Eclipse Weather Update & Thoughts from 26-Time Eclipse Chaser

August 14, 2017

9:30pm

24 hours have passed and now we’re less than 7 days from our once-in-a-lifetime eclipse in Oregon.  There have been encouraging trends in our long-range forecast models.

Eclipse Forecast 1

The GFS model has now come around and decided there will NOT be a cold upper-level trough swinging through the Pacific Northwest next Monday.  The ECMWF and GEM models have not been showing that anyway, so that trend is very good.  That’s point #1 on the graphic above.  One more reason you shouldn’t make a forecast 2 weeks out calling for a rainy and cloudy day!

Cloud Cover?

Assuming there is no organized weather system nearby, that leaves either: A) Scattered high clouds overhead, or B) Low morning stratus clouds somewhere between the coastline and west slopes of the Cascades as possible weather that could block eclipse viewing.

The GFS shows almost no cloud cover under high pressure and typical summertime weather.

GFS Clouds Rain

The ECMWF shows thin high clouds from an approaching system, although the contouring on this graphic makes that look a bit “intense”.

ECMWF_CLOUD_RAIN

Neither implies significant marine cloud cover west of the Cascades, but THIS is the one weather feature that can easily change in the last 1-3 days before the event.

By the way, one of our regular readers just happens to be a HARDCORE eclipse chaser.  I assume Mike won’t mind me re-posting his info.  This is great stuff.  I hadn’t considered the possibility of low clouds re-developing during the eclipse in the moist coastal atmosphere as temps drop:

This is my 26th eclipse trip (16 TSEs seen, 6 annulars, 3 missed because of rain, clouds,and yes, wind). I’ve been using Jay Anderson (Environment Canada, retired meteorologist, who saved my eclipse in Australia by telling me to get off shore) and his blog eclipsophile, which already is looking at the 2 Jul 2019 eclipse. I have access to several other pages there, too, and can attest to what Mark has said regarding the uselessness of predicting cloudiness this far out. A couple of thoughts:

1. High clouds don’t ruin an eclipse; very few of my total viewings were in a clear sky. Puffy cumulus clouds drive you crazy, because you don’t know what they will do. Stratus, of course, is awful. Totally clear is rare; if you get it enjoy.

2. As the atmosphere cools during the partial phases, clouds may form. Then again, any convection (looking unlikely) gets shut off. The most I’ve seen the temp drop is 11 C (20 F). With moderately high dew points, the drop will probably be less.

3. Smoke is likely to be a concern for this eclipse, but the haze we had last week would have been OK, just not optimal, for viewing. I was camped out in northern Washington a week before, and you could barely see the Sun at all.

4. That said, I will be north of Ontario, about 1300 meters if I can (4200′), and have bail out plans in both directions, although it would have to be a major difference to consider going a long distance on eclipse AM. It wouldn’t be the first time. Hope all the eclipse virgins get to see it.

I’ve give a lot of talks from here to Prairie City, and tell people three things:

1. Totality is worth seeing. (Recent TED talk worth viewing).

2. Be safe, both in getting to the path and protecting your eyes.

3. If it’s your first, don’t take pictures. You’ll see better ones, mine have gathered dust, and every second spent looking at the camera takes away from the experience. This may be the only one you ever see. Enjoy it!