Eastern Washington Fields are Blowing Away

On Saturday I was biking around the hills near Vantage, Washington with some friends, and driving home in the early evening I observed a distressing sight:  the wind was literally blowing away several freshly plowed fields, with plumes of dust extending hundreds of feet into the air and long distances downwind (see picture).

Clearly, some farmers are not being good stewards of the land entrusted to them.

The view Saturday evening around 6:30 PM from I90 near Ellensburg.

 Spring is often a dusty period in eastern Washington for two reasons:

• it is a time when some farmers plow their fields in preparation for planting
• strong winds return during this time of the year, particularly over the eastern portion of the region

To illustrate the later, here are the monthly average winds at Ellensburg and some other Washington locations.  You will notice the huge monthly variations of winds at Ellensburg along the eastern slopes of the Cascades, with the strongest winds in spring and summer.

Why are the strongest winds over the eastern side of the Columbia Basin strongest during the warm season?  Why aren't winds the strongest during the winter storm part of the year?

As illustrated in the following surface chart for July 16, 2013, high pressure builds over the eastern Pacific during the summer, while pressure falls over the heated land.  The produces a fairly strong onshore pressure difference that is accentuated by the cool air over western Washington and the warmth of the Columbia Basin.  Air accelerates eastward in the Columbia Gorge and down gaps and canyon of the eastern Cascade foothills..

The bigger the temperature difference between east and west, the larger the pressure difference and thus the stronger the winds.

Interestingly, our global climate models suggest that global warming could make these winds stronger!  Why?  Because the warming continent will have lower pressure than today and the Pacific High will strengthen.   More pressure difference and thus stronger winds.   That implies more wind energy in 50 years...and yes, more dust.

The summer winds at Ellensburg and vicinity tend to be strongest in later afternoon and early evening after the daily heating has revved up the pressure gradient during the day.  That is why the dust storm was apparent during the late afternoon but was absent in the morning.

Warm-season dust storms in eastern Washington can also be caused by strong outflow from thunderstorms or powerful winds from cold fronts moving down from British Columbia.

Blowing dust from eastern Washington farms during the spring can often be clearly seen in weather satellite imagery, such as this picture from the MODIS satellite in May 3 2010.  You can see the dust being pulled off the fields near the Columbia River and then heading towards the east.

Dust storms from thunderstorms often look very ominous and are called haboobs.  Below is a picture of one last September that was described in an earlier blog.

Picture courtesy of KauaiGuy808 on Flickr.

So how much soil is being lost from eastern Washington farms?   A study by WSU found that six high-wind events occurred over a two year period, with soil loss ranging from 43 kilograms per hectare (100 by 100 meters) during the 12-22 September 2003 event to 2320 kg (2.5 tons) per hectare on 27–29 October 2003.  So this is a significant loss.

I am no agricultural expert but surely they must be better agricultural practices that would lessen the dust storms from plowed fields, something I have seen many times on my visits to eastern Washington.