What’s on my mind this morning in terms of the weather is how dry it’s been overall. The reason I think about this this morning, is because as we close November and head into winter, you might start thinking about when are we going to get our first snowstorm. That question will be answered with the backdrop of relatively dry weather patterns. Of course, there was a drought a year ago and then we got out of the drought for a while before many areas along the coast returned into it during the second half of summer and into the fall. Fast forward to November which hasn’t been very wet. Most areas will close out the month with about half the amount of typical precipitation. This isn’t good for the water table or trees and shrubs as the ground freezes.

As we move into December, if things were to remain dry, it could start to impact the amount of snow we have. What’s interesting and something you might not know, is that because an inch of snow contains a tenth of an inch of water or it takes about an inch of rainfall to make 10 inches of snow, you can have a winter with less than average precipitation, but more than average snowfall. For example, imagine  we had 20 inches of snow in December, January, February and March.  Let’s say it all had a water equivalent of 8 inches, that would be about 50% of the typical precipitation, but snowfall would be about 20 inches over what’s normal for greater Portland.  

Snowfall varies by large amounts each winter, but these are averages from the past 30 years.

A dry pattern typically doesn’t bring a lot of snow, so we’ll have to see whether or not our dry November continues through the core of winter December, January and February. Whatever happens in the months ahead the next few days are definitely going to be dry.

Precipitation is relatively evenly distributed during the year. In winter, much of this falls as snow.

Today we find a cold front ready to push through the area. Temperatures will be seasonable but there’s going to be a brief blast of cold air late this afternoon and overnight tonight. This cold air won’t last long, but you’ll notice it. When you get up on Tuesday morning it will be quite chilly and feel like winter. The air will be dry and crisp and you’ll want the hat and gloves for the morning at least. Lows will be in the teens Tuesday morning with coastal York County remaining around 20 degrees. 

Light winds and abundant sunshine make it feel pleasantly cool Tuesday afternoon with a real warm-up for Wednesday. That day features temperatures in the 50s. The dry weather continues into Thursday, but some showers are likely Thursday night or Friday morning as a weather system affects the region. The amount of rainfall and the timing if this is still questionable, but presently it doesn’t appear to be an important system.

Follow Dave Epstein on Twitter @growingwisdom