Chinook

The 12z GFS has 9-14" for the Front Range cities, with over 12" very close to me. The NWS gridded forecasts still have 5-6" at Fort Collins with 8" at Boulder, 6-7" for Denver. This may be a time when this type of graphic showing Kuchera-ratio snowfall of over 20:1 doesn't really happen because the snow packs down better than that.

First forecast from NWS Boulder

Interesting forecast here: This is the snowiest run of the UKMET I have ever seen for our area. UKMET snow products have been on Pivotalweather since Monday or Tuesday. Otherwise, I haven't checked UKMET precip for years. Those people at Pivotalweather really must be something else to have full ECMWF data and full UKMET data.

The first winter weather advisories/watches for this storm have been issued for central Nevada up through Wyoming, including Salt Lake City. In Colorado, our area will probably get some light upslope snow on Monday, with higher snow rates later on Monday as the 500mb low approaches and the lift increases. I am hoping the heavier snow doesn't start too early on Monday, but 5:00 rush hour may be challenging. Overall, this is a pretty decent setup for snow with some easterly 700mb winds here east of the Rockies. The last time it snowed here was December 27-28th with 1.5". So the last two months were pretty much uneventful except for a few days with wind gusts, and hardly any days that were very cold. We have had just a few days with a high temperature below 40 since December 31st. I would think that we are on track for a colder week or two weeks after this. by the way, this happened a few days ago in Colorado. read the text carefully

A mix of rain and snow is happening at Denver, Colorado Springs, and Fort Morgan this afternoon. As per the radar, I don't think too much has happened in Denver city.

There were some heaps of lenticular clouds today. I haven't posted a picture of clouds or mountains for a long time, I think.

When every storm misses you

It looks like this storm is gone for good. The GFS was too happy with a closed 500mb low. One of the biases of models, in general, is to create more phased lows and huge storms. (in the long range, 7-10 days.)

Next week's storm could potentially happen on Wednesday. There are still pretty large differences between the GFS, Canadian and Euro. The situation is similar in many ways to my post yesterday. The Euro still has the 500mb troughs in two places, Montana and New Mexico. The GFS has somewhat flip-flopped today, but the 00z GFS came back with a big snowstorm with a 500mb closed low for Denver. The Canadian has a concentrated 500mb trough, but has snow mainly for the Sangre De Cristo mountains. Some days, I think the Canadian tries to do the same things as the GFS, but always comes out with worse accuracy. In this particular case, I don't know if there will be a storm. These (terrific) days, you can even check the Euro ensemble members QPF (for free) and they have some large differences in QPF.

If you look closely, the precipitation type in the red region (freezing rain) includes snow, drizzle (temp of 28 degrees at Wichita), freezing rain, unknown (question mark symbol... usually sleet), and rain. I'm glad I'm not there.

Freezing rain and possibly some sleet are starting to get going in OK, TX, with a small amount of snow in KS at this time.

I kind of assumed that nothing would happen for a while. Then the GFS and Canadian came up with different versions of this storm in about 1 week. The Euro does not have this. It has a trough in New Mexico and a trough in Montana at this time frame.

The NAM always seems to overforecast freezing rain. The 00z NAM has 0.75" to 1.18" of freezing rain accumulation near and north of Springfield MO, as well as some other various values of freezing rain from New Mexico to the Mid-Atlantic. Note: NWS gridded forecast has 0.03"- 0.08" freezing rain north of Springfield. I hope you guys don't have nasty tree damage or anything like that. Maybe the models like to keep the inversion layer there for a longer time period than is really possible.

-45 to -53F near Edmonton, Alberta

I found this annual lightning map tweeted by @brendonme. I wonder if this could be originally from NOAA

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.