July 01, 2017

The August 21st Total Eclipse: The Meteorology is Favorable

On Monday, August 21st, there will be an extraordinary astronomical event:  a total eclipse of the sun will cross our region, and specifically northern Oregon.

The map below shows the area of totality (between the two lines), which will only last for roughly 2 minutes.  Totality will occur around 10:15 AM along the Oregon coast and about 11:30 AM at the eastern border with Idaho.

For the big population centers around Puget Sound and Portland, the most convenient locations will be between Salem and Albany, Oregon...less than an hours drive from Portland and four hours from Seattle.  Rooms are impossible to get east of the Cascades, but some are still available around Salem.

The big issue, of course, is weather.  But I think the chances, based on climatology, are quite favorable in the Willamette Valley on that date.  And I will give you some tips on being meteorologically adaptive.

August is generally a warm, dry month in Salem, Oregon.  In fact, August is the driest month of the year there.
The risk of a major weather system coming in during that day is very slight.  The main threat is marine cloudiness, which is a far more serious issue for those hoping to see the eclipse along the coast.  The coastal mountains block a lot of the low clouds and the Willamette Valley is somewhat isolated from the coastal influence because there is no wide conduit from the ocean (like Seattle has with the Strait of Juan de Fuca and the Chehalis Gap).

To get an idea of the threat, I took a look at the visible satellite pictures at 11 AM on August 21st for the last 15 years.  Here is what I found around Salem, Oregon in terms of cloudiness:
Clear 50%, 43% Partly Cloudy, 7% Cloudy.

The partly cloudy days either had some thin high clouds or some scattered low clouds.  You would still be able to experience the eclipse.  The cloudy day had a continuous low cloud layer.    If I was in Salem, Oregon under such conditions, I would head up into the Cascades on routes 22 or 29 until I got above the low clouds (see map).

Eastern Oregon is obviously another possibility, with less chance of clouds.  But travel there is much longer, there are no rooms available, and the limited roads almost guarantee a huge traffic jam there.  And that region has another problem:  the potential for smoke, which has been an issue on that date in the past (see example from 2012).

NOAA, using airport stations, has provided a map of probability of clear conditions on August 21st (see below).  The suggest 60-80% chance in Salem and 80-100% east of the Cascade crest.

In the days before the event we should have good forecasts to work with, so stay tuned as we get closer in time.


  1. I went for a campground in the middle of Eastern Oregon. Didn't think about the possibility of smoke though!

  2. Another scenario that could spoil eclipse viewing,especially in Eastern Oregon and Idaho,would be the possibility of the remnants of a tropical storm or depression moving northward into that area from Baja California or Arizona.August is the monsoon season,so there is a chance of unfavorable conditions in that regard.

  3. Dr. Mass, let me tell you why my family is specifically avoiding the Willamette Valley for the eclipse.

    If everything goes well, Salem or Corvallis will be a fine place to view the eclipse. But if things go sideways with a big marine push that spills over the coast range, watch out! Totality is just after 10:15 am, which doesn't give the Sun much time to burn through a cloud deck, particularly when weakened by the Moon getting in the way of the solar disk. So, if it dawns cloudy, it will almost certainly remain cloudy for totality.

    But the bigger problem is transportation. The Willamette Valley will be a magnet for road trippers coming from as far away as Vancouver and San Francisco. The place will be absolutely packed. I-5 is familiar to people while eastern Oregon seems like too much work. Expend a little more effort and get away from the horde.

    Where I don't want to be at 7 am on the morning of the eclipse is in bumper to bumper traffic on one of the few passes over the Cascades, trying to escape Pacific clouds along with 25,000 of my newest friends.

    Yes, eastern Oregon has fewer roads, but clear skies are virtually assured there. The only real hazard is smoke, but people can predict and avoid fire more easily than they can avoid a horrible layer of marine stratus.

    Finally, US 26 runs east/west inside the path of totality all the way from Madras to John Day. Veteran eclipse chasers will tell you that a highway running inside the path of totality through a desert is the best you can do on land to ensure success. If there's fire, thunderstorms, etc., all you need to do is to put the pedal to the metal that morning and find somewhere new to set up.

    In summary, I would highly recommend that eclipse chasers plan to be somewhere between Madras, OR and Casper, WY for the best chance of success. You might succeed elsewhere, but it's a long wait to the next eclipse if you get trapped behind slow Oregon drivers in Albany.

  4. Insofar as eclipses crossing the continental US, it's not a long wait until the next eclipse which crosses the US in April 2024 from southern Texas to northern New England.

  5. Cliff, the eclipse ends at 10:30 PDT at the border with Idaho (11:30 MDT)

  6. Dan, it sounds like you're pretty experienced, maybe you can help me plan--we have reservations in Bend, so will need to drive a bit to reach the path of totality. Do you expect that would be a big problem? When would you recommend leaving to avoid getting stuck in traffic? Thanks for any suggestions you have.

