Chinook

The 00z GFS changes the look of the system in the late week. It moves up the low pressure timing at Toledo to Friday, 03z (really, Thursday, 10:00PM). It with a stronger low pressure, at 996mb. It has the rain/snow transition in Michigan/Indiana, with something like 11-14" of snow at Howell, Michigan, depending on 10:1 or Kuchera snow ratios. Kucheras are lower than 10:1. I know, it's at 5 days out or maybe 6 days out, which means that it will trend in some direction. It almost certainly will trend towards less than 11-14" of snow for any area in the Midwest. And the Canadian global model says, "what storm?" As of right now, some ECMWF and GFS ensemble members have a pretty high QPF for southeast Michigan.

I have heard reports of rivers flooding massively in California in these past days, in response to 5-15" of precipitation in northern California.

two rotations

possible strong rotation next to Chatham, LA

this is from Andy Hill, assisting Ryan Hall on his ongoing youtube stream. Unfortunately, I can't figure out what radar this was.

I think there's very strong rotation between Farmerville, Marion, and Sterlington. It's at the point where the storm is far from any radar.

It's always amazing that such a tiny cell could be a tornado producer on a day like today, but normally it would be a passing rain shower.

interesting note: dew points may be 23 to 28 degrees F above normal in the Louisiana-Arkansas area, as well as 20+ above normal along the Mississippi and Ohio Valleys.

I think there was a tornado really close to this area last month. Certainly a chance there's a tornado happening here.

The Denver NWS web site shows every type of thing you might be expected to see, and an avalanche warning. What's not shown: a winter weather advisory above 6000 ft for Larimer County and Boulder County. I guess they will decide if the north areas are worthy of a winter storm warning or a winter weather advisory later.

Every single model has this being a weak storm for Sheridan. So, sorry.

Lets' go for weenie mode here: The EPS ensemble members max QPF is 0.66" or for Denver, and 1.02" for Fort Collins. These are much higher QPF values than the 12z or 18z GFS. The overall synoptic forecast of the storm has still some questions to be answered for northern Colorado.

Models from 12z and 18z today have significant snowfall for CO, WY, and NE on January 2nd with a 500mb low developing over Denver.

The western snowpack has been impressive in far west areas. Right now, the Sierra Nevada and Nevada's great basin have the highest percentages. New Mexico isn't getting on the fun.

The spotter reports have been 3.0" to 5.5" for many city areas, and higher for Jefferson County. There is a pretty heavy area of snow at Castle Rock, and it seems to be showing the rotation at maybe 700mb if you watch a short radar loop.

My loops of the previous storm GFS Surface forecast loop NWS Surface Analysis 500mb vorticity 850mb vorticity 700mb temperature 850mb temperature 500mb temperature National/Regional Radar Composite GFS Relative Humidity (mean layer) 250mb wind speed

The lowest wind chills on December 22nd were basically -34F in the city of Denver. As I said before, in the 16 years that I lived there, Denver International Airport never was -22 (air temperature).

Wind chills for the NFL. The Titans game has been delayed until 2:00 because there are rolling power blackouts due to the cold

This tweet has, in fact incorrect information on which road it is: it is I-80

NW Ohio essentially maxed out at a 46-48 degree F temperature drop in 24 hours. Toledo went from 42 degrees to -3 degrees in 12 hours, the most impressive drop I may have ever seen for Toledo.

72 hr multi-input snowfall analysis ending at 00z

My place in the Toledo area got about 1" with some drifts. The drifts aren't really impressive. In the city, the visibility is fine, as the ground blizzard must be worse in more rural or open road setting. I can sort of feel the 50mph gusts against the house. Toledo Express Airport had ground blizzard conditions, as the reports said heavy snow but it certainly hasn't been heavy falling snow. Wind chill is negative a lot if you consider 46mph-47mph wind gusts at this time, but the actual calculation is based off the steady wind speed, so the wind chill was -29 early today. So it's a unique situation with disappointing snow amounts. And rain kind of froze onto stuff. About 10 years ago, I drove through a ground blizzard in Nebraska when the snow wasn't sticking to the road, so I had good traction. I wouldn't have tried it if I didn't have good traction.

Recent snow spotter reports have been 8" to 25" for N MI. Surprisingly it is warmer and less windy than the lower Great Lakes while this is happening, but still cold and windy. also note: news story today from NW Ohio

This situation is a little like Christmas 1935. A cold front with high winds, snow, and a temperature drop to zero happened in the lower Great Lakes Toledo's temperature and snowfall 1935 surface map

So this is happening. Cheyenne had whiteout conditions while -12 degrees, wind gusts to 38 knots, blizzard. Cheyenne was recently -25 with wind chill of -51. Denver had snow, now its -22 with wind chill of -40. That never happened when I was there.