Tornado Warning 4, NWS Jackson, MS

Area Forecast Discussion
National Weather Service Jackson MS
531 AM CST Fri Jan 12 2024

...New AVIATION...

.MESOSCALE UPDATE...
Issued at 1231 AM CST Fri Jan 12 2024

Forecast remains on track tonight, with storm initiation evident
over northern Texas as of 12:30 AM. Dewpoints remain in the upper
50s to near 60 for now, however this should increase over the next
several hours ahead of this storm system aided by a strengthening
low level jet. For now, warm air advection showers are present
across the area. As the low level jet strengthens over the next
several hours amid increasingly unstable air, we can expect the
environment to be increasingly supportive of strong to severe
storms. These storms should move through quickly this morning and
carry a threat for damaging wind gusts up to 80 mph, a few
tornadoes, and some hail to quarter size. Storms should clear the
area by noon./SAS/

&&

.DISCUSSION...
Issued at 458 AM CST Fri Jan 12 2024

Today and tonight...

The main storm complex off to our west will make its way to our area
early this morning before clearing the area by noon today. Dewpoints
continue to rise amid steady warm air advection with dewpoints in
the upper 50s, approaching 60 in some spots. SB/MLCAPE is modest in
the 500-1000 j/kg range, though sufficient amid a strongly sheared
environment, and is currently highest in western Louisiana. This
should gradually move eastward towards our area and the environment
should become increasingly favorable for strong to severe storms.
The low level jet should strengthen over the next several hours and
should aid in the northward push of more unstable air ahead of the
main storm complex. There should be a short window where surface
winds remain sufficiently backed before veering just ahead of the
line. Should any discrete storms that develop ahead of the main line
be able to tap into and utilize these more favorable low level
wind fields, a tornado cannot be ruled out. With the main line of
storms, the midlevel jet and 850 mb speed max will contribute to
strong deep layer shear which will drive the damaging wind threat,
particularly north of I-20. This line will move quickly across
the area this morning and carry with it the potential for damaging
wind gusts up to 80 mph. A tornado watch was added through 11AM
for areas along and north of Interstate 20 to account for the
tornado potential. Aside from severe threat, a tight pressure
gradient of around 10 to 12 mb will contribute to strong gradient
winds early this morning through this afternoon, even in the wake
of the line of storms. Winds could gust up to 40 to 50 mph at
times and winds should be sustained up to 30 mph. This pressure
gradient will ease tonight as a surface high moves over the area,
ending the wind threat. With the surface high overhead, the area
should be able to radiate efficiently and drop lows into the 20s
tonight. This will be the start of a very cold extended period. /SAS/

Late week through mid next week (Saturday-next Thursday)...

This weekend: Quiet weekend will precede an active & shallow arctic
airmass into the middle of next week. At the start, expect mean
longwave troughing to persist. Northwesterly flow will become
westerly as the trough ejects to the northeast but strong arctic
shallow front will be diving down through Sunday. Expect quiet &
somewhat seasonably cool conditions with lows below freezing
Saturday night, with highs seasonably cool, some 3-5 degrees
below normal, in the low to mid 50s. Sunday will be cold in the
northwest Delta, some 15-20 degrees below normal in the upper 30s
to lower 40s northwest of the Natchez Trace to extreme northwest
ArkLaMiss Delta under increasing clouds while seasonably cool some
+10 degrees below normal in the upper 40s to mid 50s in the Hwy
84 corridor. Enjoy seasonable weekend dangerous arctic airmass is
likely next week.

Next week (Through next Thursday): An impactful arctic airmass is
anticipated to begin moving in early next week, bringing
significant, dangerous cold & increased likelihood of winter
weather potential. At the start, an extremely vigorous spoke of
jet energy will be swinging across the OH Valley into the
northeast while another strong spoke of energy will dive down out
of the Canadian Rockies through the Plains to Gulf Coast by early
week around Tuesday- Wednesday. Ahead of these features, a shallow
arctic airmass will be in place through midweek, bringing
increased confidence of significant dangerous cold expected &
winter weather potential likely.

