Chinook

Interesting weather feature: along with this storm, yesterday there was a 232 kt wind at 250mb in Canada.

Nothing is really happening here, as the cold air won't lock in. Thursday, my area had a high of 59, which is the highest since the big snow in November. In the models, the consensus is that the developing 500mb storm system on Thursday-Friday is pretty good, but downsloping wind will prevail as it passes by here and creates a huge storm in the Midwest. My area still has some snow in the shade left over from November 25th-26th, like a huge mass of icy stuff next to the driveway. The Pacific Northwest snowpack is building, and low elevation areas are getting rainfall to diminish drought conditions. By my estimate, the high Cascades have gotten 8 ft - 15ft of snow since January 1st.

We need to have something more specific than simply a negative PNA index number. We need to have a trough that develops near the West Coast and tracks toward here UT and CO (Four Corners), with perhaps even a ridge just off the West Coast. The PNA index doesn't capture that well, but the index could be negative when that happens. On the other hand, we could get a lot of cold air on the Plains and have upslope event with more arctic air and less of an organized 500mb trough. The PNA or NAO indices may not capture that well. In rare circumstances (like an El Nino,) we could use a large California 500mb low to track toward us, via the Four Corners.

NWS Boulder lists top weather events of Colorado within the last 10 years

Storm reports show up to 5" - 6" in some parts of the Denver metro, with over 6" at the foothills/Palmer Divide. Also, up to 8" at Pine Bluff, Wyoming. It must have taken a long time. Here in Loveland, snow had mainly ended when I last posted (12 hours ago), we had some downslope wind off the Cheyenne ridge, with weak radar returns, so almost nothing happened beyond 10:00AM. This might be something like a 48-hour (near-blizzard?) storm for eastern South Dakota.

My area got 1-2" of snow today, with maybe some wind gusts to 20-25mph right now.

The GFS has 12" of snow for Akron CO (Washington County, CO) and the NAM has 1" and the NAM-3km has something like 2"-5" in the county. This is madness! This is mixed precipitation madness that has been happening today in KS and Nebraska:

A winter storm reaching from Mexico to Canada.

We should be close to the 500mb/700mb lows, but without a strong upslope component. So upward motion will not be concentrated on the foothills for very long. Then stronger lift will begin farther east as the surface-to-700mb low intensifies to the east, out near Goodland and into central Kansas. By the way, it looks like the Euro had another (minor) victory on this one, as the GFS had the snow to the east of us for several runs. NWS already has 8-10" for northern Nebraska through western Minnesota with this storm.

For Saturday-Sunday, the NWS is expecting 1.5"-3.9" of snow for the Front Range cities. There is a winter storm watch east of DIA. Heavier snow towards northeast Colorado and Nebraska, as well as southern Colorado and northern New Mexico.

Some ensemble members of the GFS and Euro show some hope for snow in Denver. These must have a bit of a different look at 500mb than the regular GFS at this time. Interesting fact: NWS-Fairbanks is forecasting -46F for the Tanana valley this week.

Today's Euro shows that the storm will provide about 2-3" of snowfall all over the plains of Colorado on 12/28 (96 hours) but this is somewhat of an outlier. I think it handles the 500mb low differently than the GFS and Candian.

Euro/GFS/Canadian all have a closed 500mb low in AZ/NM on December 28th, so it's definitely something to watch for the southern Rockies and areas of the plains into Kansas.

Since November 25th, Fort Collins has been -2.2 F in temperature, with 294% of normal snow and 439% of normal precipitation, (393% of normal at my place) . Snow is still on the ground here in some of the areas that face the sun. So, December has felt snowy, even though little snow fell out of the sky. Not much will happen here soon, and temps will be 40's and possibly some 50's. But that's good for my trip. I will be flying out tomorrow, and there should be few weather problems anywhere before I get back.

The Chiefs game should be in a lot of snow. There are heavy snow bands, with one location getting sleet, and, as you can see, 0.5-3.0" of snow measured recently. A couple places with rain and freezing rain just west of Joplin - rain at Pittsburg, KS.

We are getting a little snow in Larimer and Weld Counties.

00z Euro keeps the snow closer to southwest Missouri, with 7" north of Joplin (3.7" at Joplin) (10:1 snow ratio.)

I think this is a really snowy run of the GFS, compared to recent runs. Nevertheless, there could be greater snow amounts for the mountains, and possibly Denver and Colorado Springs,. Sometime soon, we'll see if the models are getting a better handle on the Midwest/Plains part of this snowy system. Northern mountains of Colorado above 9000 ft:

The Euro and Canadian show some light snow for northern Colorado Saturday to Sunday. Most models have some (heavy) snow for Colorado Springs out of the combination of events (into Monday.)

Our storm (Sunday to Monday) may be making a bit of a comeback, possibly for southern Colorado and northern New Mexico. The GFS and Euro have varied with this feature. I thought it might disappear. The Canadian was pretty insane with the snow, but it's not as accurate.

At the current time, the GFS and Euro have a lot of agreement on this snow feature in Colorado and Kansas

This is maybe not what you want to see if you are from Minnesota or Wisconsin, but the 12z GFS has -23 degrees at the Twin Cities at hour 144 (December 11th), and the 00z Euro has -19 degrees.

% of normal snow water equivalent is now about 130% for South Platte basin, other areas as shown:

A large area of the Dakotas, Minnesota, and Wisconsin got more than 12" of snow yesterday and today. Some western areas had blizzard conditions. Cheyenne and areas near me had a ground blizzard. Winds gusted to 60-70mph at Cheyenne, Wellington CO, the Boulder foothills, the open plains of Colorado, and western Nebraska This created ground blizzards. Around here, we had winds to 20 mph winds gusting up to 42mph yesterday, which created snow drifts that made new ice on the sidewalks and streets.

Loops of Tuesday's snowstorm http://www.greatlakes.salsite.com/Nov_26_2019_500mb_loop.html http://www.greatlakes.salsite.com/Nov_26_2019_850mb_loop.html http://www.greatlakes.salsite.com/Nov_26_2019_GFS_loop.html http://www.greatlakes.salsite.com/Nov_26_2019_radar_loop.html http://www.greatlakes.salsite.com/Nov_26_2019_satellite_loop.html