Chinook

It seems quite likely that scattered severe storms will move across Tennessee and Kentucky, as well as adjacent areas of Mississippi and Alabama. According to most CAMs, the storms may be quite late in the day, with some stronger storms at 00z (8:00PM eastern/7:00PM central). With strong wind fields aloft, these storms will have fast movement, and I would expect a wind/tornado threat

It looks like my area got 3.9" of snow and 1.35" of total precipitation (nearest CoCoRAHS observers.)

Today has been kind of low on the storm report total, given the two different enhanced-risk areas. This is a radar-confirmed tornado north of Little Rock.

This tornado-warned storm has tracked northeastward from Fort Smith metro area. (near Mulberry, AR)

My place has about 2" on grass, and just some slush on the streets.

A storm near Essex, IA is already starting to show signs of being a discrete supercell with 1-2" hail.

latest radar, with p-type. we have snow here, maybe 1/2" on rooftops.

I don't know if this is going to accumulate. At Fort Collins, there has been 0.77" of liquid equivalent since yesterday. There is only a trace of snow right now. I guess I can deal with that. I did plenty of shoveling in February. I'm not sure I want to do more shoveling today or tomorrow.

Why not use math? The 10% tornado area is 113,928 sq mi, the 5% tornado area is 140,381 sq mi, and the 2% tornado area is 168,806 sq mi. The SPC system forecasts a probability that any one point in a certain zone will see a report within 25 miles. That means that each point in space is something of a 25 mi radius storm-report-detector. A 25-mi radius circle takes up (pi)*(25)^2 square miles of area. Aside from using more advanced methods of statistics, let's just apply simple math. The number of 25 mile circles covered by the 10% outlook is 58.02, and likewise, 71.50 circles, and 85.97 circles. Then (58.02)*(0.10)+(71.50)*(0.05)+(85.97)*(0.02) = 11.1 tornadoes. 11 seems like a possible number of tornadoes. Qualitatively, I think it's reasonable to say the 10% risk for a large section of the Ohio Valley/Mississippi may seem too much. Otherwise, using real statistical methods may calculate a different number of expected tornadoes.

Tiny tornado vortex signature (near Albany TX)

we've had two tornado reports here. The current tornado warning is not directly over the velocity couplet (unless the radar is delayed somehow)

Storm-relative velocity shows about 75kt on the right hand side, 35 kt on the left hand side. (same storm as the last post)

This storm near Maryneal, TX has ramped up its rotation in the last couple of scans.

My place is getting 1/4" hail and some lightning right now. We haven't seen hail for a really long time!

As for the 20z HRRR, there is really only one major thunderstorm with a helicity track, and that's 2-4 counties west of Fort Worth. I expected the HRRR to have more of these.

Models have been pretty inconsistent with this storm, which should be starting tonight. The 12z GFS has a QPF of 1.85" for downtown Denver, with 12.3" of snow (Kuchera ratio.) It also has this heavy snow at 33 degrees F, with 20kt winds at the surface and 40 kt winds at 1km above ground. I would imagine that yesterday's winter storm watch for 3-7" and gale-force winds, is pretty reasonable, given the uncertainties. The NWS still could upgrade/downgrade the headlines as needed. As with fall/spring storms, this one may be rain, then transitioning to snow, which brings some uncertainty with it. Blizzard warning for Weld County, east of DIA, Castle Rock --this text valid for Greeley

The SPC has increased the wind risk to 30% and tornado risk to 10% into southern Indiana and Illinois. Some of the convection-allowing models show updraft helicity tracks in IN/IL late at night, well after 00z.

we have a winter storm watch for 3-7" across the Denver CWA, low elevations, 8-16" for over 9000ft.

I guess you can still get a burger to go...

Winter storm watches have been posted for Cheyenne's CWA and portions of Nebraska.

On Tuesday evening will have a dryline near the Pecos River, but perhaps not a lot will happen. The first interesting part of this could be Wednesday evening around Lubbock to Midland/Odessa. The low-level convergence there will be a weak cold front, with 50-55kt winds at 500mb over the region. The models have upper 40's dew points into SE New Mexico, that's why it won't be a dryline.

Today's 12z ECMWF has up to 7.8" (10:1 ratio) at Fort Collins, and 27" (10:1 ratio) in the low mountains northwest of Cheyenne for the next 10 days.

A storm system will develop on Thursday with a fairly low pressure - likely resulting in heavy snow in the Rockies and possibly near Fort Collins and Cheyenne. Edit: most models show heavy snow for east/north Wyoming into South Dakota. Another possibility is severe weather for portions of the Plains. As of yet, the SPC has not shown a 15% contour on its 4-8 day outlook. Quote:

One year ago (March 13th, 2019) an incredible 968mb low formed in southeast Colorado, bringing blizzard conditions and 7.1" of snow to Denver, and 14.0" at Cheyenne. In Fort Collins and Loveland, downsloping winds caused much of the snow to become rain or very compacted snow. That was pretty weird, but Fort Collins/Loveland has had a good share of snow in the past 12 months - March 1, 2019 to today. http://www.greatlakes.salsite.com/blizzard_of_2019_surface/12.gif

There could be a TDS near Ash Flat, AR. It's kind of tough to say, with all radars being far away from that area.