Flash Flooding in Tennessee, June 15, 2025

Area Forecast Discussion
National Weather Service Nashville TN
627 PM CDT Sun Jun 15 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 623 PM CDT Sun Jun 15 2025

- Humid with medium to high chances for showers and thunderstorms
  each day through Thursday. Greatest rain chances each afternoon
  and early evening.

- Little to no risk for severe weather, but some of the storms
  will contain torrential downpours, frequent lightning, and gusty
  winds.

- After one last round of storms Thursday, summer-like heat and
  dry weather makes an appearance across Middle Tennessee for next
  weekend.

&&

.UPDATE...
Issued at 534 PM CDT Sun Jun 15 2025

As of 5 pm CDT...showers and storms were moving across Middle
Tennessee, generally along a line from Hohenwald to Crossville.
Activity has been sub-severe with primarily lightning and heavy
downpours as the main threats. While storm motion is quite slow,
cells have not been robust enough to worry about a more flash flood
threat materializing despite PWATs being a healthy 1.6-1.9".

For the rest of the evening, expecting convection to gradually wane
as we head into the overnight hours and instability weakens.
However, it wouldn't surprise me if we have a few showers and storms
lingering throughout the overnight hours as we won't completely lose
all instability and there is a weak disturbance to our northwest
that can support continued activity. We'll also need to keep an eye
on potential fog development tonight with some areas once again
getting rain today, very light winds forecast, and less cloud cover
tonight anticipated.

For tomorrow, we may see an uptick in convection coverage as the
disturbance currently located over Missouri and Arkansas heads
slowly in our general direction. We'll once again see those
afternoon pop ups, but it's possible we see more of a loosely
organized line forming in West Tennessee, spreading across Middle
Tennessee during the late afternoon and evening hours. Once again,
with weak wind shear, mid-level lapse rates less than 6 C/km, and
PWATs approaching 2.00", our main threats with storms would be cloud-
to-ground lightning, torrential downpours, and perhaps a few gusts
of wind. Based on Sunday's high temperatures, it looks like another
quite warm and humid day for Monday with highs forecast in the mid
to upper 80s with apparent temperatures approaching to exceeding 90
degrees.

&&

.SHORT TERM...
(Rest of today through Tonight)
Issued at 1132 AM CDT Sun Jun 15 2025

Temperatures are only in the 70s at forecast time across the entire
mid-state, but so are dew points. It's sticky out there. We do have
a few showers on radar, mainly across the northern Plateau and while
they won't be the only ones to see showers today, areas east of I-65
seem to be a little more favored in hi-res models. I expect that as
clouds break up a little more from this morning and allow the air to
warm, we'll see additional showers and a few thunderstorms later
this afternoon. Taking a look at the 12Z OHX sounding, lapse rates
and shear values remain poor, so I don't even really expect any
strong storms, but if you're going to be out and about today, I'd
keep an umbrella handy.

Similar to last night, I expect most of the daytime activity to wane
after sunset, but scattered showers will be possible through the
overnight hours. Where it doesn't rain, some fog is possible, but it
shouldn't be egregious.

&&

.LONG TERM...
(Monday through next Sunday)
Issued at 1132 AM CDT Sun Jun 15 2025

The forecast remains fairly well on track for the upcoming week.
Temperatures should remain in the 80s through Thursday with
rain/thunderstorm chances each day. It's amazing how stagnant the
atmosphere has been and looks to remain for the next couple of days.
Forecast soundings show consistent poor lapse rates and a very
little shear through Tuesday. However on Wednesday, lapse rates
improve *slightly*. This could spell a little better coverage of
afternoon/early evening thunderstorm, but organization is still
lacking through Wednesday. Thursday may end up being our best day
for thunderstorm coverage as an upper level impulse swings a weak
trough through the region. If it verifies, this trough could
provide conditions for a little better organization, but I still
don't know if it'll be enough for severe storms -- maybe a couple
of strong wind gusts.

Once Friday rolls around, extended guidance continues to be bullish
with reducing rain chances as upper level ridging starts to take
over for the weekend. PoPs drop off, but temperatures start to rise.
We'll be close to 90 at BNA Friday and looking at current probs
over the weekend, NBM ensembles suggest a 90%+ chance of reaching
into the low to mid 90s both Saturday and Sunday next weekend.
We'll welcome the drier pattern, but much more summertime
temperatures may be on the way.

&&

.AVIATION...
(00Z TAFS)
Issued at 623 PM CDT Sun Jun 15 2025

Scattered thunderstorms are ongoing across Middle TN this evening,
but confidence in direct impacts to terminals through the
remainder of today is low. A complicated aviation forecast then
looks to present itself tonight through tomorrow. Overnight, cigs
and visibilities are expected to drop as low clouds and fog
redevelop. This will likely lead to widespread MVFR to IFR
conditions through early Monday morning. Yet another round of
scattered thunderstorms are then expected to develop by late
morning. Confidence in timing is low, but for now, included a
PROB30 group for TSRA where probability in storms is highest. But
do expect this timing to be refined in upcoming TAF cycles.

&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      72  88  73  87 /  40  80  70  60
Clarksville    71  85  72  86 /  30  80  70  50
Crossville     65  82  67  80 /  50  80  70  90
Columbia       69  87  70  86 /  50  80  70  70
Cookeville     67  83  68  80 /  40  80  70  80
Jamestown      66  83  67  80 /  50  80  60  90
Lawrenceburg   69  87  69  85 /  40  80  70  70
Murfreesboro   69  88  70  86 /  50  70  70  70
Waverly        69  84  69  85 /  50  80  70  40

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&

UPDATE.......Husted
SHORT TERM...Unger
LONG TERM....Unger
AVIATION.....Clements