NOTE | This post was published Friday, 12/15/2017 for subscribers. I’ve released it for public viewing 12/16.
Christmas is ten days out and folks have been really putting the pressure on for a Christmas forecast. To be completely honest, detailed forecasts for Christmas are just to far out to make with ANY amount of certainty. We can, however, look at some upper level setups that can give us a hint at what we might be looking at ten or more days out.
I will say this: If you rely on your weather app for a reliable forecast for Christmas, you’ll be disappointed. Just don’t.
WHITE CHRISTMAS MISCONCEPTIONS
When I talk to folks about Christmas weather the most-often asked question is “will we have a white Christmas?”
First, since I get many different answers when I ask what people think a ‘White Christmas’ actually is, we need a definition. Officially, and yes there really is an official definition, a White Christmas means there is one inch or more of snow on the ground on December 25th. OR, it snows one inch or more on December 25th.
There seems to be a lot of misconceptions about snow and Christmas here in the Valley. More often than not, we do not see snow here around Christmas time.
And, in reality, the chances that we DO get any snow on Christmas are really very low – on the order of 10% to 20%. Most people are surprised by the low odds for snow on Christmas.
In weather terms, 10% to 20% are slight odds for precipitation – snow or rain.
Actually, Christmas Day here in the Valley isn’t really even cold compared to what we generally think of cold during the winter. Our last really cold Christmas Day was back in 2000 and 2001. Christmas on 2015 was actually BALMY!
Since I’m kind of a facts person, I just don’t get the fascination a lot of people here have with the prospects for a White Christmas. It really is rare that we have one.
WHAT ABOUT THIS YEAR?
Like I said, with Christmas being ten days out yet we can’t really zero in on weather specifics. But, we can look at developing weather patterns and come up with a general idea of what we might be looking at around Christmas time.
GENERALLY SPEAKING the setup in the upper levels favor a stormy pattern for the Midwest at or around Christmas. AND, temperature patterns projected at the lower levels of the atmosphere bear this out quite well.
We’re looking at the 850mb level (around 5,000 feet) in the map above. At this level we see distinct masses of warm air in the east and cold air to the west and north. Storms, or at the very least unsettled weather, like to form where boundaries of warm and cold air masses meet (baroclinic zone). Summer or winter, the region where warm and cold air run into each other can be a battle zone. With this setup in the map for Christmas Day, we can clearly expect to see such a boundary somewhere within the circled region.
The question that we can’t answer with any amount of certainty is where exactly that boundary between warm air and cold air will eventually form. Will it be through Ohio? Too soon to tell. But, we can pretty much figure on it being stormy where that boundary ends up. And, models have been pretty consistent on this stormier pattern setting up for quite a while now.
- Confidence is HIGH that a stormier weather pattern will develop around Christmas
- Confidence is HIGH that temperatures will be relatively warmer going into Christmas
- MEDIUM confidence on periods of precipitation at and around Christmas
- Confidence is LOW as to precipitation type (ALL types will be in play both solid and liquid) and where storms develop (specifics)
Now that we know the basic pattern, we can begin to look at how the details might evolve over the next several days. We should begin to see those details come into better focus early next week as low pressure develops in the south and moves northeast along that battle zone (panhandle hook?). What we need to figure out yet is where that battle zone sets up which will determine where the low (storm) tracks.
If you have holiday travel plans, you’ll really want to pay attention to the forecast from around Christmas Eve and the week following.