Despite repeated blasts of cold air, the spring severe weather season has already kicked into high gear.
Following the weekend’s deadly tornado outbreak, eyes again turn to the South as another powerful ripple in the jet stream threatens a new round of damaging thunderstorms.
Although the situation — particularly how intense and widespread the storms end up — remains far from certain, there are numerous reasons to keep a close eye on this one. Damaging winds and powerful tornadoes are possible, as is excessive rain in a region that keeps seeing too much.
The culprit for this severe weather risk is a storm system that is expected to rapidly develop and move from the Southern Plains to the Midwest and Great Lakes region on Saturday. While the most significant storm threat is likely to occur on Saturday across the Mid-South, some severe weather is possible in the Southern Plains on Friday and into the Southeast by Sunday.
Weather model predictions and pattern matches suggest this is the type of storm with tremendous potential to unleash thunderstorms producing damaging winds and tornadoes, especially on Saturday. But reaching that potential is far from guaranteed for a number of reasons.
In Thursday’s outlook for Saturday, the Storm Prediction Center (SPC) writes that weaker storms early in the day could rob energy from activity that might fire up later on.
In addition, there is uncertainty as to how fast the storm will intensify — which can play a role in how many tornadoes form.
Despite this uncertainty, SPC points out “the most likely axis where conditions may become most favorable for a more substantial severe risk appears to exist from the Mississippi Delta region, east-northeast across northern Mississippi and parts of western Tennessee, and into the Tennessee Valley/northwest Alabama.”
Note this zone is somewhat to the northwest of last Sunday’s tornadoes outbreak.
Saint Louis University’s CIPS Analog identifier, which attempts to match patterns to what is forecast in different computer models, shows Saturday’s storm setup shares characteristics from past events that featured both memorable outbreaks and others that were much less notable.
This kind of bifurcated look is not too unusual for severe weather events this time of year and across the South overall. With risk of extensive storminess early Saturday limiting instability later in the day, it may take until Saturday itself to know if there is sufficient energy for a major storm outbreak into the afternoon and evening.
While Saturday is the day of greatest concern, strong storms could erupt on Friday and Sunday, as well.
On Friday, large hail seems to be the main concern over Oklahoma and into Arkansas, Louisiana and Texas.
By Sunday, the severe weather threat runs in a line from the northern Gulf Coast to the Carolinas. How widespread severe storms are Sunday is difficult to project this many days in advance. But considering the storm will have shot north into Canada by Sunday, damaging winds are more likely than many tornadoes.
We should not totally ignore the wintry weather aspect, either. It seems likely that a swath of heavy snow accumulation and the potential for blizzard conditions stretches from the Northern Plains to the Upper Midwest on the northwest side of the storm center.
Weather models also suggest another in the recent slew of storm systems is likely to race through the heartland again by the midweek of next week. It could bring another round of severe weather.
After these storms, as we head deeper into next week, there are signs that colder air will overtake the central and eastern United States into the middle of the month. It is too soon to know whether this will spur more severe thunderstorm activity.