April 18, 2016

The Warmest April Day in Seattle History

We broke major records today.

The warmest April day on record at Seattle (89F).  The previous record was 85F.

The warmest April day in record at Olympia (88F).  Previous record was 87F.

The warmest April day on record at Bellingham (83F).  Previous record was 78F.

We tied the record number of days hitting 80F or more at Seattle (two).  We will beat that record tomorrow.  It was also the warmest day since last August.

A number of local observing sites got to 90F or above.  I mean a LOT of locations--here is the map:

Not impressed yet?   The temperature at 850 hPa (around 5000 ft) at Quillayute, on the WA coast, was an amazing 16.2C.  (see plot, with light red line showing the daily record, and blue dot showing today's temperature).

It was the second warmest temperature at that level ever observed during the first four months of the year.  The warmest?  Earlier this month, April 7th, with 16.6C.

It was so warm that we started getting weird mirage effects because of superheated air over cold water.  Here is a picture sent to me by Tony Nahra, showing a marvelous superior mirage (lofting of objects on the opposite shore). The only other alternative explanation is a new Amazon complex.  I like the mirage better.

Why so warm?  Big ridge over the western U.S. aloft.

At 850 hPa (about 5000 ft), there was southerly flow with enough of an easterly component to give some offshore flow that reduced the marine influence.

And weak pressure variations at the surface (so no cool northerlies like on April 7th).  The meteorological planets were aligned for heat.


  1. According to Accuweather's new 90 day forecasts, it is also going to be a long hot summer as well. Hopefully, it won't be as hot as last year and we can get much more rain this time.

  2. I wonder if this is really something to be "proud and impressed" about as you say? Heat and fire destroys when it continually presents itself in places where it doesn't have much of a history of being, such as the pacific northwest. It's to be pitied instead; really.. just anomalies?

  3. The science of meteorology seems so circular to me in its logic. Why is it hot? A ridge, guys. Why does a ridge make it hot and why is the ridge here now because it's obviously not usually? Just because the marine effect is being minimized why does this create hot air? All the causes of hot weather are described almost irrelevantly proximately e.g. "its a ridge". Is it fair to say there is absolutely no understanding of how or why low or high air masses ultimately form? Just basically describing patterns which correlates to some common condition which too often is passed off as understanding. Bottom line we have unusual conditions now. Why? (No this isnt implying anything about global warming.) Don't tell me we have unusual high pressure, tell me why.

  4. So this was the worst April day in Seattle history. Absolutely disgusting.

  5. My tomatoes, just 24 hours in the outside dirt, are proud of you, Cliff. Keep it up.

  6. tweti yard,
    I'll try to explain. When dry air descends it warms at a rate of 1C (1.8F) per 100 meters (328 feet). It's called the "dry adiabatic lapse rate". Air under a ridge usually descends and warms. So the already warm air above was descending and warming more.

    The surface RH today was quite low or dry. Dry air warms faster than wet air because there is less water vapor to heat. Water can hold a lot of heat.

    Surface winds were low so the surface air was not mixing in any cooler air.

    As an aside, high elevations like Denver, Colorado heat up and cool down quickly because the air at 5280 feet is much thinner than air at sea level. There is less air to heat so it takes less energy to heat it up.

    I hope that helps a little bit.

  7. "Heat and fire destroys when it continually presents itself in places where it doesn't have much of a history of being, such as the pacific northwest."

    The vast majority of climatic evidence would support the opposite of what you are claiming. Heat and fire are as much a mainstay of the PNW climate as rain in Seattle in January.

