December 31, 2018

Fogs Engulfs Seattle

There was a stunning series of images this morning from the Space Needle panocam as inland fog pushed over Seattle.

It was clear this morning around sunrise over downtown Seattle, but a shallow fog bank loomed to the southeast (picture below for 7:30 AM).

By 8:30 AM the fog had begun to move across downtown.

And  by 10 AM the city was well covered, with only the top of the Columbia Center extending above the cloud deck.

At 11:30 AM,  the fog had begun to thin (see below)

But looking towards Queen Anne hill, one could see a wonderful example of a dramatic optical effect--a glory- centered at the top of the shadow of the Space Needle.  Note the circular array of colors caused by dispersion effects of diffraction.  Magnificent.

The fog bank also moved in at the NOAA facility near Magnuson Park in NE Seattle and the vertical sounder there showed how the temperature structure was altered by the fog bank (see plot below of temperature with height a various times).  At 1200 and 1300 UTC (4 and 5 AM PST), temperatures warmed with height in the lowest 100 meters (cyan and yellow lines).  But after the fog moved in (black, red and green lines), there was a large cool down in the lowest 300 meters (about 600 ft).   Not much change above that. 
Finally, the fog was evident in the 10:45 AM image from the new GOES-17 weather satellite (see below).  Fog extended east, north and south along the river valleys, but ended at the Sound.  A wonderful morning to hike up to the top of Cougar or Tiger Mountains and look down on the clouds below.  Great visibility aloft.  And the fog won't last...much will burn off during the next few hours.

1 comment:

  1. We are having lightning whatcom howdy, yesterday and this morning driving to work Thursday, that sure is interesting


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