Modified Arctic Air Reaches the Northwest, Colder Air Is Yet to Come

The coldest air of the season has reached the Pacific Northwest, and some western Washington locations are already reporting precipitation in the form of ice pellets!

You can see the impact of the cold air on visible satellite imagery taken on Monday afternoon (see below).  As frigid cold air from Alaska and northern British Columbia moves over the warmer water of the Pacific, an unstable situation develops that produces cumulus convection......towering cumulus clouds with brief showers.

You can see the cumulus showers on the satellite image (white blobs with clear spaces between them), and they are aligned with the wind direction (red arrows).

Why does cold air moving over water produce showers?  

 Because it creates a large lapse rate, a change of temperature with height, that causes the atmosphere to convect, with upward motion producing clouds and precipitation.

You could see the convective showers coming onshore late Monday afternoon, as viewed by local weather radars:

As the atmosphere cooled and showers moved in, snow started to fall in the mountains, such as at  Hurricane Ridge at around 5000 ft in the Olympics. 

Late Monday afternoon, the freezing level was about 1600 ft in the Olympics, which means the snow level was roughly 600 ft.  It will decline further over the next few days.

During today (Tuesday) and Wednesday, very cold arctic air will push into southern British Columbia, with some of it leading into western Washington through the Fraser River valley.  

The situation Wednesday AM is shown below, with the purple and white colors indicating the coldest air.

Wow.  The Arctic will be getting very close to us.

A closer view on early Thursday AM (below) shows very cold temperatures over Washington...cold enough for lowland snow.  The only thing missing will be precipitation.

The latest UW model forecast showing predicted snowfall totals through Thursday morning does show some lowland snow from Tacoma southward.  Details uncertain, but there is a good chance that some lowland folks will see some flakes, with some localized minor accumulation.

Lowland snow will occur in the Willamette Valley as well, which is more isolated from the warming effects of the Pacific.

Finally, expect particularly cold air moving southwestward down the Fraser Valley into Bellingham.  This is illustrated by the ensemble of many high-resolution forecasts at Bellingham (below).  Temperatures will drop way below freezing.  Windy as well.  

Some wind chills may decline below 0F.  BRRR.

Light Lowland Snow Coming to Western Washington and Oregon

 I have held off talking about this until we were closer in time and uncertainty had declined, but there is a very good chance that some of you living in the western Washington and western Oregon lowlands will see some flakes on Tuesday and Wednesday.

I don't want to paint this as a snowy apocalypse, but there is a significant chance for some light snow, with marginal accumulation.

It won't be this bad

Let's begin with the latest UW WRF model snow forecasts. 

Let me be VERY clear about something. 

Snowfall is NOT the same as snow depth.  Snow melts on the surface and gets compressed.  Snow depth is generally MUCH less than snowfall.

The predicted snowfall total through Thursday morning is shown below.

The Olympics get hit hard, with much of the lowlands experiencing some flakes, including some bands of a few inches of wet flakes.  

Oregon will get even more snowy bounty with lots in the mountains and some accumulation in the southern Willamette Valley:

The lower-resolution European Model is similar, but has less snow over the western Washington lowlands.

When will the snow start, and what is the uncertainty in the forecasts?   

A good tool for answering these questions is ensembles of many forecasts.

The National Weather Service global model ensemble forecasts (below) for Bellingham are very generous with snow (I suspect too much). The gray lines show that the various solutions were all over the place (substantial uncertainty), with the highest resolution model indicated by blue (and the average of all the forecasts by black).   

Starts on Tuesday, with the greatest amounts on the 20th.

So what is going on?

As shown by the upper-level (500 hPa, about 18,000 ft) forecasts for late Monday, a strong trough of upper-level low pressure will move southward down our coast.

This is a well known as a cold pattern for our region.

As shown by the surface forecast for Wednesday morning, this will bring VERY cold air into British Columbia (purple colors, blue is cold enough to snow) and low pressure just east of Astoira.  

This configuration will pull cold air from Canada into northwest WA, particularly through the Fraser River Valley.

To illustrate, below are the predicted winds and temperatures on Thursday morning.  You can see the cold northwesterly flow coming out of Canada.

Give me the chills to look at it.

During the next few weeks, there will be substantial snow in the mountains, as shown by the predicted totals through March 2 (below).    

Hopefully, this bountiful snow will calm down some of the current panic in the media and social media about the current low snowpack.

Cold, Wet, and Snowy Period Ahead

 Get your umbrella handy, find those wool mittens, and look for your skis.....an extended period of cool, wet weather is ahead.

Let's start with the predicted precipitation (below).   The western U.S. is going to be very wet.

