HIGH RISK ISSUED: VIOLENT, LONG-TRACK TORNADOES EXPECTED!

The Storm Prediction Center has issued MODERATE RISK of severe weather for this evening and tonight across much of the Middle MS River Valley. In addition, SPC has just issued a very rare HIGH RISK of severe storms and tornadoes across the Deep South for Saturday. The last one was May 6th of last year.

A storm that we started tracking more than a week ago arrives this evening with an outbreak of severe thunderstorms and some tornadoes expected. The severe threat shifts to the south on Saturday with a significant threat for tornadoes, some of which could be violent and long-lived.

Thunderstorms are expected to explode (data from 3kNAM below) across Western Missouri late this afternoon as we head into this evening. These storms look to form an arcing QLCS (quasi-linear convective system) squal line that is expected to race to the east and north through the evening hours and overnight with a high threat for damaging winds, large hail and tornadoes.

Looking at some of the individual parameters below showing STP (significant tornado parameter) and "helicity tracks", which shows where strong rotating updrafts (ie supercell thunderstorms) are expected raising the possibility of several tornadoes some of which could be strong. The STP nmbers are particularly high across Southeast MO and Northeast AR this evening.

In fact, the Storm Prediction Center has painted a large area in DARK RED, showing where "significant tornadoes" (defined as F3 and above) will be possible. The significant tornado threat extends from far SE Iowa all the way down to parts of the south, centered over the Middle MS Valley tonight. This significant tornado threat shifts throughout out Dixie and the Gulf Coast tomorrow with a very broad area under the risk of strong, possibly long-lived tornadoes.

A close up look at the 3k NAM shows storms will be ongoing overnight across parts of the Lower MS Valley late tonight before re-energizing with heating and the advance of a batch of strong upper level support during the afternoon on Saturday. I'm particularly concerned about storms that are expected to fire across Central MS travel into Central-Northern MS late afternoon and during the evening.

These storm will be able to feed on seasonally, very high instability (not shown), but also a ton of wind energy above. This is usually a bad set up for the south and the severe parameters reflect that below with STP being maximized at above 10 again, but also this time with a ton of fuel. These cells should be able to rotate hard for several hours as indicated by the helicity tracks below.

So what do I think?

TONIGHT: I think tonight's situation looks to lend itself to more of a high wind and hail threat. I'm not saying tornadoes won't occur, because they certainly will. It just looks like they will struggle to maintain in an environment that may actually be a little too strongly "sheared" (too much upper wind) compared to the amount of fuel that will be avaible to maintain longer lived updrafts.

SATURDAY: Unfortunately, I am expecting ALL THE MAJOR INGREDIENTS that you would need for a major tornado outbreak to come together and, it appears, that "Violent, Long-Track Tornadoes" are not just possible, but likely tomorrow. THIS IS A VERY DANGEROUS SITUATION for the Deep South and particularly those that live in Mississippi and Alabama. This should be monitored closely.

I would love to be wrong on this and if they do occur I pray they miss the major population centers. But I think it's best to plan for the worst.

Stay tuned. Stay safe.

Jeremy Kappell

Meteorologist, Writer, Journalist