083
FXUS64 KJAN 212326 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
526 PM CST Thu Nov 21 2024

...New AVIATION...

.DISCUSSION...
Issued at 246 PM CST Thu Nov 21 2024

Tonight through Friday...

Tonight: Stout cold core trough is progged to continue to swing to
the east out of the OH Valley into the Mid Atlantic states, with a
sfc low progged to retrograde near the Northeast states. At the sfc
further south, high pressure & continued northwesterly flow will
persist as >1025mb high sags southeastward out of south-central
Canada & southwards into the Great Plains. Between the sfc low off
the Northeast & high pressure over the northern Plains, 2-3mb
pressure gradient will keep broad northwesterly sfc winds but
lighter into the evening.

For sensible weather elements, lows will be seasonably cool both
nights, some 4-8F below, in the 33-40F tonight. Due to some wind
around, frost/freeze potential will be somewhat mitigated,
especially in east MS & less potential into the Delta. If gradient
can relax/sfc winds decouple, patchy frost remains probable
southeast of the ArkLaMiss Delta, focused in the I-55, Hwy 25 to Hwy
82 corridor. Kept ongoing "Limited" in the HWO but made some
expansions to the area to the west-southwest. The region
overachieved this morning so leaned towards even the warmest
reasonable probabilistic blended guidance, which still remains a
touch colder than guidance blend. There are decent HREF/NBM probs
>40-60% for <36F & even some low probs <32F, mainly in cold drainage
areas near the Hwy 82 corridor.

Friday: As the mean synoptic/sfc pattern builds eastward, expect the
sfc pressure gradient to continue to relax. Cold advection (CAA)
will persist, supporting seasonably cool highs in the 54-60F range.
Aftn mixing will continue but not expecting as efficient RH drop as
today as highs are a touch cooler. Winds will be sustained up to
10mph & gusts under 20mph. /DC/

Friday night through late next week...

Overall in the long term the upper jet pattern looks active, while
the surface pattern is fairly cool across the CONUS, largely driven
by high latitude blocking. To start, Friday night looks to be our
coldest of the period, with high pressure settling in over the area
allowing for efficient radiational cooling. Temperatures should drop
to near or below freezing for a good portion of the area. A solid
frost/freeze is anticipated and as such have highlighted
limited/elevated in HWO graphic, with primary focus in the northeast
quadrant. Having not yet experienced a solid freeze, a lot of
vegetation still remains vulnerable.

As the high shifts east later Saturday, temperatures quickly recover
as southerly flow becomes reestablished. This will keep milder
overnight lows Saturday night, though areas east of I-55 will still
be under the influence of the high and could still radiate cooler. A
limited frost/freeze risk has been highlighted to capture this last
bit of a cold before we transition to warmer temperatures early next
week.

A warm advection regime will keep temperatures very warm Monday with
high temperatures in the 70s to near 80, about 10 to 15 degrees
above normal for this time of year. Additionally, a tightened
pressure gradient on the western periphery of the high will support
gusty gradient winds around 35mph. A limited HWO graphic may
eventually be needed for Monday. With ongoing S/SW flow, moisture
recovers ahead of a surface low over Missouri. Rain chances will
increase Monday into Tuesday as a trailing cold front associated
with the aforementioned low pushes across the area. The front loses
support and looks to stall across the area, which will keep rain
chances in the forecast through much of next week. This will also
prevent any deeper cold air intrusion and delay the push of colder
air to beyond the period.

The evolution of the pattern beyond this point is a bit murky in the
guidance. In general, the southern stream looks active. However, the
Euro specifically depicts stronger blocking downstream and more
negatively tilted trough. This allows for a greater low level
response that could support strong to severe storms. The GFS on the
other hand has a more suppressed pattern with weaker blocking
downstream. Additionally, with PWAT in excess of 1.5 inches, flash
flood potential is there. Given the timing for this would be around
the Thanksgiving holiday, we will watch this closely over the coming
days as impacts could be amplified with holiday travel./SAS/

&&

.AVIATION...
(00Z TAFS)
Issued at 526 PM CST Thu Nov 21 2024

VFR conditions will prevail through the TAF period. Northwesterly
low level wind shear may impact the areas around GTR and MEI
during the overnight hours, diminishing before sunrise. /DL/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       37  57  35  64 /   0   0   0   0
Meridian      34  57  31  63 /   0   0   0   0
Vicksburg     35  58  33  65 /   0   0   0   0
Hattiesburg   37  62  33  67 /   0   0   0   0
Natchez       38  59  35  66 /   0   0   0   0
Greenville    36  55  35  62 /   0   0   0   0
Greenwood     34  56  33  63 /   0   0   0   0

&&

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

$$

DC/SAS/DL