  7. For the traveler staying in Bend, congratulations -- Bend is a great place to stay the night before. I don't have much advice to offer, just this:

    1. Know exactly what the weather is doing a couple days before the eclipse, and keep checking every 12 hours. If there is fire, then you also need to know where the smoke is and the potential for winds to change. Always get upwind of a fire for better visibility.

    2. You'll have more choices the earlier you leave that morning. Personally, I would eat a hearty breakfast and be on the road no later than 6:30. The partial phase starts just after 9, and ideally you'll find a great place by then.

    3. Do not trap yourself anywhere. I understand the appeal of wanting to see the eclipse at a huge event like the one being held in Madras, but I would personally choose to be just off US 26 somewhere in the desert. That way, I could respond to any changes by hopping in the car. Also to that point, don't take equipment with long setup/breakdown times like an equatorial-mounted telescope. Get regular binoculars fitted with solar filters over the objective lenses, paper eclipse glasses for everyone in your party, and you're good to go. (*Test* your setup thoroughly with the regular Sun to make sure everything works while filters are still available for purchase.)

    **3a. I'm going to take an old Rand McNally Road Atlas and mark it up carefully with the path of totality and a few timings so that I have a paper reference at the ready. Do NOT count on cell phones for navigation or other time-critical information. Expect cell towers to be either sparse or overtaxed.

    4. Consider bodily needs. Make sure that you have plenty of cold drinks and food for your party, and have a way for everyone to go to the bathroom away from town. Folding chairs, sunscreen and perhaps an umbrella might be helpful.

    5. Finally, have at least one watch synchronized to time.gov. If you have great luck you might not need this, but if you're fleeing clouds on a desert road, it will be invaluable.

    Good luck and enjoy the lunar shadow!

  8. Pierre, that's easy for you to say. I'm old enough that I don't buy green bananas anymore!

    For those staying in Bend, from what I've read, it's best NOT to count on getting to the path of totality the morning of the eclipse.

  9. Dan is right about taking a map and marking it up. A delorme atlas will have exceptional detail of side roads and back roads. Far eastern Oregon is glorious by itself and there are ample places to pull out and park.

  10. Great words of wisdom from Dan. I've see 2 TSEs ('79 Oregon and '91 Kona), and on both of them, we ended up having to put the pedal to the metal when the eclipse was partial due to clouds.

    I would also caution the Day-tripper from Puget Sound to err on the side of "way, way, way too early". I suspect that I-5 southbound will be pretty much bumper-to-bumper from Olympia to Salem from 5am onward. If you're counting on that normal 3 hours to Portland drive, you will likely be disappointed at 10am when you're still in traffic and nowhere near the northern limit of totality.

    And the path of totality matters. Even I f you are in a 99.9% area, you will NOT see and experience the wonderments of totality. You absolutely MUST be in the path of totality. It's literally the difference between day and night, so don't waste this opportunity. Get into the path.

  11. The officials in Wheeler County and surrounding counties in Oregon are planning to close the roads leading into the Madras area early in the day of the eclipse, to prevent cars from gridlocking the roads. Make sure you have a full tank of gas before approaching the area, so you do not run out of gas when stuck in traffic. Plan to arrive in the area well before dawn, because they have no idea when the roads will be closed to incoming traffic. Bring food, water, a way to go to the bathroom, and sleeping bags. After the eclipse, plan to remain in place for at least 4 hours until the exiting traffic dies down. Remember, full tank of gas! If you bring jerry cans of gas, you will be able to sell them at a huge profit to people who did not plan ahead.

  12. If you pull off to the side of the road to park and watch the eclipse, do NOT pull into an area with grass or other vegetation. Only pull off onto gravel or a paved surface. Modern cars all have catalytic converters on the bottom, which are very hot and will cause a fire if you drive over dry grass or other combustible vegetation. If a fire does start, it would be deadly since the roads will be so packed that cars and people will be unable to escape.

  13. Can't wait. Then planning for years. We are heading east. That where we are sure to be pretty far away from any potential clouds and crowds. Dan's advice is very good.

    Lastly remember to caution those who may not be as educated about the TSEa as those reading this blog post. There's no such thing as almost seeing it. You are either in the Umbra or you missed a massive chance to see one of the most amazing things human eyes can ever witness. Get the to the shadow.

  14. Just over 6 weeks away!!

    Were leaving Tacoma On thursday night for the Madras area with the travel trailer in tow, fully stocked w/food, beverages, water and extra fuel for the generator and truck, to stay in a big campground with 2000 or so of our new camp friends. A great time should be had by all. Looking foward to seeing the show the heavens are going to put on for us.

  15. We're staying near Pendleton, then driving down early-early toward John Day. Probably will hit the road around 4:00am, with a full tank, and find somewhere to park within totality.

  16. Jackson Hole, Jackson Hole, Jackson Hole --- the place to go!

  17. As much as I want to see the event, the information from inn keepers, forest service and highway patrol in the path of totality tell me it will be a zoo. If only I had rented a houseboat on Lake Billy Chinook in time!

  18. Cliff, who is going to be the source for hourly weather updates inside of 24 hours to the event? Who will be on the ball with accurate info and satellite pics?


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