072
FXUS64 KJAN 250919
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
419 AM CDT Tue Jun 25 2024

...New DISCUSSION...

.DISCUSSION...
Issued at 419 AM CDT Tue Jun 25 2024

Today and tonight: Oppressive heat and increased heat stress
concerns will be the weather headlines of the day. Though the
upper level ridge has begun to retreat westward, H7 ridging
remains centered over the Deep South today, and a weak stationary
front extends roughly along the AL/MS state line. All in all,
conditions will be similar to yesterday, but this time without a
band of morning clouds/precip disrupting early day insolation.
Once again, any influence of drier air in east MS may only provide
greater capacity for warming in those areas, and the triple
digits will be attainable. Within the more moist airmass west of
the weak front, isolated diurnal convection is probable again this
afternoon, but it should mostly initiate well after heat indices
have already begun to reach critical thresholds across most of the
area. Forecast temps/dewpoints are yielding heat indices above
110F across much of the ArkLaMiss Delta area again today, and
accordingly, the Heat Advisory has been upgraded to an Excessive
Heat Warning in that area. Meanwhile, the Heat Advisory remains in
effect for all other areas. Tonight may offer little heat relief,
with temps in some of our northwestern areas potentially
struggling to fall into the 70s. /DL/

Midweek through early next week (Wednesday-next Monday)...

Mid-late week (Wednesday-Friday): Increased coverage of rain &
storms will give way to decreased heat stress through late week.
The synoptic pattern will consist of 594DM 500mb mean ridge over
West TX & northern Mexico while deepening longwave trough/jet
energy carving out east of the MS River Valley. This will drive a
sfc front down from the northwest, helping provide increased
convergence & high moisture pooling ahead of the boundary, well
above 90th percentile, near the climatological maxima around 2.25
inches. As this front dives down, rain & storm chances should
begin to convect just prior to midday, with coverage becoming more
scattered-numerous by the aftn to evening hours. With seasonably
warm highs in the low-mid 90s, heat stress will peak near 105F
degrees, potentially exceeding it. However, confidence is lowered
due to scattered to numerous shower & storm coverage expected, so
kept just an areawide "Limited" in the HWO graphics for now. Will
let later shifts evaluate if any areal upgrade or heat headlines
are needed, but we could reach near criteria before midday prior
to convective initiation. Storms will also have some flow for some
organization, nearly 15-25kts in the 0- 2/0-3km & even through
6km, so the inherited "Marginal" from SPC looked good. Did expand
southward, from northern Morehouse, West- East Carroll in LA &
into Issaquena-Yazoo to Winston-Noxubee counties in MS. Damaging
winds & quarter size hail are the main concerns. As the front
dives southward, slightly less oppressive heat & humidity are
expected Thursday, with seasonable highs in the low 90s & heat
indices near 105F. Rain & storm chances will be confined mainly
southeast of the Natchez Trace & especially into the Hwy 84 to
I-59 corridors. Can`t rule out a few stronger storms in the south,
but convective organization isn`t expected to be as much as a
concern as Wednesday. 592DM 500mb ridge is progged to build
eastward, shunting the best moisture & isolated to scattered rain
& storm chances southeast of the Natchez Trace by late week. Heat
will be on a gradual rise again, with HWO graphics likely needed
again late week into the weekend. Holding off for now but will
reassess with future forecast packages.

Next weekend into early next week (Saturday-next Monday): 500mb
ridge axis will be centered right across the Mid-South, building
to nearly 595-598DM by late weekend. With WAA bringing thermal
profiles into the upper teens to near 20 deg C @ 850mb & mid 20s
deg C at 925mb, seasonably warm highs in the mid-upper 90s are
again likely. This will bring another round of dangerous to
potentially excessive heat into the weekend, so heat related
outlooks & headlines will likely be needed as we get closer. Rain
& storm coverage will mainly be confined southeast of the Natchez
Trace, but a longwave trough/front moving through the Great Lakes
could drive down a sfc boundary & increased convective potential
into late weekend into early next week (i.e. Sunday into Monday).
With some flow & potentially excessive heat around, some
marginally severe storms can`t be ruled out this time. There isn`t
a ton of support in the CSU machine learning probs, so will have
to monitor this potential. /DC/

&&

.AVIATION...
(06Z TAFS)
Issued at 1225 AM CDT Tue Jun 25 2024

VFR conditions will prevail through the majority of the TAF
period. Isolated SHRA or TS are possible mainly during the Tue
afternoon hours, which may result in localized brief categorical
reductions. Winds will be light. /DL/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       97  76  94  74 /  20  20  60  50
Meridian     101  75  96  72 /  20  20  60  50
Vicksburg     99  77  94  74 /  20  20  50  50
Hattiesburg   99  76  94  75 /  20  20  60  40
Natchez       95  76  93  74 /  20  20  40  40
Greenville    99  79  95  74 /  20  20  60  50
Greenwood     99  78  94  73 /  20  20  60  50

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Excessive Heat Warning from 10 AM this morning to 8 PM CDT this
     evening for MSZ018-019-025>027-034>036-040>042-047.

     Heat Advisory from 10 AM this morning to 8 PM CDT this evening
     for MSZ028>033-037>039-043>046-048>066-072>074.

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

     Heat Advisory from 10 AM this morning to 8 PM CDT this evening
     for LAZ023>026.

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

&&

$$

DL/DC