COLORADO, USA — This snow blog follows the signals in the long-range computer modeling.
It will be updated daily until the next time it snows in Denver.
Monday Update
Nov. 25-26
Sunday morning's computer model runs had the storm impacting the Denver metro more between 4 p.m. and 8 p.m., but now those hours don't appear to be too bad.
Tuesday morning will be the main event in the Denver area and the rest of the northeastern plains.
That storm is currently right on the doorstep and will start impacting Colorado before noon, mainly to north of the Denver area for most of today.
There could be a little rain in spots first, but by about 2 p.m. or 3 p.m., there should be some heavy snow starting to fall near Ft. Collins. Snow will impact Interstate 25 north from about Broomfield to Cheyenne between 2 p.m. and 7 p.m., and then the snow will start to impact the metro.
By 7 p.m., we could see 3-4 inches of snow on the ground from Loveland to Ft. Collins, but no accumulation in Denver.
After 7 p.m., it should start to snow more steadily for the rest of the Denver area, but I don't expect to see too much trouble until morning. By 10 p.m., there will likely be some snow accumulation on the ground, but probably not much.
Usually when the storm times out like this, people start to send 9NEWS emails at about 10 p.m. saying that the storm was a total bust in Denver, and then they make plans to drive on Tuesday morning. I believe this will be a mistake.
Between midnight tonight and noon Tuesday, there is expected to be very heavy snowfall in metro Denver. The morning commute will be very slow and difficult. We could see more than 10 inches of snow in parts of the metro by noon Tuesday.
This storm will be focused east of the Continental Divide and north of Interstate 70, but areas along the foothills south of I-70 could get some good storm action.
The snow should start to wind down between 10 a.m. and noon Tuesday on the I-25 corridor, and by 5 p.m., it will be completely out of the state.
Nov. 27-30
Still looks like two storms will pass through the area in this time frame.
The first one is small in size and originates in the Baja of Mexico. It should make its way east just to the south of Colorado.
That should bring most of the snow to New Mexico and the Texas Panhandle on Wednesday and Thursday, but also impact parts of southern Colorado.
Then the larger system moves through Colorado right behind it on Thursday, bringing some Thanksgiving Day snow to the high country, mostly the Western Slope and the San Juans, and eventually spreading to the eastern half of the state on Friday.
That will be the best chance of seeing snow on the Front Range, but so far the impacts look to be pretty minimal.
Chance of snow in Denver: 5%
Dec. 3-4
A small mountain-only storm looks possible. There will be no impacts to the Front Range.
Chance of snow in Denver: 0%
Dec. 7
This looks to be mostly a light mountain event with little impact to the Front Range.
Chance of snow in Denver: 0%
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Sunday Update
Nov. 25-26
A strong and potentially dangerous winter storm is only about 24 hours away from impact in northeast Colorado. Winter Storm Warnings haven’t been issued yet, but it is safe to say that most of the areas in the Winter Storm Watch will get a warning issued sometime tonight.
Snowfall Rates
The trouble with this storm will not be the total of snow accumulation, but more the character and duration of that snowfall. I have covered dozens of storms in the field that have totaled more than 6 inches, and I can tell you that many of those with 6 inches have been just as bad as those with 16 inches.
So it’s more about how much snow falls in 1 hour, and what is the timing of that heavy snow.
This storm will very likely feature very heavy snowfall rates for about a 12-hour period. The snow could fall at 1 to 2 inches per hour. At that rate, snow plows will not be able to keep the roads cleared, even if the traffic is light, and visibility will be very limited when driving, especially since most of the snow will fall in the dark.
If you are in an area with a Winter Storm Watch, you are very likely to see some of this very heavy snow fall. That is regardless of how that watch gets separated into warnings and advisories later. That is pretty much all of NE Colorado, southeast Wyoming, the Nebraska Panhandle, an even parts of southwest Nebraska, and northwest Kansas.
