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windfind
Joined: 18 Mar 1997
Posts: 1902
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 Posted: Tue Jun 14, 2016 8:23 am Post subject: Cold Front animation: All night SI & 3rd. winds! |
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Hi Gang,
The new animation at the bottom of this thread should help you understand the strange all night wind mentioned below.
Take a look at the imagery below. As you have probably guessed something is "wrong" with the wind this season. Coast and many Peninsula people have been wind deprived while many kiters/sailors to the north have had a great season like the N. bay used to have long ago.
Dawn today really illustrates how strange the wind patterns have become. Sherman island blew all night long except for one big lull. That is cool except we all know that all night blows only happens when there is deep fog and the coast winds are SW.
But the Mt. Tam cam shows blue skies at dawn and strong NW wind on the ocean.
And 3rd. Ave. has crazy strong 30 knot winds at dawn. Sure that happens sometimes in the spring during NW clearing winds after a storm. But there was no storm and 3rd. blew in the 25 to 40 knot range all night long.
So what is going on?
I don't know!
But I am working on a blog to figure out at least today. But why the mostly weird season... that is the puzzle that has your forecasters going crazy each forecast day.
Meanwhile post your thoughts or mail me at mike@iwindsurf.com
Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com
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Last edited by windfind on Fri Jun 17, 2016 10:44 am; edited 4 times in total |
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Arrgh
Joined: 05 May 1998
Posts: 864
Location: Rio
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| Posted: Tue Jun 14, 2016 10:20 am Post subject: |
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| I live in Trilogy(old folks' home) in Rio Vista, a couple of miles from the river, and we often get a lot less of the west wind than SI does. Sometimes I wake up to a still day and, when I check iWindurf, I'm surprised to see how windy it is at Sherman. This Spring it's been pretty windy at home. Last night I woke up about 1 to silence. Then the wind kicked back up just like the graph shows. Delta wind seems to always be a mystery.
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windfind
Joined: 18 Mar 1997
Posts: 1902
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| Posted: Tue Jun 14, 2016 11:28 am Post subject: |
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dennis_c said: Last night I woke up about 1 to silence. Then the wind kicked back up just like the graph shows. Delta wind seems to always be a mystery.
Hi dennis c & everyone,
Well I solved the mystery at least for today regarding the powerful Sherman and 3rd. all night wind. I even figured out why both had that "silence" you mentioned.
The answer is in the animation below. Watch the cold front advancing through the pacific and passing over the Bay Area. Then check out the Sherman Island and 3rd. Ave. wind graphs above. Especially note the dip in each wind graph
Can you figure out what happened?
If not check out the blog I will produce later.
Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com
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ethurlow
Joined: 07 Dec 2002
Posts: 119
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| Posted: Wed Jun 15, 2016 12:40 am Post subject: Maybe Cold Ocean Water relative to Interior Temps |
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| It seems like an early August with the SW and strong windspeeds at 3rd Ave. Maybe the colder ocean temps have returned and causing the early/deep fog patterns.
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windfind
Joined: 18 Mar 1997
Posts: 1902
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| Posted: Wed Jun 15, 2016 8:38 am Post subject: |
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| Quote: | | Maybe the colder ocean temps have returned and causing the early/deep fog patterns. |
Hi Ernie,
I don't think so. Look below at the SSTs for the coastal pacific this morning. The pacific overall is warmer than average (but is should begin cooling as La Nina develops). However you can see the cool water along the coast which shows the area of spring/early summer upwelling that occurs as the NPH's wind blows relatively warm surface water away from the coast allowing chilly subsurface water to pool at the surface.
As you say this pool of cold water encourages fog formation and creates a thermal high pressure along the coast that helps the wind a bit.
But the upwelling near the Bay Area is in the normal range. What is different is the extensive area of cool water upwelling near Cape Mendocino. My guess is that this is the result of the atypically frequent NNW ocean winds this season that accelerate around the Cape.
And it is those NNW winds that encourage eddy formation which in turn created the unusually frequent southerly wind on the coast and near Coyote and 3rd. Ave. this year that spoiled the wind. (and of course make great winds N. of the Bay Bridge)
Incidentally I have been spending about an hour per day this season trying to figure out the causes of the often crappy wind inside at Coyote and 3rd. Ave. this year and the consequent crappy forecasts.
The frequent eddies are an obvious cause that we can forecast but we are seeing W to WSW winds inside on 3rd. even on days with strong NW ocean wind. I think I finally have the answer but making graphics to explain it takes time.
And even with an explanation being able to forecast those crappy winds inside in advance is still beyond me. At least I am having some success warning that it "might" happen.
Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com
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airwave
Joined: 29 Jun 2000
Posts: 386
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| Posted: Thu Jun 16, 2016 12:47 pm Post subject: |
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Windfind,
Can you get this fixed?
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windfind
Joined: 18 Mar 1997
Posts: 1902
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| Posted: Fri Jun 17, 2016 10:41 am Post subject: |
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Hi Gang,
The animation below will help you understand the strong all night winds at Sherman Island and 3rd. mentioned in the first posting of this thread.
Looking at the animation below and the animation above you can picture this passing over Sherman Island and 3rd. and you can see why the winds were so strong and why there was a deep lull followed by a switch in wind direction. Then as the cold front passed the winds weakened.
Of course the cold front that night was dry so there was only clouds with no rain.
Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com
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| Imagery adapted from Pearson, Prentice Hall |
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