If you have a short memory, here's a little reminder of what temperatures looked like during the month of November. Cold air came to North America early and often, especially here in the Midwest.
December represents the other side of the pillow. Look at the difference between the two months. Canada and the Arctic have dramatically flipped to warm this month.
Here's a tighter view of December departures the past 2 weeks.
Here's the past 7 days. The heat is on.
The reason it's so warm is the fact low pressure dominates Canada. When surface pressures are low temperatures are mild. All the areas in blue depict lower than normal surface pressures. Mild weather by December standards rules the roost.
Now, look what is projected to happen by December 28th. Pressures are rising all across Canada. That seeds the area with colder air. And, as the saying goes, if you build it...it will come. This is a strong signal that January is going to have a much different feel than December.
As this transition to a colder pattern takes place, the weather will also turn stormier across the Midwest for the first time in nearly 3 weeks. You can see the past 14 days how the southern stream jet has kept storms and moisture well to the southeast. This is total precipitation over the 2 week period.
A tighter view of Iowa and my local area. If we do not get measurable precipitation in Cedar Rapids Wednesday it will be the 17th consecutive day in Cedar Rapids without it.
Now look at what the future holds beginning around Christmas or just after, the pattern turns active as the baroclinic zone between the coming cold and the existing warmth lights up with storms. Here's the total precipitation forecast from the EURO EPS ensembles through January 2nd.
The GEFS ensemble means are similar...even heavier over the southeast.
With regards to storms, there is a system that models are very divergent on Christmas Eve night or Christmas Day. The EURO has been showing some light snow accumulation around my area in that period but the GFS is high and dry. The 0z run of the EURO has backed off substantially so for now this looks to be a minimal event...if at all.
A potentially major storm appears a near certainty December 26-28th. All the major models are in agreement that a deep cyclone will track through the state of Iowa delivering a wide variety of weather. The warm sector (which my area will likely reside in) should see rain and very mild temperatures ahead of the system. Thunderstorms will even be a possibility. The cold sector will see sleet, freezing rain, and heavy snow with near blizzard conditions. All parts of the Midwest will experience very strong winds that could exceed 40 mph in spots if the storm reaches its projected strength. The GFS shows this beast heading for Iowa mid-day December 26th. Heavy precipitation and powerful winds are raking the region.
If nothing else, things are starting to cook in the weather kitchen after a steady diet of tofu. I'm hungry for something to sink my teeth into! More to come. Roll weather...TS