Colder Regime Takes Over, Earlier Than First Thought

Frosted over leaves on a cold, but still snow-free
Saturday morning in St. Albans, Vermont.

Several days ago, I said the weather this December would be even more unpredictable than usual, and so far it's playing out that way. 

It looks like the guess work on how the rest of the month will go will remain extra tricky, too.

Long range forecasts issued in November suggested we'd have a cold December.  Those predictions flip flopped to warm as the month opened. 

But now that we're supposed to be in the midst of a warm spell, it has abruptly turned colder. Not super cold, but chilly enough.

Friday was the first day since November 29 that was cooler than average. Not by much, but it was on the chilly side. 

It was in the low to mid teens almost statewide this morning, and many of us won't make it out of the 20s this afternoon. It will sort of on the chilly side most of the upcoming week. But again, nothing that out of the ordinary. 

Even with the new chill arriving, the march into winter remains behind schedule. Friday was the first day this season that did not get above freezing all day. I checked back over the past 40 years and found only two years - 2015 and 1998 - that had a later first fully subfreezing day. 

In case you haven't noticed, there's not much in the way of snow out there, either. At least not yet. Meteorologists are still expecting a little light snow tomorrow afternoon and night, mostly south and west of Interstate 89. But nobodyi in Vermont  will receive more than an inch or two. 

Another storm might or might not come along at the end of the week. Some forecast models give us a snowstorm. Some give us a mix. Some give us nothing at all. Go figure.

All this unpredictability in the daily weather this month is ironically because of a rather well forecasted weather pattern.

It features a huge blocking high pressure system over and near Greenland that wants to help send cold air south into the eastern United States, and possibly provide an environment for snowfalls.

Meanwhile, a warm ridge of high pressure wants to make the eastern U.S. warm. Since I last wrote about this feature on December 4 the battle continues and the uncertainty remains. 

Record warmth has bathed the south  under that warm ridge that's causing the battle of seasons further north.

As the Washington Post's Capital Weather Gang reports, Mobile, Alabama (85 degrees), Macon, Georgia, (83 degrees)  and Savannah, Georgia (86 degrees) had their hottest temperatures for any December date on record.  

It's been in the 80s on six days this month in Houston already. The high temperature of 85 degrees on Tuesday. That would have been Houston's hottest December day on record, except for the fact it got up to 87 degrees just last December. 

Although we don't know whether this weather pattern will ultimately lead to storminess here in Vermont, it is leading to bad weather in swaths of the nation.

Much of the western United States is dealing this weekend with snow and wind. In the northern Plains, a winter storm watch is in effect for the first half of the upcoming week. 

Meanwhile, the Gulf Coast states are bracing for a possible tornado  and severe thunderstorm outbreak early next week