Chinook

Thunderstorms near Tupelo MS seem to be increasing in intensity quickly.

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

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.

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.

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.

Here's an interesting slightly new plot type from SPC HREF- Max and Min (highly negative) updraft helicity tracks. As has been discussed, there is a range of possibilities with supercells/ elevated supercells tomorrow. The SPC may move the risk area farther north into parts of Indiana.

The 00z models are in the process of finishing up the forecasts for tomorrow. At this time, I don't think there's a need to extend the slight risk much north of Cincinnati OH. The 00z HRRR may be unrealistic about deep convection near Indianapolis. I'm not sure. Maybe elevated CAPE could produce some hail near Indianapolis.

I am wondering if we should start a new medium-range tornado/severe weather thread, for general purposes. At the current time, there are no days with a slight risk or 15% risk on the extended SPC outlooks. This could change soon, but I'm not sure.

Low-level rotation track for the tornadic supercell at Nashville

This was the radar from the reported tornado at Crofton KY earlier (8:00PM CST/ 9:00PM EST). At the current time, some tornado warnings are ongoing around Waverly, Tennessee/ Tennessee City

I am not sure if you saw my recent post about the recent Iceland low pressure. There have been several strong low pressures have been in the Iceland region this winter. Seemingly, no matter what happens, Europe continues to get warmer air masses. I have heard that January 2020 was tied for the warmest January on record. (Source: Brian Brettscheider/ Climatologist49 on twitter.) I have barely seen any TropicalTidbits maps where the surface temperature was below normal in eastern Europe.

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.

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.

Euro/GFS/Canadian all have a closed 500mb low in AZ/NM on December 28th, so it's definitely something to watch for the southern Rockies and areas of the plains into Kansas.

The Chiefs game should be in a lot of snow. There are heavy snow bands, with one location getting sleet, and, as you can see, 0.5-3.0" of snow measured recently. A couple places with rain and freezing rain just west of Joplin - rain at Pittsburg, KS.

00z Euro keeps the snow closer to southwest Missouri, with 7" north of Joplin (3.7" at Joplin) (10:1 snow ratio.)

Lorain to Cleveland is 34-36 degrees right now, but you can already see the evidence of the LES north of Lorain on the radar, in the midst of the synoptic snow.

Fayetteville, AR says thunderstorm in vicinity, heavy rain, 34 degrees, Bentonville AR has unknown precipitation, Rogers AR (next to Bentonville) has freezing rain. Apparently the Tulsa metro area has freezing drizzle, snow, and unknown precipitation.

On Monday night (Tuesday 00z) the Euro and Canadian show a synoptic snow/ LES combo for Cleveland, and synoptic snow for other parts of Ohio. Yesterday's GFS run(s) had this also. It might be worth checking some model runs on this. Even if the synoptic snowfall doesn't materialize, the GFS says 850 temps will be down to -17C over Lake Erie. So this is massively cold considering October was some +3F above normal.

The Canadian predicts a monster sleet-storm for Kansas. Just to let you know, the Canadian is not always that accurate.

24-hr precip may have been as much as 9-16" near and southwest of Galveston

Maybe Oklahoma City is getting a very wet August? By the way, 87mph wind report near Piedmont, OK. I have heard that there was a probable tornado near Edmond.

Japan's radar web site shows that the eyewall has tracked over Tarama Island recently. This is close to Ishigaki. https://www.jma.go.jp/en/radnowc/

GFS has two storms in the next few days in the Pacific. Typhoon Lekima, farther west, is expected to be 130 kt (Category 4) near Ishigakijima, Japan and also at 80 kt near the Chinese landfall point (JTWC)