April 23, 2023

The Upcoming Northwest Heatwave and Snowmelt

 It is now certain that our region (and the entire western U.S.) will experience a welcome spring "heatwave", with substantial snowmelt causing a surge in river levels.

The origin of the big change is the development of a major upper-level ridge along the West Coast later this week.  To illustrate, here are the forecast 500-hPa heights (think of it as pressure around 18,000 ft) for 5 AM Friday.  The red colors indicated heights/pressures well above normal).   This major ridge is associated with warmer-than-normal air that will rapidly sink, warming by compression.

The latest National Weather Service predictions for Seattle indicate temperatures reaching the mid-70s on Friday and Saturday.  Add another ten degrees for the Columbia Basin.

The recent UW WRF model forecast suggests that some places in the west will get into the 80s in western Washington, with Portland rising into the mid-80s.

Folks are going to go wild after one of the coolest springs in Northwest history.

And then there are the rivers.....

Our snowpack is now above normal and this warmth will cause substantial melting of snow, particularly over the eastern slopes of the Cascades.   Currently, the snowpack is above normal over most of Washington State.    Way above normal in Oregon.

The surge in temperatures will result in substantial snowmelt, with some rivers rising rapidly.   Consider the situation on the Yakima River at Umtahum (see below).  The river will rise to near-record levels for the date by next weekend.  Snowmelt inspired spring flooding was a tradition in the Northwest before the dams went in.

Folks forget that the dams save many lives and much property by storing the water from springtime snowmelt, something the anti-dam crowd should learn more about.


  1. What test data is there that shows how changes in CO2 concentration changes heat transfer? Has anyone used a Pirani gauge to measure heat transfer in air, N2, O2, CO2 and CH4?

    The Pirani gauge is a small device. What about creating a large test device (~100-ft in size) to measure the same heat transfer characteristics?


  2. Despite being the wettest April since that of 2019, April 2023 will end up with only ~60% of normal precip at BLI. By the end of the month, calendar year-to-date precip will be less than 50% of normal and comfortably in 1st place for driest first third of any calendar year on record there. The 2022-2023 water year-to-date will be nearly neck and neck with the driest such on record, that of 1993-1994, and now has a solid chance at displacing it by the end of September.

  3. "...something the anti-dam crowd should learn more about."

    Why would they do that, and wind up experiencing cognitive dissonance for the first time in their lives?

  4. I found it interesting that the Mt Baker ski area snowpack was 196" at PanDome day in recent days, just before the season closed (16' 4" is deep for that date). The season closes for market reasons, not snow-depth, by the way, if anyone's curious. ANYWAY, there is snow - even more this morning. So, yes, I'll be tracking river flow as I always do ...daily ...correlating temperature and precipitation to flow and water supply. This will continue to be a fascinating year in the headwaters.

  5. Hi Cliff,
    I'm interested in your comment about the "anti-dam crowd". I'm not sure who you mean, but to some extent I'm probably one of them. I think most people understand that dams provide flood control, regulate irrigation supply, provide hydropower, and other benefits. However, there is a big trade-off in terms of ecological river function. It's well established that dams can can decimate fish populations, destroy riparian forests, and drastically reduce the ecological services provided by functional floodplains. Probably most people would agree that these are desirable things for society, and that removing some dams to restore these functions is a net positive. Your comment sounded like you might have an axe to grind-do you have a problem with dam removal, or people that advocate for that?

    1. Northwest dams are a net positive. A big net positive. The hydropower is clean and critically needed. The NW used to have huge floods on the Columbia and other rivers....they killed people and did major environmental damage. No longer. They allow navigation far up river...fostering commerce and reducing need for fossil fuels. They provide critical water for huge agricultural productivity. Like apples, grapes, etc? Irrigation is important. Yes, we sacrificed some fish, but that is a small price to pay for huge benefits.

    2. Thanks for being clear about where you stand. I, along with plenty of other people, strongly disagree. "Some fish" drastically understates the damage. I guess we'll see where the ongoing debate lands for the large river hydrodams. I also think that the framing is very different for the thousands of smaller dams that litter riverscapes, like the Elwha used to.

    3. I think a balanced view of the pros and con of big dams inevitably indicate that the positives far outweigh the negatives. That is my point. For those concerned about climate change, dams are a big positive. For feeding people, a big positive. For saving lives, a big positive. There has been a lot of mitigation for fish runs...and more is possible. Work on that rather than destroy the dams.

    4. it is not just fish, dams destroy riparian habitats and everyone who lives in them. this is well documented, saving lives? what about killing lives. fish and frogs have lives too!

  6. Umtanum Creek meets the Yakima River here:
    46.855691, -120.484456

  7. Nice try Cliff. All dams eventually will fill in with sediment behind the dam. Long range thinking should evolve to restoring rivers without some dams and removing infrastructure in floodplains. This would over time restore ground water basins for sustained use instead of over allocation as all western states have done. How people fit in with ecosystems is the future, not our old out dated control mother nature thinking.

    1. aaaaa, sediment can be removed behind dams....already being done. I am afraid that mankind can not turn back the clock on our modification of the environment. You like water, power, and food? You are stuck with the dams/reservoirs...there is no way around that. To support human populations we need technology....sorry....cm


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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