The predicted totals through next Tuesday afternoon are impressive, particularly over California.  But Washington and Oregon get their share.

The accumulated totals one week later are even more impressive, with the Northwest getting substantial amounts.

Temperatures will be colder than normal over the next ten days...from BC to southern California (blue and green colors indicate below normal temperatures)

Cold and wet means snow...and lots of it...for the entire West Coast.  Here are the totals through February 25th.  Let's say that skiers will have big smiles on their faces.  So will those concerned about snowpack.

What is producing this wet/cold/snowy bounty?

Answer:  a total reversal of the upper-level pattern, with troughing (low pressure) along the West Coast.

Sunday morning?   A strong, immense low off California.

Tuesday morning? An even stronger low off southern Oregon.

You will not believe what I will show you next.  Sunday evening on 22 February, a crazy strong low is STILL THERE.

The National Weather Service 8-14 day outlooks predict cold, wet conditions along the West Coast (see below).

Expect several feet of fresh snow in the Cascades and a radical improvement in the snowpack, with the reservoirs remaining in excellent shape.

What will the media, such as the Seattle Times Climate Lab, have to say about this reversal of the meteorological situation?  

I asked Grok to give me its best estimate of a future Seattle Times headline based on the current forecast. This is what it came up with:

Announcement

I will hold a special online Zoom session at 10 AM on Saturday for Patreon supporters.  Will answer questions and talk more about the snow situation.

Was January's Low Snowfall the Result of Global Warming? The Facts are Clear

As you can tell from my previous blog posts, I am really concerned about deliberately deceptive media stories and false information being distributed by certain groups.

Well, tall tale distributors have been working overtime recently, suggesting that the poor January snowpack over the Northwest is mainly the result of human-caused global warming.

These claims are demonstrably false.

Yesterday, the Seattle Times had a story, which stated:

The record-low snowpack is mostly due to how warm the West has been, which is connected to climate change from the burning of coal, oil, and natural gas, several scientists said.

Public Radio Station KUOW is on the same page as the Seattle Times, noting that:

With the global climate changing rapidly due to fossil fuel pollution, scientists say we should expect more warm winters like this one.

I could give you another dozen of these, but you get the drift:  global warming "advocates" are jumping all over the lack of mid-winter snowfall, claiming the warming from increasing CO2 concentrations gave us a dry, warm month that resulted in minimal snowfall.

It is easy to show that these claims are false.

The warm, dry January was produced by a very strong (and unusual) upper-level high-pressure area (see below), with colors indicating the difference from normal.  Red colors are crazy high pressure.

The location of this high pressure was in the perfect position to suppress Northwest snow, drying us out and forcing sinking and warming air.

There is no evidence that global warming causes more high-pressure systems in winter over the region.   

For example, climate model simulations don't predict them.

Would you like more proof?  Below is a plot of sea-level pressure on the Washington Coast over the last 30 years at Quillayute, on the northwest Washington coast.

No upward trend in high pressure in winter.

But I can disprove the global-warming explanation for the lack of January snow in other ways.

If we plot the January precipitation totals on the western slopes of the Cascades since the late 1800s (below), there is no long-term trend.  There would be if global warming were building high-pressure ridges more frequently over our region

What about temperature?  Below is a plot of temperature over the Cascades during the period that global warming has been most significant (since 1975) 

A slow increase by about 2F over the period, with several Januaries being warmer than this year (such as 1981).  This modest warming is NOT the explanation for this January's low snowfall.

Finally, to really put the global warming claims to rest, here are the April 1 snowpack totals over the Northwest mountains.  Only a minimal decline over time.

The bottom line is this:  the poor January snowpack over the region was predominantly associated with an unusual, persistent, high-pressure area over the region, not global warming.

The slowly warming planet is only a minor contributor to the snow deficit (perhaps 1-10% of the deficit).    

The claims by some of the media regarding the global warming origin of the poor January snow are more than disappointing; they represent deliberate misinformation.

Announcement

I will hold a special online Zoom session at 10 AM on Saturday for Patreon supporters.  Will answer questions and talk more about the snow situation.

Precipitation and Cooler Temperatures Return to the West Coast

The persistent ridge of high pressure over the western U.S., which brought generally dry conditions and less snowfall, is now history, with persistent low pressure and wet conditions taking its place.

Good news for those concerned about water resources in the West.

To get some perspective, the figure below shows the difference from normal precipitation over the past 90 days across the West Coast.

Near normal over much of western Washington and normal to wetter than normal over central and southern California.  But substantially drier than normal over western Oregon and northern CA.

