585
FXUS64 KMEG 051932
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
232 PM CDT Sun May 5 2024

...New SYNOPSIS, DISCUSSION...

.SYNOPSIS...
Issued at 232 PM CDT Sun May 5 2024

Showers and thunderstorms will affect the Mid-South through
tonight with more isolated activity on Monday. A few strong to
severe storms possible. Another round of storms will be possible
late Monday night and Tuesday with a stronger system forecast to
affect the region Wednesday. Cooler and drier conditions are
expected Friday into the weekend.

&&

.DISCUSSION...
(This evening through next Saturday)
Issued at 232 PM CDT Sun May 5 2024

A shortwave trough is moving across the Ozarks this afternoon,
enhancing large-scale forcing for ascent across the region. A
northwest-southeast oriented band of showers and thunderstorms
will continue to lift poleward across the area through 00z (7
pm), with more scattered convection in its wake this evening and
overnight. A few strong to severe thunderstorms are possible with
this activity, with the primary concern being damaging wind.
Hodographs lengthen tonight as the low-level flow increases, but
the nocturnal boundary layer is likely to become capped, resulting
in mostly elevated storms within a few hours of sunset.
Lingering showers are expected tomorrow morning, mainly east of
the MS River followed by a midday lull as shortwave ridging
develops over the region. However, there is a potential for
isolated showers or thunderstorms late tomorrow afternoon as the
next approaching waves interacts with residual moisture and warm
surface temperatures.

Convection will develop upstream over KS/OK Monday afternoon ahead
of a cold front. Storms are expected to grow upscale into a linear
MCS, weakening early Tuesday morning as they approach the Mid-
South. The Day 2 SPC Outlook extended the marginal risk east to
account for this activity, but confidence is low that it will
maintain its intensity into the Mid-South. Nonetheless, a few
strong storms appear to be possible late Monday night. The upper-
level shortwave axis will swing across the area early Tuesday but
broad west- southwest flow aloft will likely maintain at least
weak synoptic forcing associated with embedded perturbations
within the mean flow. Diurnal destabilization is anticipated after
morning convection which should lead to additional development
during the afternoon. Multicellular convection looks to be the
primary mode, resulting in a damaging wind threat.

A more robust system looks to affect the region Wednesday. A Rex
Block develops over the western CONUS with a broad trough over the
Plains. A strengthening subtropical jet will develop over the
Lower MS Valley, enhancing winds aloft (and deep-layer shear).
This jet will also enhance lift within the left exit region,
perhaps coupling with the right entrance region of the polar jet
over the northern OH Valley. The amount of synoptic forcing for
Wednesday will partially depend on the timing of any shortwave
troughs rotating around the base of the main trough. The global
ensembles maintain fairly strong agreement on the evolution of
this pattern with the best lift during the afternoon and evening.
Parameter space is concerning regarding the severe weather
potential with the joint probability of at least 1500 J/kg of
SBCAPE and 40 kts of deep-layer shear at or above 70% along and
north of I-40 with decreasing probability to the south south
(weaker shear). The CSU machine leaning probabilities for severe
weather are ominous and the Craven-Wiedenfeld Aggregate Severe
Parameter (CWASP) is well into the 70s (and even 80s in some
areas). The big question is whether or not the large scale forcing
and diurnal heating will be sufficient to break the mid-level
capping inversion. Stay tuned.

Rain chances linger through Thursday but drier conditions will
advect into the region behind the departing trough as we approach
the weekend. The weakening Rex Block will maintain a trough over
the eastern CONUS. The NAEFS mean 500 mb heights are in the 10th
percentile this weekend, implying below normal temperatures across
the Mid-South. This is reflected in the current forecast with
highs in the mid 70s and lows in the low/mid 50s. Generally dry
weather is anticipated Friday and Saturday, but we`ll have to keep
an eye on the potential trough on Sunday.

MJ

&&

.AVIATION...
(18Z TAFS)
Issued at 1248 PM CDT Sun May 5 2024

Primary forecast concern remains timing of TSRA. At 1745Z, KNQA
radar showed widespread -SHRA and embedded TSRA over eastern AR
and northwest MS near CKM. This activity will take a couple hours
to translate east with the parent shortwave, but additional
development will be possible to the east as temperatures warm.
Overall, few changes from the earlier TAFs.

CAMs and TCF point toward a modest bump in TSRA chances late this
evening, as a secondary midlevel trough axis rotates through.
Better than even chances exists for IFR/low MVFR toward sunrise, in
the wake of this feature.

PWB

&&

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

$$

PUBLIC FORECAST...MJ
AVIATION...PWB