Now, let’s all say that fast three times…severe storms Saturday/Sunday….severe storms Saturday/Sunday….severe storms Saturday/Sunday. OK, enough with the frivolity…let’s get down to business. The SPC has put most of TN under a SLIGHT risk of severe weather on Saturday.
So…what can we expect? Latest NAM Hi-Res model data shows a rather robust QLCS-type system coming through our area during the overnight period. The image below is valid for 10pm Saturday night.
During severe weather episodes, weather geeks like us look for certain ingredients that can help shed a little light on what we *really* can expect during said severe weather episode. Those ingredients include — but are not limited to — instability, temperature, dew point, wind shear. In this instance, model data has been consistent in giving us plenty of instability (CAPE) with values ranging anywhere from 1500-2000 j/kg, temperatures will range between 70-75F as storms enter the area, dew points look to be around 65F (which can best be equated to putting 89 octane in your gas tank. That’s some very rich air, and storms “run” much better with moisture-rich air). These three indicators tell me that we’ll definitely hear some thunder and might see some thunderstorm wind damage after all is said and done.
I know some of you will ask, ‘What about the tornado threat?” and it’s always a valid question. Given the abundance of instability, temperature, and dew point, I’d say the chances for a tornado or two is decent, but one mitigating factor to this equation could be the lack of overall “shear” — or turning — in the atmosphere. There doesn’t appear to be a whole lot of wind energy with this system. That’s not to say, however, that a stray tornado warning or two will not be issued. Any severe thunderstorm carries with it the risk of a tornado, and we’re very likely to see several severe thunderstorms with this system.
One thing is for certain…we’re going to see torrential downpours embedded within this line of storms. PWATs, or precipitable water indexes, are averaging 1.7, depending upon which model data suite you subscribe to. Don’t be surprised if the curbs on your street suddenly turn into the Amazon River during monsoon season. Flash flooding *could* occur given the relative dryness we’ve seen. Most of the compacted clay that make up our yards have solidified and the concrete-like consistency could help to promote run-off.
That’s all I’ve got…now you know as much as I do. Take the time to prepare now for what could be coming our way Saturday night. If there are any substantial changes to the model data, you’ll be seeing me again. Happy Friday, everyone!