Timing
The timing of the storm is from about noon on Monday to about 5pm on Tuesday. The most dangerous time to be out on the roads in the Denver area will be from 5pm Monday to about 10am Tuesday.
Snow could impact southeast Wyoming before noon, and gradually spread southward. Should see some snow from Ft. Collins to Denver between 1-4pm. It may not be until 5 or 6pm before the snow starts sticking to the roads in the metro. I would try to get off the streets not long after sunset.
Monday night will be very dangerous for travel, but Tuesday morning may be even worse. Heavy snow still falling, colder temperatures, and more commuters. I would expect many schools and businesses to close.
Locations
The highest potential for heavy snow with longest durations will likely be the Front Range foothills. Models are showing between 7-14 inches from north Jefferson through Larimer Counties. With a little colder temperatures, that should translate to a little more. Canyons will be slick and dangerous for driving.
The Denver Metro has the biggest question mark on it. System has been trending further north, which could leave the south and southeast metro with less impact, although it still looks like there is potential for 4-8 inches there.
Higher impacts to the north and northwest metro areas. Potential for more than 10 inches.
The I-25 corridor from Denver to Cheyenne looks to get hit hard, also with potential for more than 10 inches.
A little less snow potential on the eastern plains north of I-70 including Kansas and Nebraska. Still looking at extremely heavy snow, just less accumulation potential.
The Palmer Divide is looking a some extremely heavy snow as well. Although less duration, so less accumulation.
There will likely be a steep drop-off in the snow duration to the south of I-70. There will be heavy snow spreading all the way to the southern Colorado state line, just less duration as you move south.
Try not to focus on snow totals if you are in an area that is forecast to receive less snow. 6 inches of snow in 16 hours is a lot of snow, and the heavy waves of snow will be impactful.
Nov. 27-30
Still looks like two storms in this window. One from the south and one from the north.
The first one is a small storm that originates in the Baja of Mexico and makes more of a southern move. That should bring most of the snow to New Mexico and the Texas Panhandle on Wednesday and Thursday, but also impact parts of Colorado.
Then the larger system moves through Colorado on Thursday, bringing some Thanksgiving Day snow to the high country. Mostly the Western Slope and the San Juans.
Eventually spreading to the eastern half of the state on Friday. So far the impacts to the Front Range look minimal.
Chance of snow in Denver: 5%
Dec. 3
GFS shows a light mountain storm on the 3rd now. Not a strong signal.
Chance of snow in Denver: 0%
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Saturday Update
Nov. 25-26
Computer models are still indicating that a strong winter storm will develop near British Columbia on Sunday and start to bend down towards Colorado.
The GFS model has been unwavering in its solution over the last few days, and has continued that consistency into this morning's run. It shows a somewhat strong and slow-moving surface low taking shape in the Four Corners area and tracking across the bottom of Colorado. Surface lows do get disrupted a little as they move over the mountain range, but it shows it as a 994mb storm by the time it gets to the southeast corner of the state. This is a great track to deliver heavy upslope snow to northeast Colorado and the Front Range.
There is high confidence in the GFS because of its consistency with this storm solution over the past 4 days, and also due to the fact that it has been very reliable so far this season.
The timing with this current solution would start mountains snow by about sunrise on Sunday morning, but the real focus with an upslope storm is the foothills and plains. The timing for the snow to start accumulating there would be about 3 p.m. Sunday.
Temperatures on the plains will probably be in the upper 30’s or maybe even low 40’s when the snow begins, so accumulation will be slow at first, but extremely heavy snowfall rates should overcome that heat with in a matter of just a few hours. Except in the foothills where temps are colder.
The GFS is showing that by nightfall on Monday, the Front Range foothills and the I-25 corridor between Castle Rock and Cheyenne, will be in the midst of a major winter storm. It is also showing it lasting all the way through the morning commute on Tuesday.
