November 08, 2019

Will You See the Transit of Mercury on Monday Morning?

A relatively unusual astronomical event will take place at sunrise (here in the Northwest) on Monday morning:  a transit of Mercury across the Sun.

The last time Mercury cross the sun was in 2016, and the next time will be 2032.  Here in Seattle, the transit will begin at 7:08 AM (sunrise), be at the midpoint at 7:20 AM, and end at 10:04 AM.  Total duration will be 2 hour, 56 minutes and the transit will be already started when the sun rises.

The big question is clouds.   Let's examine this issue by looking at the UW WRF cloud forecast for 7 AM Monday morning.  The model is predicting a middle/higher level cloud deck, albeit thin over our region (the gray color).

A simulated infrared satellite image, based on the model output, is shown below. Thin high clouds.

The bottom line is that viewing of the transit is uncertain.  If the cloud veil is thin enough, perhaps.   But the transit is a subtle feature--a small dot moving across sun's disk.

And we have another nail biter tonight.   If it doesn't rain before midnight, Seattle will tie the record for dry days in November (14th).  But the radar shows the frontal precipitation approaching offshore at 9 PM (see below).  Fingers crossed.


  1. Cliff, hope is not lost despite it being November. I managed to view the November 2006 Mercury transit during my lunch break in Redmond. I used 10x50 binocs fitted with solar filters and clearly saw the small round dot that wasn't a sunspot.

  2. Picked up 0.09" of precip so far today in NW Bellingham. First precip since 10/25.

  3. Thanks for the heads up, Cliff. I will be watching assuming conditions are right.

  4. cliff, i'm 14 and love weather haha i check you're blog everyday in my class because im that into i. I wait for new updates every day but most of all you inspired me to start my own blogs, there not good but not bad i'm waiting for you to say*we are getting snow* thats all i want to hear love the blogs cliff!! from: judah brediger, Lake stevens washington.

  5. Jonathan Doe and others ... "location, location, location." Precip was reported in the Whatcom-Belingham area on both 10/26 and 10/27. (Just saying) Do you keep an eye on the CoCoRaHS daily precipitation maps? They do span 24-hr periods, most reports ~7 am. Select place and date, and hit "Get Map"


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