Tuesday, June 18, 2019

A Wetter than Normal Period Ahead

As suggested by extended forecasts a week ago, we are now going into a wetter than normal period over the Northwest.  The latest European Center high-resolution forecast of cumulative precipitation over the next week shows .3-1 inch over the lowlands of western Washington and much more over the northern Cascades and southern B.C.

The European Center forecast highs and lows, as well as precipitation, for Seattle over the next two weeks indicates no heat waves, with temperatures in the mid to upper 60s on many of the days.

Of course, as I have stressed in many blogs, one always wants to look at an ensemble of many forecasts, each a little different, to gauge the uncertainty in the forecasts.  Thus, below you find the cumulative precipitation forecasts for Seattle from the 51 member European Center ensemble for the next 10 days.  ALL of them are going for precipitation, with the average of the ensembles producing more rain than the high-resolution simulation shown above.    I would get an umbrella handy.


The reason for these wet periods is a breakdown in the ridge of high pressure and the predicted arrival of upper level troughs into our region.  For example, at 2 AM Thursday, an impressive trough will be moving into Washington State (see below).


2 AM Monday?  Another trough.


What about the rest of the summer?   Extended forecast skill is never great, but consider that the latest European Center 46-day forecast through early August, predicts wetter than normal conditions over our region and much of the U.S. (see below).  Importantly, also for British Columbia and Alberta.

 And the latest international model ensemble forecast of the precipitation anomaly (difference from normal) for July through September indicates normal to above normal precipitation.


 Rain and cooler temperature this time of the year is of substantial value in reducing the risk of wildfires and smoke, since our fire season ends in three months (mid-September).  Right now there are no major fires over the region and number/acreage of fires for the Northwest and the nation have been below normal.  Good news.

Don't get me wrong--there will be fires--but the situation during the next few weeks is favorable for pushing the wildfire season out in time.  And it will also reduce water usage and help fill our streams.


22 comments:

  1. Why do we always rely on European models for our region than the U.S models?

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  2. I think there's going to be a heat wave first half of July.

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  3. Latest 06z GFS looks insane for BC

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  4. Rain through the rest of June? No worries; I predict an extended period of warm weather will arrive right on time Monday. Monday, July 8th to be exact.

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  5. Sounds perfect! I would LOVE a little more summer rain than usual around here. (Usual being none, except on the 4th of July of course.) Less time watering the garden, and better still, no apocalyptic smoky air.

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  6. A few months ago the Seattle Times predicted a severe drought.

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  7. thomas, the Seattle Times didn't predict it. The USDA did, and the Times reported it.

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  8. Hopefully it will dump rain in the North Cascades.There has been some recent spotty thunder storms but the mountains need a good soak.

    What little snow we had this year is fading fast and the high hiking is opening up faster than usual.

    Chris H.
    Heli-free North Cascades

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  9. Ugh. What a craptastic 'summer' we're apparently going to have. More like a severely extended Spring. :P

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  10. Hi Cliff,

    This is off-topic, but I was wondering if you knew anything about the modeling behind the Rainier Recreational Forecast at https://a.atmos.washington.edu/data/rainier_report.html. In particular, is it using a hydrostatic model and what is the grid spacing? I can't find any information on how this model is generated, if it's just derived from GFS or something else.

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  11. Dr Mass, do you think the more active than normal Typhoon season that is predicted for the NW Pacific could lead to a late August or September heavy rain event here?

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  12. Hi from Winthrop. Thanks Cliff for the good news. While the rain is welcome and will likely push out the start of fire season, I suspect it isn't going to much help the river flow situation. The okanogan river river flow as measured at Mallot (USGS station 12443200) is at an all time low for this time of year (2350 cfs as compared to the previous minimum of 2630 cfs and a median of 8060 cfs). The Methow river flow as measured at Pateros (near the Columbia river, USGS station 12449950) is a little better (1890 cfs vs the minimum of 1240 cfs and a median flow of 4830 cfs).
    The snowpack is largely gone and the flow has started its summer decline to low levels. The recent rain caused a slight bump in flow but based on past behavior this is a short term reprieve. The bottom line is that I still think the state was correct in designating drought emergency for Okanogan county.

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  13. Uh-oh, does this mean that Jay Inslee will declare a Global Warming Flood Emergency?

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  14. Deek - We had an early melt-out this year. It has happened many times before. We did not used to declare emergencies over them.

    We had early melt-outs in every measured decade before this, and we used to recognize these anomalies for what they were and not panic as if they were never before seen events. Our grandparents lived through them, and our parents, and now us. In fact, my great-grandparents lost their orchard in Eastern Washington in a drought in the 20's, a very serious drought the likes of which we have not seen here in decades. They would laugh at a "drought emergency" in a year with this much water.

    To compare an early melt-out year in mid-June to the (flow) mean is the same as comparing a late melt-out year to the mean in early July, it just tells you what you already know. But neither one matters as the summer progresses; the vast majority of Cascade snowpack - in an early year or a late year - is gone by early July. Knowing that, can you please tell us why this July/August/Sept period will be at emergency levels - i.e implying vastly lower than normal flow - in the Methow?

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  15. Inslee's "drought emergency" is actually about federal rules involving support for farmers, not any individual emergency. Our national support for farmers is dismal (sink or swim without any life preserver, but with heavy boots). This state is more supportive of its farmers than many. Farming is not profitable most years. This year bodes to be a loser for most of the big farms (a lot in eastern WA, but here also. True for small farms as well.
    Farms depend on rain to provide the soil moisture for sprouting and growing plants. And we really don't need to risk established orchards & vineyards, as well as ranches that raise the livestock for those who eat meat. It takes over a year (2 is better) to raise a steer to butcher.

