WINTER STORM WARNINGS HOISTED...
You would never know it by the weather today but a healthy winter storm is taking aim on the Midwest. About the only obvious clue Friday will be the stratus, areas of fog, and drizzle (freezing in a few spots north) that blankets the area. The stratus is the result of abundant low level moisture that's trapped beneath a strong inversion.
Those conditions are not likely to break until Friday night when colder air arrives behind a strong cold front. That makes the last day of 2021 a dreary one with a big range in temperatures. Snow covered areas will remain in the low to mid 30s while those with bare ground should reach the 40s, perhaps nearing 50 in the far south.
For anyone with plans to ring in the new year Friday night, the weather should be cooperative with no impacts from the impending winter storm anticipated until Saturday morning at the earliest. I'll have the latest on the winter storm in the rest of my post below.
STILL A FEW SEATS AVAILABLE FOR WEATHER SCHOOL. TSwails.com is offering a very special opportunity for you to learn first-hand the ins and outs of weather forecasting with one of the most experienced meteorologists in the country and a talented team of experts. Get the agenda, details, and limited seats by clicking the banner below.
JUST HOW MUCH SNOW WILL I BE SHOVELING?
The big question on everyone's mind is when is this "winter storm" hitting and how much will I be shoveling? Those are the issues I will tackle as the storm looms 24 hours away. The first thing I will mention is that while the storm will have significant impacts, it's not classic. By that I mean its an open wave at 500mb and the surface low is not especially deep. If this were a fully phased system the dynamics would have been there for a full throated blizzard considering the Arctic air that gets involved and the amount of available moisture.
Even without all the bells and whistles, ahead of the positively tilted trough the right entrance region of the jet is aimed at my southern counties producing significant lift. Additionally there is strong frontogenesis taking place just above the surface. (This is where a sharp horizontal thermal gradient exists between very cold air to the north and warm moist air to the south). It creates strong vertical motion and lift which enhances precipitation. Add to the scenario available water vapor in the 90th percentile category and you get yourself a set-up that can still be an efficient snow producer. Some models have a tight closed 850 circulation which I really like to see in a heavy snow producing event. Other's are more broad and in general those are the ones with lower snowfall output which makes sense.
Here's the surface depiction of the storm at noon New Years day. At that time snow is falling in earnest with a 995mb surface low in SC Illinois. Gusty NE winds up to 30 mph are also blowing as evidenced by the packed isobars.
As it stand now, the NWS has not pulled the trigger on winter storm warnings but I would hope that happens in the forecast updates overnight and be in effect by daybreak Friday. It should approximate the current watch area which looks like this. Further north winter weather advisories are likely if not warnings to HWY 20.
The Weather Prediction Center has finally upgraded their winter storm severity index to include high-end moderate impacts for much of my area near and south of HWY 30. That could have easily been done a day earlier. So it goes.
WPC also shows my entire area with a 90-95 percent chance of an inch or more of snow. I'm willing to go 100%.
Odds are 80 percent of 4 inches or more in the south. I would say more than 95%.
That brings me to the part you've all been waiting for, how much snow and when? Starting with the when, it appears New Years day will dawn cloudy and quiet. Snow will develop by 8:00AM in the SW Saturday and rapidly spread NE encompassing encompassing all of the region by noon. Significant snow falls through the afternoon and early evening before tapering off from west to east by midnight. Temperatures to start the day will range from about 10 in the north to the low 20s far south. Readings will hold steady or slowly fall all day long. Saturday night Arctic air invades the region allowing temperatures to plummet and come Sunday morning readings west of the Mississippi will be a bit below zero while east of it just a few degrees above. A general range of 5 below to 5 above.
Wind gusts at the height of the storm could reach 30-35 mph and with a powdery snow considerable blowing and drifting is likely in the open country. Travel could be quite difficult from afternoon through New Years night, especially with the cold temperatures and a stiff wind creating wind chills of 15 to 25 below zero. Plan accordingly!
As for snowfall, the NWS has come out with their official forecast and it looks like this. For the most part I think it looks good. For my part with about 24 hours to go, I am leaning towards the higher end of the ranges shown.
The various models that forecasts are constructed from look like this. None of these are necessarily right or wrong. It's just raw guidance that we use establish trends. What you will see at least for now is that we have reached a point late Thursday night where there is good consistency leading to high confidence in where the significant snow will fall. Most of the output is significantly higher than what the NWS is showing but models often have a tendency to be a couple inches too high. What is impressive is that most of them indicate totals in some part of my area greater than a foot. We will see if they hold to that on Friday. Meantime, as I said earlier I am leaning towards the higher ranges of the NWS forecast shown above. Here you go.
The GFS
The HRRR
The 3k NAM
The NAM
The GEM
The last model to come in off the 0z runs is the EURO. The northern edge of its precipitation shield is lighter and further south producing somewhat lighter snowfall totals in my northern counties. This is not at all out of the question but it is an outlier compared to the other models. There is going to be a very sharp cut-off to the northern extent of the snow band due to very cold dry air battling the saturation process necessary to get snow down to ground level. We will get three more models runs before the show to access its trends.
With that, I will wrap this up. New data will be in around noon Friday and I will do a live video at that time to update everyone on the latest trends. You can view it on my Terry Swails Facebook page at your convenience (or Navigate to my Page on Facebook).
"Like" the Page and continue hovering over the "Like" button
When the drop down menu appears, select Get Notifications
This will then activate notifications to you from me. Roll weather and white gold....T. Swails
PLEASE CONSIDER SUPPORTING TSWAILS...
Hi everybody, I'm asking that those of you who find value in the site to consider a $12 dollar voluntary subscription covering operating expenses and the time and effort I put into the site. My $12 dollar asking fee is the cost of a pizza or a dozen donuts. Those are gone in a day, TSwails.com is here for you all year long. It's a heck of a value and all I'm asking is that if you enjoy the site and see value in it, that you please consider a voluntary subscription. I'm asking $12.00 dollars a year. That's $1 dollar a month or 3 cents a blog. Thank you for your support and consideration. Terry
Comments