BIG TIME COLD AIR POSSIBLE FIRST HALF OF JANUARY

2024 is wrapping up on a warm, but very wet note as a series of storm systems tracked across the Deep South and Lower Ohio Valley bringing more than 2" of rainfall to most, if not all, of Southern Illinois.

As we look ahead to the last few days of the years, another storm system is expected to track across the region Monday night and into Tuesday morning. The position of the low, which will track through the St. Louis Metro, will keep the heaviest rain north of our area, but an additional 0.25-0.50" of rainfall is possible through Tuesday morning.

In the wake of this system, COLDER air will begin moving into the region to kick off 2025. New Year's Day will feature afternoon temperatures in the upper 30s. A more pattern typical of winter will stick around the remainder of the week and into the first weekend of the new year. A much larger Arctic Blast is in the works towards the middle of January. (more on that below).

Finally, there will a 4-5 day window without precipitation the forecast. There are a few weak disturbances that may bring a few flurries or light snow showers, but measurable precipitation appears unlikely until next weekend.

At this point, it's too early to know what, if any, impacts a more significant storm system will have on the region beginning Saturday night and continuing into Sunday. There could be more moisture available, but details that will determine the amounts and if precipitation is snow, freezing rain, or rain are still very uncertain. If you have weekend plans primarily focused Saturday night and into Sunday, it's something to keep a close eye on.

The pattern beginning January 5 through January 15 is one that is already generating a lot of buzz on social media. Teleconnections, which identify common patterns that drive large-scale patterns, are indicating that a VERY COLD and potentially very active pattern will develop over the central and eastern U.S. When the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) go into negative phases while the Pacific North American Oscillation (PNA) is in a positive phase, watch out in the Midwest and Mid-Atlantic. Essentially, large amounts of warm air are being nudged northward into the Arctic regions of Alaska and western Canadian, displacing the Arctic air southward into the eastern half of the United States. It's safe bet to assume morning temperatures in the single digits with afternoon highs below freezing. Sub-zero temperatures are on the table, but in our region, that's often driven by snow cover on the ground.

In addition to the amount of cold air plunging south, the duration looks to be significant. We might see up to a week of below freezing temperatures.

Will this lead to snow? That answer is a bit more tricky. The cold air will be in place, but the upper-level pattern from the northwest is not typically conducive to producing systems with a lot of available moisture in the central U.S. Time will tell on the snow chances, but get ready for bitterly cold weather.

Stay tuned, January looks to be a wild ride!