248
FXUS64 KJAN 131742 AAC
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1242 PM CDT Mon May 13 2024

...New AVIATION...

.MESOSCALE UPDATE...
Issued at 1043 AM CDT Mon May 13 2024

Rest of Today...Convection that moved across mainly southern
portions of the area overnight and into this morning, is finally
exiting the CWA into Alabama.  While some isolated to scattered
showers and storms can`t be ruled out through the remainder of the
afternoon hours, overall quiet conditions will exist now into early
this evening.  Clouds will remain a near permanent fixture over the
area today, as highs this afternoon top out in the from the mid 70s
to the lower 80s.

The overall forecast is in good shape.  I did adjust POPs based on
current radar trends, along with a few other hourly elements of the
forecast.  I also adjusted the HWO graphic this morning to show the
better potential for severe storms suppressed south of the CWA late
today and overnight, more along the gulf coast and off shore.
Southern portions of the CWA were worked over by this morning
convection, and as a result of said convection, the warm front along
the coast has remained anchored there.  Model data is picking up on
this trend as well, with keeping the strongest convection further
south of the CWA and in the vicinity of the warm front and in the
warm sector.  That said, there does remain some adequate levels of
wind shear and low end instability over portions of the area.  Thus,
an isolated severe storm will be possible across western portions
and southern portions of the CWA later tonight and into early
Tuesday morning, where the better combination of shear and
instability resides.  Damaging wind gusts will be the primary
concern with the most intense storms. /19/

&&

.DISCUSSION...
Issued at 433 AM CDT Mon May 13 2024

Today & Tonight...

Today: Morning convection has rapidly moved in & thrown a kink in
the overall hazard fcst. Storms are evolving pretty rapidly, with
convection becoming more organized as it moves across the Hwy 84
corridor. Cold core low is currently situated across the central
Plains, with a lead shortwave ejecting across the region. This is
bringing increased warm advection showers & storms across the
region. Mesoanalysis early this morning indicate storms were not sfc
based just earlier, but there is increased orthogonal organization
in the Hwy 84 & nearly 30-55kts mean bulk shear in the 0-3km to 0-
6km layer, respectively, for some strong-severe wind gusts to be
possible. With the convective allowing models being slow to catch
up, some 2-4 hours, guidance has been all over the place. Recent
HRRR seems to be catching onto the idea that early morning
convection & widespread stratiform convection will keep any future
MCS shunted closer to the coast into the aftn. Adjusted the HWO
graphics to focus on the early morning convection through 7AM but
looks to be out of here within an hour or so. In addition, there
has been a pretty stout wake low in the wake, with nearly 40-50mph
southeasterly winds observed. With the front not fully pushed
through this aftn, there conceivably be some redevelopment but in
terms of aftn severe potential, remains more murky/uncertain.
Only going to advertise this morning convection & let the day
shift reanalyze the mesoscale details as large changes to the
going messaging for the aftn-evening hours will likely be needed.
Left the flash flood threat messaging in HWO graphics/flood watch
as is but quick, localized heavy rates will likely be highest
along the Hwy 84 corridor & south. Majority looks to remain rooted
closer to the Gulf Coast, but there will likely be a very tight
gradient to the south. With the aftn fcst drier, we should be able
to warm into the mid 70s east to low 80s to the west.

Tonight: As the cold core trough builds eastward, sfc low pressure
system will build into the Ozarks, with another round of rain &
storms moving along the Gulf Coast. Convective allowing models
(CAMs), mainly the HRRR, are finally catching up on limited
redevelopment to the north with a developing MCS moving across the
Gulf Coast. For now, as mentioned before, holding off any mention of
the threat of storms after 12Z & anything lingering into the evening
as details are much more unclear if that will be valid in the wake
of these storms. Expect warm lows in the mid-upper 60s, especially
northwest of the Natchez Trace corridor. /DC/

Tuesday through Sunday night...The main upper trough axis will move
across the area on Tuesday and this may kick of some scattered
showers or isolated storms early, but will end from west to east
during the afternoon hours. High pressure will begin to build in
Tuesday night into Wednesday, as the upper trough moves east. High
pressure and dry conditions return briefly on Wednesday, with highs
mostly in the low to mid 80s.

As high pressure shifts east the flow will once again turn around
with increasing moisture Wednesday night into Thursday. A series of
short waves will move across the area on Thursday, with a strong
short wave/cold front moving across the area Thursday night and
Friday. More heavy rainfall looks like the primary risk during this
period, but strong to severe storms will once again be possible. The
short wave/cold front will move east of the area on Friday night
along with the bulk of the storms. The latest model runs have been
very inconsistent over the weekend and both the GFS/ECMWF differ on
the their solutions. Will just leave chance pops over the weekend
until the models become more consistent. Highs over the weekend will
be in the mid/upper 80s with lows in the 60s. /15/

&&

.AVIATION...
(18Z TAFS)
Issued at 1241 PM CDT Mon May 13 2024

MVFR/IFR flight categories will continue to prevail at area TAF
sites throughout much of the 18Z forecast package. This is as a
result of mainly low stratus encompassing much of the region.
Convection associated with an upper level disturbance that moved
through the region this morning, has exited the Pine Belt into
Southwest Alabama. While much of the area will remain dry through
the afternoon hours, some isolated to scattered showers and storms
can`t ruled out as a result of daytime heating. Chances for
showers and storms will increase overnight, as yet another
disturbance moves through the region ahead of a cold front that`ll
move through on Tuesday. Winds today will be from the southeast
between 7-12 knots, with a few gusts between 15-20 knots possible.
Winds will become more southerly overnight, and decrease to
around 5 knots. /19/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       65  83  63  84 /  50  30   0   0
Meridian      65  85  62  85 /  70  50  10   0
Vicksburg     65  84  63  86 /  50  10   0   0
Hattiesburg   67  87  65  87 /  70  40   0   0
Natchez       64  84  62  86 /  60  10   0   0
Greenville    67  81  64  84 /  50  30   0   0
Greenwood     66  81  63  82 /  60  50   0   0

&&

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

$$

19