752
FXUS64 KJAN 231837 AAC
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
137 PM CDT Thu May 23 2024

...New AVIATION...

.MESOSCALE UPDATE...
Issued at 1037 AM CDT Thu May 23 2024

Assessing the current environment and short-term forecast, a few
things should be noted. First, the various high-res models will
struggle in this environment as much of the forcing is driven by
ongoing convection and cold pool dynamics. Additionally, the
environment is partially affected by the last round of storms that
blew through parts of the forecast area last night. Therefore, the
latest mesoanalysis and trends in radar/satellite imagery are
more important to anticipating how weather will evolve into this
evening time frame.

With west-to-east flow aloft associated with the jet stream, mean
flow and deep-layer shear vectors are oriented to the east.
Meanwhile the most unstable air is focused across east Texas and
western Louisiana, with a gradient set up west to east across our
area. This aligns with how we are seeing the remnants of this
morning`s convection behave as it has rolled out of Arkansas. The
eastern portions of that line are now propagating southward to
favor the available instability, while the part of the line
farther to the west (still in the unstable air) has now become
aligned more perpendicular to the flow and is being steered
eastward. This mess of convection remains capable of some brief
damaging wind gusts and small hail, but expect it to run out of
steam as storm segments run into each other and get cut off from
the better instability back to the west. Visible satellite
imagery shows a more diffuse outflow boundary to the west across
northwest Louisiana, with cloud elements becoming more unstable
and moving northward again. Farther southeast, daytime cumulus
field can be seen advancing northward through southwest
Mississippi. Dewpoints should recover into the lower and mid 70s
as this air mass returns northward. Despite the varying solutions,
most of the guidance does agree that convection should redevelop
this afternoon and evening with daytime heating. The deep-layer
shear and adequate instability will allow for some organized
severe storm threat to develop, so will maintain the current
hazardous weather outlook graphics. I did increase POPs and QPF
some for today and tonight, as blended NBM guidance was washing
out the various solutions. /NF/

&&

.DISCUSSION...
Issued at 427 AM CDT Thu May 23 2024

Today through Tonight:

An ongoing threat for severe will continue today before
diminishing later this evening. Model consensus continues to
highlight a 998 mb sfc low developing across the NW CONUS before
shifting eastward towards southern Canada later this morning. As
the sfc low shifts north towards Canada, broad longwave troughing
will continue to dominate the western and central CONUS. Any
disturbances that ripple out of this longwave trough will provide
the support for diurnal activity to organize and propagate
eastward across the forecast area through this evening. The Slight
Risk area closer to the front (northwest of our CWA) has been
extended further south in order to capture the severe potential
across the Delta. The Marginal Risk (1 out of 5) has been extended
further south in order to capture areas along and north of the
I-20 corridor with the threat for damaging wind gusts and hail up
to quarter size cannot be ruled out.

In addition to the severe potential, there may be some potential for
multiple storms to move across the area and produce locally heavy
rainfall of 2 to 3 inches at times which could lead to minor runoff
issues in poor drainage areas along with the potential for localized
flash flooding in a couple of areas. The severe potential will start
to diminish across the area as we head into overnight period with
lingering showers and storms along and north of the Hwy 82 corridor.
The combination of lingering showers and cloud cover will keep
nighttime temperatures in the 70s across the area. /CR/

Friday through Wednesday:Come Friday morning we will still have a
warm moist airmass over our region with PWATs around an inch and a
half with upper 60s to lower 70s dew points. A nearly stacked low
over the northern Plains will be lifting up into Ontario and leaving
a trailing cold front to drift into northern Mississippi and stall.
During the heat of the afternoon storms are expected to develop
along and just ahead of the cold front and spread into our CWA.
Isolated severe storms capable of damaging wind gusts and hail up to
quarter size will be the main threats with the storms but a brief
tornado or two cannot be ruled out. This activity is expected to
wain during the evening with the loss of heating. The stalled front
will still be across northern Mississippi Saturday but a little
farther north. Isolated severe storms will again be possible with
the same threats but over less of our CWA; mainly along and north of
Highway 82 during the late afternoon and early evening. Sunday mid
level ridging across our south will strengthen some while another
weak low pressure system tracks east across the Plains and southern
Great Lakes region. This low pressure system will try to drop a weak
cold front back into northern Mississippi. There will be the
potential for isolated severe storms across our north again.
Saturday and Sunday across the southern half of moved out of the
warned area.**!the area where greater insolation is expected due to
the mid level ridge, temperatures will top out in the low to mid 90s
resulting in peak heat index values around 100F. Severe storm
potential across the north along with heat and humidity across the
south will continue Monday but, a more potent low pressure system
tracking east across the Great Lakes region Monday night and Tuesday
looks to bring some relief Tuesday through Wednesday as a clearing
cold front is expected. PWATs are expected to be knocked back below
one inch with lower 60 dew points by Tuesday morning. /22/

&&

.AVIATION...
(18Z TAFS)
Issued at 133 PM CDT Thu May 23 2024

Better chances for impacts from SHRA and TSRA will be at KGLH,
KGWO, and KGTR through the TAF period, however the chance cannot
entirely be ruled out at the other TAF sites. Low stratus apart
from areas of rain overnight will likely produce MVFR to IFR
ceilings at the TAF sites, with gradual mixing and lifting to VFR
conditions after 15Z Friday. /NF/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       89  71  91  72 /  20  40  10  10
Meridian      89  70  91  71 /  10  20  10  10
Vicksburg     90  72  92  72 /  40  50  10  10
Hattiesburg   91  72  92  72 /   0  10  10   0
Natchez       90  73  91  72 /  20  30  10   0
Greenville    87  72  90  72 /  70  70  10  40
Greenwood     86  70  90  72 /  70  60  20  30

&&

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

$$

CR/22/NF