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321
FXUS64 KJAN 171739
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
1239 PM CDT Fri May 17 2024

...New MESOSCALE UPDATE...

.MESOSCALE UPDATE...
Issued at 1239 PM CDT Fri May 17 2024

Rest of today...

Overall fcst is running generally on track. Water vapor/RAP
analysis this aftn indicated stalled upper low parked over the
central Plains, with widespread moist ascent over the warm frontal
boundary along the Gulf Coast. Convergence along the low-level
frontogenetical boundary is decreasing & thus the rain rates are
letting up. There was a good swath of 3-6 inches that fell this
morning across an area from Natchez to Crystal Springs/Hazlehurst
to Mendenhall to Raleigh to near Quitman, with areas from Crystal
Springs/Hazlehurst eastward having nearly 4-7 inches. The ongoing
flash flooding threat remains for the ongoing Flash Flood Watch,
with nearly 99th percentile PWs & 925-850mb 340-350K Theta E
residing across southeastern portions of the area. There should
be a lull in most vigorous convection early this aftn, but
increased destabilization is ongoing south of the Hwy 98 corridor
& expected to increase this aftn-evening. The ongoing severe
potential looks to be at earliest late aftn but most likely into
late evening to overnight in the Hwy 98 to I-59 corridors in the
Pine Belt in southeast MS. Future adjustments to the going severe
graphic are likely. It is in this timeframe, especially into the
evening, with flash flooding threat possibly peaking back up in
the Pine Belt. For now, keeping ongoing hazards as is but future
configuration changes to the areal extent/HWO graphics will
probably be needed. Updates are out. /DC/

&&

.MESOSCALE UPDATE...
Issued at 727 AM CDT Fri May 17 2024

In the wake of last night`s storms, a warm frontal type feature is
focusing moisture convergence and lift this morning. While various
guidance were having a hard time pinning the location of the
feature down, this is the anticipated flash flooding threat we
have been advertising. Warm and very moist air running into a
west-east oriented boundary - with deep layer flow that is
parallel to the boundary - is a setup for heavy rain with training
thunderstorms. We will continue to monitor trends through the
morning, but anticipate flash flooding in the near term. /NF/

&&

.DISCUSSION...
Issued at 442 AM CDT Fri May 17 2024

Today and Tonight:

A positively-tilted trough remains stretched from west to north of
our forecast area early this morning, but it is on the move today.
Despite the MCS that blew east along the Gulf Coast overnight,
continued southwesterly flow aloft associated with the trough should
help some with moisture recovery into the daytime today. Resulting
destabilization across south-central and southeastern MS will
coincide with persistent 40-50 kts of deep-layer wind shear, so any
thunderstorms that develop or move into the southeastern 1/3rd of
our forecast area today into tonight could pose a threat for
organized severe weather. A Slight Risk for severe storms covers
much of the Pine Belt. The threat for heavy rain also accompanies
this activity, with 1.5-2.0 inch PWAT values along the central Gulf
Coast supporting efficient rain-producing storms.  Given the recent
rainfall in those areas, a quick 2 to 3 inches of rain with any
heavier storms could lead to flash flooding. Will therefore keep the
Flash Flood Watch in effect heading into tonight. /NF/

Saturday through Thursday:

Showers and thunderstorms will continue on Saturday as a cold front
moves across the region. A "Marginal" risk for severe weather will
be possible along the I-59 corridor and the Pine Belt. Along with
severe weather potential, a flash flooding threat continues as
additional 0.5 to 1 inch of rainfall will be possible. A Flood Watch
will remain in effect until Saturday afternoon as an "Elevated" risk
continues for areas south of I-20 and near the Pine Belt. Rainfall
is expected to come to an end as a frontal boundary migrates
eastward Saturday afternoon. Isolated showers will be possible post
passage but is expected to diminish throughout the evening.

Beginning Sunday, a drying period is expected to begin as a ridging
pattern builds in from the southwest. Southerly flow will advect
warm and moist air into the region thanks to an from an amplifying
ridge heading into mid-week. As a result, a warming trend will take
place and bring high temperatures to the lower 90s and lows in the
upper 60s/lower 70s. By the close of the extended period, the
aforementioned ridge will slide eastward, allowing for
shower/thunderstorm chances to return ahead of the next frontal
boundary moving towards the southeastern CONUS. /SW/

&&

.AVIATION...
(12Z TAFS)
Issued at 727 AM CDT Fri May 17 2024

Showers, thunderstorms, and low stratus will cause generally poor
flying conditions through at least 18Z today, with some chance for
improvement after that time frame. Amendments may be necessary. /NF/

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Jackson       67  83  65  87 /  20  50  10  10
Meridian      67  84  64  88 /  40  70  20  10
Vicksburg     67  85  67  88 /  20  40  10   0
Hattiesburg   68  84  66  89 /  60  60  10  10
Natchez       66  84  66  88 /  30  30  10   0
Greenville    68  84  67  88 /  30  50   0   0
Greenwood     67  83  65  88 /  20  60  10   0
-- End Changed Discussion --

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Flood Watch through Saturday morning for MSZ049>052-054>066-
     072>074.

LA...Flood Watch through Saturday morning for LAZ024-026.

AR...None.
&&

$$

DC/SW/NF