July 16, 2021

Why are Northwest Summers So Dry? And a Cool Forecast for the Next Week

Midsummers in the Pacific Northwest are dry on average.

Really dry.  Drier than Phoenix.  In my podcast, I tell you why.

And then there is the forecast for this weekend and next week.   As expected this time of the year, it will be dry.  

But it will also be cool, as a trough of low pressure parks of our coast, while high pressure builds inland. (see image for Sunday morning).  The results will be onshore flow west of the Cascade crest, with low clouds in the morning, but sun during the afternoon most days.

Upper level (500hPa, about 18,000 ft) heights (like pressure) at 8 AM Sunday morning.  A deep low is west of BC and a ridge is found just west of the Rockies.

Worried about smoke?  Actually, this pattern will be favorable for western Washington and Oregon, with BC, eastern WA, and CA smoke pushed eastward.  

To hear the full story, listen to my podcast below or select your preferred streaming service

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  1. Cliff, could you post a graph showing how the NW summer precipitation has been trending in the last 40 years or so? I think I have said this before: When I starting in the 70's, and through the 80's, I think about 1 in 3-4 hikes were rained out. It seems like there was usually some rain every month even in summer. Not so now: I don't have hard data to back it up but it really seems like now it basically doesn't rain from about mid June to mid September. Which could explain the big increase in forest fires.

    1. It's interesting how our minds play tricks on us over time. People claim it's hotter, or wetter, or dryer than they remember it being. But actually, it isn't any of those things. Of course now people are certain their inclinations are all true because of "Climate Change". We are a funny species.

    2. We haven’t had a big increase in forest fires in western WA or near the Cascade Crest. It does seem like we’ve had a lot of grass/mixed grass and dry forest fires in the Methow and San Poil watersheds.

  2. Ansel... just plotted it up. Actually very little trend. The plot is here"

  3. anything to do with cool ocean and Puget Sound having low evaporation and cool inland not reaching dewpoint?


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