993
FXUS64 KJAN 050329 CCA
AFDJAN

Area Forecast Discussion...corrected for typo
National Weather Service Jackson MS
927 PM CST Wed Dec 4 2024

...New MESOSCALE UPDATE...

.MESOSCALE UPDATE...
Issued at 927 PM CST Wed Dec 4 2024

Overall, the forecast is on track and no significant adjustments
were needed for the overnight. Greater low level moisture transport
has largely been anchored over central LA, but recent trends
indicate a gradual eastward shift into southwest portions of the
forecast area, and this is where the heaviest rainfall of up to two
inches will be. Another rainfall maximum of up to one inch could
occur north of the I-20 corridor after midnight when frontal ascent
associated with the approaching polar stream front will help to
enhance rain intensity.
/EC/

&&

.DISCUSSION...
Issued at 242 PM CST Wed Dec 4 2024

Through Tonight...

The overall synoptic pattern at all levels will be dominated by high
heights/ridging, that being said, there is a low expected to
continue to pivot around this ridging and move into the area
tonight. This low has already started to affect western forecast
zones, by enhancing isentropic lift and producing rain showers and
substantial cloud coverage. This low, while not dynamically
supported will pinwheel around the overall anticyclonic pattern and
track through central Louisiana. These two primary lifting factors
together will make way for precipitation chances to steadily
increase tonight building in from the west, and progressing over the
entire CWA. There will be isolated embedded thunderstorms within the
overall shower pattern, but these storms are not expected to produce
strong winds nor flooding. Highs will range a bit warmer than
yesterday, being in the mid 50s north of I-20, and mid 60s south.

Early Tomorrow Morning...

Precipitation will begin to clear out late tonight/early tomorrow
morning with the passage of an upstream cold front that is currently
lying through central Missouri. This cold front will cause
temperatures to plummet and the overall atmospheric profile to dry
significantly as yet another blast of arctic air pushes into the
area. Areas north of Highway 82 will experience frontal passage
about 3AM Thursday, which will consequently clear out the showers in
those zones. Zones around I-20 will undergo frontal passage about
5AM and, finally, push through the entire CWA by 10AM. Large
temperature swings towards colder temperatures will be moderated
during the day time owing to sunshine and general thermal inertia so
highs will break into the mid 50s for most counties/parishes, sans
regions north of Highway 82 which will range between 50F and 45F.
Expect temperatures to nosedive after sunset, as radiational cooling
and reinforcing arctic air behind the aforementioned front work in
tandem to rapidly cool all locations./OAJ/

Thursday night through next Tuesday...

By Thursday night, an upper trough is expected to bring another cold
frontal boundary through the Lower Mississippi River Valley. By the
overnight, northwesterly flow. As the Lower MS Valley sits on the
Western portion of the upper ridge on the west side of an upper
trough will bring very cold temperatures into the ArkLaMiss region
early Friday morning. Low temperatures are expected to reach the
low 20 to upper 20s. In addition, an upper jet and tightening
pressure gradient will support surface gusts up to 20 mph
overnight, which will enable wind chills in the middle to upper
teens across the CWA. Despite the bitterly cold conditions, we are
not expecting to issue any products as it does not meet dangerous
cold criteria nor any freeze products, as we have made criteria
this season. Regardless, please take necessary precautions to
protect plants, pipes, and pets. In addition, be sure to check on
those who are more vulnerable and sensitive to these conditions.
By Friday, highs are expected to range in the middle 40s to low
50s with dry conditions and clear skies.

A pattern change is expected to occur through the weekend as
a subtropical high is progged to develop over the Gulf of Mexico. As
the Lower MS Valley sits on the Western portion of the upper ridge,
deep moisture looks to be restored, with PWATS over 1.5 inches
forecasted across the CWA. Rain chances will increase Saturday night
into Sunday and become widespread on Sunday night, ahead of a upper
shortwave that is expected to bring heavy rainfall across the area.
Rainfall totals look to range between 1-3" with locally higher
amounts possible, especially west of I-55. Additionally, some
localized flash flooding may be possible, but confidence is fairly
low to advertise anything at this time. By Monday, rain chances are
expected to stick around, with mostly showers possible through
Wednesday morning as a surface boundary hangs up across the CWA
before the primary upper low pressure system digs into the region
mid-week. Temperatures over the weekend will range in the upper 50s
to upper 60s and increase to the low 70s on Monday before a weak
surface front brings highs to the middle 60s on Tuesday and 50s on
Wednesday. /AJ/

&&

.AVIATION...
(00Z TAFS)
Issued at 551 PM CST Wed Dec 4 2024

Widespread rain with ocnl IFR category cigs/vsby increasing from
west to east will be the general rule overnight, then a cold
front will push south through the area and clear the rain/skies
out as we go through Thursday morning. /EC/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       48  55  25  49 /  90  10   0   0
Meridian      46  55  24  48 / 100  20   0   0
Vicksburg     47  54  24  48 / 100   0   0   0
Hattiesburg   51  62  28  52 /  90  50   0   0
Natchez       50  57  26  50 / 100  10   0   0
Greenville    41  46  24  43 /  90   0   0   0
Greenwood     41  48  23  46 /  90   0   0   0

&&

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

$$

OAJ/AJ/EC