A few days ago, the pattern shifted, and a plume of moisture moved into Oregon (see satellite image on Sunday)

The result has been healthy precipitation totals just where we needed them (see total for the past 48 hours below).   Some locations got more than 3 inches.

During the next week or so, one strong trough after another of low pressure will be moving into the West Coast, bringing rain and snow.

The maps below will show heights at 500 hPa (think of it as pressure at 18,000 ft) at various times during the next week or so.  Differences from normal are shown by colors (blue, lower than normal pressure, troughs;  red, higher than normal pressure, ridge).

Tomorrow at 4 PM.  Major trough to our south.

Next Monday, another strong trough of lower pressure

Thursday, 20 Feb.  ANOTHER strong trough

The Sunday after.....ANOTHER trough.

These troughs will bring a lot of water to the West Coast, with big stuff to our south, where they really need it. Only modest precipitation over Washington State.

Below is the UW model precipitation total through next Thursday.  Western Oregon and California will be sodden.   We will only get wet. Really heavy precipitation over the Sierra Nevada.

The latest NOAA Climate Prediction Center 8-14 day forecast is for cooler than normal and wetter than normal conditions over the western U.S 

It appears that this pattern shift has staying power, and the water/snow situation over the western U.S. should improve substantially during the next few weeks.

Misinformation in the Seattle TImes About Drought, Snowpack, and Climate Change

It is frustrating to read stories by the ClimateLab folks in the Seattle Times that are simply not true.

Another story was published yesterday that predicts a major drought year ahead due to poor snowpack.

A poor snowpack driven by climate change.

The problem:   their claims are easily shown to be false

The Truth

In December,  the region was hit by several strong atmospheric rivers that produced massive precipitation.  

Soils became saturated, rivers flooded, and all regional reservoirs were filled to above normal levels.

Atmospheric rivers are associated with warm conditions, thus working against snowpack accumulation.  And January was relatively dry and warm aloft due to high pressure aloft.

Consider the critically important Yakima River reservoir system.  

The heavy rain caused a huge increase in reservoir storage (blue line).  Higher than ANY TIME OF LAST YEAR and equivalent to early May levels in a normal year.

Yakima water storage will easily reach 1 million acre-feet just with rain and snow melt during the last month, resulting in a full reservoir system.

To provide 100% of the water requested, the Yakima System needs to deliver 2.3 million acre feet, with the remainder coming from melting snowpack AND late spring/early summer rainfall.  

We are only halfway through the snow accumulation season in the Cascades, and there is PLENTY of opportunity to gain much more snowpack.

Currently, the snowpack in the Yakima Basin is roughtly 48% of normal, and this percentage will only increase...and substantially.   

Even if there was no additional snow this year, just rain, one would expect about 750,000 acre-feet from melting the snow that is now on the ground.

So WITH NO SNOW, we would get to 1.75 million acres feet.   76% of normal.

Snowpack percentage of normal yesterday for the Yakima drainage.

But we are only about halfway through the snow accumulation season, and models are going for a cooler/snowier period ahead.  For example, the European Center model predicts lots of mountain snow through February 22:

Extended seasonal forecasts are for a wet spring with normal temperatures (see below).

That means plenty of snow.

Moving beyond the Yakima River situation, snowpack is above normal over the eastern slopes of the North Cascades, and the snowpack supporting the important Columbia Basin is normal (and the water level behind the Grand Coulee dam is above normal).  

Regional reservoirs are in very good shape.

No drought.

Even Worst

As bad as all the unsupportable Seattle Times claims of regional drought, there is clear misinformation about the cause of the lack of snow last month.

The Seattle Times claims it is because of warming due to climate change:

Substantial portions of the article push the global warming origin of the thin snowpack.

This is demonstrably untrue.

The last month was warm and dry because of the persistent ridge of high pressure over the region.  

The map below shows the anomaly (or difference) from normal of the heights (equivalent to pressure) at 500 hPa (about 18,000 ft).  

A very strong ridge of high pressure over the western U.S. and an intense trough (low pressure) over the eastern U.S.

This pattern suppressed snow over the Western U.S. and ENHANCED snow over the East.

Such patterns have little to do with global warming (there is a VERY large published literature on this).

The claim of the Seattle Times that our low snowpack is connected with global warming is simply false, with the impact of global warming on regional snow quite modest, something proven by the lack of downward trend in the observed Northwest snowpack over the past decades (see below, SWE is snow water equivalent, the amount of water in the snowpack).

The continued deceptive information from the Seattle Times on climate issues is very worrisome and shows the dangers of journalism funded by advocacy groups (the Seattle Times Climate Lab sponsors).