The possibility of severe thunderstorms this afternoon is occupying most of our attention today, but before the storms develop we’re going to be dealing with plenty of heat and humidity. High temperatures will reach the low 90s this afternoon:
With dew points still in the low to mid 70s:
That means the heat index will max out in the upper 90s to around 100 degrees (I think Futurecast is a little too toasty, but these numbers are certainly in the realm of possibility):
In a word, gross.
The heat and humidity will be the fuel for some strong thunderstorms this afternoon and this evening. The forecast models are depicting slightly different scenarios regarding storm development, strength and timing…the RPM model shows spotty storms popping up by noon, with scattered strong storms coming at us in waves — one round of storms by mid-afternoon, another this evening, and still more strong storms late this evening and overnight:
The HRRR model keeps a lid on the early-afternoon activity, but brings a line of strong thunderstorms through the Midstate late this afternoon and early this evening, with another line heading in after sunset:
As always though, no model is perfect.
Any thunderstorm that develops today will have the potential to become severe — the main severe weather threat will be damaging straight-line winds (from “wet microbursts” producing 60+mph gusts). ANY storm, regardless of severity, will produce a lot of cloud-to-ground lightning and some locally heavy rainfall:
There isn’t enough wind shear in the atmosphere overhead to make tornadoes a cause for concern, and the depth of the hot air in the atmosphere should be sufficient to melt any large hail before it reaches the ground.
This morning, the Storm Prediction Center initially outlined a “Marginal Risk” (level 1 of 5) for severe thunderstorms, only along and north of the TN/KY state line. I didn’t buy that, and apparently neither did the next shift of SPC forecasters, because their 8am outlook significantly expanded the Marginal Risk and “Slight Risk” (level 2 of 5) regions:
That’s a lot closer to my line of thinking, but I think the Slight Risk will eventually end up around I-40 — the SPC’s own forecast model (the short-range ensemble forecast) shows a 40-50% chance of thunderstorms with severe characteristics this afternoon:
The best chance of spotty storms on Thursday looks to develop to the north and northeast of Nashville, but we’ll keep a close eye out for changes — today’s storms could re-arrange the environment a bit and mess things up:
There are some day-to-day differences in the 7-day forecast, but the overall theme is the same through early next week: it will be hot, it will be muggy, and scattered storms will be possible every afternoon.
Nerdiness a-plenty today…links will be posted by 9am.
- The hottest place on Earth just broke a record.
- The story behind the most impressive thunderstorm picture I’ve ever seen.
- A small change in the earliest conditions of the solar system could have led to a life-filled Venus and a searing hot Earth (instead of the other way around).
- Why scientists are so excited about NASA’s Juno mission to Jupiter.
- What comes next for NASA after the Juno mission? Unfortunately, not much any time soon. Thanks, Congress!
- Other space agencies around the world will be sending spacecraft toward Jupiter, though…and eventually NASA will jump back into things as well. Here are the next spacecraft to visit the Jovian system.
- The search continues for “Planet Nine” in the outer solar system, and now astronomers have some new clues as to its location.
- What happens when you fill a giant balloon with liquid nitrogen?
- Two Canadian pilots recently flew a rescue mission to the South Pole (remember it’s nighttime for another couple of months there). They talk about the experience like it’s no big deal, but it sounds significantly less-than-fun to me.
- How many germs are actually on a toilet seat? Should you even care?