snow...Snow...SNOW!!!

Finally, after about one and a half winters in Grand Forks, I have a decent snowstorm to look forward to. Just a couple weeks ago, as GFK wrapped up a month of seemingly endless stratus and -FF ('-' for light, and the second 'F' for flurries, and for those that don't know, I'll let you figure out what the first 'F' means). I worried it would be until the end of February or early March before we had a real shot at a decent snowstorm (the idea being we would need some influence from Gulf moisture. Fortunately, the jet stream is transforming (at least temporarily) to a highly meridional flow - thanks to the system moving northward through the Mississippi River Valley, in coincidence with a return to much colder temperatures. In response, a trough has developed over the west, with cyclogenesis expected over the Nebraska panhandle overnight into morning - then tracking northeastward towards MN tomorrow.

Until the colder air arrives and we get some moisture in the dendritic growth zone, there will likely be chances for freezing drizzle/freezing rain through much of morning. Snow should then develop during afternoon, sometime between 1-6pm. After a bit of a scare from the 12Z NAM in which  the mid-levels stayed dry until midnight tomorrow night, the 00Z NAM has come around and gives us a changeover to all snow by 4pm.

What I also like about the 00Z NAM is that the 700mb charts are very favorable for the heaviest snow band being near or just NW of GFK tomorrow night as shown by the following 09Z Saturday chart:

I certainly think that between 1-7am, snow magic should be happening, with a 6 hour period of 0.5"-1"/hour snowfall rates. After examining total QPF during the "all snow period", here are the estimated SWE for various models:

1/10 12Z Ensemble GGEM: 0.50"
1/10 12Z Ensemble GFS: 0.40" (noticeable down from 0.70", 24 hours ago)
1/10 15Z SREF Plume Mean: 0.44"
1/10 12Z Euro: 0.45-0.50"
1/11 00z NAM: 0.35-0.45"
1/11 00Z GFS: 0.45"

Except for the case of the Ensemble GFS (which was previously high in QPF), all models have been fairly consistent over the last 24-48 hours. Just taking a raw average of those QPF values, you get about 0.45" SWE. Snow ratios will increase through tomorrow night and Saturday morning, trending  from 10:1 at changeover, to 30:1 before ending. Climatological average snow ratios here are about 16:1 during January, according to a Saint Louis University study. So with that in mind, I think a total snowfall of around 7" is well within reach.  A couple days ago, I called for 5-9" and I feel that still holds valid.

It really should be nuts here around or just after midnight. Take a look at the 00Z GFS BUFKIT which has a thick DGZ saturated from around 600mb to 875mb.

You'll also notice those 925mb winds out of the north at 45 knots that are sure to mix down. Certainly seems like a recipe for near-blizzard to blizzard conditions Friday night. Ground blizzard conditions are then possible through mid-day Saturday. It is going to be a wild/thrilling ride to work at 5am Saturday that's for sure!

I will close with a snow map I made for the region, which I look forward to matching up against reports. Again, still thinking 5-9" here in Grand Forks, and if I had to pick an exact number, I'd go with 7".

Though, I wouldn't mind if the highest outliers of the SREF plume charts came true!! Total snow range of 6.7"-18.3", with an ensemble mean of 11.7"!  :-)