Dangerous Cold: Significant, dangerous cold remains likely as 1040-
1050mb high sink southeast out of the Rockies/Intermountain West
into preceding dangerous cold airmass across the Plains, before
sliding south & east into the Gulf Coast region through midweek.
Guidance indicates 2 PVU zone, indicative of strong stratospheric
intrusion, down to around 500-600mb & diving more across the
Ozarks to Mid South through Tuesday. Continued to lean towards
towards cold probabilistic guidance, with more gradient
wind/advection driven cold on Monday into Tuesday & significant
dangerous & potentially record breaking cold persisting through
Wednesday morning. Highs will struggle to reach above freezing
northwest of the Natchez Trace corridor Monday, with widespread
lows in the 20s to even teens Monday morning & dangerous cold
persisting through midweek. Highs will struggle to reach freezing
for majority of the area, outside of the Pine Belt on Tuesday,
with areawide lows below 20 degrees & even teens Tuesday
morning. Some areas along the Natchez Trace to north of I-20
could fall into the single digits Wednesday morning, with brutal
wind chills near sub-zero in these areas both Tuesday & Wednesday
mornings. Expanded the "Significant" in HWO graphic further south
down to Catahoula/Concordia Parish in LA to Jefferson to Clarke
Counties in MS. With this being a long duration freeze, with some
areas falling below freezing Sunday night & not rising above for
36-48 hours, precautions should be taken protect exposed pipes,
infrastructure & limit outdoor exposure as much as possible.

Winter weather: There has been a trend towards some continued
moist ascent overrunning this cold air, with wet-bulb temps
around or below freezing. There could be enough shallow moisture &
some warm layer for some changeover across the Delta by Sunday
night & sliding southeast across the area through midday Tuesday.
With an earlier onset of wintry precip, p-type looks to be some
freezing rain at the onset, then becoming a mix of sleet to all
snow for areas along & northwest of the Natchez Trace, while
wintry mix of freezing rain/sleet/rain could sink into central-
southeast MS. There is increased probs of measurable snowfall
along & northwest of the Natchez Trace corridor, with probs >1-2
inches in the Highway 82 corridor. Added an "Elevated" in the HWO
graphic along & northwest of a line from Morehouse to West/East
Carroll Parishes in LA to Issaquena to Grenada County in MS. These
areas could see enough snow/sleet with temperatures struggling to
reach the 25-28 degree range, for more impactful road conditions.
This could cause roads to become covered with this sleet/snow
wintry mix & hazardous driving conditions possible. For areas
where heavier banding occurs, some downed trees/power outages
could be possible. Combined with the dangerous cold & any accums
persisting, impacts could be heightened & will have to monitor
for any potential categorical upgrade.

As the sfc high builds east into late week, some low-level return of
some moderating temperatures into late week. This will be in advance
of the next trough & frontal system, which could bring some rain
chances into late week. /DC/

&&

.AVIATION...
(12Z TAFS)
Issued at 527 AM CST Fri Jan 12 2024

MVFR and isolated IFR conditions will prevail for the first part
of the period. A line of strong thunderstorms will sweep across
the area this morning, mainly between 9 am and noon. Aside from
the storms, strong wind gusts are expected with sustained winds up
to 30 mph and wind gusts 40 to 50 mph. Southerly winds will turn
from the west in the wake of the line of storms. Skies will
gradually clear this afternoon and tonight and winds will diminish
generally after midnight./SAS/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       68  28  54  28 /  90   0   0   0
Meridian      71  27  54  27 /  90   0   0   0
Vicksburg     68  27  54  29 /  90   0   0   0
Hattiesburg   70  29  56  30 /  80   0   0   0
Natchez       68  28  56  30 /  90   0   0   0
Greenville    63  28  50  24 / 100   0   0   0
Greenwood     66  26  51  25 / 100   0   0   0

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Wind Advisory until 6 PM CST this evening for MSZ018-019-025>066-
     072>074.

LA...Wind Advisory until 6 PM CST this evening for LAZ007>009-015-016-
     023>026.

AR...Wind Advisory until 6 PM CST this evening for ARZ074-075.

&&

SAS20/DC/SAS20