7:30 AM UPDATE TUESDAY
Womp.
Big goose eggs around Denver. This was a tough one as I was messaging all along. There were/are still blizzard conditions on the northeast Plains. This is a current look at road closures out there.
So, while the forecast was a bust for Denver, it’s definitely verifying out east. Light to moderate snow and heavy winds will continue through the day.
The mountains faired well. Steamboat got a foot of snow with more on the way.
9:30 PM UPDATE
The Southern Palmer Divide near Monument and the Air Force Academy has been upgraded to a winter storm warning. Colorado Springs and Pueblo have been added to the winter weather advisory. High end totals in Denver and Ft. Collins have went up.
Looking over the latest hi-res models. There’s going to be a big boom somewhere. Recent thoughts have me eying Denver airport for upwards up 8-12″ of snow. There’s still going to be a sharp gradient of snow to the west of DEN. Downtown may ‘only’ get 2-4″ while Boulder get’s an inch.
This will create very tough driving conditions in Aurora all day Tuesday. Get ready in that area of town and down towards Parker.
Monument and the Air Force Academy in northern El Paso county are also expecting more snow. 3-7″ there with very gusty winds.
Colorado Springs an Pueblo and out towards Las Animas – 1-3″ of snow is expected in bursts which will make for tough driving overnight and Tuesday morning.
I’m thinking this trend we’ve been watching is going to continue. If the radar continues to fills in around Denver from 11-midnight, I have no reason to doubt areas like Aurora and DEN getting upwards of 8-10″ of snow. Blizzard conditions will be felt *at times* Tuesday morning with blowing snow into the afternoon in those areas.
This is quite the storm!
For giggles. Here’s the latest run of the HRRR (pronounced her) model. It’s a hi-res and has been producing quite the gradient of snow over the Denver metro.
This shows 10″ of snow in Aurora, Parker and DEN.
4-6″ in Glendale and Centennial.
1-3″ in Denver downtown and Englewood.
<1″ In Broomfield and Arvada.
This is a wild gradient and is the product of good storm conditions with unfavorable downslope winds.
3:30 PM UPDATE
This is a fun storm for meteorologists. The excitement is growing of what is going to happen with this storm and most of all, it seems like the general public that like weather agrees and understands what this storm is about and that’s very reassuring. Thanks y’all!
Short term models continue the trend of a slower storm with a slight shift west. Both of these are what is making for a higher forecast for snow up to the I-25 corridor. Downtown should be ready for 2-4″ of snow with 35-40 mph wind gusts Tuesday. Boulder and Golden are on tap for 1-2″ of snow and 50 mph wind gusts as well. The biggest impacts will still be felt northeast of Denver.
Here’s messaging from the National Weather Service in Boulder
WE'RE CONTINUING TO STRESS THE IMPACT OF EXTENDED ROAD CLOSURES AND IMPASSABLE RURAL ROADS WHICH COULD LAST A DAY OR TWO AFTER THE SNOW ENDS SINCE THE WIND CONTINUES. THE WESTWARD SHIFT OF THE SIGNIFICANT SNOW COULD PULL SOME OF THESE IMPACTS WESTWARD INTO PLACES LIKE SOUTHEAST WELD, CENTRAL ADAMS AND ARAPAHOE, AND ELBERT COUNTIES MAINLY DUE TO THE STRENGTH AND DURATION OF THE WIND.NWS Boulder Forecast Discussion
The “impacts getting pulled westward” trend is something that could continue. If that’s the case Aurora is up for 5-7″ of snow and Downtown is up for 4-6″.
It will stop snowing midday and start to clear into Tuesday evening region-wide. It will stay windy through Thursday with blowing snow conditions lingering till then across the Plains.
Here’s an example of the snow that could happen around here.
And these numbers could get bumped up in many areas.
1:30 PM UPDATE
Denver to Ft. Collins have been added to the weather alerts. Recent models are trending a bit further west and are developing a band of heavier snow near I-25 during the overnight hours. Winds have also ticked up because of this. Please keep checking back here for more updates. This storm is going to be a “nowcasting” storm. Meaning that the forecast will be changing as the event begins and continues.
