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Cut-Off Low today: the North Pacific High's surface NW wind?

 
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windfind



Joined: 18 Mar 1997
Posts: 774

PostPosted: Wed Aug 21, 2013 1:30 pm    Post subject: Cut-Off Low today: the North Pacific High's surface NW wind? Reply with quote

Hi Gang,

UPDATE: The first image below is an an image showing how the Cut-Off Low west of the Bay Area has help to totally disrupt the North Pacific High's surface NW winds.

Way back on Aug. 18 I posted this unusual satellite video below of an upper trough at ≈ 18,000 ft. turning into a Cut-Off Low just west of the Bay Area and deepening the marine layer clouds and creating SW flow just aloft:

http://blog.weatherflow.com/?p=14413

Since then the Cut-Off Low has wobbled about off the California but this morning, Aug. 21 it is back to its birth location just west of the Bay Area as you can see in the video below. Hence the East Bay and Sherman Island winds today.

Now look at the third image. Find the Cut-Off Low and California. Now look out at the pacific just north of Hawaii and find the inbound upper trough at 18,000 ft. If Benjamin's extended forecast for today is right that upper trough will suck up the Cut-Off Low and bring an end to our SW flow.

But remember Cut-Off Lows are disconnected from the upper level winds so they are pretty unpredictable so don't be surprised if the forecast changes overnight.

The weatherflow forecast team has already been burnt by this Cut-Off Low. My extended Southern California last Sunday night was for Southern California to have weak winds Mon.-Wed since some models had the Cut-Off Low dropping towards Southern California. Instead it stayed near the Bay Area so Southern California kept its wind.

Other models had the Cut-Off Low rejoining an upper trough and slide towards the Gorge bringing mid to upper 20's to The Wall etc. Instead it lingered near the Bay and the Gorge had mild winds.

Mike Godsey
iwindsurf.com



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Last edited by windfind on Wed Aug 21, 2013 5:25 pm; edited 2 times in total
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2bluehawaiins



Joined: 07 Mar 2002
Posts: 167

PostPosted: Wed Aug 21, 2013 4:31 pm    Post subject: cut off low Reply with quote

Thanks Mike for the great description of the cut off low and upper trough
and how it is effecting our bay area wind and weather. It makes the forecast
make more since when you can visualize it with pictures and video's.
Cool
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