101
FXUS64 KMEG 212035
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
335 PM CDT Tue May 21 2024

...New SYNOPSIS, DISCUSSION...

.SYNOPSIS...
Issued at 327 PM CDT Tue May 21 2024

A ridge of high pressure will weaken tonight with a cold front
bringing a return of shower and thunderstorm chances back to the
Mid-South. A strong to severe thunderstorm is possible across
portions of northeast Arkansas and the Missouri Bootheel late
tonight, However, the greatest potential for severe thunderstorms
will be Wednesday afternoon into Wednesday night across the Mid-
South. Damaging winds will be the primary severe weather threat
with a secondary threat of large hail, heavy rainfall, and
possibly a tornado. A period of unsettled weather will persist
across the Mid-South beginning late tonight and continuing through
early next week.

&&

.DISCUSSION...
(This evening through next Monday)
Issued at 327 PM CDT Tue May 21 2024

GOES-16 Water Vapor Satellite trends this afternoon show a mid-
level trough moving into the Upper Midwest, an elongated
upper-level ridge present from the Great Lakes Region back through
the Southeast U.S. and portions of the Lower Mississippi Valley.
This has resulted in another warm and dry afternoon with
temperatures in the middle to upper 80s as of 2 PM CDT. Strong to
severe thunderstorm potential will remain the predominant concern
in this afternoon`s forecast issuance, especially for the next
two days.

Short-term models indicate the aforementioned upper-level ridge
will begin to break down tonight across the Lower Mississippi
Valley with 20-30 dm 500 mb height falls occurring north of I-40.
A mid-level shortwave trough and associated cold front will drop
into the Mid-South late tonight into Wednesday morning bringing a
return of showers and thunderstorms back to the area. Short-term
models, particularly the operational CAMs have struggled with the
overall evolution of convection across the Mid-South into
Wednesday night. Nonetheless, a broken convective line is
expected to gradually weaken north of I-40 overnight. Steep
700-500 mb mid-level lapse rates, surface-based CAPE values, and
0-6 km bulk shear values between 40-45 kts suggest a potential for
strong to severe thunderstorms initially with damaging winds and
large hail being the severe weather threats until the storms
become elevated late in the night.

This weakening convection is expected to leave behind outflow
boundaries which may interact with with an MCS/MCV to produce
redevelopment of showers and and thunderstorms across the Mid-
South Wednesday afternoon into Wednesday evening. Large hail and
damaging winds will continue to be the primary severe weather
threats, with a secondary threat of heavy rainfall as precipitable
water values will remain high. A tornado or two may be possible if
there is enough streamwise vorticity available in the pre-
convective environment as can be the case with MCVs.

Operational and ensemble model runs indicate an unsettled pattern
will persist for Thursday through early next week as the
aforementioned cold front washes out over the Lower Mississippi
Valley and another front drops into the region for Memorial Day.
Additional strong to severe thunderstorms are possible during this
period, especially for portions of the forecast area Thursday and
again on Sunday.

CJC

&&

.AVIATION...
(18Z TAFS)
Issued at 1237 PM CDT Tue May 21 2024

VFR this afternoon with gusty south winds at 12-20 kts with higher
gusts. Winds will diminish some this evening though remain above
threshold at MEM. First round of TSRAs should push into the area
later tonight and early Wednesday. Expect low clouds across much
of the area Wednesday morning. The first round of storms will
leave behind outflow boundaries that will influence the next round
convection expected Wednesday afternoon. Timing of the convection
remain difficult with the 12z CAMs offering a variety of
solutions.

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&

$$

PUBLIC FORECAST...CJC
AVIATION...SJM