Dec 15: December Warmup and more Pacific Northwest Rain

It has been an active pattern for winter weather lovers across the eastern half of the US. Last week we had several clippers that brought multiple rounds of snow as you can see in the image below: 

Then, over the weekend, another clipper tracked from the Northern Plains across the Midwest and into the Northeast: 

This brought the first measurable snow of the season to Philadelphia, New York City, and Boston. It was a Winter Wonderland for our camera just outside of Manhattan on Sunday morning: 

Behind the weekend system, temperatures took a nose dive and many places saw single digit lows and lows in the teens. Freezing lows made it all the way to the Florida Panhandle and Gulf Coast: 

On Tuesday morning, while temperatures will be warmer than Monday AM, it will still be quite cold across the Eastern US: 

However, a warming trend will commence and lead to much warmer temperatures for at least the next week. Below is the 7 day anomaly from Thu Dec 18 to Christmas Morning:

The few areas not expected to go above average are the Great Lakes to Northeast. Still, this warm up will lead to the next system we are tracking bring more rain than snow later this week. This system will track across the eastern half of the country starting early Thursday and move off the east coast by Friday afternoon. The below animation shows Thu 1 am Eastern to Sat 1 am Eastern: 

The biggest weather concern for the next several days is yet another round of heavy rain from an atmospheric river that will impact the already water-logged Pacific Northwest: 

This time, the heavy rain will make it farther south down the coast and eventually bring precipitation to California: 

Unfortunately, it will be a pretty warm event with snow levels quite high. The snowpack in the West is already running well below where it should be this time of year. Most stations have less than 50% of what their normal snow water equivalent is:  

As far as the weather for the upcoming holiday, let's take a look at the general pattern we are expecting. The 5 day temperature anomaly from Mon Dec 22 to Sat Dec 27 shows warmer air for everyone except the Northeast: 

The precipitation pattern for that same time frame shows above average rain expected across the West, including California but below average precipitation for most places east of the Rockies. The one exception being the Northeast: 

And if you are hoping for a White Christmas this year, you'll likely have to head pretty far north to get it with the warmer temperatures expected to melt what is currently out there. Below is the forecast snow depth Christmas morning from the Euro model ensemble: