January 2014: cold and snowy compared to average, plus a polar vortex attack

January generated plenty of weather headlines with a few snow events around the area and the notoriously named Polar Vortex attack early in the month, delivering D.C.’s coldest temperatures of the 2000s so far.  From a monthly standpoint, January’s 3.8F below the 30-year normal was the coldest monthly temperature anomaly of any month since December 2010′s -4.9F departure.  The monthly snowfall at National of 6.6″ was the snowiest month since January 2011′s 7.3″ result and it was the first above normal snow month since our marginal +0.3″ surplus last March.

Related: January 2014: the coldest in decades in D.C. by many counts

Temperatures

The average temperature of 32.2F was right on the freezing mark and the fourth coldest January of the 2000s.  January 2004 is still the coldest and 2006 is by far the warmest, over 10 degrees warmer than this year.  You can see the rankings and the variability of January temperatures through the 2000s in the following ranking table and 2000s line chart.

janmean2014

The month would have competed for the coldest of the 2000s at National if not for a burst of warming right in the middle third of the month.  You can see this big cold weather “time-out” in the data series below. We had enough cold early in the month and again late to still keep the end result as a colder-than-normal one.

jan2014dailyanomalies

Looking at the monthly extremes compared to January 2013 reveals just how much colder we were this year.  We still managed to reach up to the low 60s, but not the low 70s we saw last January!  And instead of middle teens, we found our coldest temperatures this January in the middle single digits.   National Airport spent an impressive seven days this month below the freezing mark (last year yielded only three).

jan2014extremes

Precipitation

January’s 2.58″ liquid total was .23″ drier than normal, but the fifth wettest of the 2000s actually.  You can see the breakout by day below along with the ones that resulted in snow:

jan2014dailyprecip

2014 delivered the 4th snowiest January of the 2000s with the final total of 6.6″ running about 1″ snowier than normal.  You can see how the 2000s have performed in the table and chart below.  2006 only measured a trace while 2000 picked up a big 14.5″ mostly due to a surprise snowstorm that year.  You’ll notice that most years come in below the 30-year normal and that is the nature of D.C. winters.  The big snow years are so much bigger than most years that it skews the 30-year climatology higher than what a “typical” snow result tends to be.  We usually have lots of smaller years and then a bigger one every few years to tilt that mean.

dcameansnow2014

Temperature and precipitation records were set at all three airports in association with both snow and cold weather.  Here is the round-up by station:

Washington National

Record Daily Snowfall January 21:  3.8″ besting 1982′s 3.5″

Record Low Maximum January 22:  19F besting 1961′s 21F

Washington Dulles

Record Daily Snowfall (Tie) January 2:  3″ tying 1987

Record Daily Low January 7:  1F besting 1988′s 8F

Record Low Maximum January 7:  18F besting 1988 and 1996′s 21F

Record Daily Snowfall January 21:  8.5″ besting 2001′s 3.5″

Record Low Maximum January 22:  15F beating 1970′s 20F

Record Low Maximum January 24:  21F beating 1963 and 1987′s 25F

Record Low Maximum January 28:  18F beating 1966 and 1986′s 21F

Baltimore

Record Daily Low January 7:  3F besting 1988′s 8F

Record Low Maximum January 22:  16F beating 1878, 1988, 1996′s 22F

Record Daily Snowfall January 21:  5.1″ besting 1982′s 2.0″

Record Low Maximum January 22:  15F beating 1961′s 19F

The weather pattern

January 2014 continued the trends from December’s amplified jet stream pattern with stronger upper level ridging toward Alaska, the Gulf of Alaska, and along the North American West Coast.  This set up the “sliding board” of significant cold air deliveries into the Lower 48.  Frequently, pieces of the Polar vortex (which was stuck around the Hudson Bay frequently) broke off and came barreling down into the U.S. with significant chunks of air from the Arctic.

jan2014upperlevel

February 2014

Our new month looks like it will be a challenging one for weather forecasting.  We should still see some occasionally stronger cold air deliveries, but the storm track looks to be wily and it bit more orientated like a La Niña winter where we find ourselves on the warmer side of the storm track.  That could mean we sometimes see rain systems and sometimes enough cold air damming for significant mixed precipitation problems.  But even in these types of winter patterns, we can see a significant snow threat at times.  So we will need to watch each system carefully.  While we are getting occasional short-lived warm-ups in this pattern, we have a shot at a more sustained one toward the middle of the month with more cold weather likely at the end again.

The National Weather Service has the D.C. area in the “equal chances” category for temperatures with cold weather focused in the Midwest and warmth in the South.  But we are in the above normal precipitation category, suggesting we’ll be frequently on the battleground between warm and cold weather dealing with more precipitation than typical.  So we have a shot at finding our way to getting enough snow at times to compete with normal again (National needs 5.7″ to match normal).  You can see the NWS February forecast here.

For further information

The National Weather Service publishes nice monthly assessments:

You can click on your closest airport location here:

Reagan National (DCA)

Dulles Airport (IAD)

Baltimore-Washington (BWI)

Also on Capital Weather Gang

Ice risk Tuesday night into Wednesday; significant storm possible this weekend