds that typical as has Sherman Island but often with WNW winds. The proximal reason for this is:

1. the North Pacific High is, on the average, is centered closer to the Bay Area than normal rather than being centered west of the Gorge (where the phrase of the month is "The Gorge is broken". This NPH location favors Waddell and helps Sherman Island PM winds.

2. Usually, the dominant pressure gradient pathway over Sherman Island is towards Sacramento which creates Sherman winds but when it gets really hot towards Sac that pressure gradient fades. This July the main gradient pathway has often been towards Stockton and on to Bakersfield due to the frequent intense heat in Southern California. This heat does not reach Sherman Island hence the wind does not fade. But having the pressure gradient more to the south makes the Sherman wind more WNW. This same factor is responsible for the more frequent up and down winds or major fades at Pt. Isabel and Berkeley since their wind can get to Stockton by either the Sherman Island route OR the Altamont Pass route.

If you look at the isobars in the above image you can see the very strong low pressure over Bakersfield and Southern California that is creating these Delta winds.

The ultimate causation of these events is beyond me.

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



Joined: 04 Jul 1999
Posts: 45

PostPosted: Wed Jul 25, 2018 10:51 am    Post subject: Reply with quote

I think that makes sense, Mike. The gradient being better to the South helps explain it. It might also help to explain why San Luis has been ripping a lot this month.
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ctuna



Joined: 27 Jun 1995
Posts: 816
Location: Santa Cruz Ca

PostPosted: Wed Jul 25, 2018 11:36 pm    Post subject: On San Luis it only ripped the first week of July Reply with quote

On San Luis it only ripped the first week of July.
Mega eddy time

Since then it starts blowing around 5 or 6 then stops by early
morning . Then it bakes all day .

But Rio is still going all day . Why?
Because of the weird flows from the South?

The fog hangs very close to candlestick making it iffy .
It has blown early and then at 3 when it usually comes up
it drops.


Last edited by ctuna on Thu Jul 26, 2018 2:21 pm; edited 1 time in total
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dllee



Joined: 03 Jul 2009
Posts: 3975
Location: East Bay

PostPosted: Thu Jul 26, 2018 8:15 am    Post subject: Reply with quote

That's the wind MO at Berkeley also, as it rises to almost sailable by 3, then stubs it's toe, peaks, and goes shifty as it drops off the map.
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windfind



Joined: 18 Mar 1997
Posts: 1453

PostPosted: Thu Jul 26, 2018 9:12 am    Post subject: Reply with quote

Hi Gang,

The upper high pressure you see in the animation above has heated the Southern California deserts heating above 115 and Bakersfield to 108 today. Meanwhile Sacramento "only" reaches 104. This makes the Central Valley low pressure more intense to our south which changes the wind pathways.

Normally the most important pressure gradient for the sites N. of the Bay Bridge is the gradient towards Sacramento/Redding So wind coming through the Golden Gate heads towards the East Bay but curves towards Sherman Island over the Bay waters and/or the East Bay flatlands. This flow provides our normal wind direction as well as build and die times.

With a very strong pressure gradient towards Stockton to Bakersfield the East Bay wind now has 2 pathways to the Central Valley. 1. the normal pathway described above and 2. wind diverting towards the Altamont Pass. This diversion mostly takes place over flatlands and when it happens the wind weakens abruptly. (this is very different than the frequent sudden fades that happen when there are very strong NW winds just aloft over the East Bay)

Similar things are happening on the Peninsula as winds take either the Altamont Pass route OR the Morgan Hill to Pacheco Pass route to the Central Valley. All this makes forecasting challenging especially with all of our Hi-Res models down.

Mike Godsey
weatherflow.com
windalert.com
iwindsurf.com
ikitesurf.com
sailflow.com
fishweather.com
USAfishing.com
https://windnotes.smugmug.com
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