830
FXUS64 KJAN 161517 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1017 AM CDT Fri Aug 16 2024

...New MESOSCALE UPDATE...

.MESOSCALE UPDATE...
Issued at 1013 AM CDT Fri Aug 16 2024

A few mid and upper clouds are hanging around this morning with
little evidence of cumulus development just yet per visible
satellite imagery. Anticipate as we continue to warm we`ll see
convective development and eventually thunderstorms this
afternoon. With very warm temperatures approaching 100 F in some
places and deep boundary layer moisture, a few of these storms
could be briefly stronger with gusty winds possible.

The forecast looks on track and heat products were maintained.
Adjustments forthcoming will likely include an extension of the
heat advisory/excessive heat warning into Saturday. /86/

&&

.DISCUSSION...
Issued at 414 AM CDT Fri Aug 16 2024

Today and Tonight:

A moist tropical air mass remains in place across the Lower
Mississippi River Valley today, with analyzed PW values of 1.8-2.0
inches this morning representing the 50-75th percentile range for
mid August. An upper-level low pressure system is spinning over the
upper Midwest this morning, and a shortwave trough rounding its base
is sustaining thunderstorms along a frontal boundary that extends
from near the Great Lakes back towards Oklahoma. Warm advection is
ongoing south of the front, helping to bring the heat from the
Southwest ridge toward our forecast area. High temps again today
should be in the 97-101 range for most of the area, especially if
rain can hold off until the afternoon. The moist air mass in the
region is capable of supporting shower and thunderstorm development
with daytime heating again today, and it appears that convergence
along an outflow boundary from storms in the Interstate 40 corridor
this morning may serve to trigger additional convection by this
afternoon as the disturbance continues south and east. Additionally,
air mass thunderstorms are possible as convective temps are met
during the day. Storms will have 2500-3500 J/kg of SBCAPE and 1000+
J/kg of DCAPE to work with, so localized damaging winds are possible
with any strong to severe storms. Wind shear is expected to be a
little stronger to the north and this should add a little more
organization to storms especially if they can hold together along
the outflow boundary as it approaches from the north. There is a
Marginal Risk for severe thunderstorms tied specifically to this
possibility this afternoon and evening, but again it is worth noting
some isolated microburst potential exists elsewhere too. /NF/

Saturday through next Thursday...

By Saturday, deep layer ridging will continue to prevail over the
Southern Plains/Lower Miss Valley region as a strong midlevel high
pressure spins over the Rockies into the Southern Plains. At the
surface, anticyclonic flow will continue to promote westerly flow
into the ArkLaMiss region, keeping dangerous heat in the headlines
through the remainder of the weekend. High temperatures in the upper
90s to triple digits as well as heat indices ranging 105-115 degrees
will be expected. The highest potential for "Significant" to
"Extreme" heat stress are expected along and west of the I-55
corridor. Overnight lows on Saturday are expected to remain in the
upper to middle 70s, which will continue the dangerous heat stress
conditions. By Sunday, surface ridging is expected to maximize
across the region ahead of a "cold" frontal boundary. Sunday looks
to be our hottest day this week, with many areas along and west of I-
20 reaching triple digit highs and heat indices. Excessive Heat
Warning/Heat Advisory products will be likely on Saturday and Sunday
as dangerous heat stress dominates the beginning of the extended
period. In addition to heat, conditions for a Marginal Chance of
severe storms will be possible (5-15% chance) on Saturday and
Sunday. Enhanced westerly flow along with increased instability will
create the potential for damaging wind gusts with with more mature
updrafts. The main threat for severe storms looks to exists mostly
in the afternoon into the late evening.

By Sunday afternoon into the evening, an upper trough is expected to
bring a weak frontal boundary into the region, allowing for lower
temperatures and drier air to infiltrate the ArkLaMiss region. By
Monday into the remainder of the extended period, a much needed
break from dangerous heat will take place. High temperatures will
range in the upper 80s to lower 90s through Thursday, with lows in
the low 60s to low 70s. Rain chances will remain fairly minimal with
isolated (15-30%) chances in the far southeast on Thursday through
beyond the extended period. /AJ/

&&

.AVIATION...
(12Z TAFS)
Issued at 712 AM CDT Fri Aug 16 2024

VFR conditions are expected to prevail through the TAF period,
however the chance for SHRA or TSRA between around 20Z today to
01Z Saturday will bring possible brief periods of variable
ceilings or visibility. /NF/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       98  76  99  77 /  30  20  40  20
Meridian      99  75  99  73 /  50  20  50  20
Vicksburg     98  77  99  78 /  20  20  20  10
Hattiesburg   98  76  98  76 /  50  20  40  10
Natchez       97  76  97  77 /  40  20  20  10
Greenville   100  78  99  76 /  20  20  10  10
Greenwood    100  77  99  75 /  20  20  20  20

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Excessive Heat Warning until 8 PM CDT this evening for MSZ018-
     019-025>029-032-034>037-040>044-047>050-053>057-059>066-
     072>074.

     Heat Advisory until 8 PM CDT this evening for MSZ030-031-033-038-
     039-045-046-051-052-058.

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

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

&&

$$

LP/AJ/NF