Severe Thunderstorm Warning 69, NWS Memphis, TN

Area Forecast Discussion
National Weather Service Memphis TN
616 PM CDT Sat Apr 15 2023

...New AVIATION...

.SYNOPSIS...
Issued at 315 PM CDT Sat Apr 15 2023

Showers and thunderstorms will lift through the Midsouth this
evening, along a Pacific cold front and aided by a strong upper
level disturbance. Dry conditions will prevail from Sunday through
the middle of next week. Our next rain chance will arrive Thursday
into early Friday, as another Pacific cold front and upper level
disturbance bring thunderstorms to the region.

&&

.DISCUSSION...
(This evening through next Friday)
Issued at 315 PM CDT Sat Apr 15 2023

Storms appear on track to pass through the Midsouth this evening,
ahead of a negatively-tilted midlevel trough ejecting through the
Ozarks. Storms will form along a Pacific cold front/dryline,
encountering 1500-2000 J/kg of mixed-layer CAPE over eastern AR
at 7-8PM. 0-6km bulk shear will not be particularly impressive,
at 35-40 knots. Strong frontal forcing will likely result in
linear storm mode, with damaging winds the primary threat. Linear
mode aside, 700-500mb lapse rates in excess of 8C/km, and large
hail certainly cannot be ruled out west of the MS River. Tornado
threat will likely be confined to storm scale interactions/bookend
vortices that may yield a brief spin-up or two.

Mixed layer CAPE will decrease to 500-1000 J/kg over west TN and
north MS after 9 PM. A marginal damaging wind threat will persist,
given 50-60 knot 850mb-700mb rear inflow. Severe storm threat
should be largely over by midnight, as mixed-layer CAPE drops to
below 500 J/kg near the TN River and northeast MS. In the
interim, the legacy Duct Function product from the NAM model
suggests some favorable propagation of thunderstorm outflows. The
takeaway: The weakening storms may be efficient wind producers.

Dry and cooler conditions will prevail on Sunday, with dewpoints
cooling to the 30s. Surface winds will gust during the day and
remain sufficiently high Sunday night to preclude frost concerns.

Temperatures will warm through Thursday, ahead of an approaching
upper level longwave trough. Rain chances return late Thursday and
early Friday, as the trough and associated surface cold front lift
through much of the MS River Valley.

PWB

&&

.AVIATION...
(00Z TAFS)
Issued at 601 PM CDT Sat Apr 15 2023

Current VFR conditions will begin to lower to MVFR as as
organized line of storms is expected to move from west to east
starting around 01z. During FROPA, brief TSRA conditions and gusty
winds will be possible. TEMPO groups cover this well. The farther
east this line gets, the weaker the convection is expected to be.

Guidance isn't hitting hard on low ceilings with this system with
the lowest MVFR deck ~1500ft. After FROPA, conditions will
gradually lift back to VFR and all sites should be back to VFR by
tomorrow morning. Winds will continue to be elevated and gusty
throughout the period. SSW winds around 10-15kts and gusts up to
25kts are pre-frontal conditions. As the front passes winds will
veer NNW remaining elevated with higher gusts possible.

DNM

&&

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

PUBLIC FORECAST...PWB
AVIATION...DNM