    We are definitely in drought conditions in western WA also. Things are really dry. Look at the fire risk today. The soil is dust-dry. Those who depend on wells are seeing ground water levels dropping. We have to preserve river flows for the salmon and others, and rivers are reducing to streams because of lack of snow in the Cascades.

    If your great-grandparents and grandparents were here, they might be appreciative of our governor's move. They might not have to face losing their farm.

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  16. Cliff,

    The rain and cooler temps are working well for me. It's nice to have comfortable weather and I enjoy the rain.

    Of course, any weather conditions that reduce wildfire risk to people and their property are welcome.

    I was interested to see CA PC&E filing for bankruptcy regarding Paradise and other local wildfire damages caused by their equipment, etc. It doesn't include people's homes or other losses, but it seems to focus on damaged infrastructure. We will see how the court sorts this out. These types of decisions will likely set precedent for wildfire and perhaps other natural events that cause destruction.




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  17. @Sue Willard, there is no "drought emergency" anywhere in the state. Some parts are dry and others are not. You know, like most years?

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  18. re sunsnow12: can you please tell us why this July/August/Sept period will be at emergency levels - i.e implying vastly lower than normal flow - in the Methow?

    The Methow valley generally relies on the snow pack to store water for the summer as we have just a very small number of small reservoirs. Once the snow pack is gone the flow comes from draining lakes, ponds and groundwater. Every summer the flow in the rivers decreases in what looks like an exponential decay to a very low level in August/Sept. The profile of this decay is fairly reproducible from year to year with the starting point determined by the state of the snowpack. If anyone is interested, you can check the stream flow (and historical data) for a large number of streams in Washington state at the USGS website: https://waterdata.usgs.gov/wa/nwis/current/?type=flow

    One might reasonably expect that summer rain would impact the stream flows but in practice the impact is fairly low. We will see a bump in flow after a major rain but it is short lived (days). I can also add that major rains in the summer in the Methow and Chewuch river basins during the summer are not common. This is part of the reason why much of the Pasayten wilderness and surrounding forest has burned in the last 20 years.

    At this point I can assure you the snowpack is essentially gone in our river basins. I was at Harts pass last weekend and there are just a few patches of snow left. The Harts pass snotel indicates the snow water equivalent was zero at least 2 weeks ago (about June 8). This is about 2 weeks earlier than the 30 year median and at least 4 weeks earlier than the 30 year average.

    Since I am on an irrigation system that draws water from the Chewuch river which flows south into the Methow north of winthrop, I routinely monitor the river flow. At this point the flow is below the 25th percentile; the current flow is 380 cfs and the 25th percentile is 508 cfs. The stream flow began the summer decline from a low level on or about June 1. In fact the water situation on the Chewuch appears to be very comparable to the 2015 water year which you may recall was a very dry year.

    The main issue is that if stream flows drop to far, the irrigation systems are subject to various flow restrictions or complete shutdown to protect the fish (endangered and threatened species). I tend to agree that the term emergency is a little over done. However for those that depend on irrigation water the situation certainly is cause for anxiety. If the water is shut off or curtailed, it happens during August/September just when water is most needed. For those impacted by loss of water, this is an emergency.

    I hope this explanation helps.

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  19. Sue - please see the not one... but two... posts Cliff just did on this subject. He objectively showed, using multiple data points, that you are not correct when you say "we are definitely in drought conditions in western WA". So if you disagree, please provide actual data - not press reports or releases from organizations that have a vested interest in making these fear-based claims.

    Deek - I get it. My question is: why does an early melt-out affect stream flows in July/August/Sept? Every year - early melt-out or late melt-out - the flow in the Methow, as the summer progresses, drops substantially due to the vast majority of snow having melted. Are you claiming there is low or mid-level snowpack in the N. Cascades in September in average years that feeds these streams, and this year there won't be? If so, please provide the location data on that.

    The fact is these streams, in the majority of the summer and particularly as it progresses, are dependent on high elevation snowpack that is highly limited geographically in *any* year (and is not as affected by an early melt-out of lower/mid elevation snow, and particularly in this cool June we are experiencing).

    Adding... I bet it has been beautiful up there this spring!

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  20. sunsnow12: My question is: why does an early melt-out affect stream flows in July/August/Sept?

    I'm not really sure and I can only speculate. I think there are 2 factors that will lead to low flow later in the summer. One is a less than normal snowpack. The other is the early melt out. Consider an analogy with a bathtub emptying and assume the bath tub has a bunch of saturated soil in it to retain water. The sooner you pull the plug to start the draining (snow pack gone) the sooner the water in the tub is gone and the lower the drain rate (stream flow) by the time the fall rains come.

    For whatever reasons, the Northwest river forecast center is predicting the total flow in the Methow river over the next 120 days to be 40% of normal at Pateros (where the river enters the Columbia).

    You are correct, it has been a nice spring in the valley. We had nearly double the average rain in May but just a trace in June so far. Hence we had a really nice bloom of spring flowers but also a heavy growth of fuel and noxious weeds.

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  21. Yesterday was longest day of the year. i have my hot cocoa and longjohns at the ready. Gonna get brisk out there sooner then later.

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  22. Maybe the people in the Methow valley should begin asking the state to build more reservoirs there.

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