330
FXUS64 KJAN 281748
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
1248 PM CDT Sun Apr 28 2024

...New AVIATION...

.MESOSCALE UPDATE...
Issued at 1157 AM CDT Sun Apr 28 2024

As anticipated, weaker inhibition today is allowing for warm
advection showers to develop in southern Louisiana and
Mississippi to spread northward. Heading into this afternoon,
there is the possibility for some isolated thunderstorms with this
activity, but deep layer shear is not favorable for organized
updrafts. Expect quick moving, and short-lived storms where they
do develop. Have updated POPs and timing of weather elements
through the daytime tomorrow based on current observational trends
and 12Z hi-res guidance suite. Regional radar mosaic showed
weakening activity associated with an overnight MCS in TX/OK/AR,
with that line having broken down into an assortment of
individual storms, stratiform rain, and a wavy outflow boundary in
those regions. Hi-res guidance all struggle exactly with where
reintensification will occur in those zones this afternoon, but
they do all generally get to the point of one or more MCS segments
drifting east through Louisiana and Arkansas toward Mississippi
late tonight. Southerly low-level jet winds and greatest
instability located to the south of any MCS activity will favor
southward propagating MCS activity by morning (or at least most
intense MCS activity farther south along the line). Forecast
MLCAPE values over 1000 J/kg seem to favor MCS trajectory to be
along or southwest of a diagonal line roughly from Ruston, LA down
Natchez, MS or so. Depending on timing and placement of overnight
storms, the potential for severe storms could extend farther east
to around the Interstate 55 corridor. Bowing segments along any
line could lead to increased potential for damaging wind gusts and
possible spinup tornadoes. The Slight Risk for severe storms was
expanded to account for this wind and isolated tornado potential -
including southeast Arkansas, northeast and central Louisiana,
and far southwestern Mississippi. The Marginal Risk area extends
south through Mississippi generally along Interstate 55. In
addition to any severe threat, heavy rainfall could cause
localized flash flooding concerns. And gradient winds ahead of
this system will result in continued 25-20 mph winds with gusts up
to around 30-35 mph possible into the afternoon hours today. /NF/

&&

.DISCUSSION...
Issued at 334 AM CDT Sun Apr 28 2024

Through tonight: We remain in a warm southerly flow regime this
morning with a moderate surface pressure gradient between a potent
storm system over the Plains and ridging along the Atlantic
coast. Within this regime, low stratus clouds are increasing early
this morning and may remain a bit more prolific into the daytime
than yesterday. However, with increasing mixing they should lift
by late morning into this afternoon. Scattered showers or perhaps
a storm cannot be ruled out this afternoon across southeast MS,
where a ribbon of greater mid level moisture is forecast to lift
across the area. Most areas will remain dry through the day,
though. Once again, due to the surface pressure gradient and
deep mixing up to near 800 mb, winds will be gusty at times
through the day. We will continue to advertise a limited threat
for gradient wind gusts, but gusts are expected to remain below
advisory criteria.

Through the day, the upper trough to our west will progress
eastward, with the associated surface cyclone lifting northward
toward the upper Midwest into tonight. Convection is expected to
occur today ahead of the trailing cold front from coastal Texas
through the ArkLaTex into the Ozarks. As these storms progress
eastward into tonight, they will begin to reach our southeast AR
and northeast LA areas during the overnight hours. Recent runs of
the HRRR have brought these storms into the area notably earlier
than most other solutions, but these runs have been quite
consistent. Given this, we will continue to hedge the beginning of
the severe threat to as early as around midnight for our
westernmost areas. In terms of hazards, the overnight timing
increases the likelihood that convective mode will mainly be
linear, most favoring damaging wind potential. However, mid level
lapse rates are forecast to be rather steep, so large hail will
also be possible. In addition, with respectable low level SRH
forecast, tornadoes will also be possible, especially for any
discrete cells or line segments that surge more northeastward in
better alignment with marginally supportive 0-3 km bulk shear
vectors. /DL/

Monday through early next week...

Our area will continue to see no real airmass change through the
week under the influence of a late spring regime. Intermittent
disturbances keep rain and storm chances through the forecast
period, with the primary focus on a system Monday. Strong to
severe storms and heavy rain appear probable, thus a
slight/marginal risk and limited risk have been highlighted for
severe and flood respectively. Right entrance region of the mid-
upper jet will provide synoptic scale ascent over the area as a
shortwave pushes across the area Monday. Convection will be
ongoing Sunday night into early Monday morning, mainly west of the
River, and this activity will pose a threat for damaging winds
and possibly a brief weak tornado. There exists some uncertainty
regarding the evolution of this complex given boundary parallel
flow and tendency for cold pool dominance. However, the shortwave
and associated speed max could enhance organization. At least a
brief window for cold pool driven damaging wind gusts appears
probable, especially further west. In addition, PWAT in excess of
1.5 inches and deep warm cloud layer will result in efficient
rainfall rates, thus a flash flood threat also appears possible.

Warm and humid conditions will continue through the rest of the
period under the influence of broad upper ridging with
intermittent disturbances. These disturbances should continue to
support rain and storm chances throughout the week, though nothing
of significance is likely. Late week, a weak cold front could
bring slightly cooler temperatures, especially north of HWY 82,
though significant airmass change is unlikely./SAS/

&&

.AVIATION...
(18Z TAFS)
Issued at 1248 PM CDT Sun Apr 28 2024

The stratus deck has started to lift across central MS allowing for
VFR ceilings to occur across all TAF sites to start off the TAF
period. S/SE winds will remain gusty at times through the period
with gusts to around 30 kts possible. A brief period of low-level
wind shear will be possible across several eastern TAF sites from
03Z Monday through 07Z Monday. Similar to the previous day, another
round of MVFR/IFR stratus will expand across the area late tonight
into early tomorrow morning. Furthermore, a line of showers and
severe storms will enter the area from the west late tonight/early
Monday morning. Primary concerns with these storms will be large
hail, 50 kt wind, and a tornado cannot be ruled out. Storms will
continue across the area through Monday afternoon. Conditions will
begin to improve a little after 10Z Tuesday as storms start to clear
the area around this timeframe. /CR/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       68  78  64  83 /  20  80  60  20
Meridian      64  81  64  84 /   0  70  80  30
Vicksburg     69  77  64  85 /  40  90  40  20
Hattiesburg   67  81  64  85 /  10  70  70  40
Natchez       68  76  65  84 /  30  90  40  30
Greenville    68  75  64  82 /  50  90  40  10
Greenwood     68  76  64  83 /  20  90  60  10

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&

$$

NF/DL/SAS/CR