678
FXUS64 KJAN 282351
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
651 PM CDT Fri Jun 28 2024

...New AVIATION...

.DISCUSSION...
Issued at 149 PM CDT Fri Jun 28 2024

Tonight through Monday...

Dangerous heat continues to be the main concern in the near term as
upper ridging builds in over the area. Low level flow will remain
southwesterly through Saturday and will allow dewpoints to hold in
the mid to upper 70s. The resulting heat indices will be in the 105-
115 range areawide. As such, have opted to issue an excessive heat
warning for the Delta and areas west of the Mississippi River where
confidence is greatest on upper 70s to near 80 dewpoint. Further
east, advisory criteria should be met, so have issued heat advisory
for these areas. It is possible that some counties under heat
advisory could be upgraded to excessive heat warning should
confidence increase for higher dewpoints. Rain chances could perhaps
be somewhat of a limiting factor across the Pine Belt, still
temperatures should climb into the mid 90s. Further adding to the
heat stress, will be overnight lows in the mid to upper 70s,
providing for very little relief overnight.

Upper ridging peaks Sunday ahead of a surface boundary that is
progged to push southward Sunday into Monday. Ahead of this
boundary, moisture pooling will likely hold dewpoints in the upper
70s, so have continued heat products and messaging into Sunday as
well. Rain and storms will be on the increase Sunday into Monday
ahead of a surface frontal boundary pushing southward. Despite this,
heat criteria should be met.

Drier air in the wake of the front Monday will briefly bring relief
from the heat for areas north of I-20. However south of I-20,
moisture will continue to be abundant and dewpoints still hold in
the upper 70s. As such, dangerous heat will likely continue in this
area and heat headlines may be needed Monday as well. Unfortunately
there is no relief in sight for these areas as heat begins to build
back in areawide through next week./SAS/

For the Monday to Friday periods...main focus will be
the heat an humidity which will result in dangerous heat stress. In
saying that, it`s not just a blanket hot/humid everywhere, there
will be some evolution to things.

Overall, starting the work week we will see some aspect of the stout
and anomalous upper ridge/high weaken an morph. Look for a slight
lowering of the heights Monday which will allow for a weak surface
front to enter or near our forecast area. I mention both as there`s
uncertainty on if the said boundary will make it well into the area.
At this time, the most likely case is our N/NE areas will see the
boundary push through and lower the Td some which will bring a small
bit of relief from the humidity. Temps will still be hot and abv avg
but lesser RH will keep heat indices (HI) in check for that portion
of the forecast area. At this time, the highest heat stress
conditions look to be along and S of I-20 for Monday. Our current
graphic messages this well and will leave as is.

For mid to late week, the upper ridge/high will re-orient itself and
build. The center will be more over the SE US and our area will be
just to the W of the ridge center. This means building heat, at
least in a small sense, as we go from more mid 90s to more upper
90s. Also, low level moisture will return and we will see more
mid/upper 70s type Td values for mid to late week. This will result
in HI more in the 103 to 110 range and trending into the 107-115
range. For now, we will not add any additional graphics/messaging
for Tue-Fri of next week and will wait for a few days to pass with
the current heat before moving on to the next.

As for rain/storm potential next week...the pattern fit some diurnal
activity and with current PoPs in the 20-40% range mainly over the
S/SE half of the area. This seems to fit but I can see values
lowering some to more Isolated ranges as the ridge and more
subsident air prevails through the week.

As for tropics, there`s a low pressure area NHC is watching and has
90% for potential development into next week. The overall pattern
from ensemble guidance supports the SE ridge being strong enough to
keep any system suppressed more south and no concern for our area at
this time.  /CME/

&&

.AVIATION...
(00Z TAFS)
Issued at 650 PM CDT Fri Jun 28 2024

VFR conditions and light mostly southerly surface wind will
prevail through the forecast period. Isolated TSRA may briefly
impact the southeast half of the area Sat aftn. Otherwise, early
morning fog is not expected to be a significant concern. /EC/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       76  92  76  93 /  10  50  10  60
Meridian      74  93  74  95 /  20  60  20  60
Vicksburg     77  94  77  95 /   0  20  10  40
Hattiesburg   76  93  77  95 /  30  70  20  60
Natchez       76  92  75  94 /  10  40  10  40
Greenville    77  96  79  96 /   0  10   0  50
Greenwood     76  95  77  94 /   0  20  10  60

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Heat Advisory until 8 PM CDT this evening for MSZ018-019-025-
     034>036-040>042-047-048-053-054-059>061.

     Excessive Heat Warning from 10 AM Saturday to 8 PM CDT Sunday
     for MSZ018-019-025>027-034>036-040>042-047-053-059-060.

     Heat Advisory from 10 AM Saturday to 8 PM CDT Sunday for
     MSZ028>033-037>039-043>046-048>052-054>058-061>066-072>074.

LA...Heat Advisory until 8 PM CDT this evening for LAZ007>009-015-016-
     023>026.

     Excessive Heat Warning from 10 AM Saturday to 8 PM CDT Sunday
     for LAZ007>009-015-016-023>026.

AR...Heat Advisory until 8 PM CDT this evening for ARZ074-075.

     Excessive Heat Warning from 10 AM Saturday to 8 PM CDT Sunday
     for ARZ074-075.

&&

$$

SAS20/CME/EC