Severe Thunderstorm Warning 201, NWS Memphis, TN

Area Forecast Discussion
National Weather Service Memphis TN
1159 PM CDT Wed Aug 19 2026

...New DISCUSSION, AVIATION, FIRE WEATHER...

.KEY MESSAGES...
Issued at 1159 PM CDT Wed Aug 19 2026

- A Marginal to Slight Risk for severe thunderstorms overnight
  mainly north of I-40. Damaging winds and large hail are the main
  threats.

- A Heat Advisory remains in effect from 11 AM through 8 PM CDT
  Thursday, with heat index values expected to range between 105
  to 109 degrees.

- A transition to a zonal/northwest flow regime late this week
  will bring drier air and cooler temperatures for the weekend,
  providing relief from the oppressive heat.

&&

.DISCUSSION...
(Tonight through next Wednesday)
Issued at 1159 PM CDT Wed Aug 19 2026

GOES Water Vapor satellite trends finally show convective
initiation occurring over portions of southern Missouri and north
central Arkansas late this evening as a mid-level shortwave moves
across the Middle Mississippi Valley. Latest short-term model
soundings and mesoanalysis indicates this upstream activity is
elevated with a low-level inversion in place and convective
inhibition. The convective parameter space shows strong
instability with MLCAPE values between 2000-4000 J/kg, and DCAPE
values around 1000 J/kg. Additionally, effective shear in excess
of 40 kts, moderately steep mid-level lapse rates above 6.5 C/km,
0-3 km storm relative helicity values between 150-200 m2/s2, and
precipitable water values approaching 2 inches is located across
northern portions of the Mid-South.

Short-term models have struggled to resolve the development and
propagation of this activity overnight across the area. Short-
term trends and upward propagation vectors suggest this mixed
mode activity of multicell clusters and perhaps some
supercellular-like structures will eventually propagate southeast
towards the Tennessee River overnight. Damaging winds and large
hail are the primary severe weather threats with low confidence
in tornado development occurring across this area due to the
elevated nature of the convection. Localized heavy rainfall is
also possible with the high precipitable water values. Further
south, confidence is much lower with any convective activity
occurring closer to the TN/MS border.

Very hot temperatures are expected again across the Mid-South
Thursday southwest of the nearly stalled surface boundary over
portions of east Arkansas and north Mississippi where
temperatures will rise to the upper 90s once again. These very
hot temperatures combined with dewpoints in the 70s will
translate to heat index values between 105 to 109 degrees with a
Heat Advisory remaining in effect across these areas. Heat index
values may approach advisory criteria in the Memphis metro area.
However, confidence is limited as outflow boundaries from
upstream convection may lower surface dewpoints below advisory
criteria.

Additional showers and thunderstorms are possible south of I-
40 on Thursday as the boundary moves through as a weak cold
front. Strong instability and weak shear may result in a few
severe thunderstorms over north Mississippi during peak heating
with damaging winds as the main threat.

Long-term models indicate slightly cooler air will gradually
arrive later this weekend into early next week as a mid-level
trough settles in across the eastern U.S. Heat advisory potential
will remain limited to the southwest portion of the forecast
area.

&&

.AVIATION...
(06Z TAFS)
Issued at 1159 PM CDT Wed Aug 19 2026

Showers and thunderstorms remain north of the TN/KY border as of
11PM Wednesday. Additional activity is attempting to pop over
northeast AR, but a strong capping inversion is hampering upscale
growth. Given uncertainty in overnight trends, opted to keep
PROB30 groups in at JBR, MKL, and MEM. Otherwise, VFR conditions
will remain with southerly winds veering north by the end of the
period.

&&

.FIRE WEATHER...
Issued at 1159 PM CDT Wed Aug 19 2026

An overall low fire weather risk will hold over the next three
days. While temperatures remain hot, light winds and adequate
moisture levels will keep critical fire weather conditions under
control. Rainfall through Thursday will result in the development
of fog late Thursday night east of the Mississippi river.

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Heat Advisory from 11 AM to 8 PM CDT Thursday for ARZ048-049-058.

MO...None.
MS...Heat Advisory from 11 AM to 8 PM CDT Thursday for MSZ007-008-
     010>017-020>024.

TN...None.
&&

PUBLIC FORECAST...CJC
AVIATION...ANS

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