Friday, August 18, 2017

Eclipse Weather Update: Will the Partial Eclipse Be Visible in Seattle? What will happen in Oregon?

Many of you are in the final planning stages for the big solar eclipse.    So lets update the situation and discuss some of the nuances and details that I left out in previous blogs.

The basic story is still the same.  Partial cloudiness around Seattle, lots of clouds along the Pacific coast.   Good viewing in the Willamette Valley eastward, with the threat of smoke in parts of eastern Oregon.

First, the wildfire/smoke issue. There are several fires burning in the Oregon Cascades and some of the smoke is being blown to the east and south.  Fortunately, most of the smoke is avoiding much of the totality region in northeast Oregon.  The Willamette Valley is clear.  Smoke is probably not a major issue until you are near or immediately downstream of the fires.


Next, lets turn to the low cloud forecast of the latest high-resolution (4km grid spacing) UW WRF model run.  The resolution is important, since we need to get the blocking effects of the coastal mountains correct.

At 8 AM PDT, lots of clouds over the coast and some marine clouds over Puget Sound.

 By 9 AM, Oregon is clear (except for the coast) and the low clouds are retreating around Puget Sound (still near the water).
 By 10 AM (right before the greatest lunar coverage of the sun), Puget Sound is clear, but the Strait and the coast are covered.

 No here is a major issue.  The UW WRF model does not have the reduction of solar radiation by the eclipse, which will start to become significant around 9 AM.  So the clouds may burn off more slowly than forecast after 9 AM.

Thus, the Puget Sound region  is on the edge.  There could be some low clouds, particularly near the water, at eclipse time.   My advice is you want to see the eclipse and clouds are there around 8 AM...head east or up in elevation.  Even Bellevue and Issaquah would be much better.

Still looks good in the Willamette Valley based on the UW WRF model.

How about the European Center model?  Here is the forecast for 11 AM (don't have it every hour).  Oregon looks fine, although there is some high clouds (cirrus) around Portland.  An irritant, but you would still seen the show.   The coast is cloudy like UW WRF.  Puget Sound looks clear, but clouds in the Strait. Thicker high clouds over eastern WA.


How about the official National Weather Service forecast for cloud cover at 11 AM?  Good in the Willamette Valley (4% coverage), 0-2% coverage in eastern Oregon, bad on the coast, but good (7%) in Puget Sound.


As we get closer to the event, another modeling system will be available (the NWS HRRR), which DOES include the reduced strength of the sun in its prediction.   I will be watching it carefully and let you know.

So the bottom line is still pretty much the same.  The coast will not be the best place...if you are there, head a few miles east and upwards into the coastal mountains.  Salem and vicinity should be great, with no smoke.  Eastern Oregon will be clear, with smoke in places.   Seattle is on the edge, but probably will have decent sky opening away from Sound.

Enjoy.   I received about 20 emails today from folks looking for eclipse glasses...sorry, I don't know if any local stores have stock....many are sold out.

11 comments:

Dan said...

Hi Cliff,

Thanks for showing us the European Center model which covers the whole northwest of the United States. We're in Pocatello heading toward Yellowstone, and I have seen no less than 100 other Washington-licensed vehicles here in Idaho doing the same. We'll be keeping our fingers crossed for clear skies in Jackson Hole.

Bryan Black said...

Thanks for the update! You really are the best weather guru in the NW. You understand the nuances of Oregon's terrain so well.

Keeping fingers crossed that no little shortwaves sneak in and we will have the best view in the country for this as long as that high cirrus deck is over Portland and not Salem. This really could be an amazing confluence of events. Possible solar flare view during the eclipse too.

K.R. Burgess said...


Dr.Mass,

What are your thoughts of everyone being able to get,extended,ECMWF data?
https://weather.us/model-charts/euro

Mark Svendsen said...

I had just switched my plans from Western to Central Oregon because of the NWS forecaster discussions from yesterday:

National Weather Service Portland OR
926 PM PDT Fri Aug 18 2017
...
An increase of low-level moisture may allow more clouds to develop
inland early Monday morning than we previously thought, mainly along
the SW Washington and north Oregon Cascade foothills. There is a
chance that these clouds will expand with north winds steering them
south into parts of the Central Willamette Valley. These
possibilities are not fully in the forecast yet, but it is a
possibility, and has decreased the forecast confidence for clear
skies in the Willamette Valley during the time of the eclipse.

The main reason this possibility is not in the current forecast, is
that the weather pattern expected for Sunday night and Monday is
almost identical to what we had last night (Thursday night) and this
morning (Friday).
...
The best option for clear skies Monday morning continues to be east
of the Cascades pending areas near fires where smoke may be a
nuisance.

Unknown said...

My .02.
Folks will be semi unimpressed with a partial eclipse

It's go full or go home. Keep expectations nuetral and you'll be ok.

Bryan Duncan said...

Thank you for this. I, as well as many others, appreciate your expertise.

Joel said...

Smoke and clouds from Milli Fire, looking SE, near Sisters, OR. This was about 16:00 PT, Saturday:
https://1drv.ms/i/s!ApIjSVVFlOSOhN9Tc-_QBWtT_7CqMQ

Winds from the North are keeping the smoke out of the totality area for now.

Unknown said...

We have tickets for s trip up to the top of Msry's Peak Monday morning what do the models say?
Should we stay down in Corvallis instead of heading up the hill?

singliar said...

No eclipse glasses here, so as a fun project I'm building a camera obscura tomorrow (Sun) with the kids.

Michael Riordan said...

Joel is correct. We drove along US97 from Madras to Sunriver south of Bend on Early Saturday evening. Hazy but still fairly clear down to Redmond at edge of totality, with some high cirrus, but smoke from Milli fire was being blown SE by NW winds and completely covered Bend, which is out of totality. Woke up to clear skies this morning in Sunriver, but I see there now is a 6mph SW wind in Bend, which may blow smoke towards Madras and Redmond. Cliff, it would help if you could weigh in again with satellite photos today.

Bruce Kay said...

we await, breathlessly.....

https://www.youtube.com/watch?v=1qQEsVl0wkQ&feature=share