Why So Cold So Far This Winter?

Meteorologist Carrie Rose explained on Friday's edition of Virginia This Morning some of the weather and climate patterns that can and are influencing our Winter of 2010-2011 so far. December 2010 for Richmond was the 7th coldest on record, and average temperatures so far in January 2011 have been running about 2 degrees colder than normal, which isn't as drastic as December, but certainly continues the cooler-than-normal temperature pattern. We also already have recorded 10" of snow at Richmond International Airport, when an average entire snowfall season will produce about a foot of snow (11.7" average 1971-2000, or 13.0" average 1897-Present Day). You can watch the video of Carrie explaining this by clicking here. Here's a hint: this graphic explains the dominant atmospheric pattern influencing our weather much of December and January.

Next Tuesday's Storm System

Our next chance of precipitation will arrive next Tuesday, and although it appears as though it will just be a cold rain, there are a few things worth watching. As always, there will be shifts in the track and timing of the storm system. The air mass this time around will be relatively warm, so things will need to come together just right for us to get a good snow. Based on the location of high pressure over New England early next week, if we get wintry weather on Tuesday, it could be in the form of freezing rain. Computer forecast models don't do a good job of resolving low-level cold air advection, and this is a case where pattern recognition is more valuable in forecasting than anything else. When strong high pressure develops over New England we get an effect in central Virginia called cold air damming, also called a "wedge". Dense cold surface air rotating around the high will funnel down the east side of the Appalachians, creating a shallow layer of cold air at the surface. The GFS is indicating temperatures in the mid to upper 50s early next week, but we won't even get close to that if the high is located where it is suggesting it will be. I've gone mid-40s for highs on Tuesday as somewhat of a middle ground, but if there is more consistency with this pattern, 30s will be more likely, and freezing rain could be a possibility. There's always the chance, of course, that I'll wake up tomorrow morning to see something very different depicted in the models next Tuesday. So goes medium range forecasting. I'll have another update on Friday after getting a few more looks at the data.

A Few Useful Links

Here are a few links to help you track snow totals from this storm. They will update later this morning (roughly 10AM).

http://bit.ly/fIW8A6
http://lwf.ncdc.noaa.gov/snow-and-ice/recent.php
http://www.hpc.ncep.noaa.gov/discussions/nfdscc3.html

You can also check out the latest road conditions here:

http://www.511virginia.org/Conditions.aspx?r=1