A lot of snow and rain is currently impacting the eastern third of the country. This morning's radar composite sums it up nicely.
All this active weather...but where is the surface low? Here was this morning's 12Z GFS surface analysis:
This high pressure center looks to be here to stay--by tomorrow morning it is forecast to have set up shop in the central plains, bringing down much colder air than we've been seeing in the central and eastern US as of late. Here's tomorrow morning's GFS forecast:
Notice the very strong temperature contrasts still on the leading edge of this high pressure center. Furthermore, as this cold air moves down over the land surface, it encounters much warmer air over the open waters of the Gulf of Mexico and off the east coast. This is setting up some very strong-looking temperature gradients that follow the coastline. It also looks to be driving some cyclogenesis off the east coast. Furthermore, with such a strong high pressure center, the pressure gradients are also very strong, and this means strong winds--you can see some 15-20 knot winds forecast over the upper Mississippi valley and into the southeast. This means when the cold air arrives, it's going to arrive with quite the blast.
This high continues to linger into Sunday, according to the 48-hour GFS forecast:
With this huge high pressure center crashing the party, it looks like the weather pattern is finally turning to something more winter-like. Seattle is once again back to having its rounds of rain with relatively cool weather, frigid temperatures are building back across the northern Plains, and with the presence of this high pressure center things look to dry out a bit from the rainier-than-normal conditions some places in the south and east have seen lately. Perhaps these La-Nina-based seasonal predictions will come true after all...