Short-term forecastWe'll start with the short-term though. Arctic high pressure has, once again, seeped into the region. If you walked outside this afternoon, you could tell. Wind chills by dusk were already below 20. As the high settles in, wind drops off, but high clouds will slow the temperature fall with most areas ending up in the upper teens tonight. A brief warm-up commences Friday and, more noticeably, Saturday as highs reach the lower 40s tomorrow and low to mid 50s Saturday with dry weather on tap.
|Arctic high pressure will dominate the Mississippi River Valley tonight, bringing cold temperatures overnight. All graphics courtesy WxBell Analytics|
By Saturday night, the next cold front ushers in another Arctic airmass, which sets the stage for winter weather mischief early next week. Sunday will be another very cold day with temps climbing from the lower 20s in the morning to the mid 30s by afternoon. North wind will keep wind chills well below freezing. Beginning Sunday night, a 48-hour period of unsettled weather will feature two likely rounds of precipitation.
|By mid-day Sunday, another strong Arctic high, centered over the Great Lakes, extends into the Mid-South, providing the cold air necessary for incoming precipitation to be wintry.|
Sunday night through TuesdayDuring that 48 hours, what we know is that precipitation is likely and temperatures will be sufficiently cold to produce freezing or frozen precip. The big questions lie in the timing, degree of cold air (always so critical), and precip amounts. In other words, while the general pattern is fairly well understood, the details are yet to be ironed out.
The first round of precip will accompany a mid-level disturbance from the Plains that moves through Sunday night into Monday morning. This first round has been moving earlier with each model run and now could start as early as Sunday evening. Temperatures during this event appear to favor snow or sleet. Amounts are very uncertain, but some accumulation looks possible and Monday morning's rush hour could be impacted. Fortunately it is a holiday for many of you and many schools are out, which should help a great deal.
|A mid-level atmospheric disturbance moves through Sunday night and early Monday, triggering the first wave of precipitation.|
The second round looks to be during the day Tuesday as a large-scale trough and Arctic cold front (yes, another one!) move through. Once again, temperatures appear to support some sort of wintry precipitation. Though the models agree well on the arrival of this large trough, they differ greatly on how much precip accompanies it. In addition, a recent trend in the models has been for a period of dry weather Monday night into early Tuesday, where previously it was wet. This could be very good news as total precip amounts have diminished some with that new "dry" period.
|A huge ("full latitude") upper-level trough dominates the middle section of the nation on Tuesday evening. It's approach triggers the second wave of precip and ushers in perhaps the coldest air of the season by Wednesday.|
Bitter cold to end the weekAlso fairly certain is that behind the Tuesday front, bitterly cold air arrives for Wednesday and Thursday. The degree of cold air will be affected by any snow or ice on the ground, but suffice it to say, we could be talking single digit lows Wednesday morning and temperatures remaining below freezing all day Wednesday and possibly Thursday.
PreparationWhile there is much uncertainty in the details, I have to say that this system brings the best potential for winter weather that we have seen yet this season. I encourage you to stay tuned to the latest forecasts for the next couple of days and be prepared for the possibility of ice or snow Sunday night through Tuesday.
"Beware the Share" - don't blindly share snow accumulation maps from that don't "pass the eye test" from sources you don't absolutely trust. (You'll notice we didn't post a single snow accumulation map in this discussion. It's simply to early to conjecture and it WILL change.) We'll provide updates on our social media accounts listed below and the latest thinking will be reflected in our MWN Forecast available via web, mobile web, and mobile apps. Another blog will also be written when some of the details get a little clearer, but no later than Saturday.
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