Published by Jason Sharp - January 4, 2011

Winter 2009-2010
The story really begins in December 2009 since that month helped make the winter of 2009-2010, not only the second snowiest in the Asheville area’s record keeping history, but also it’s 3rd coldest. By the time it was all over with 39.2 inches fell in Asheville. Thanks to an active southern jet stream and continuous cold, Asheville saw storm after storm with measurable snow accumulation in every month from December to March. First there was the storm of Dec 18-21, 2009 that left about 10 inches at the airport and more than a foot in the surrounding areas.

Snow accumulation Dec 18-20, 2009 Courtesy: National Weather Service

Not to be outdone, January 2010 saw another big storm that also left more than a foot of snow in some places. According to the National Weather Service this marked the first time that a winter season saw two events that produced snow accumulation at or above 10 inches.

Snow accumulation Jan 29-30, 2010 Courtesy: National Weather Service

February saw two more systems that helped end the month with nearly 6 inches of snow. The first of these storms was followed by heavy rains and helped produce flooding in parts of the French Broad River. Just when we didn’t think we could take it anymore, March 2-3 saw yet another storm that helped Asheville rack up nearly 10 inches of snow at the airport by the end of the month. On top of all this, the Southeast saw wave after wave of cold air spill into the region which made Asheville’s winter season finish off as the 3rd coldest in recorded history. All in all, over 3 feet of snow fell throughout the winter of 2009-2010!

Some interesting tidbits about the winter season:

• The maximum 24-hour snowfall for the months of December, January, and February were records for that day:

• There were ten days in January where the daytime high did not get above 32° F. The average is about 3 days.

Why so active?
So, was there good reason for such an active winter? Turns out, yes. There was a confluence of global weather patterns which came together that in isolation might have produced an average winter, but together made it very active. One was a fairly moderate El Nino that gathered strength in the middle of 2009 and continued throughout the winter. El Nino has the effect of making the southern branch of the jet stream more active. According to the Southeast Regional Climate Center thevalues used to measure El Nino were in the top 10 for each month that winter. There was another pattern in play called the Arctic Oscillation (AO). Without getting too technical, this is basically a pattern of higher and lower pressures in the polar regions. When there is lower pressure (positive phase) storms and cold air are usually kept to the north. When there are higher pressures (negative pressure) the opposite is the case and the Southeast can see more spillage of cold air into the region. The AO saw record negative values throughout the winter months. So, in a nutshell, a pattern that normally brings wetter conditions to the Southeast combined with a pattern that normally brings colder than average temperatures to the region. This produced unprecedented snow and cold for Asheville.

Then there was the heat…..
Summer was just plain hot. In fact, it was the hottest. Who could forget walking around downtown during Bele Chere weekend in the 90 degree heat and the storyof revelers passing out from heat exhaustion. The period from June to August was the hottest on record for North Carolina. Asheville also saw it’s hottest summer season ever. This period produced a whopping 19 days where the high temperature hit 90° or above.  The average for these three months is about 9 days. July produced 5 nights of record high minimums, while August saw 9 nights, one of which was an all-time record for the month of August.

Average temperatures June to August. Courtesy: NCDC

Then there was the snow and cold…again…
December 2010 saw two days of record 24-hr snowfalls. One was on the 12th with 3.8 inches at the airport and the other one was, of course, on Christmas day with 6.5 inches at the airport. Surrounding areas saw more than twice that. In addition, this turned out to be the second coldest December on record in Asheville. The 13th and 14th both saw record minimum daytime highs for those days.

Snowfall totals in WNC for Dec 25-27 Courtesy: National Weather Service

As with the 2009-2010 winter, a negative phase of the Arctic Oscillation as well as strong negative values of it’s cousin, the North Atlantic Oscillation (NAO) helped keep the end of 2010 so cold. As Dr. Jeff Masters points on his blog, the NAO was the second most negative since 1950. Essentially higher-than-normal pressure around Greenland and Iceland blocked cold air from going anywhere except south.

What a wild year for weather in Asheville! It was truly a year of highs, lows and epic snows.