088
FXUS64 KMEG 241139 AAA
AFDMEG

Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
539 AM CST Tue Dec 24 2024

...New AVIATION...

.SYNOPSIS...
Issued at 233 AM CST Tue Dec 24 2024

Rain showers will be possible today and tonight, mainly across
northwest Tennessee, southeast Missouri, and eastern Arkansas,
but rainfall amounts will generally be light. Temperatures will
run a few degrees above normal with highs in the mid 50s to around
60 degrees. Periods of unsettled weather are expected through the
weekend, but the potential for severe weather is relatively low
with temperatures at or above normal.

&&

.DISCUSSION...
(Today through Monday)
Issued at 233 AM CST Tue Dec 24 2024

A split-flow pattern exists across North America this morning. The
current batch of rain showers have developed in the right-entrance
region of an upper tropospheric jet downstream of a shortwave
trough moving across the Southern Plains. This wave is rather weak
but is expected to amplify in the next 12-24 hours as it phases
with the northern stream trough moving across the northern High
Plains. Stronger forcing for ascent will overspread the Ozarks and
bleed into the Mid-South later this afternoon into this evening.
GFS/NAM isentropic analyses indicate relatively strong ascent in
the 290-295 K layers (generally between 925-800 mb) with low
condensation pressure deficits. This indicates a greater
likelihood of overrunning light rain and/or drizzle. Instability
is limited but the HRRR and CAM-weighted NBM PoPs appear to be
underforecasting rain chances this evening.

This wave will move slowly across the region on Wednesday,
deamplifying as it moves into the ridge building over the eastern
CONUS. Rain chances will range from 20-40% across most of the Mid-
South, though areas near the TN River are more likely to remain
dry. The synoptic flow remains progressive through the latter half
of the week. By Thursday, the shortwave trough currently located
just off the West Coast will be traversing the Southern Plains.
Global guidance in good agreement that it will lift northeast
across the Ozarks Thursday night. This should provide the next
shot at organized precipitation Thursday night into early Friday.
Instability again remains quite low, though minimal CAPE above a
low-level inversion could support a few elevated thunderstorms.

Yet another shortwave trough will lift northeast across the Ozarks
Friday into Friday night. Slightly better moisture/instability
is expected to accompany this wave, but surface-based CAPE is
still on the low end. The ensemble mean SBCAPE values are on the
order of 200-300 J/kg with the 90th percentile generally around
500 J/kg or less. Additionally, the kinematics aren`t very
impressive with deep-layer bulk shear generally on the order of 30
kts which is low for typical high shear low CAPE setups.
Widespread rain showers and a few thunderstorms are likely with
this system heading into the weekend, but the severe weather
potential appear limited, albeit non-zero, across our neck of the
woods barring warmer (than the forecast mid 60s) surface
temperatures leading to greater instability.

A strong (150+ kt) upper-level jet will propagate into the western
CONUS late in the week, carving out a broad trough over much of
the CONUS by early next week. We look to dry out a bit late Sunday
and Monday in the wake of a Pacific cold front, but temperatures
won`t really take a hit and are forecast remain above normal with
highs in the upper 50s and lower 60s.

MJ

&&

.AVIATION...
(12Z TAFS)
Issued at 539 AM CST Tue Dec 24 2024

No significant aviation weather impacts are expected today as
winds remain light and mid to high altitude clouds stream over
relatively dry low level airmass. JBR will be on the eastern
edge of a light rain shield over AR.

Rain will make modest eastward progress tonight, perhaps to MEM
after 06Z. JBR may drop to MVFR toward 12Z, in advance of a more
organized round of light rain lifting into central and eastern AR.

PWB

&&

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

$$

PUBLIC FORECAST...MJ
AVIATION...PWB