Snowfall Forecast for Monday/Tuesday Storm

The state of the atmosphere this week is undergoing another big change with our next weather-maker set to arrive Monday evening. The system will bring with it another chance for rain and snow to eastern Colorado.

This has been a challenging system to track, but as discussed last night, there's better consensus as we end the weekend that this will be a good storm for some, but likely not the absolute blockbuster the GFS once advertised. The speed of the storm will simply be too fast for an historic storm for the state.

For greatest storm totals with this system, we like the Palmer Ridge, plus or minus north and south. Someone out east near the Kansas border is likely to do well as well, but whether that bullseye is Washington, Yuma, Kit Carson counties or elsewhere, it's still a bit hazy.

Timing and impacts
The center of the system will move over the Four Corners Monday to Central Kansas Tuesday. A snow lover would like that to take three to four days, not 24 hours.

There is good agreement between the GFS, GEM, and ECMWF as to the speed and position of the storm and their respective snowfall outputs are consistent enough. All put a heavy swath of snow of around 6-12" over the Palmer Divide, south of the city.

These three show a marked decrease in snowfall across the city from south to north, with little expected in the northern urban corridor.

For Denver, we'll go with 3 - 8" of snow, with the greatest totals landing on the south side of town, and lighter totals north. We'll keep the Bust Index high for the city at this time, as there remains disagreement in where (and how steep) a gradient there will be from the heavier snow south, to lighter amounts north.

Here is our snowfall forecast for Monday evening through Tuesday:

Weather5280 snowfall forecast November 15, 2015

Unlike with the last system there may be some tweaks that need to be made over the next 12 to 24 hours, so please check back. We'll see how things look tonight, and there's a chance we'll need to go lower. We have some concern that models are overdoing QPF, but running with a slightly more bullish forecast for now seems right. Again, the trickiest forecast may be in Denver proper, where a sharp north/south gradient across the city will likely mean big variations in snowfall totals for the city – hence the big spread in the forecast of 3 - 8".

Early Tuesday morning looks to be the worst of the system for eastern Colorado, with high winds and heavy snow likely making travel treacherous. As Bledsoe pointed out last night, if you have travel plans, or livestock on the eastern Plains, it's important to take this storm seriously, even if it's not delivering feet of snow.

Winds will be whipping across the eastern Plains of Colorado early Tuesday morning | Weather5820 Models

What to watch for
Over the next 12 to 24 hours we'll need to continue to watch this system closely. As you are well aware, a slight shift in track in the 11th hour can have big implications around here. If the system slows a bit snowfall totals may increase, if it continues to look like it will progress very quickly east, totals may need to be nudged down in a few locations.

Additionally, while we see decent model agreement, there are still a few concerning features showing up. The latest ECMWF ensemble mean for KDEN is just 2", which, while an outlier, is far less than its control, and should be considered. If the ECMWF ensembles continue to be less, and closer in line with the [now] much-less-snowy-GFS through tonight, totals may need to be nudged down a bit.

Enough uncertainty remains with this system that the National Weather Service has not issued any Watches or Advisories yet for Eastern Colorado. That may change by this evening.

As always, please travel safely, and share your latest storm reports and snow images in the comments below! Don't forget to stay with Weather5280 for all the latest.

Go Broncos!


This is a collaborative post from multiple authors at Weather5280.

Denver, Colorado
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