January Was No Month for Vacation in the Columbia Basin

Cold, with temperatures generally remaining below freezing.

Cloudy almost all the time, with very little sunshine

Icy, with freezing fog on many days.

Some location in the interior of Alaska?    Siberia?

No, the Columbia Basin of Eastern Washington.

Day after day, cold air and associated low clouds pooled in the Columbia Basin (see imagery below on January 28th)

WSDOT highway cams show fog and low clouds nearly every day (see an example for January 14th below)

With the unending veil of clouds, the temperature stayed nearly constant and cold--close to freezing for extended periods.

Below is something amazing...and disturbing.  The temperatures at Patterson in Benton County.  For more than half the month, temperatures were between 30 and 35, with many days showing almost no diurnal (daily) variations.   Just constant murk, cold, and freezing fog.  Very unpleasant.  I would take 20F and blue skies any day over that.

Even more depressing is the solar radiation measurement, with many days remaining less than 100 W/square meter).  Several near 50.  Full sun is around 450 by the end of the month.

On many days, Seattle (not known as the winter mecca of sun loves) had considerably more sun.

Ironically, there are several solar projects completed or planned for eastern Washington...they should not expect to generate much electricity in mid-winter I suspect.

Why is the Columbia Basin so cloudy and cool during the winter?   

Because it is a basin, in which cold, dense air collects (see terrain map).  Cold air can enter through the Okanagan Valley or can be generated on the surrounding slopes (by infrared radiation to space) and then settles into the lower elevations of the Basin (cold air is dense and tends to sink).  The Columbia Basin has only one real exit....the Columbia Gorge... and that is quite narrow, limiting its ability to "drain" the cold air in the Basin.

Warm air from the west often overrides the cold air of the Columbia Basin, producing a strong inversion, in which temperature increases with height.   This structure is illustrated by vertical sounding at Spokane during the morning of January 13 (below).   Inversions prevent mixing of air in the vertical, which further "protects" the low-level cold air.

But it is even worst than that!   The low-level low clouds within the Columbia Basin tend to radiate infrared energy to space, further cooling the near-surface frigid layer. It is like having a refrigeration unit on top of the low clouds.

The  Columbia Basin cold pool has some other unpleasant issues.   Subfreezing air near the surface can foster freezing rain and ice storms, when warm rain falls into the cold air and is supercooled to below freezing.  And the inversion can separate strong winds aloft from "dead air" within the cold pool.  The result can be strong wind shear (large changes of wind with height) that results in considerable low-level turbulence--producing a bumpy ride for aircraft landing in towns such as Richland and Moses Lake.

Because of the persistent cold air in the Columbia Basin, the climatology of the region is one of great extremes.   

Consider the average temperatures by month in the Tri-Cities. (below).  December and January are cold, with temperatures averaging in the 30s.  This is the season of the Columbia Basin  low-level cold pool.  But something wonderful happens in February.  Increasing sun finally has an impact, warming the surface, increasing vertical mixing, and weakening/destroying the cold poor. Temperatures surge.  

By March the cold pool is history and the Columbia Basin becomes warmer than western WA.  

Courtesy of Weatherspark