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000
FXUS64 KJAN 201728
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
1228 PM CDT Sat Apr 20 2024

...New AVIATION...

.MESOSCALE UPDATE...
Issued at 1004 AM CDT Sat Apr 20 2024

Already this morning a few severe thunderstorm warnings have been
issued for portions of southeast Ar stretching into the Delta as
heavy downpours and hail have impacted the region. As a surface
low track through the northern half of our area showers and
thunderstorms will be a common occurrence throughout the day for
areas north of I-20. In addition there remains a Marginal risk for
isolated severe storms and a limited flash flooding threat for
areas across the Pine Belt as better moisture, instability and
wind shear will exist later today creating a more favorable storm
environment that could see possible storm training this afternoon
and evening./KP/

&&

.DISCUSSION...
Issued at 421 AM CDT Sat Apr 20 2024

Today and Tonight:

A stationary frontal boundary currently resides along a northeast
to southwest line stretching from just south of Meridian, to near
Brookhaven, to just south of both Concordia and Catahoula
Parishes on Louisiana. Behind this front, northerly winds will
allow for cooler drier air to filter south into the CWA, while
moisture pools ahead of it under southerly surface winds. For
today, a mid/upper level disturbance embedded in zonal flow aloft
will traverse the region along this boundary. This`ll result in
widespread showers and scattered thunderstorms developing across
the forecast area through the day. There will be a lull in
activity this evening as the first disturbance exits the region.
However, another disturbance will again track east across the
region late tonight in early Sunday morning. This will yet again
bring widespread showers to the forecast area, as the cold front
finally pushes southeast and out of the CWA.

Although cold advection is occurring in the wake of this boundary,
the process is currently quite slow.  With precipitable H2O values
across much of the CWA progged between 1.50-1.75 inches and
convection forecast to move west to east across the CWA, heavy
downpours can be expected with today`s activity, and again with
tonight`s as the front pushes out of the area.  As a result, a
limited threat for flash flooding exists today into tonight. This
will particularly be the case over areas mainly along and north of
the Interstate 20 corridor where widespread heavy rainfall fell late
last week, & again during the middle of this week, & as today and
tonight`s convection is progged to train across the same locations.
Here, 1-3 inches of rain will be possible. This could result in
further flash flooding of low-lying and poor drainages areas, as
well as further contribute to ongoing river flooding in the area.

In addition to this limited flash flooding threat, a "Marginal Risk"
for isolated severe storms will exist across the Pine Belt region
this afternoon and early evening.  Here, the better combination of
instability, wind shear, and steep mid-level lapse rates will exist.
As a result, isolated severe storms capable of producing damaging
wind gusts and hail up to the size of quarters will be possible from
around 1 PM today through 7 PM this evening.

As far as temperatures are concerned through the period, a decent
spread of temperatures is expected from north to south across the
CWA due to the aforementioned stalled frontal boundary.  Look for
highs to range from around 60 across the Delta region, to around 80
across the Pine Belt.  Then for tonight, lows will range from the
middle 40s north to middle 50s south. /19/

Sunday through Friday:

The chance for rain will continue into the afternoon Sunday,
clearing from north to south as an upper-level shortwave trough axis
clears the region and drier surface air works into the region with
high pressure. Overnight lows have a chance to radiate a little
cooler with the surface high sliding overhead Sunday night and
Monday night, but at this time think even the cooler locations
should remain too warm for frost. That said, a brief touch of frost
cannot entirely be ruled out in those typically cold drainage
locations in northern Mississippi either night. Otherwise, the rest
of the forecast period will see a warming trend as an upper-level
ridge steadily builds and shifts eastward toward the Mississippi
River Valley by late week. Models begin to diverge with regard to
timing of a shortwave ejecting from the Southwest U.S. later in the
week, but a glancing blow from the wave could bring a chance for
showers and thunderstorms to at least northwestern parts of our
forecast area by the end of the week. /NF/

&&

.AVIATION...
(18Z TAFS)
Issued at 1228 PM CDT Sat Apr 20 2024

MVFR/IFR categories will prevail at most TAF sites though
the forecast period. Widespread low stratus and likely mix of
showers, and isolated to scattered storms will likely keep TAF
sites in reduced category through early Sunday afternoon before
conditions improve. Isolates severe storms capable of producing
damaging wind gusts, large hail and heavy downpour will be
possible through this evening along and south the Hwy-84 corridor
and east of I-55. Northern TAF sites GLH/GTR/GWO will improve
conditions and bounce categories from MVFR/VFR throughout the
period. Winds will be northerly with possible 20kt gusts nearing
the end of the period./KP/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       49  62  42  68 /  90  60   0   0
Meridian      47  62  42  69 /  90  70   0   0
Vicksburg     49  63  42  69 /  90  50   0   0
Hattiesburg   53  62  45  71 /  70  60   0   0
Natchez       49  62  43  69 /  90  50   0   0
Greenville    50  62  43  67 /  90  20   0   0
Greenwood     48  63  42  68 /  90  30   0   0

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&

$$

KP/NF/KP