Well, it had to happen sooner or later. Apparently, we’re not allowed to have quiet weather around here for too long this year! For today (Wednesday) and again on Thursday, it’s no big deal here locally. The weather will be similar to the past few days… warm temperatures, partly cloudy and hazy conditions. We’re just going to add a 20-30% chance of a few spotty hit-or-miss type afternoon and evening thundershowers. One or two of you might get a brief heavy downpour and some lightning and thunder for a short time, and that’s about it. Thursday afternoon, there could be a few strong storms with gusty winds and small hail from west Tennessee up into Kentucky and northward, but that threat will stay to the northwest of our viewing area.
Friday and the weekend is when things shift toward a much more active and stormy pattern. We’ll have a persistent upper-level trough of low pressure digging through the Great Lakes. That helping the upper-level ridge near us break down and shift west into Texas and northern Mexico will shift the upper jet stream southward closer to our area and set up a bit of a northwest flow type pattern. That will provide the roadmap for clusters of rain and thunderstorms to track out of the Southern and Central Plains into the Southeast and Tennessee Valley. This type of activity will be possible on Friday, Saturday, and Sunday either in the local area and/or very nearby. The exact specific timing of these waves of storms are up in the air a bit for now because a lot of that is controlled by the inner mechanics of the individual thunderstorm complexes, and a lot of what happens on a certain day is heavily affected by the details of what happened the day before. Neither are something that can be modeled with significant detail and accuracy until a day or maybe two days before each individual round of storms. What we can do now is identify the basic pattern that is favorable for this activity and a generalized area of where the setup is favorable and a broad sense of the general rough timing.
These thunderstorm clusters will carry with them the potential for severe storms. It’s not really a tornado type situation we’re looking at here, although you can NEVER completely rule out a tornado any time there is a severe thunderstorm. The primary hazard type with these thunderstorm complexes would be damaging straight-line winds. This is the classic early summertime activity we often see when big complexes of thunderstorms roll in from the west or northwest and produce damaging straight-line winds, heavy rainfall and localized flooding, and a lot of intense cloud-to-ground lightning.
FRIDAY: Of the days we’re watching, this might be the one where there is the most obvious potential for storms to have a “clean” environment to work with to have plenty of instability, because there’s not really a chance of the environment locally being worked over from storms the previous day. We will be on guard from midday into the evening for any complexes of thunderstorms rolling in from the west or northwest. As mentioned earlier, it’s too soon for any type of specific timing, but that’s the general window where we need to watch. Any thunderstorm complex that rolls in would have the potential for damaging straight-line winds, heavy rainfall, and frequent cloud-to-ground lightning. Any tornado threat would be very small, but as with any severe thunderstorm, it wouldn’t be completely zero. Some model data hints at a second cluster of rain and storms being possible late Friday night into early Saturday morning. We would need to watch that as well, but a lot of that would hinge on how worked over the environment is from midday to afternoon to early evening activity. We simply don’t have a way of knowing that right now.
SATURDAY: Similar to Friday, we will be on the watch for any clusters or complexes of showers and storms, but getting farther out in time and the details of Saturday being dependent on the specifics of what happen on Friday, we’re not able to know a whole lot. Any cluster or complex would again have the potential of damaging straight-line winds, heavy rainfall, frequent cloud-to-ground lightning, and a very low but not zero tornado threat. We just don’t have a way of figuring out specific timing or impact details until we have a good handle on the specifics of how Friday’s storms will play out.
SUNDAY: This looks like the day, of the three, with the best upper-air support and forcing… with the trough trying to swing in closer to the area. However, this is also the day that is the most uncertain. Not only are we even farther out in time, but with two days of storm activity leading up to Sunday, there’s a legitimate chance that pooling of rain-cooled air MIGHT try to shunt the best instability and frontal focus for storm activity off to our south. That is NOT a guarantee, but the models are trying to shift in that direction. For now, we will keep in the likely chance of showers and thunderstorms and then adjust that forecast as we get closer and details become more certain. Again on Sunday, any storm activity would have the potential for damaging straight-line winds, heavy rainfall, and cloud-to-ground lightning. We’re just not sure yet if that will be here in the immediate local area or if the rain-cooled air from Friday and Saturday activity shunts that higher storm risk off to our south. We will adjust the forecast as those details work themselves out!
