Snow expected to start early Tuesday afternoon: Winter storm forecast update
Everything you need to know about the timing and strength of this week's winter storm
UPDATE – TUE, 10:30 a.m.: Winter Storm Warnings will go into effect at 5 p.m. MDT Tuesday, and expire Thursday morning at 11:00 MDT. However, an additional Blizzard Warning will go into effect for some counties in eastern SD at noon on Wednesday, and expire at noon on Thursday.
We expect scattered rain and snow to fall throughout western SD through Tuesday morning, with a quick transition to snow right around noon as temperatures drop. These first few inches of snow on Tuesday afternoon may melt on surfaces and cause some icing later on as temperatures continue to fall into the night.
Snow will continue to fall through the day on Wednesday, making travel difficult all day Wednesday and on Thursday morning. Temperatures will also be below zero on both Wednesday and Thursday, so stay safe!
UPDATE – MON, 2:45 PM: Most of the winter storm watches have now been upgraded to winter storm warnings. The difference with the warning is that there is now high confidence that a severe winter storm will impact the area.
With the updated warnings, there is a change in the timing and expected snowfall. The system is expected to move in a little earlier, so the warnings will go into effect Tuesday morning and continue through Thursday around noon.
With this system, especially on Wednesday, There is a strong possibility for blowing snow and low visibility. The lighter, fluffier snow that falls at lower temperatures can blow around much easier than the heavier snow can. This means that drifting snow will also be an issue.
Expected snow totals have increased slightly since the last update. However, when we’re dealing with a system like this, the exact amount doesn’t matter because there will still be significant impacts. roads will ice over as temperatures drop well below freezing on Tuesday night. Additional snow on top of that is only going to make matters worse.
Again, DO NOT travel during this storm unless it is absolutely necessary. If you must travel, have a winter survival kit with you. You should have things like blankets, nonperishable food items, and a candle and matches or a lighter wouldn’t hurt to have on hand. If you happen to get stuck, it will take a while for emergency services to get to you, so you want to be prepared for the worst.
All of your winter storm prep should be wrapped up by tonight (Monday), but, at the very latest, early Tuesday morning. Be safe.
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RAPID CITY, S.D.
SUN – 3:30 PM, Confidence is increasing that a potent winter storm will impact the area on Tuesday and Wednesday this week. At the moment, this storm is looking like one of the most significant winter weather events of the season. While blizzard conditions may not be present, we could get very close at times during this storm. -This storm is not a joke- travel will be very hazardous for most of South Dakota and Wyoming. WE will see significant snow accumulation along with bitterly cold temperatures. As always, forecasts can change with time, but here’s what we know about the storm so far:
Timing
A potent upper-level trough is expected to dive into the western half of the country on Tuesday. There is also a low pressure system off of the coast of southern California that will be dragged to the northeast. This combination will give this storm system a lot of lift to work with and plenty of moisture. The low pressure system from California will combine with a very cold air mass from Canada, dropping the temperatures drastically.
One thing of note with this system is that the central low pressure system won’t be super compact, which means that the area of snow will be very broad and will take a while to move out of the area.
Precipitation is expected to move into the area sometime Tuesday morning. In some areas, this will start off as rain or a mix of snow and rain. this will make for a dangerous combination on the roads. As the roads cool down, the rain will freeze, then a layer of slush will form over the ice, after the precipitation switches over to a dryer snow as temperatures drop, fluffy snow will fall over the slush and ice. This combination is especially dangerous because the differences in the layers mean that there will be different levels of traction for each layer, causing the layers to slip on each other.
The beginning and middle portions of the day on Tuesday won’t be too bad, but conditions will deteriorate quickly as the evening approaches.
After the sun sets on Tuesday, rain will switch to snow, piling on top of the rain that fell earlier.
As the sun comes up on Wednesday, the storm is just getting started. Wednesday will likely be the most dangerous day, featuring the heaviest snow of the system and the strongest winds. Sustained winds of 20-30 mph will persist throughout the day and there will likely be gusts in excess of 40 mph. The fairly strong winds will reduce visibility by blowing around the snow that is already on the ground and the snow that is falling.
The winds will also drop the wind chill temperatures to dangerously low levels. These won’t be the coldest temperatures that we’ve seen this season, but they will be dangerous for anyone who gets stuck outside. If you have to travel, BRING A WINTER SURVIVAL KIT. Emergency services will likely take a while to reach you. Again, DO NOT TRAVEL UNLESS YOU ABSOLUTELY HAVE TO. Especially from Tuesday night through Thursday morning.
The heaviest snow looks like it will occur between Wednesday afternoon and evening. This will happen after many places have already received several inches of snow.
By early Thursday morning, the snow will begin to dissipate.
By midday on Thursday, the western and southern portions of South Dakota will be out of the snow – but not in the clear. Temperatures will continue to drop into the evening hours, reaching dangerous levels. With all of the snow and ice likely still on the roads, travel is still not advised throughout the day on Thursday.
Again, the will likely be the most impactful winter event that we’ve seen so far this season. DO NOT travel unless it is absolutely necessary.
Weather advisories
The Rapid City NWS has already issued winter storm watches for the area. As time goes on, and confidence increases, a portion of these watches will likely be upgraded to winter storm warnings.
There are three main concerns with this storm:
- Large, widespread snow accumulation.
- Strong winds, reducing visibility.
- Bitterly cold wind chills, especially at night on Wednesday and Thursday.
This storm is no joke. Take time now to prepare for this storm. ALL preparation should be finished up by no later than Tuesday morning.
Snow Totals
Unlike many of our past storms, the Black Hills will only have a minor effect on snow accumulation. This will be a very widespread event, so every area in South Dakota, NE Wyoming, and northern Nebraska will see significant impacts. Snow totals will be higher in the Black Hills, simply because of the effect that the higher elevation has on precipitation, but the surrounding plains will still see significant accumulation.
There will be regular updates on this storm as they come in. Stayed tuned, and be prepared for the worst case scenario.
