First Frost of the Season is Revealing

Most of the region saw its first frost today.  

And it offers a lot to learn from.

Let's begin by looking at the surface low temperatures observed across the region (see below).  

Keep in mind that "surface" air temperatures reported at airports and other locations are NOT at ground level, but taken at 2 meters (about 6 feet) above the surface.

On cold nights, the temperature at the surface is usually colder than at 2 meters, often by 2-5 degrees F.  

Wow.  Substantial temperature range... from around 50F to below freezing!  

Warm near the water (around 50F near the coast), relatively warm near the Sound and the Strait (mid to upper 40s), but below freezing in the western interior (e.g., near Olympia Airport).    

30s in eastern Washington

Minimum temperatures were cooler at the surface than aloft (the opposite of the normal daytime situation), as shown by the temperature profiler at SeaTac Airport (see below at 8 AM).  

The warmest temperatures were at around 1600 ft.

The situation changes during the day, as the surface is warmed by the sun, as illustrated by the Seattle temperature profile at noon (see below).

As noted in previous blogs, the cold overnight temperatures are associated with longer nights and a lack of clouds aloft, which result in very effective cooling at the surface by the emission of infrared radiation from the surface (see below).

The visible satellite image from this morning shows the situation, with clear skies over much of the region and filaments of fog in a few valleys.

Now the problem.

 

In my "day job", I work to improve the skill of atmospheric forecast models.

A potent tool in doing so is comparing model simulations against observations. At Seattle-Tacoma Airport, the model simulation (colored lines) did a good job in matching reality (orange dots).

But at Olympia Airport, where temperatures got colder, the simulations were not as good, with models being too warm for the morning lows (but quite good for the daytime highs).

More work is needed, which is good. 😀   

The Puget Sound Convergence Zone Delivers and Well-Timed Precipitation and Smart Water Management Keep Yakima Crops Yields High

Before I get into the Yakima Valley situation, let me note yesterday's substantial precipitation over central Puget Sound from a decent Puget Sound Convergence Zone.

Remember, Puget Sound Convergence Zones often occur after the passage of a Pacific front, when air approaching the coast turns to the west and northwest (see schematic below).  

Air moves around the Olympics and then converges over central Puget Sound, producing upward motion, clouds, and precipitation.

A very well-defined convergence zone formed yesterday afternoon, as illustrated by the radar image around 3:30 PM.

The precipitation totals for the past days show a nice band of precipitation around the central Sound, with particularly heavy rain in the mountains (reaching 2 inches!).   

Very good for Seattle's reservoirs,  which got a large hit of rain yesterday.

The Spada Lake reservoir, which supplies the North Sound area, is filled to above normal now.

Another interesting precipitation story has been the Yakima Valley.    

After all the angst in the media about drought and low snowpack, there was sufficient water for Yakima agriculture, with all important crops of good quality and with near-normal harvests.

How cold this be with a low snowpack?   

Annual precipitation was near normal due to heavy winter precipitation, so reservoirs were filled to normal or above normal levels.    The summer was not particularly hot.

And then there was was divine intervention

There was substantial precipitation over the Yakima Basin during the summer and autumn (see below).  

Just stunning.   

With substantial precipitation,  all water limitations have been removed in the Yakima Valley.  Both senior and junior rights folks can receive their full water allotment!

Sometimes when meteorologists pray to the weather gods, our supplications are answered.  

Seattle Times Story on Skagit Flooding and Global Warming is Clearly Wrong

 It happens again and again.

The Seattle Times Climate Lab runs a story claiming global warming will create a dangerous situation.

A story that is factually incorrect or grossly exaggerated.

And it happened again yesterday in a Seattle Times story about Skagit Valley flooding:

This article claims that global warming will cause serious flooding of the Skagit River.   This is clearly wrong.

Specifically:

• The article is based on a report by an advocacy group.  A report that has serious technical flaws.
• The Seattle Times provides no analysis of the claims' viability, nor does it examine historical data to determine whether such an ominous trend is occurring.
• The report claims that "today’s 100-year flood events, or those considered to have a 1% chance of happening in any given year, will happen about four to five times as often by the 2040s. 

The Seattle Times suggests that existing infrastructure will not protect communities.   Disaster looms due to climate change.

Written by the Climate Lab project of the Seattle Times, it is an unfortunate example of "sponsored journalism" paid for by local advocacy groups. 

The article is based on a report led by the Swinomish Indian Tribal Community, which has secured tens of millions of dollars of funding from state and federal sources for adaptation to global warming.   

There are serious technical flaws in this report and the ST articles.   

For example, the climate models considered are driven by unrealistic increases in warming greenhouse gases, such as CO2.   

Specifically, they make use of an average of the RCP 4.5 and 8.5 climate change scenarios. Unfortunately, RCP 8.5 is considered wildly excessive, so much so that the Intergovernmental Panel on Climate Change (IPCC) has dropped it.

The report and the Seattle Times failed to examine the actual historical trends of the high water on the Skagit River, which is important since global warming has occurred for several decades.

Let me show you the actual data.    Below are the OBSERVED long-term trends of the annual peak streamflows of the Skagit River at Nehalem and Concrete.  It is not rising, but DECLINING slightly.   

Please note that peak streamflows were higher earlier in the century, before the reservoirs were in place.

No wonder they failed to show past observations.  It does not support their narrative. 

What about the future under global warming?  

