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 slopes, 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.

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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.