163
FXUS64 KJAN 230519 AAC
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1119 PM CST Fri Nov 22 2024

...New AVIATION...

.MESOSCALE UPDATE...
Issued at 855 PM CST Fri Nov 22 2024

The evening is off to a mostly clear and chilly start. A couple of
sites have already dipped into the upper 30s. With winds calm at
most sites and continued minimal cloudcover, conditions will be
favorable for frost development heading into early Saturday
morning, with some locations, particularly in the cooler pockets
in north and east MS, falling to below freezing. Aside from
updating hourly temps to account for obs trends, no changes are
planned for the going forecast and freeze products. /DL/

&&

.DISCUSSION...
Issued at 241 PM CST Fri Nov 22 2024

Tonight through Saturday...

Tonight: Cold core trough/sfc low will finally begin to swing
northeastward, centered in the Atlantic off the southern Nova Scotia
coastline. At the sfc, the nearly 1025mb high in the Plains will
build southeast into region. With anomalously dry atmospheric
profiles, this will support light to decoupling sfc winds & lows
falling near to below freezing. There still remains some variability
in the operational blended guidance with some slow catchup on lows.
Probabilistic guidance remains narrowed, with 60-90% of reaching
<=30F in the I-55 to I-20 corridors, focused in central, north-
central & northeast MS. Kept the "Elevated" going with minor
adjustments to the graphic. The Freeze Warning was expanded to
include Copiah/Jones counties in MS as probabilities remain high
enough. Areas to the northwest of the MS River & into the ArkLaMiss
Delta confidence/probabilities are lower, so dropped the Freeze
Watch in some of those areas. Some portions of southeast AR could
fall near freezing but for configuration sake, left them out of any
Freeze Watch. These areas are still covered by the "Limited" in the
HWO where patchy frost remains possible. This frost/freeze will
cause damage to unprotected sensitive vegetation, so now is the time
to take precautions. For sensible weather elements, lows will be
seasonably, some 5-12F below, in the 29-35F range.

Saturday: As the mean ridge to the west/sfc high builds eastward,
expect the sfc pressure gradient to remain relaxed. Cool advection
will persist, supporting near seasonable highs in the 60-66F range.
Aftn mixing will persist but with cool temps, RH drop will remain
above critical levels. Light southerly winds will be the norm. /DC/

Saturday night through late next week...

As high pressure 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 few frosty spots will be possible in the east, so a
limited risk has been highlighted for this area before we transition
to warmer temperatures early next week.

A warm advection regime will keep temperatures very warm Monday with
high temperatures in the mid 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 30mph. 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 somewhere near the coast. Despite this,
there appears to be little change in airmass in the wake, as the
stalled boundary prevents deeper cold air intrusion.

The evolution of the pattern beyond this point is still a bit murky,
however guidance has come into better agreement compared to 24 hours
ago. A short wave trough is progged to eject across the Ozarks
Wednesday into Thursday. While tilt is still quite positive, greater
amplification is eliciting a greater low level response. The
aforementioned stalled frontal boundary then lifts north across the
area as a warm front. With the low track a tad south (central
Arkansas) and stratiform rain in closer proximity to the low, the
northern extent of the warm sector is limited. As such, any
favorable convective parameters for strong to severe storms are
confined to the southern half (I-20 and and south) in this set up.
With that said, strong deep shear around 50kts, overlaid with ample
instability supported by dewpoints in the mid to upper 60s, does
suggest that severe storms are probable, especially along and south
of I-20. The Euro on the other hand is transposed further north,
with even greater low level response, which results in increased
instability. These kinks will still need to be worked out, but given
the timing for this would be around the Thanksgiving holiday (most
probable Wednesday night through Thursday afternoon), we will watch
this closely over the coming days as impacts could be amplified with
holiday travel.

In the wake, high pressure out of Canada will allow for cold air
intrusion once again. Temperatures could drop into the upper 20s and
low 30s by the end of next week. Impacts from this second freeze
will largely depend on how vulnerable the vegetation is after this
first freeze tonight (11/22-11/23), however this could be a harder
freeze for northern areas./SAS/

&&

.AVIATION...
(06Z TAFS)
Issued at 1119 PM CST Fri Nov 22 2024

VFR conditions will prevail through the TAF period with light
wind. Patchy fog cannot be ruled out early Saturday morning, but
confidence in this occurring at any TAF site is too low to
include in the forecast. /DL/

&&

.CLIMATE...
Issued at 241 PM CST Fri Nov 22 2024

This has been a very warm November across the board at all sites
with monthly averages running 5 to 7 degrees above the record.
With the above normal temperatures upcoming next week, we could
see record warm November across most if not all climate sites. All
time warm November lows have been set at TVR, GLH. GWO, and all
time November high temperature has been tied at HBG. Additionally,
most sites are running slightly above record warm fall, however
this will be much closer than November record as this is only
around 1 to 2 degrees, with 9 days still to go./SAS/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       34  64  40  73 /   0   0   0   0
Meridian      31  63  36  70 /   0   0   0   0
Vicksburg     33  64  40  74 /   0   0   0   0
Hattiesburg   33  66  38  74 /   0   0   0   0
Natchez       35  65  40  74 /   0   0   0   0
Greenville    34  62  39  71 /   0   0   0   0
Greenwood     33  62  40  71 /   0   0   0   0

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Freeze Watch until 8 AM CST Saturday for MSZ019-025-035-040-041-
     055-059>065-072>074.

     Freeze Warning until 8 AM CST Saturday for MSZ026>033-036>039-
     042>054-056>058-066.

LA...Freeze Watch until 8 AM CST Saturday for LAZ016-025-026.

AR...None.
&&

$$

DL/DC/SAS