Area Forecast Discussion

KEY MESSAGES

Updated at 137 PM EDT Thu Jun 11 2026

- Pretty high risk of severe storms area wide tomorrow. Damaging winds are the most likely hazard, and could be quite strong (possibly as high as 80mph). Hail and flash flooding are also a concern.

- Unsettled pattern continues through the middle of next week.

DISCUSSION

Issued at 137 PM EDT Thu Jun 11 2026

The primary concern for the next few days is the chance of severe storms tomorrow afternoon across our forecast area. As such, the discussion will focus on that almost exclusively.

Shortwave energy will move from the central plains to the western Great Lakes region today and tonight, driving a cold front southeastward towards the southern Appalachian region tomorrow. Ahead of the front, widespread convection expected across the Midwest later on this afternoon. This activity will lay out an outflow boundary that will be pushing into the Cumberland Plateau tomorrow afternoon, sparking off widespread strong to severe storms across East Tennessee. There are some timing uncertainties here, and potential failure modes, but it appears likely that we see very strong/severe storms tomorrow capable of damaging winds a bit higher than what we'd normally expect in this area.

Hazards:

Tomorrow looks primarily like a damaging wind threat. However, there is also a threat of severe sized hail as well as flash flooding. They're less a threat than damaging winds but I can't ignore them. The tornado risk looks negligible due to lack of shear. Going back to the damaging wind threat, the model consensus seems to be that surface based CAPE values will exceed 2,500 - 3,000 J/kg tomorrow afternoon. This is backed by roughly a 70-80 percent chance in probabilistic guidance of exceeding 2,000 J/kg sfc CAPE. Meanwhile, downdraft CAPE looks to exceed 1,000 J/kg, with plenty of mid level dry air intrusion and very strong lapse rates. Lack of shear (effective bulk shear values of less than 15-20kt) means that the initial convective mode will likely wind up being cellular or multicell clusters, but this may transition into some quasi-linear state later in the evening as convection becomes more widespread. As such, the damaging wind risk will be sporadic initially. I'd expect the potential for 70-80mph winds given the instability and resulting storms heights we'll be dealing with. Speaking of instability and storm heights, let's talk about hail. The lack of shear means less organized convection which will work against severe sized hail, as will the fairly high freezing levels. But the forecast instability means there's at least a mentionable risk of some severe sized hail. I would not be surprised to see some 1" hail reports of perhaps slightly larger.

As for the heavy rain and flash flooding threat, this should be isolated but it certainly exists. PWATs are high, and the strong to severe nature of storms tomorrow means that heavy rainfall rates will be possible. The limiting factor I think will be the lifespan of any given storm and whether or not we have any training effects. Mean winds aren't perfectly aligned with the incoming outflow boundary and front, but they're close, which may support some training effects. Lack of shear means that storm lifespans will be shorter (more on the summertime cellular end of the spectrum versus supercells) so I think that we'll need some degree of training effects to really get any significant flooding.

Timing and Uncertainties:

Current timing favors storm initiation over the northern Cumberland Plateau around 2-3 PM EDT roughly. I lump timing and uncertainties in together here because storm initiation is almost certainly going to be along the incoming outflow boundary and there is some disagreement on when that makes it in and exactly when/where storms initiate. Most guidance favors it arriving in the plateau during that 2-3 PM EDT window, with storm initiation occurring at that time. But some guidance has initiation occurring squarely in the TN valley and it doing so a couple of hours later. The plateau oftentimes convects as early in the afternoon as the higher terrain of the Smokies does, so I would expect that early afternoon time to be the most likely. Most guidance moves storms off to our southeast by 9-10 PM EDT as well, so it won't linger into the overnight hours.

As for the remainder of the forecast period, this front pushes south of us on Saturday. We may get a reprieve from the humidity in the northern areas, and also some dry conditions that day, but an incoming shortwave in the zonal flow aloft may spark off some additional storms at least near/south of the I-40 corridor. Better chances exist on Sunday though as another, stronger impulse moves through. Moving into early next week, upper flow becomes SELY over the deep south and southern Appalachian region Monday through Wednesday. We'll continue to monitor this as this pattern will support widespread heavy rains and the potential for flooding. The question is really, where will that set up. There remains quite a bit of uncertainty there. Current trends show the heavy rains staying mostly to our south, but we're close enough to keep an eye on it.

AVIATION

(18Z TAFS) Issued at 137 PM EDT Thu Jun 11 2026

We do have some ISOLD SHRA in the TN valley this afternoon, one of which was near KTYS as of the writing of this. Threw in some VCSH at TYS and CHA to account for current radar trends but those should die off in the next couple of hours. Otherwise, VFR flight categories should prevail through the 18z period. Widespread SHRA/TSRA will be moving into the TN valley shortly after the end of the period though.

PRELIMINARY POINT TEMPS/POPS

MRX WATCHES / WARNINGS / ADVISORIES

NC...NONE. TN...NONE. VA...NONE.