Lucy, Tennessee Weather Forecast Discussion

121
FXUS64 KMEG 220447
AFDMEG
Area Forecast Discussion
National Weather Service Memphis TN
1147 PM CDT Sun Sep 21 2025
...New DISCUSSION, AVIATION, FIRE WEATHER...
.KEY MESSAGES...
Updated at 1147 PM CDT Sun Sep 21 2025
-Scattered showers and thunderstorms are expected this morning,
 with an unsettled pattern bringing daily rain chances through
 this week.
-An increasing potential for strong to severe thunderstorms and
 heavy rain exists for Wednesday and Thursday.
-A significant pattern change late this week will bring much
 cooler, fall-like temperatures to the Mid-South.
&&
.DISCUSSION...
(Tonight through next Sunday)
Issued at 1147 PM CDT Sun Sep 21 2025
Weak, large-scale troughing persists across the central CONUS
tonight. A shortwave feature is currently moving into the region
from the west, and will pass through the region tonight.
Convection has already reformed within an associated zone of weak
PVA and southerly WAA where additional, scattered convection is
possible through this morning. Heights will continue to be
relaxed into this afternoon, which is expected to allow for
additional diurnal convection. Shear will remain low, keeping the
overall severe threat low, but local microbursts and sub- severe
hail will still be possible. Highs will still be in the low 90s
with local relief from precipitation.
The Mid-South will remain in a zonal upper flow pattern Tuesday,
keeping the region in a wetter pattern with similar weather to
today. Convective coverage does, however, remain more uncertain as
the main forcing mechanisms will be weak, small upper
perturbations. Regardless, RAP/NAM/NBM guidance is still keen on
WAA convection and, presumably, some diurnal convection. Shear is
expected to increase through the afternoon to around 20-30 knots
as upper level winds increase in response to the deepening trough
to the west. This shear, in combination with 1500-2000 J/kg
MUCAPE, supports at least marginal severe environment capable of
organized storm clusters capable of strong winds and hail. The
cessation of convection is equally as uncertain with the potential
for multiple small-scale, mid-level perturbations throughout the
night.
The trough over the Central Plains will begin to become cutoff
from the polar westerlies Tuesday and into Wednesday with a high
positive tilt. LREF and deterministic guidance bring the base of
the trough east throughout the day Wednesday. However, significant
uncertainty still exists regarding the exact placement and
amplitude of the system as it nears the region. Surface
cyclogenesis will try to begin somewhere in the ArkLaTex, but will
be heavily dependent on the upper jet dynamics. Therefore, the
evolution of surface boundaries and precipitation is heavily
uncertain, even at 72 hours out. There do appear to be two
primary solutions to draw from: 1) a closed surface low tracking
north of the region and 2) a convectively reinforced boundary with
no defined surface low. Scenario 1 appears to be more favored as
depicted within GFS/ECMWF/NAM guidance. If this were to occur, a
north/south axis of 70+ F dew points would exist across the region
by Wednesday afternoon. With the base of the upper trough nearing
by this point, each of these models depicts bulk shear values
above 30 knots. Details regarding instability remain in question
with a large spread amounts these three models. These details
will be worked out over the coming forecast cycles, but it does
appear that a more concerted severe weather threat is on the table
for Wednesday afternoon.
A cold front will exist somewhere across the region Thursday where
additional storm development will be possible throughout the
afternoon. Cooler air will envelope the region behind it with
highs dropping into the upper 70s and low 80s. These conditions
will remain through the end of the forecast as the upper trough
stalls over the southeastern CONUS, keeping the region in
northwest flow.
&&
.AVIATION...
(06Z TAFS)
Issued at 1147 PM CDT Sun Sep 21 2025
Weakening convective activity over western Arkansas may affect JBR
and MEM towards sunrise and have included PROB30 for rain showers.
Latest guidance indicating the potential for redevelopment of
showers and thunderstorms at JBR, MEM, and MKL Monday afternoon.
Thus, PROB30`s have been introduced in this TAF set. Light winds
will increase to South winds between 7-10 kts on Monday.
&&
.FIRE WEATHER...
Issued at 1147 PM CDT Sun Sep 21 2025
Wetting rain chances will tick upwards early this week with
widespread rainfall returning by the middle of this week with a
cold front. Drought-improving rainfall will occur in areas along
and north of the I-40 corridor. Conditions will trend cooler
behind the front late this week.
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...JAB
AVIATION...CJC

NWS MEG Office Area Forecast Discussion