Forecast Discussion

925
FXUS64 KMEG 300859
AFDMEG

Area Forecast Discussion
National Weather Service Memphis TN
359 AM CDT Wed Apr 30 2025

...New DISCUSSION...

.KEY MESSAGES...
Updated at 359 AM CDT Wed Apr 30 2025

- Additional severe weather could occur tonight and into Thursday,
  but uncertainty remains. Isolated to scattered thunderstorms will
  remain in the forecast through Friday Night.

- Temperatures will fall this weekend behind a cold front with dry
  conditions. Highs are forecast to be in the 70s with lows in
  the 50s and 60s Saturday and Sunday.

&&

.DISCUSSION...
(Today through Tuesday)
Issued at 359 AM CDT Wed Apr 30 2025

More warm weather today as ridging continues across the
southeastern CONUS. Highs are likely to reach into the mid to
upper 80s once again with light southerly winds around 10 mph.
A trough from the west will begin to nudge the ridge east
throughout the day with storm potential returning again after
sunset. Storms will be a continuation of convection that forms
along a dry line in the form of a weakening MCS with a low (30%)
chance of some storms out ahead of the line. The ceiling of any
severe threat will be determined by the amount of remaining
instability which is forecast by CAMs/RAP to fall drastically
after sunset. Mean MLCAPE values hover around 500-1000 J/kg with
around 40 knots of effective shear. This should be enough to
maintain a limited severe threat through AR/MO into portions of
west TN along the MS river. The SPC has outlined these areas in a
marginal (level 1/5) risk for severe wind and a low (2%) chance
for a tornado, which only occurs a few times per May on average.
Storms will weaken with time as declining shear and instability
damage storm organization eventually becoming heavy downpours in
the eastern half of the region after midnight Thursday.

Storms are possible again Thursday across the entire area,
although the exact location and degree of the severe threat is
still somewhat uncertain. The upper trough from the west will
translate through the region throughout the day with varying
speeds in short-term guidance. A weak surface low and associated
southerly response will occur during this time and help keep
moisture in the region. Overnight convection has the chance to
scour moisture south of the CWA, which could limit the northern
extent of any airmass recovery throughout the day even with
ongoing moisture advection. This has led to large (500-700 J/kg)
spread between the 25th and 75th percentiles in HREF SBCAPE
throughout the day. To complicate things more, one or more outflow
boundaries are likely to be draped across the region which would
act as focal points for convection and barriers to airmass
recovery behind them. Regardless, mean SBCAPE values still reach
up to 2000 J/kg by early afternoon across portions of the region
where thunderstorms have a 70% or greater chance to form as
favorable upper forcing overspreads arrives. Any storms that form
will encounter an environment with 0-6 km shear at or below 30
knots with < 100 SRH, favoring multicellular storm structures and
coalescing cold pools. DCAPE is also rather moderately high with
a well mixed boundary layer and an 850-500 mb EML that could lead
to a few downbursts. As such, the SPC has covered the entire area
in a slight (level 2/5) risk for severe winds, hail, and isolated
tornadoes. Convective coverage should wane after sunset with
isolated showers remaining across north MS overnight. It will be
noted that there is still uncertainty with regards to convective
coverage and severity and this forecast could change in the coming
24 hours.

Another trough will approach the region from the north behind the
first one Friday morning. Ahead of this system, a cold front will
approach the region throughout the day. Diurnal heating and the
cold front will, again, bring moderately high (> 50%) storm
chances Friday afternoon. There are still differences in the
location of the upper jet stream at this time with the GFS keeping
stronger flow north of the region and the NAM/ECMWF keeping it
closer to the Midsouth. Regardless, ample (> 2000 J/kg
MLCAPE) instability will exist with storm mode being driven by the
magnitude of shear that will overspread the region. At this time,
severe wind is the the most likely severe hazard with the tornado
and hail threat dependent on the aforementioned uncertainties
with shear.

The cold front will pass Friday night and bring cooler air into
the region for next weekend. Highs on both Saturday and Sunday
will be in the 70s region-wide with lows in the 50s and 60s with
clearing skies. This cooler, dry forecast could very well last
into next week as the upper pattern produces a blocking low over
Florida through at least Tuesday as ensemble and deterministic
guidance suggests. After this point, an omega blocking pattern is
appearing more and more likely through the end of the period with
high pressure and remaining over the Midsouth. Diurnal showers
could form in this pattern, but the coverage and severity would
remain limited.

&&

.AVIATION...
(06Z TAFS)
Issued at 1125 PM CDT Tue Apr 29 2025

Showers and thunderstorms are possible across extreme northern
sections of the Mid-South for Wednesday morning and afternoon. A
second round of showers and thunderstorms will start moving into
east Arkansas Wednesday evening. Mainly VFR conditions are
expected for much of the forecast period. Southeast winds around 5
knots overnight becoming south at around 10 knots on Wednesday.
Gusty winds are expected for Wednesday afternoon and evening.

&&

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

$$

PUBLIC FORECAST...JAB
AVIATION...ARS