Chinook

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

Interesting stats: on this NWS web site, you can see the exact population covered by each watch, warning or advisory. Winter Storm Warnings cover 10,558,946 people in the Northeast (including West Virginia)

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

These areas of snowfall developed tonight (8:16PM). It looks kind of cool on radar. I have a small snow accumulation.

Every run of the models seemed to get better and better for this area. There were a couple of weird model runs, but not too many. Inaccurate predictions of snow sometimes just happen, but this time, the NWS Watches/Warnings were pretty decent. The first banding started on the east side of the Rockies at about 12PM - 2PM on Monday. Then I started to notice snow at 2PM. It was steady snow. I noticed 6" or more by 8PM, 10 to 11" by 10:30PM. At 9:30 PM, the radar was starting to fill in for Denver. Some snow banding was just north of Denver started in after 6:00PM, though. I measured 16.0 - 16.5" by Tuesday morning. Not many storms have produced 1" per hour for so many hours. Many storms around here seem to be 5-6" in several hours, usually a night time. Some storms last 9 hours, with a band that is north of a cold front. Not a lot of storms have stronger 700mb easterly winds like this one. It's weird though, because this wasn't much of a closed circulation at 500mb, but did have that closed circulation at 700mb. I don't know how this one pulled in the Pacific moisture just right. There has not been a 12" storm in Fort Collins since February 2nd, 2016, if I remember correctly. watches, warnings, advisories

The upcoming western US storm will hit New Mexico, and western Colorado. There is more uncertainty regarding the impacts in the northern Plains, Wyoming, and Montana mountains. Things are always complicated in New Mexico. What's not too hard to understand is the San Juan Mountain range (CO) getting heavy snow with southwest flow aloft. If you are interested, there is a 975mb low moving onshore near Eureka CA/ Southwest Oregon, with some wind gusts of 50-60mph close to the coast and snow starting to hit mountainous areas.

This could be one of those situations where some 45mph steady wind speeds over Lake Erie funnel the air and water toward Buffalo, with a seiche (high water) and wind gusts over 65mph at Buffalo.

Now western Kansas is getting 2" per hour, and winds picking up to 20-30mph.

I measured 16" on the grass that was bare grass before the storm. It was even hard to find the grass/sidewalk edge. Here's a neat little drift near a roof

This could be around 15". I will measure snow and shovel some snow soon. recent storm reports: 14-14.5 at Fort Collins.

It's quite a lot here. I got 10-11" at 10:30PM. I attempted to take a measurement on the north side of the street, where there was bare grass.

I'm going to take a measurement in 10:00 or 11:00. As you can see, storm reports are 4.5" or better in the band. I am near the 8".

My place has gotten possibly 6" in 6 hours. It already has exceeded the greatest one storm at my place last year.

It's nearly the same here, the radar shows a max of precipitation here at Loveland, Lyons, and Estes Park.

Sometimes I'm not sure how the NAM deals with upslope flow when things are less obvious with upslope flow direction and speed. The GFS is more consistent at predicting snowfall amounts near my place. Anyway, the snow has started here at about 2:00 or slightly earlier. We already have 1" of snow in less than 2 hours. Greeley is above freezing with rain, currently. That will change quickly. At the end of the storm, I will make a loop of 850mb temps, 500mb vorticity, composite radar, and GFS-6hr precip/SLP. note: 18z models still have 10-12" at locations of 5-10 mi southeast of Denver, with ECMWF still at 10" (8" on map, but ratios will be higher than 10:1)

Just for fun, I checked the SREF plumes for Fort Collins-Loveland, which have QPF values of 0.44" to 1.90", which could be 4.4" to 19.0" at 10:1 ratio. The GEFS plumes for GXY (Greeley) have 0.44" to 1.13" which could be 4.4" to 11.3". Also, just for fun, if you check the SPC web page, the HREF (high-resolution models ensemble) is within range to give a max snowfall amount. The regular NAM has 0.8" of QPF (Denver) up to 1.6" of QPF (Fort Collins-Loveland). Let's just say, in my entire time in Fort Collins/Loveland, the best November snowstorms were 7.4" in 2006, and 9.0" in 2011. When I lived in the Midwest, November did not produce this type of snow.

NWS digital forecast as of this morning

NWS digital forecasts are now at 9.1" for Fort Collins-Loveland and also the same for Denver (Stapleton) up to Tuesday, 5:00PM.

Thanksgiving Week = traffic snarled with heavy snow across the country

We will get a winter storm watch for the northern half of Colorado.

As I mentioned in October (I believe,) there are above normal water temps in the North Pacific, south of Anchorage, by 2 degrees C. I think this has, in this 30-day time period, helped larger ridges to form in the NE Pacific, leading to troughs in the central US. I think the warmer water temps in many recent years have led to larger 500mb-ridges in Alaska, helping to send down arctic air, like during "the blob" of 2013 or 2014 or something like that. So, too much ridge action near Seattle means that little precipitation has fallen. Now, of course, our synoptic systems are also linked to other things, most notably the MJO and east Asian jet streams.

Tuesday: The GFS and Canadian continue to have 7.9" - 14.1" for Fort Collins-Longmont-Denver stations on the maps. The 00z and 12z Euro went north to Scottsbluff Nebraska with a large amount of snow, and the Front Range cities are mostly dry. I think the Euro has the surface front farther north.

Much later than I posted this, the snowfall really started. Apparently it snowed 2.5" to 3.5" in Denver overnight. My area got about 1" overnight.

2nd piece of our snow storm is coming in right now. The 12z Euro has 6-7" of snow all around Denver metro, up to my area, for Monday-Tuesday.