The risk for severe thunderstorms on Saturday is on the increase, and NOAA’s Storm Prediction Center has ratcheted up its severe weather outlook for the start of the three-day holiday weekend.
While the greatest threat of severe weather will be further northwest, the SPC has now included Scott County on the eastern fringe of an “enhanced risk” outlook for severe weather on Saturday. An “enhanced risk” means there is a 30 percent chance for severe weather. Previously, Scott County was in a “slight risk,” meaning a 15 percent chance for severe weather. Further north and west, along the upper Mississippi River Valley, the SPC has highlighted a “moderate,” or 45 percent, risk for severe weather.
The National Weather Service in Morristown continues to bump up storm chances for the northern Cumberland Plateau, now calling for a 50 percent chance of storms on Saturday, a 60 percent chance Saturday night and a 70 percent chance on Sunday.
NWS-Morristown remains rather vague in its mention of severe weather potential, except to say that the biggest threat is north of Interstate 40 on Saturday, and that strong-to-severe storms are possible again on Sunday.
For now, quite a bit of uncertainty remains this far east. Further west, across the Ozarks and into the Missouri bootheel, an outflow boundary from a cluster of thunderstorms that are expected tonight should serve as an initiator for storms to start firing on Saturday, and moderate wind shear and very unstable air could help create a dynamic situation where all modes of severe weather — including tornadoes — are possible.
This far east, however, the dynamics are less impressive. Still, the lower level jet will be sufficiently tilted to keep a severe weather threat in place here, and any storms that develop during the afternoon hours could become strong or severe. The tornado threat is minuscule here, but forecast soundings are sufficient for straight-line winds and large hail.
One major caveat is whether the atmosphere will be capped, which would help limit storm formation. The NAM model is showing that scenario, whereas other models are weaker with the cap. If the atmosphere remains capped through the afternoon, there will be fewer thunderstorms — meaning the storms will be more scattered in nature and not everyone will see rain.
Eye to the Sky is a weather blog by Independent Herald editor Ben Garrett. Garrett is a weather enthusiast who has long blogged about interesting weather on his personal website. He is not a professional forecaster or a meteorologist and information on this blog should not be considered a substitute for forecasts, advisories or other products from the National Weather Service.