003
FXUS64 KJAN 181118
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
618 AM CDT Thu Jul 18 2024

...New AVIATION...

.DISCUSSION...
Issued at 414 AM CDT Thu Jul 18 2024

Today and tonight...

This morning, an upper trough will continue to dig into our CWA,
bringing deep moisture into the region along a frontal boundary
progged to hang up across central MS later this afternoon. Early
morning radar imagery depicts precipitation diminishing across the
northern portions of our area, but is expected to be short lived as
we inch closer to daybreak. Isolated showers and some storms are
present across the I-20 corridor, but is expected to remain isolated
for the next few hours. By the early afternoon hours, showers and
storms will increase from the S/SW and become scattered to numerous
across the region as boundary brings a moist airmass into the area.
Ahead of rain potential, heat indices are expected to increase to or
near 105 degrees across portions of central and southeast MS. A Heat
Advisory is in effect from 10am - 7pm to account for areas that may
not see widespread precipitation until later in the afternoon.

By this evening into the overnight, showers and storms are expected
to continue across the CWA. Some guidance suggests slow
moving/training storms across western portions of the CWA, but
confidence is low for any widespread flash flooding issues. Some
locally heavy rainfall and intense rainfall rates could create
isolated flooding for these areas. For now, flood products will not
be advertised, but the low end threat seems to remain in guidance.
Cloud cover will increase overnight with lows in the upper 60s to
low 70s. /AJ/

Late week through mid next week (Friday-next Wednesday)...

The synoptic pattern will consist of persistent longwave troughing
over the MS River Valley up through the Great Lakes, with more
perturbed/jet energy focused across the northern portions of the
nation into eastern Canada. The Gulf Coast will remain in perturbed
southwesterly flow late this week all the way through the middle of
next week. This is mainly driven by two features: deep ridge axis
over the Four Corners & gradually building northward into the
northern Rockies to west-northwestern Canada & southwestern Atlantic
subtropical ridging extending into the FL Peninsula to southeast
Gulf of Mexico. This is will keep a Rex Block type pattern with
nearly 600DM 500mb ridge across the Four Corners to Intermountain
West & broad troughing east of the Rockies through the MS River
Valley into the Great Lakes to northeast. There will be a series of
perturbations that will dive southeast through the period, with the
first shortwave moving through tomorrow into Saturday, with some
drier building in the wake in the Delta this weekend. This will aid
in the highest coverage this weekend of scattered to numerous
showers & storms along & southeast of the Natchez Trace corridor,
while more scattered to the northwest. With light upwind propagation
vectors, soupy tropical airmass of > 2inch precipitable water (PWs)
& support from the HREF, there are localized prob match mean /
maximum of the ensemble envelope that could support some 2-4", with
localized 4-6" rainfall amounts. HREF prob match mean indicate 30%
probs of >3 inches, which is usually a solid indicator of flash
flooding potential. However, this remains low confidence in
narrowing a corridor & also don`t feel the need to broad brush an
areawide "Limited" in the HWO. The most likely area would be along
the I-55 corridor to the southwest, southeast of the ArkLaMiss
Delta, towards the I-20 corridor west of Vicksburg. WPC currently
has "Marginal" advertised Friday & shifting southeast through the
weekend. If an areal focus can be narrowed down, we will likely need
to advertise some focused area in the HWO. Holding off for now.
Temperatures will be seasonably cool Friday in the low-mid 80s
before moderating into the upper 80s into the weekend, with
seasonable lows in the upper 60s-low 70s through the weekend. Heat
stress will be held in check through the weekend. Some patchy fog is
possible as well through the weekend, especially in areas that
receive sufficient rainfall. While some strong storms can`t be ruled
out, severe convection is not anticipated at this time through the
weekend.

The first round of convection will be focused southeast of the
Natchez Trace along the stationary frontal boundary, which is
progged to lift back northward into early next week. This will be in
response to a stronger shortwave diving into the Great Lakes early-
middle of next week, with the trough axis deepening across the
ArkLaTex into the Mid-Upper MS Valley. This will help drive deeper
moisture back to the northwest, lifting scattered to numerous rain &
storm chances northwest across the area, with the highest remaining
southeast of the Natchez Trace corridor. This wet, rainy & stagnant
pattern will keep highs slightly below seasonable values in the mid-
upper 80s, with seasonable lows in the upper 60s-low 70s. This
pattern will keep needed relief from any heat stress concerns
through the middle of next week. With soupy, tropical airmass
remaining in the area, lapse rates will remain poor, so poorly
organized convection will be the case through the middle of next
week. /DC/

&&

.AVIATION...
(12Z TAFS)
Issued at 613 AM CDT Thu Jul 18 2024

IFR/MVFR vis are expected to improve by 12Z for PIB/HBG as FG/BR
diminishes through daybreak. Conditions will gradually deteriorate
late this morning as MVFR/IFR conditions are expected to prevail
across the all sites by 18Z as a second round of TSRA/SHRA moves
into the region. As a boundary hangs up across central MS,
precipitation will become more widespread through 03Z. /AJ/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       91  71  84  70 /  80  80  80  60
Meridian      94  70  85  69 /  90  70  90  70
Vicksburg     89  71  84  70 /  70  80  70  40
Hattiesburg   94  73  88  73 /  80  80 100  70
Natchez       89  71  84  70 /  90  80  80  50
Greenville    85  70  83  68 /  60  60  40  20
Greenwood     89  70  84  69 /  70  70  50  30

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Heat Advisory from 10 AM this morning to 7 PM CDT this evening
     for MSZ054-055-059>066-072>074.

LA...None.
AR...None.
&&

$$

AJ/DC/AJ