    Historically, the PNW is known for dry (and hot, on the east side) summers and wet (west side and Cascades) winters. In the case of Seattle, the dry summers are the reason our city founders constructed the large reservoirs and water systems we have today. Here is CM back in 2013 documenting all the reasons why our summers are spectacular, see point #5 in particular: "We have practically NO RAIN in the summer. Really. Seattle is drier than Phoenix in July." http://cliffmass.blogspot.com/2013/07/secret-revealed-northwest-has-best.html

    Regarding heat and fires: It is well documented that the forests, particularly on the east side of the Cascades, often burned unabated from June through October for generations before we ever got here. Here is an example from 1910 (actually recent in historical terms) of one that changed policy: The Big Blowup, burned 3 million acres and killed 85, with "hurricane" force winds: http://www.foresthistory.org/ASPNET/Policy/Fire/FamousFires/1910Fires.aspx

    Summer fires are a major part (actually an important part) of the forest life between the Cascades and the Rockies and have been for as long as we can document. What has changed is how we humans respond to them.

  8. Did Cliff say we should be "proud & impressed", marie? If so, I'm missing the reference to pride. He did suggest the conditions are impressive. While that word often has a positive connotation, one can be "impressed" simply by the remarkable nature of an event. That's the case here. I'm impressed by these mid-April temps in that they're unusual. But much as I
    enjoy warm summer evenings, I don't want to run in 80+ degree weather in spring!

  9. Tweti yard,
    Sorry, I missed the second part of your question.

    The general circulation of the planetary atmosphere creates ridges and troughs.

    In very general terms, warm air at the equator ascends, cools, moves poleward then descends. Where this air descends creates deserts like North Africa, The American southwest, the Australian outback. Cold air at the poles sinks and moves toward the equator.

    Earth rotates at almost a 1,000 miles per hour at the equator and almost 0 mph at the poles. As air moves south or north the ground underneath it is changing speed so the air appears to curve, it's called the coriolis effect. It causes the air to spin.

    As an aside, hurricanes can't form along the equator because there is not enough coriolis effect to make them spin. What you end up with is a bunch of thunderstorms or the ITZC (inter-tropical convergence zone). The ITZC follows the sun over the year as it moves north and south of the equator.

    If you look at satellite maps near the equator you will see this band of clouds and thunderstorms. This is where you have tropical rainforests: Brasil, central Africa, Indonesia. The ITZC moves roughly 22.5 degrees north and south of the equator. If you live at the equator, it will pass over you during the spring and autumn equinoxes or twice each year. The equatorial region has two rainy seasons and two dry seasons. Further from the equator, there is one rainy season and one dry season. The dry season has two parts, a cold dry period and a hot dry period. It's hottest just before the rains begins.

    Weather at the mid-latitudes or temperate region is the toughest place to forecast weather because air masses from the equator and the polar region are mixing. Which one dominates changes from week to week. It's relatively easy to forecast weather for places like Bangkok, Thailand or Barrow, Alaska but for Chicago...Forecasts get busted.

    There are planetary wind bands. The Polar Easterlies, the mid-latitude westerlies (where Seattle is) and the trade-winds. Seattle doesn't see much westerly wind because it lies in a valley, the Puget Sound, sandwiched between two mountain ranges. The surface wind is forced to move north or south or up and down this valley.

  10. If global warming has not yet happened in the Pacific Northwest, and if random variation accounts for the spate of temperature extremes in recent years, shouldn't we be experiencing roughly as many record low temperatures as we do record highs? But it seems that most of our recent temperature extremes have been on the high end.

    1. Global warming is a hoax. The Bible states clearly that God controls the weather.

  11. If the recent string of record high temperatures in the Pacific Northwest does not indicate that global warming is already happening in this region, why is it that in recent years nearly all of the temperature records have been on the high side? If the record temperatures are the result of random variation, shouldn't there be roughly as many record lows as record highs? And yet we hardly ever see record low temperatures around here anymore.

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  13. I guess that 1/2 degree celsius contributed by climate change was just enough to get us over the record, eh? :,)

  14. Rest easy folks, in six weeks June Gloom is coming to save the day (or month)!

  15. This is the first record heat day I can think of where my social media was eerily quiet about it. Normally when we get a warm, sunny day the whole city goes manic mode. I think in this case people are more uneasy/disturbed than anything. We are so very screwed.

