411
FXUS64 KJAN 040909
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
409 AM CDT Thu Jul 4 2024

...New DISCUSSION...

.DISCUSSION...
Issued at 322 AM CDT Thu Jul 4 2024

Today and Tonight:

Happy Independence Day, ArkLaMiss!

Today won`t be very independent of the week it resides in, however,
with hot and humid conditions continuing. One silver lining to that
grey cloud, however, is... well, grey clouds. As increasing depth of
the low level moisture continues amid consistent southerly flow and
500 mb heights falling from around 594-996 dam to the 592-594 dam
range, we should see a bit more shower and storm coverage with the
best chances across southern Mississippi where some afternoon
seabreeze influence could offer additional lift. The rain chances
are unlikely to cool the area off too much though and the only
noticeable difference may be from southeast, where the best rain
chances reside, to the northwest where lowest chances are expected.
This will likely mean that southern Mississippi is slightly less
oppressively hot compared to the north where heat indices are likely
to reach 110-120 F compared to "only" 106-110 F further south.

Excessive heat warnings and heat advisories delineate these areas
and the lack of overnight relief as lows this morning (and yesterday
morning..) hang out around 80 F will mean that the heat is
especially dangerous. Greenville, for example, recorded max heat
indices around 109 F Tuesday, 120 F Wednesday, and will likely see
>110 F again today. For that reason, and especially for the Delta
but area wide too, extra caution should be taken when outdoors
particularly from mid morning into the early evening as heat stroke
will be likely with prolonged activity.

Temperatures will be slow to fall tonight with overnight lows again
in the upper 70s F to near 80 F. Exceptions will be in those lucky
cooler spots that see evening rain showers where temperatures likely
settle into the middle 70s. In those areas, however, patchy fog will
be likely late tomorrow night amid weak winds and dewpoints in the
middle 70s F alongside those temperatures. /86/

Friday through next Wednesday: Most guidance indicate a small
shift in the upper level pattern as westerlies are forecast to dip
farther south and suppress the subtropical ridge. Overall, this
should help to reduce heat stress and increase convective
rainfall coverage over the forecast area.

A cold front is expected to move into northern portions of the
area Friday. As the front interacts with tropical-like moisture
during peak heating, we should see considerable shower/storm
coverage, especially over central/eastern MS. With mid level flow
up to about 20kt, multicell storm line segments seem plausible,
which may help to increase storm organization and wind gust
potential. It appears the very humid boundary layer will heat up
significantly ahead of the front, and have therefore expanded the
elevated threat to include the entire area.

Going through the weekend, greater moisture convergence and
associated rain chances will be suppressed and confined mainly to
southern portions of the forecast. Likewise, reduced boundary
layer humidity will help to limit heat stress to more tolerable
levels.

Looking ahead to early/mid next week, while Hurricane Beryl is not
expected to have a direct impact on the Lower Mississippi Valley
region, there is a good bit of uncertainty on how the system will
interact with the upper level pattern. It is possible that
tropical moisture will help to enhance rainfall coverage, and
we`ll be monitoring that potential. Otherwise, fairly typical
summertime weather is forecast with diurnally driven convective
rainfall. /EC/

&&

.AVIATION...
(00Z TAFS)

VFR conditions with light, generally southerly winds will continue
until near dawn when patchy fog and lowered ceilings may result in
MVFR conditions. VFR conditions return shortly after sunrise with
daytime mixing. Afternoon SHRA/TSRA likely after 18z across the
area. /86/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       94  77  92  74 /  60  20  80  70
Meridian      94  76  93  73 /  70  20  80  70
Vicksburg     95  78  92  73 /  40  20  70  60
Hattiesburg   94  77  94  76 /  70  30  80  70
Natchez       93  77  92  73 /  40  10  70  60
Greenville    97  78  92  73 /  40  40  60  50
Greenwood     96  77  91  71 /  40  40  70  60

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Excessive Heat Warning from 10 AM this morning to 8 PM CDT this
     evening for MSZ018-019-025>030-032-034>037-040>043-047-048-
     053-054-059-060.

     Heat Advisory from 10 AM this morning to 8 PM CDT this evening
     for MSZ031-033-038-039-044>046-049>052-055>058-061>066-
     072>074.

LA...Excessive Heat Warning from 10 AM this morning to 8 PM CDT this
     evening for LAZ007>009-015-016-023>026.

AR...Excessive Heat Warning from 10 AM this morning to 8 PM CDT this
     evening for ARZ074-075.

&&

$$

LP/EC