Large Areas of Human-Caused Cooling

 The media is full of stories about human-caused global warming.

But did you know there are large areas of the planet where humans are causing cooling?

Importantly, Washington is a prime example of our ability to massively cool the surface.

We do this by irrigating vast areas of eastern Washington and northern Oregon.

Consider a recent satellite image of our region (below).  

The Columbia Basin should be a desert.  Instead of desert or arid rangeland, we have irrigated vast areas, with the evidence being all the green dots and squares covering much of the basin.

Spraying water for irrigation causes massive cooling by evaporation.  Or evaporation from a wet ground or wet plants results in strong cooling.

When the sun's rays hit the surface, much of that energy goes into evaporating water rather than warming the surface.

You can see the impacts of irrigation on temperatures quite easily. Below are some satellite images (so you can see where the irrigation is taking place) and high temperatures on a recent day (May 9) over a portion of the Columbia Basin (you can see the Columbia River).  Generally, in the 70s over irrigated areas and low-80s over the nearby desert lands.

Here is a blow-up of the next day.  Much cooler over the irrigated area.

The amount of irrigation in the Columbia Basin was rapidly increased in the late 1940s into the 1950s... and it had a profound impact on the temperature trends.  Typically, irrigation results in 2-5 F cooling.  Sometimes more.

At Othello, the mean high temperatures during summer actually DECLINED during the mid-century and stayed down.

Similar lack of warming in Ritzville.

So perhaps you can understand why fewer folks in Eastern Washington are concerned about global warming.😊

If you aren't impressed with the massive temperature experiment in eastern Washington, imagine the profound cooling impacts of the irrigation of large areas of the central valley of CA (see below).

Looking at a station there (Denar 3), you can see a similar lack of warming during the past century.  Cooling due to the effects of irrigation played a role in this.

"Drought-Buster" Rain (and Snow) Coming to the Northwest

If you were thinking of putting away your umbrella or rain jacket for the summer season, think again.

Substantial precipitation is coming to the Northwest, including high-elevation snow.  

In this blog, I have sometimes evaluated the scientific validity of the Drought Monitor graphic, which often exaggerates "droughts".    For example, below is the latest graphic, which suggests moderate drought over the western side of the Cascades.

 

Comparing this to the percent of normal precipitation for the current water year (starting Oct. 1), we see that eastern Washington and most of Oregon have been wetter than normal (green colors), while western WA and the Cascades are 70-90% of normal.

A key point is that Western WA does not need 100% of normal precipitation to be fine.  

We get more more precipitation than we need.  For example, the water levels for the Seattle reservoirs today is ABOVE normal (see below).  The huge Spada Lake reservoir that provides water for Everett is the same.  

So starting in a good position, we are about to be hit with lots of rain during the next few weeks....much more than normal.  Substantial precipitation now is golden---filling reservoirs and streams and moistening the ground before the dry, summer season.  

We start with a weak system coming through on Tuesday and Wednesday, which will give the region a good wetting, with about a third of an inch over the lowlands and up to 2 inches in the mountains (the total through Thursday at 5 PM is shown below).   Enough to keep the lawns green.

 But the really impressive action is predicted for next week.  A very large and deep low will develop in the Gulf of Alaska (11 AM on 27 May shown)

Which will drive a plume of moisture into our region (green colors are the moisture plume)

The 5-day precipitation total ending at 11 PM 30 May is shown below.  Up to 3.5 inches of additional precipitation in the mountains.   Enough to quiet any drought talk for a while.

 

And with a cold, low-pressure area offshore, we will even get substantial snow in the mountains (see forecast below).  Enjoy....