It is showing total precipitation for the metro area in the 1 inch to inch and a half range, and the foothills from 2” to 2.5”. This is some crazy moisture. Temps should get into the middle to low 20’s, which means the snow to water ratio should be higher the 10:1 for even the metro. At 12:1, that would give put the metro in the 12 to 18-inch range of potential snowfall, 15:1 is possible. A 20:1 in the foothills would put the potential in the 40 to 50-inch range of potential.
The current most reasonable estimates would be for 6-12” on the I-25 corridor, and 10-24” in the foothills. The eastern plains will have some good potential as well, especially north of I-70. Probably the 4-8” range at the moment. That’s just if you believe the GFS solution, which I am not completely sold on yet.
This is just some of the data from the GFS. Of course, the storm has not even formed yet, and we are talking about it like it is going to happen already. But that is just kind of where we are at right now with the confidence in these computer models 3 days out. Of course, we just had a storm make a big change in movement speed within the 3-day window, so anything is possible. I will say that the storm was very cut-off from the stirring currents of the jet stream, where this one is a little more predictable.
The European model is still showing a bit of a different solution than the GFS. It has the surface low just a little further north, not much, maybe about 50-75 miles. That makes all the difference in where the biggest snowfall will be for us though.
It shows the bulk of the snow just north of Denver. Hitting Larimer, and Weld Counties in Colorado, as well as southeast Wyoming and the Nebraska Panhandle. For the Denver area, it shows between 3-6”. It also shows less of a hit in the Jefferson and Boulder County foothills.
Either way, there is a very high chance that Denver and the rest of northeast Colorado will get hit by a pretty potent winter storm on Monday and Tuesday. Don’t be surprised to see Winter Storm Watches go up late tonight, but most likely they will wait until Sunday to put them up.
Chance of snow in Denver: 75%
Nov. 27-30
There are basically two storms in this window. Kind of like the recent storm where there was a near merger of two storms.
The first one is a small storm that originates in the Baja of Mexico and makes more of a southern move. That should bring most of the snow to New Mexico and the Texas Panhandle on Wednesday and Thursday, but also impact parts of Colorado.
Then the larger system moves through Colorado on Thursday, bringing some Thanksgiving Day snow to the high country, with the best chance for snow in the metro on Friday.
Chance of snow in Denver: 5%
Dec. 4
GFS shows a light mountain storm on this day.
Chance of snow in Denver: 0%
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Friday Update
Nov. 25-26
The next winter storm will come from Canada and arrive in Colorado early Monday morning. There is some indication in the computer modeling that this storm will stack down and become a moderately strong surface low.
The GFS has been sticking to a solution of the surface low strengthening on the lee side of the Rockies near the southeast corner of Colorado, which is a prime spot for upslope snow on the Front Range.
If this location verifies, it would bring heavy snow to the Front Range foothills starting Monday after about noon, while the snow spreads onto the metro areas and adjacent plains with the heaviest snow on Tuesday morning there.
Three days out is not too early to talk about snow totals, which would be in the 2-6 inch range for the metro and even higher in the foothills. The problem is that the Euro has turned its back on this solution.
The Euro has also been on board with a southern Colorado surface low for a couple of days, but it is now showing a weaker low that is a little farther north.
This would still bring a little snow to the Front Range, but the more significant impact would be to southeastern Wyoming and the Nebraska Panhandle.
When it comes to positioning, the Euro does have a better track record three days out. These signals are all based on the current state of the atmosphere, and won't have a good agreement until the storm forms in Canada on Sunday.
Chance of snow in Denver: 55%
Nov. 27-30
During this time frame, it looks like there could be a quick and weak disturbance move through from the eastern Pacific. Mostly light mountain snow with this one, but could impact some parts of the Denver metro on Wednesday.
At the same time, a larger Pacific Northwest trough will be diving down the western U.S., bringing a wave of Thanksgiving snow to the mountains.
Then on its way out, it could bring snow to the Front Range on Friday.
Chance of snow in Denver: 5%
Dec. 1-4
Looks like this active stretch could slow down in December, although the GFS does should a few weak signals in the first four days.
Chance of snow in Denver: 0%
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