On the 12th day before Christmas, when all throughout the Midwest
Forecasts were teasing snow, but some say it's still a guess.
Poetic cuteness aside, significant changes are coming to the weather pattern in the next two weeks that will have many snow lovers rejoicing. Others will just be bothered by the bitter cold. Nonetheless, chances of a white Christmas are more than twice as high (compared to normal) this year from the Upper Midwest to the Southern Plains.
Confidence is high in a colder-than-normal holiday period for much of the continental United States. Credible forecast models all project below-normal temperatures for the seven days surrounding December 25 in all locations east of the Rockies. However, they do differ in the extent and magnitude of extreme cold (compared to normal) during this period, which is also likely a factor of timing.
The three images below show 7-day average temperature anomalies from multiple runs of the GFS (American), ECMWF (European), and CFS (NOAA).
Temperatures are likely to be at least 10 to 15 degrees below normal from the Northern Plains to the Mid-South on or around Christmas Day. The numbers could be a lot colder than that in some areas, depending on snow cover and the track of multiple storm systems leading up to the holiday.
Here's an example long-range forecast for St. Louis from the GFS. The red box is drawn around a projected stretch of more than a week with subfreezing temperatures (day and night). According to this model, temperatures might even not top 20ยบ for 72 hours straight!
Details on exactly how cold, and for how long, will become more apparent in the days to come. And those specifics will be significantly related to who gets snow or not.
Chances of at least one inch of snow on the ground (or falling) on Christmas Day are more than two times as high as the 30-year average across a large area of the nation's midsection. The interactive graphic below compares the historical probability (1981-2020) to my 2022 forecast.
Cities such as Oklahoma City, Little Rock, and Nashville that historically have less than a 1 in 10 chance of a white Christmas have elevated probabilities of 20 to 30 percent this year. Chances are also more than two times as high (compared to normal) across the Ozarks and lower Ohio River Valley.
The Arctic air that has been bottled up in western Canada since Thanksgiving is about to be unleashed by the powerful storm system moving across the nation this week. It will then be driven farther south by another storm system next week (Dec 19-23), with potentially a third cold front delivering the "knock out" blow of arctic air deep into Dixie.
At this time, significant differences and inconsistencies in model solutions preclude me from posting details on when, where, and how much snow or ice may fall during the week of Christmas. I will be posting numerous times on those details as they become available, including credible modeling and road condition data from my employer Baron Weather.
But for now, just know that this year's Christmas will likely be much colder than normal (and possibly white) from Montana to Mississippi. Temperature anomalies along the west and east coasts are less certain, but an active jet stream pattern is sure to deliver bouts of cold and snow in those areas as well in the coming weeks.
The rumors have been flying for days. And some of them are true!
Another winter storm is taking aim on the Mid-South and Southeast this weekend.
For some, this will be the third winter wallop in two weeks after many wondered if winter would ever come.
Winter had been missing for much of the eastern two-thirds of the nation prior to the start of the new year. However, back-to-back winter storms have since swept through the same areas targeted by this weekend's event.
Forecast models have converged on two swaths of significant wintry precipitation arcing from the Midwest to the Southeast. I've listed them below, along with details on where I see the most noteworthy amounts occurring.
The storm will start like a classic Alberta Clipper system, diving quickly to the south through the eastern Dakotas and Minnesota to Missouri.
Generally speaking, a 24-hour window of light to moderate snow will leave most areas with 2 to 6 inches, but higher amounts of 4 to 8 inches are possible roughly 100 miles either side of a line from Sioux Falls, SD to Kirksville, MO.
The storm will be strengthening as it dives into the Mid-South Saturday night, pulling in more moisture from the Gulf of Mexico.
Confidence is much lower on amounts and location of the heaviest bands as the storm goes through this transition. This will likely result in gaps in heavier snowfall totals across portions of Missouri and Arkansas. The highest totals in these states, potentially up to six inches, will likely occur in the higher terrain of the Ozarks on either side of the state line.
Forecast map on more specific amounts across Mid-South will be available when confidence is high enough to be credible.
Snowfall rates will pick up quickly as the storm matures through the Tennessee Valley Sunday. This is also when a mixture of freezing rain and sleet will overspread northeast Georgia and the Upstate regions of South and North Carolina. North and west of where ice accumulations occur, a swath of 4 to 8 inches of snow is becoming increasingly likely. A consensus of the most reliable forecast data places this 100 miles either side of a line from just east of Memphis to Knoxville in Tennessee, then across the Appalachians from northeast Georgia to Pennsylvania.
Lighter amounts of wintry precipitation will also fall outside of the aforementioned areas, but with lesser confidence in how much. Dry air will lead to a sharp cutoff in snowfall amounts on the northern side of the storm track, whereas the timing of a changeover from rain to frozen precipitation will affect amounts on the southern side.
The "enhanced risk" of severe storms capable of producing a tornado or wind damage has been expanded north to include the greater St. Louis metro area, according to an update from the Storm Prediction Center Friday morning.
Latest forecast data also suggests the storms may form several hours later than originally posted in Missouri and Arkansas. My latest thinking is listed below.
A powerful cold front is expected to develop across the Central Plains Friday, igniting strong storms ahead of it as it encounters an increasingly unstable airmass across the Mid-South Friday night.
The strongest storms will be capable of producing a tornado or damaging wind gusts up to 60 mph. The risk is greatest after dark across portions of eastern Arkansas, southeast Missouri, northern Mississippi, and western Kentucky and Tennessee.
Forecast data suggests the first cells might not even develop along the front until after 4 pm CST Friday.
Confidence in this forecast is near average for two days prior to the event. The highest degree of uncertainty exists on the location of storm initiation Friday evening. This will depend on the forward motion of the cold front as it is matures and accelerates over the Ozarks Friday afternoon. Storm coverage may also be a bit disorganized or scattered at times, preventing this from becoming a widespread or larger scale event.