The Tuesday and Wednesday commutes will be rough because of the snow but mostly because of the wind and drifting snow. Snow totals may continue to wiggle over the next several hours so prepare for it now.
This is how things could play out and it won’t be fun for some and it will be real fun for others. You know who’s going to get blamed when people are surprised or mad? This guy. Bring it on.
________________________________________________________________
There’s been a lot of talk about the incoming storm and I know you’re at least a bit abreast of the changes that are incoming. I hope you enjoyed the weather Sunday because we won’t have a day like that until after Christmas Christmas.
I’ve been keeping my eye on a storm for several days now and models have been in awfully good agreement, even many days out, that there would be some kind of impactful storm over/near Colorado for the Monday-Tuesday timeframe. Starting late tonight on the Plains, that storm will make itself known.
For Denver/the Front Range to get a big snowstorm, ideally we’ll have a low pressure form or track near the Four Corners and then more E-NE towards the Kansas and Nebraska Plains. In this position, the winds that wrap around the low pressure push air up the slopes of the Rockies and deliver some of the areas biggest snowstorms.
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The storm we’re watching coming in is over California and Nevada right now. It will be pushing through the Intermountain west before moving into Colorado Monday afternoon. This storm looks to develop a low pressure around Limon/Burlington, CO before pushing NE into Nebraska. Here’s a look at the current major weather models and the positioning for the storm.
It’s pretty impressive actually to see this kind of agreement with this size/strength storm. This is one of those storms that’s really, kind of frustrating for meteorologists. But the issue here is, if this storm develops/trends about 30-50 miles south or east or west than where current thinking suggests, it will have pretty major implications on the forecast.
Right now, this storm is tracking a bit too far north for a major snowstorm around Denver. What’s pretty much guaranteed is that it will get much colder and it will be very windy at times and there will be at least some snow around the northern I-25 corridor.
Since winds are a big factor in our snowstorms here, take a look at this graphic showing which direction the wind should come from to produce the best upslope/snowstorms across the state.
So, as you read forecasts in the future, know that EVERY.SINGLE.AREA of Colorado requires something a bit different to get that good, good snow. Winds are truly of the upmost importance in winter forecasting here. The opposite of upslope winds – which causes air to rise and condense into snow is downslope winds. Downslope winds warm and dry as they run from the top of mountains to the lower elevations. NE Colorado will be impacted by upslope and downslope winds throughout this storm which makes this forecast nice and fun. As always 🙂
Another factor of this storm is, surprisingly, severe storms. There is a chance for severe thunderstorms across the Nebraska and Kansas border this afternoon and evening.
The last time a marginal risk of severe weather was forecast in December in Colorado was back in 2015. Not that common of a sight.
Either way, let’s talk winter deets.
Forecast
We’ll start off this storm with a nice, warm southerly SWerly wind. That will keep us mild through the first part of the day before the cold front comes swinging through. As it stands now, it looks like the cold front will move through Ft. Collins/Boulder/Denver between 2-6pm on Monday. After that, temps will drop pretty quickly into the 30s and 20s overnight.
This is a big storm. It will bring major travel delays to the high Plains of the Dakotas and Nebraska and will bring blizzard conditions to many areas. The NE Plains of Colorado will also see blizzard conditions.
That’s a busy weather map. All the highlighted areas are under some kind of winter alert from this storm – which is a lot of real estate. Areas highlighted in Orange are under a BLIZZARD warning. This forecast is pretty complex and this isn’t like any of the storms we’ve had this season (we’ve all heard that before, but this rings true). There are three main impacts coming from this storm. Wind, snow and cold. I’ll break these down individually.
Wind
Let’s start with everyone’s favorite. Wind.
Here’s an animation of the wind wind now through Wednesday. You’ll notice SWerly winds pumping in warm air will at first on Monday, then the swirl of the low pressure followed by strong NWerly winds that will funnel in cold air for Tuesday and Wednesday.
The Plains will be the windiest over the next several days with gusts up to 40-60 mph Monday night to Wednesday evening. The Foothills will also get very windy Tuesday through Thursday with 50-60 mph gusts from Estes Park to Idaho Springs to Genesee.
