By: David M. Higgins
California, MD- Here it comes! Earlier this winter, forecasters predicted there were signs that the dreaded “Polar Vortex” would be making it’s presence known in January. While the Polar Vortex will pass just north of us, the Southern Maryland region will feel temperatures 10-20 degrees below normal.
The timing of this event is expected to be late next week for SoMd. The piece of the “polar vortex” that will impact SoMd will being making its way in Wednesday night through Saturday. On those days you can expect temperatures to be in the single-digits with possible sub-zero wind chills. Current forecasts for the region expect us to be below freezing Wednesday through Sunday.
A polar vortex is an upper level low-pressure area lying near the Earth’s poles. There are two polar vortices in the Earth’s atmosphere, overlying the North and South Poles. Each polar vortex is a persistent, large-scale, low pressure zone that rotates counter-clockwise at the North Pole (called a cyclone), and clockwise at the South Pole, i.e. both polar vortices rotate eastward around the poles. The bases of the two polar vortices are located in the middle and upper troposphere and extend into the stratosphere. Beneath that lies a large mass of cold, dense arctic air.
Now this is an early forecast and we have to be careful. The American and European models suggest there could be some snow/wintry mix involved, and these models tend to over-estimate the speed at which the cold air crosses the mountains with frontal boundaries. We have a history here east of the Appalachian Mountains to “rain out” prior to the arrival of the cold air to change the rain over to snow.
There is an exception to this “rule”; and that is we can develop a wave of low pressure to ride the frontal boundary from south to north. This would throw moisture back into the cold air and get the snow going.
Once the polar vortex takes control though, we tend to see very little snow due to how cold, and dry the air mass is.
Stay with us for updated forecasting as we get closer to what could be the coldest part of winter.