The UW effort to run high-resolution climate models driven by the more reasonable RCP 4.5 scenario (blue line) shows little increase in precipitation in the Cascades through 2080 during the winter at any site (Stampede Pass is shown below).  

While the article makes big claims about climate change for Skagit flooding, it conveniently avoids other issues, such as land use changes.   

For example, dike and levee construction has resulted in increased river confinement. By walling off roughly 100,000 acres of the natural floodplain, the river lost its ability to naturally spread out and slow down. Instead, the water is funneled into a highly confined channel, forcing the river stage to rise much higher and faster at narrow points like downtown Mount Vernon. 

Urbanization and increased impervious surfaces have also been a factor

The growth of urban centers along the river, such as Mount Vernon, Burlington, and Sedro-Woolley, has converted porous, forested, and rural land into asphalt, concrete, and roof surfaces. 

Thus, when heavy rain or atmospheric rivers strike the basin, the water is impeded from soaking into the ground. Instead, it turns into rapid urban runoff that empties directly into local tributaries and the main stem of the Skagit River, causing rapid spikes in water levels. 

Deforestation and logjam removal

The removal of upper-basin forest cover and natural river obstructions permanently increased the velocity and volume of water and sediment rushing downstream toward Mount Vernon during major storm events. 

Reduced snowpack as a cause?

Finally, both this article and report claim that reduced snowpack is an important element in Cascade flooding.   They say this because global warming clearly reduces Cascade snowpack.

But they got it wrong.   

Severe flooding in western WA is always associated with intense, warm atmospheric rivers in which nearly all the precipitation falls as rain.  Furthermore, the melting of snow is always secondary for western Washington flooding.   

In short, this kind of  "supported" journalism at the Seattle Times is not meant to inform but to push a certain agenda

Really unfortunate.  

Lowland Fog Season

The visible satellite image this morning was an October classic:  

Low clouds (stratus and fog) within the valleys of western Washington, Oregon, and southern British Columbia.

The Seattle PanoCam said it all (below) and contrasted sharply with the cam on Crystal Mountain (also shown).

The low-level fog layer was associated with an intense low-level temperature inversion with cold air near the surface and MUCH warmer air above.  

To show this, the temperature above SeaTac airport, based on aircraft data, is shown below. 

52 F at the surface and 65F at 3000 ft!

Why such an inversion (temperature increasing with height)?

With clear skies above, the surface can radiate (infrared) heat to space, allowing surface cooling.

Nights are getting much longer, providing more time to cool.

And there is a ridge of high pressure aloft (see upper-level map above), which not only produces clear skies and good radiative cooling at the surface, but also forces sinking aloft, which results in upper-level warming (air warms by compression when it sinks).

Orange colors indicate higher-than-normal 500 hPa heights (higher pressure than normal, around 18,000 ft).  This is called ridging and is associated with sinking and warming air aloft.

Autumn is the time of the year when everything comes together to produce fog and low clouds, as shown in the figure below.   

October is the foggiest month of the year.

If you enjoy hiking and want a meteorological treat, try an early morning hike in the foothills of our local mountains.  You will start cold, but rapidly warm up as you ascend through the inversion. 

Just pick a day with a ridge overhead, like today.

______________________

Potential for Aurora tonight.  

The Planetary K Index is elevated, and some folks (such as Greg Johnson of Skunk Bay Weather) saw a good display last night.   

No guarantees, but there could be a repeat tonight.

This Year is 2050 in the Pacific Northwest

We went through a meteorological time machine this year.  You experienced the meteorology of 25-50 years into the future.

For example, we have lived through a summer with the snowpack expected in 2050.  

The second-lowest snowpack over the past decades.

Let me prove this to you.  

Below is a plot of Pacific Northwest snowpack on April 1 (after the winter accumulation season) since 1984.  

Wow, we had the second-lowest snowpack in over 40 years. Roughly 50% of normal.

When would we expect such a reduction in snow based on global warming?   

Let us assume the RCP 4.5 global warming scenario, which is typically used by the research community these days.

Under this scenario, here are the April 1 snowpack predictions for the Puget Sound region.    Snowpack doesn't decline to as much as this year until the end of the century!

Same thing for the entire Pacific Northwest:

So this year provides a taste of the snowpack in roughly 75 years into the future, assuming nothing major is done about greenhouse gas emissions.

What about temperatures?   As shown below, it was much warmer than normal tduring the past year, roughly 2-4 F above normal in much of the area!

Again, comparing to a regional climate simulation, this is like being transported in time to around 2050.

This meteorological time travel is exhausting!  

The last year has experienced conditions that will be typical during the middle to latter parts of this century if global warming increases without change.

Now the controversial part of this blog.

Those suggesting that such warming represents the end of the world and an acute threat to our survival are simply wrong.

There was sufficient water for human consumption (see Lake Roosevelt Level behind Grand Coulee Dam below)

Blue is this year, red is average

Regional agriculture has done well, with most crops near normal.

Forest fire areas were modest, with most of the fires being in grass/range vegetation (which is little influenced by climate change).

Those claiming the climatological sky was falling were simply wrong. 

We need to do what we can to mitigate global warming, but it is not an emergency or an acute threat to humanity.

Announcement

I will hold a special online Zoom session at 10 AM on Sunday for Patreon supporters. I plan to talk about the extended range forecasts and the strange conditions often apparent on super el nino years.