  16. I am not a meteorologist and barely an amateur, but what I see in our summers and mild winters (nightly lows especially) I find very troubling. Professionals such as CM and those weather geeks in the know that follow him seem to adamantly claim there is no proof of sustained global warming man made or otherwise yet the physical evidence of such abounds globally! Are their heads really that deep in the sand, or are they being told not to admit it? We ARE so very screwed!

    1. It's interesting you admit to not being a meteorologist yet, in the same paragraph, claim to know more then an actual professional meteorologist.

  17. My recording thermometer showed 91.9 degrees, on the Bothell-Mill Creek Line, for yesterday's high. I guess a lot of the 90+ temps were in my area.

    It's the first time I ever saw 90+ in Washington in April.

    As an aside, there were seven of us that rode to work yesterday. I noticed only four bikes today including mine. I guess people figure it was TOO warm for biking! I myself find that the first intense heat is harder to take, but that later I sort of adapt. In this case I think it is partly psychological, because the heat is so out of the ordinary for the season.

  18. Not even 80 at the admiralty inlet.. Nice marine breeze in the afternoon. Tomato's sure are happy... Maybe should start the melons:)

  19. It is concerning to us all, well the ones that don't have their heads buried in the sand. I can't believe it was warmer in Seattle than Central Washington yesterday, but it was. We are also way above normal, but the heat is leaving come Friday. It is bizarre that this is happening after such a cold and wet winter. I do think climate change is affecting it, but I also think the heat being given up by the receding El Nino is driving these weird temps. If anybody is following, the edges of the El Nino are collapsing in temps. Only the 3 and 3.4 are over 1 C at this point, both around 1.3 or 1.2 C above normal. I do believe temps should regulate when ENSO Neutral happens, which isn't far off BTW. And if you look at temp charts, it is clear the north pacific is nowhere near the temperature as it was last year, a lot cooler. No blob this year I think at all. But remember, averages take in the highs and lows, so that 1 point whatever degrees the world is now over the 20th century does not mean just that temps will be about 1-2 degrees warmer, but that the chance is there for much warmer and some areas much cooler, it is random. But worse with climate change.

  20. Interesting comments, if I may use that word.

    I remember the time when unusually nice, warm days in April were greeted with enthusiasm. Just a simple, "my, this is an unusually fine week" kind of reaction.

    But now some people (as seen in some previous comments) are filled with anxiety and fear when the weather gets too nice, and start thinking that an Apocalyptic end is near.

    Personally, I'm enjoying the heck out of this week. Besides, we've got this thing called Thursday which will cool us back down if it gets too hot. Beautiful. One of the best parts about the PNW.

    My plants are absolutely going bonkers, but in a very, very good way.

  21. I know this is a weather blog and all, but jeez! Enjoy the nice weather, folks. Your beloved gloom will be back soon.


  22. Went SWIMMING today outside- at Martha Lake. First time ever in April. Absolutely unbelievable. I'd say the water was about 66 degrees. I was out twice about ten minutes.

  23. John Marshall, this past weak's heat wave was unseasonably warm for July. This wasn't your nice, run-of-the-mill spring break from the gloom and doom. April has brought unprecedented warmth that is obliterating all kinds of records. So excuse those of us that are lifting a concerned eyebrow. More people should be worried but instead they're ecstatic about how well their tomato gardens are doing. Talk about putting your head in the sand ( or dirt).

    Our weather feels broken and it has been that way for awhile now. Climate change isn't going to happen in 2050, which is often asserted on this site. It's happening now.

  24. You no longer have to be a professional meteorologist to know something just ain't right. All you have to do is sit outside and "feel the burn" of temps that are 30 degrees above average for April!

  25. I am interested in the research on increasing levels of CO2 in the atmosphere, not just the temperature issue.


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