321
FXUS64 KOHX 220654
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
154 AM CDT Sun Sep 22 2024

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(Today through Monday)
Issued at 148 AM CDT Sun Sep 22 2024

Temperatures have cooled nicely so far with temps areawide in the
upper 60s to low 70s. Relative humidity values are between
80-100%, so areas of patchy fog are likely to develop as
temperatures continue to cool. The areas that received rainfall
yesterday are the mostly likely to get denser fog, otherwise be
on the lookout for patchy fog if you`re out and about overnight.
Today`s forecast features perhaps more widespread rain and
thunderstorm chances, but still on the lower side near 30%. The
greatest chances exist along the TN/KY border, however, if any
outflows push out of the convection in Kentucky this afternoon,
that would serve as a lifting mechanism to get more convection
going. Looking at the latest CAMS, the environment will be fairly
unstable this afternoon with surface-based CAPE values around 2500
J/kg. Bulk shear values also peak this afternoon near 30 kts
which is more than sufficient for a storm to produce gusty winds.
PW values show 2" with DCAPE values near 800 J/kg, so microburst-
type thunderstorms would certainly not be out of the question.
Overall, low severe risk since there`s not a great deal of forcing
and lapse rates are only in the 5.5-6.0 C/km range; not ideal for
long term convection. Storm activity will start to diminish after
sunset with overnight lows dropping into the upper 60s.

Our upper air pattern starts to shift on Monday as a trough begins
building in from the Great Plains. This will introduce increased
rain and storm chances between 30-50% on Monday with highs near
90. While the chance for severe storms is still low, it`s a bit
higher on Monday than Sunday. We will have more forcing for storms
to work with thanks to an embedded shortwave trough moving across
Missouri/Arkansas. 500mb maps show a tongue of 45 to 50 kts
moving along the TN/KY bored Monday afternoon. This will provide a
greater risk for damaging winds as bulk shear increase to near 45
kts. Mid-level lapse rates are still on the low side, but are a
touch higher near 6.5 C/km, so some small hail could be possible
in any stronger storms. A marginal risk for severe weather is in
place for the northern half of our CWA Monday.

&&

.LONG TERM...
(Monday Night through next Sunday)
Issued at 148 AM CDT Sun Sep 22 2024

Storms will again start to diminish Monday night. Models continue to
signal a strong cold front moving through the area Tuesday that will
be accompanied by more rain and thunderstorms. The chance for
rain and storm is currently 60-70% for the majority of Middle TN.
There will be a noticeable drop in our afternoon highs on
Wednesday as temps only reach into the upper 70s to low 80s. The
temperatures look to stay around this range through the remainder
of the week.

As noted in the previous forecast discussion, models are still
struggling to capture the upper air pattern beyond Wednesday. The
GFS takes the upper-level low up into the Great Lakes while the Euro
and Canadian keep it just off to our west, thus leading to a low
confidence forecast for the remainder of the extended. The NBM
favors keeping widespread 25-30% rain chances in areawide and, for
now, that seems like a good bet to make. As models come into better
agreement, we will continue to fine-tune the forecast.

&&

.AVIATION...
(06Z TAFS)
Issued at 1238 AM CDT Sun Sep 22 2024

VFR Conditions expected for the next few hours before some
possible MVFR (and maybe even IFR) fog develops. Uncertainty
continues with the extent and area of this developing fog, but
think the best chances are across areas which experienced rain
Saturday afternoon as well as KCSV and KSRB. VFR returns after
12Z with the main concern being the timing and coverage of any
TSRA/VCTS this afternoon. Too uncertain to pinpoint specific
time/location, so carried VCTS for now.

&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      93  72  90  70 /  30  20  40  30
Clarksville    90  69  86  68 /  40  20  40  60
Crossville     86  64  85  63 /  20  10  50  20
Columbia       93  68  91  69 /  20  10  30  20
Cookeville     87  67  86  66 /  20  20  50  30
Jamestown      87  65  84  65 /  30  20  60  30
Lawrenceburg   92  67  90  68 /  20  10  30  20
Murfreesboro   93  69  91  69 /  30  10  30  20
Waverly        91  69  89  67 /  30  20  40  50

&&

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

$$

SHORT TERM...Baggett
LONG TERM....Baggett
AVIATION.....Hurley