Wind gusts in Denver will be upwards of 25-40 mph from Tuesday to Wednesday.
As you can see, the winds will be a bit all over the place over the next few days. At times, this wind will help produce heavy snowfall while at other times, it will completely eradicate it which is a big component of why this forecast is so tough.
If you’re not a fan of the wind, I’m sorry. Neither am I. This wind will be what brings blizzard conditions to the region Tuesday and Wednesday.
Cold
There is some deep cold coming in. I mean, it’s going to be cold for a long time. The 6-14 day outlooks show colder than average air staying put all the way up until Christmas day and possibly longer.
There are some large-scale weather patterns happening across the Northern Hemisphere including a large ridge of high pressure building over the northern Pacific. It looks like that will stay put for a while meaning that air will continually be flowing up and over that ridge and down through the northern Rockies and Plains.
Take a look at some of the forecasts over the next week. The I-25 corridor with struggle to rise above 35º starting Tuesday and lasting through Christmas so this is long-term cold so be ready for it and mentally prepare for that change.
By the end of the week, we’ll be talking about overnight lows in the single digits for many and sub-zero for many mountain valleys. There are no signs that temperatures will rise above 40º anytime soon.
This cold will allow the snow that falls to really hang around for awhile. Again, just be ready for cold air and even colder windchills.
Snow
This storm has been very complicated to watch. There are a lot of factors that make this difficult but the storm track is the main one. It will bring favorable snows to the mountains which is a guarantee but the snow that occurs on the Plains will vary greatly from west to east.
This is one of those storms that will produce more snow at DEN than downtown, which will get more snow than Boulder too. Places along I-76 from Ft. Morgan to Sterling will be the big winners in terms of snow on the Plains. That will also be the area that could see blizzard-like conditions.
Denver is currently under no alerts due to the uncertainty that is still present. You could drive from Greeley, where less than an inch of snow may fall to Ft. Morgan where 8″ could add up with blizzard conditions. There’s a 50 mile difference and a huge difference in weather.
Here’s a look at the NWS’s current thinking in terms of snowfall. I’ll show both the expected amounts and the high end amounts.
Denver should end up with 1-3″ of snow by Tuesday afternoon. If you live in Aurora, you’ll get more than what falls in Lakewood. If you live along I-76, you’ll get more snow than those along I-25.
The mountains will do well with this storm.
The northern mountains (Steamboat, RMNP) should expect 8-16″ of snow with Steamboat really doing well in this cycle. Pow days ahead! The Central mountains of Aspen, Breckenridge and Crested Butte should expected 5-10″ of snow with upwards of a foot possible by Wednesday evening. Pow pow! The SW mountains around TElluride and Wolf Creek will see 6-12″ of snow as well! Great snows and snowpack building.
The main issue with this storm will be the upslope vs. downslope winds. We really won’t have a great handle on what’s happening till it’s happening unfortunately.
In the past, these setups usually bring the low end amounts to the I-25 corridor but blizzard conditions to the Plains. If the ingredients come together in just the right way, Denver could get 4-6″ of snow but that chance isn’t that high.
Here’s a look at hi-res simulated radar from now through early Wednesday morning.
There’s a burst of snow along I-25 overnight followed by snow continuing in the mountains and Plains through Tuesday and into Wednesday. This hi-res model paints a bleak picture for snow totals across the Urban Corridor but a major snowstorm on the NE Plains.
In this forecast run, FoCo, Boulder and Denver may not even get an inch of snow while Limon, Akron and Ft. Morgan and Sterling get 8-12″. That’s the kind of variety we’re looking at here. I wouldn’t be surprised at this outcome.
For now, here’s what I think will happen.
This will be a widely varying storm with impacts anywhere you go. Please be ready for that. Tuesday morning will be rough in Denver and the surrounding areas with those tough conditions lasting through Tuesday night and Wednesday. The NE Plains will have tough driving conditions from Monday night through Wednesday thanks to lingering snow and wind there.
Avalanche danger will once again be high in the coming days so please keep this in mind if you’re planning on heading out.
Y’all be safe, stay warm and enjoy the weather!
We may have a few more chances of snow before the official holidays as well so keep an eye out.
~Andy
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