Tuesday, July 23, 2013

Less Fog in Bellingham

I started a post that I titled "Fog Free Bellingham", but this morning let me down as Bellingham turned foggy after I woke up this morning.

GOES WEST at 8:00 this morning

As can readily be seen, the Pacific Ocean off our coast is foggy. With an onshore push of air the fog rolls in through the low gaps south of the Olympics, flows up the Columbia River and into the Strait of Juan de Fuca. This morning it partly filled into Puget Sound and had pushed up into the mountain valleys of the Cascades. By 11 this morning the fog was gone from all but the outer coast.

GOES WEST at 11:45 this morning

Yesterday the surge of fog was thicker and lingered longer, but Bellingham was fog free.

GOES WEST July 22, 2013, 12:00 pm

Cliff Mass had a nice write up on why the fog was so thick and wet last Saturday in Puget Sound, July 20, 2013 (cliffmass.blogspot). But Bellingham was mostly fog free Saturday. 

GOES WEST image via Cliff Mass

Both the Saturday image via Dr. Mass and the one I pulled up from Monday show Bellingham (my town) fog free. I left off labeling the images assuming the reader will know or can figure out where Bellingham is.

Bellingham being fog free in the summer is one of the peculiar micro climates of western Washington. The stratus clouds push in during the evening and night and filled in essentially the entire western Washington low land except Bellingham. This is commonly the case for Bellingham (but not this morning). While walking to work on Monday I could see the fog bank just to the west of town, but we were sunny all day while to the south the lowlands were in the gloom. 

I suspect Bellingham's less frequent fog has to do with the local topography. There is essentially a mountain range extending from the Cascades out into the San Juan Islands just south and west of Bellingham. The range is by no means a solid mountain front, and the peaks are modest in height compared to the Cascades and Olympics, but they are high enough to distrupt the low level air flow. And even when the fog does penetrate into Bellingham, Bellingham is on the edge of the fog with the nearby slopes fog free and thus the fog burns off in Bellingham sooner than cities to the south that are further distance from the fog edge.

I have not done a statistical analyses of this observation. But have experienced the difference often enough to be convinced. The fog issue is of some note to my work. I will sometimes fly to the San Juan Islands, and learned from experience to check the weather before heading to the airport as in the summer the airports in the San Juans will be fogged in while the sun shines in Bellingham. And even between downtown Bellingham and the airport (where the Bellingham weather station is located) there is often a fog bank as the airport is located out away from the Chuckanut Range that abuts the rest of Bellingham.

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