January 30, 2018

Don't Give Up in Watching Tomorrow Morning's Eclilpse!

In only a few hours, a very special total eclipse of the moon will begin.  That is a Supermoon, Blue Moon, Total Lunar Eclipse.    The moon is now a supermoon, larger than normal because of its relative close proximity to the Earth.  And it is a blue moon, because we will enjoy two full moons this month (the definition of a blue moon).  As shown by the table below, the total eclipse will run from 4:51 AM through 6:07 AM.

There has been a lot of talk about clouds ruining the viewing, but I think there is a real chance for those of us in Puget Sound to get a glimpse of the total eclipse sometime during totality.

We are fortunate to have westerly flow over the area, which means that central and southern Puget Sound  probably will be in the rain/cloud shadow of the Olympics.   The 8:30 PM weather radar imagery tonight  shows the rainshadow over Puget Sound clearly (see below).

And the infrared satellite imagery at roughly the same time, shows the approaching showers, but some breaks over the south Sound.  Not good over the windward (western) slopes of the Cascades, but much better over the Kitsap Peninsula.

The UW WRF model produces a cloud image that is mean to simulate what a satellite image would look like.  The forecast for 4 AM shows a mixed band over Puget Sound (there are breaks) and very good conditions east of the Cascade crest.  So if you really want to view the eclipse, head over to Ellensburg.

As I have explained a number of times in this blog, one should never look at a single forecast, but rather make use of an ensemble of many prediction to get an idea of probabilities.  Here is an ensemble of cloud forecasts for 4 AM tomorrow.  Some of the ensemble members have clouds, some don't.  Some have a veil of a thin mid-level deck of clouds.

Based on all these forecasts, I suspect that the odds of seeing the eclipse from Seattle to Olympia between 4 and 6 AM is around 50-50.    Good enough to be worth getting up to see an astronomical spectacle that won't be visible for a very, very long time.


  1. Cliff, on the subject of cloud cover, might you be able to get a blog post out of this as it compares to anywhere in the PNW, assuming such data is recorded? I know this area has a reputation for being overcast in the winter months, but 6 whole minutes over an entire month seems beyond unlikely. It's never THAT consistent here, at least that I've noticed. Even Moscow's average for December of 18 hours feels much lower than a PNW December average.


  2. If you're into two full moons in one of our calendar months, might as well go look at a calendar -- visibility is guaranteed and the moon doesn't care.

    I also am curious whether people can see a supermoon versus a plain moon in a blind A/B test. I'd think it would be swamped by the moon/horizon illusion.

    Lunar eclipses are fun, though, and they get unfairly shorted on public attention due to being common, so if people see a lunar eclipse that's great.

  3. well, technically we have a partial lunar eclipse 90+% of every 28 days.... :-)

  4. It was perfectly visible today over here in Spokane.It looked exactly like the Super Smoked Out full moon of last September.

  5. Oh, the viewing conditions this morning were so, so marginal. I and those who watched it with me were teased to death.

    The deck was scudding overhead fairly quickly, with healthy-looking holes appearing every so often, but the holes never did line up perfectly with the eclipsed Moon. I kept scanning with 10x50 binocs hoping to get lucky, and I did get one faint glimpse of a round orange shape, but it disappeared.

    By the time the Moon emerged from totality at 6:08, we were all socked in. I think I've now been clouded out four times attempting to view lunar eclipses from Richmond Beach. I just can't be bothered to drive over a pass to see one of these things, when another will be coming by within a few years. Rare conjunctions, yes. A total solar eclipse, absolutely. A bright comet or supernova, I'm there yesterday.

    But a lowly lunar eclipse? I didn't even want to drive to Mt. Vernon to get to the center of the rain shadow.

  6. Because it's the 2nd full moon of the month, and it's a super moon, and there's an eclipse, I think the occasion calls for a special name. How about 'moon indigo'?

  7. didn't see anything this time around here in Kirkland. Just a bunch of clouds

  8. You called it beautifully for Bellingham! The clouds parted at around 5:10 AM and for roughly 20 minutes the eclipsed moon was visible and gorgeous. Like so many things in the NW, the moon was all the more beautiful when framed by the clouds moving by.


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