Strangely Quiet Out There Due To An Atmospheric Traffic Jam

Mild temperatures for this time of year prompted snow
to slide halfway off my St. Albans, Vermont roof and 
hang there. Light winds and relatively mild 
temperatures might keep this little snow sculpture
going the rest of the week, who knows?

This time of year, the heart of winter, the atmosphere is really dynamic.  The jet stream overhead screams by, powering big storms and dramatic changes in weather from stormy to frigid to warm back to frigid and our stormy again. 

Except now over Vermont and much of the Northeast and Midwest. 

Crickets. 

I mentioned this yesterday, but it's worth looking at more: There's a big traffic jam in the atmosphere, caused by an unusual ridge of high pressure in the atmosphere near Greenland. 

This is causing the usual parade of weather systems in North America and the western Atlantic come to a screeching halt. 

We're in the middle of this traffic jam, so the kind of weather that settled in Sunday won't change much at all during the week.  It'll feature light winds, cloudy skies and no excitement in the weather department. 

Even the strong upper level winds many thousands of feet overhead have gone mostly silent for now.  The guns of January - cold winds, storms, blowing snow - have gone quiet for awhile. 

The usual January weather excitement is avoiding us. Just like motorists in a traffic jam on Interstate 89, weather systems have to find some way to get around the mess. So storms from the Pacific Ocean take a detour, turning right so that they cross the southern United States instead of further north as usual.  

These storms eventually head off the southern U.S. coast and spin up nor'easters way offshore, too far away to have much effect on the East Coast.

These storms end up becoming part of the jam out in the Atlantic Ocean.  Like impatient motorists on Interstate 89, they just eventually make the problem worse. 

Those stalled offshore nor'easters, just sitting and spinning out there, do manage to throw back a little moisture our way, so we get clouds and even flurries. 

High pressure stalled to our north also contributes to the clouds. A temperature inversion forms beneath this high pressure. An inversion is when temperatures rise with elevation, instead of dropping with height like they usually do. 

This inversion creates a low level cloud deck. In the warmer times of the year, strong sun helps mix the atmosphere, breaking up the inversion and the clouds. The sun is low and weak this time of year, so the inversion holds pretty much all day.

So we linger under mostly cloudy, boring skies.  The sun does manage to peek through sometimes, but it's hit and miss.  We will also get virtually no precipitation for the next seven days. That's an oddly long time to avoid the snow or mixed precipitation we so frequently get in January. 

Usually, high pressure to our north in the winter feeds frigid Arctic air towards us.  Not this time. This high pressure is strangely warm.  At least for Canada.

That means for us this week, high temperatures during the day will be near or just above normal. Not that big a deal. However, nights will be toasty by Vermont standards, only dipping into the 20s, with some upper teens later this week.  It's usually in the single digits at night this time of year. 

The traffic jam extends into the Midwest.  It's so calm out there that freezing fog has been developing at night, making roads slick but creating beautiful frost on trees.  

It's possible we'll get patches of freezing fog at night here this week, though it's fairly unlikely. 

This traffic jam will eventually break, but probably not until mid-month at least. Despite the blocking in the atmosphere, some storms or weather systems might somehow get through and affect us more than a week from now, but it's hard to predict how that would happen this far in advance.