329
FXUS64 KOHX 171428
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
928 AM CDT Tue Jun 17 2025

...New MESOSCALE UPDATE...

.KEY MESSAGES...
Updated at 925 AM CDT Tue Jun 17 2025

- Showers and thunderstorms continue to be the pattern for the
  upcoming week with low chances of severe weather and medium
  chances of flash flooding.

- Summer-like heat and drier weather makes an appearance across
  Middle Tennessee for next weekend. Heat indices climb to 100
  degrees Saturday through Monday.

&&

.MESOSCALE UPDATE FOR TODAY`S STORM POTENTIAL...
Issued at 925 AM CDT Tue Jun 17 2025

The morning sounding from OHX shows a wet environment with only
modest instability. The Precipitable Water is 1.91, which gives us
a PWAT+ of 148 (observed PWAT is 148% of the daily mean value),
and puts us close to a daily max and definitely above the 90th
percentile for this date. When modifying for the expected max
temp, we get a surface-based CAPE in excess of 1,300 J/kg and a
Lifted Index of -5. However, the 700-500 mb lapse rate is only
5.5C/km, and there is very little low-level wind shear. So the
big takeaway is a very low severe potential. The tall, thin CAPE
that were seeing pretty much rules out any large hail potential.
So were left with an isolated damaging wind threat and a heavy
rainfall potential. We will have to monitor for localized flooding
with any slow movers, as the high PWAT value suggests the
possibility of very high rainfall rates. Meanwhile, the 13Z HRRR
shows at least scattered activity occurring across Middle
Tennessee for the remainder of the morning and through the
afternoon, then diminishing after 00Z. The lack of any real
organization means that trying to highlight specific timing is
impossible; the storm threat will be ongoing for the next several
hours.

&&

.SHORT TERM...
(Tonight through Wednesday)
Issued at 1030 PM CDT Mon Jun 16 2025

Water vapor imagery this evening shows an upper-level trough
starting to move through the Midwest and will continue to track east
through the area into Tuesday. There is an abundant amount of
moisture present with the PWAT on this evening`s sounding coming in
at an impressive 1.97 inches. That`s well above the 90th
percentile for the date, but does fall short of a daily record.
While today`s thunderstorm activity is tapering off, isolated
showers will likely continue overnight due to this moisture and
the trough swinging through the area. But thunderstorm coverage
will increase again Tuesday morning and into the afternoon hours.
With plenty of instability and PWATs remaining near 2 inches,
heavy rain continues to be the primary threat with stronger
thunderstorms. And after days of rainfall, a flooding threat
remains due to already saturated soils. Fortunately, with the
trough moving through the area, storm motions should be quick
enough to prevent slow-moving/stationary storms exacerbating the
flood threat. Similar to the past several days, coverage will
trend down after sunset with isolated activity likely continuing
through the overnight hours.

The trough exits the area late Tuesday, but plenty of moisture
sticks around into Wednesday to lead to more scattered
thunderstorms. The primary threat heading into Wednesday continues
to be heavy rain and flooding. Especially since steering flow is
weak on Wednesday with no upper-level support, and slow storm
motions will increase the flooding threat.

&&

.LONG TERM...
(Wednesday Night through next Tuesday)
Issued at 1030 PM CDT Mon Jun 16 2025

One more active wave is expected Wednesday night and into Thursday
as another upper-level trough tracks through the Midwest, sending a
front through the area. PWATs remain high at around 1.75", and along
and ahead of this boundary will be slightly better wind shear and
lapse rates. This supports a low severe weather threat Wednesday
night and into early Thursday where the main threat would be
strong to damaging winds. The current SPC Outlook (at the time of
this writing) has almost all of Middle TN in a marginal risk.

A break from the daily rain chances arrives Friday and into the
weekend, but it comes at a price. And fittingly so as the first
official day of summer is Friday. A strong area of high pressure
builds over the SE US through the weekend. This suppresses our
rain chances, but sends temperatures soaring. Highs will warm into
the upper-80s along the Plateau and into the mid-90s west of it.
It unfortunately will be humid, too, which sends heat index values
into the upper-90s and even into the triple digits. If you have
outdoor plans this weekend, be sure to stay hydrated.

&&

.AVIATION...
(12Z TAFS)
Issued at 630 AM CDT Tue Jun 17 2025

While we`ve been VFR most of the night at our mid-state terminals,
MVFR cigs will accompany morning showers at CKV/BNA/MQY that
should arrive around 13Z. While these will only last a few hours
and VFR should return around 17Z, scattered afternoon showers and
storms are expected at all terminals. Timing is on the lower
confidence side, so covered with PROBs and will have to adjust.
Southwest winds will be less than 10 kts through 16Z then become
breezy with gusts up to 20 kts until sunset.

&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      84  73  89  74 /  90  40  30  60
Clarksville    82  73  88  73 /  80  20  30  70
Crossville     80  66  82  68 /  90  70  70  50
Columbia       83  71  89  72 /  80  30  30  50
Cookeville     82  69  84  69 /  90  60  60  50
Jamestown      82  67  84  67 /  90  70  70  50
Lawrenceburg   83  70  88  71 /  90  40  40  50
Murfreesboro   85  71  90  72 /  80  40  40  50
Waverly        81  70  87  70 /  80  20  30  70

&&

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

$$

SHORT TERM...Rose
LONG TERM....Rose
AVIATION.....Unger