December 2009 Revisited

Compared to historical averages, December in Hood River was way colder, with less precipitation, and not so windy.

The average temperature (30.9°) was much colder than long term averages (36.1°), and ditto for more recent averages of 36.2° (2000-2008). There was 3.51" of precipitation, compared to an average December total of 4.84". The wind speed was considerably lower than average (1.2 mph vs 1.6 mph), consistent with the lower average wind speeds for the past 4 months.

December started out with normal seasonal temperatures. But then, on Dec 6th, a cold, dry arctic air mass descended upon us, and didn't moderate above freezing until Dec 13th. During that time, the temperature dropped to 5°, and we had a minimum dew point of -9°. Wind chills were brutal. Don't ask me exactly how brutal, because my stupid database doesn't maintain that data.

As we transitioned out of the arctic air, freezing rain hit the western Gorge, and I84 was closed overnight Dec 12-13. Lots of precipitation arrived between Dec 14th and 22nd. A couple of days of minor snow/ice/slush in our area, then just rain, then dry. Piles of snow in parking lots and yards persisted through Christmas, so technically, it was a White Christmas. Or not.

I won't even mention the inversion event between Dec 24th and Dec 29, because I hate inversions, and mentioning it would give it more attention that it deserves.

Precipitation returned on Dec 29th, culminating in a record 6" snowfall on Dec 31, breaking the previous record of 3.5" in 1931. All in all, a fitting weather climax to 2009 and the "aught" years!

The data below is from my home weather station. To view its December monthly summary and graphs at Weather Underground, click here.

The "historical average" numbers for temperature and rainfall are from the Hood River MCAREC data. Historical wind average is from my station's 2000 to 2008 data. Note that average wind speeds include all 24 hours of the day and night, which is why they are way lower than daytime peak winds. In addition, the wind speed at this station is considerably lower than on the Columbia River.

	High	Low	Average	Historical Average
Temperature (F)	48	5	30.9	36.1
Wind (mph)	26		1.2	1.6
Rainfall (in)	0.97		3.51 (total)	5.81

Thank goodness for strong magnetic fields!