819
FXUS64 KJAN 210539
AFDJAN
Area Forecast Discussion
National Weather Service Jackson MS
1139 PM CST Mon Jan 20 2025
...New AVIATION...
.MESOSCALE UPDATE...
Issued at 919 PM CST Mon Jan 20 2025
The anticipated winter storm is here on our doorstep. Broad
longwave troughing over the entire CONUS tonight, with a shortwave
digging through the Desert Southwest and set to scrape the Gulf
Coast region heading into tomorrow. The right entrance region of a
jet streak associated with the main trough and the left exit
region of a jet streak associated with the approaching shortwave
will phase favorably by Tuesday morning to enhance lift and
moisture transport over the TX/LA/MS Gulf Coast region.
With a deep cold Arctic air mass in place over our region, this
lift and moisture transport is already beginning to saturate lower
levels of the atmosphere. Last hourly mPING and METAR
observations showed a mix of light sleet and snow flurries were
beginning to fall in south Louisiana and central Louisiana up
through around the Alexandria area. Additionally, light
reflectivity returns on regional radars indicate
evaporating/sublimating snow level has reached down to around 3000
feet over southwestern Mississippi and southeastern Louisiana as
of this hour. It is only a matter of time before light snow and
sleet begin to fall in our forecast area, spreading from southwest
to northeast through the morning hours. Latest NBM probabilistic
data incorporating the latest high-res guidance, latest SREF, and
latest global model guidance all continue to highlight the US
Highway 84 corridor and southward (in our CWA) for 1 to 4 inch
accumulations of snow through the day tomorrow. Lighter
accumulations of up to 1 inch are possible northward into the
Interstate 20 corridor, and a more significant snow event is more
likely south into the LCH and LIX forecast areas.
At this phase of the forecast process we will be monitoring
trends and updating products as necessary, but there is little
room for further adjustments. Mesoscale banding in areas of snow
can always cause local upward or downward adjustments in snowfall
totals that are observed, but the general expectation remains the
same from the previous forecasts. Where snow is falling,
wetbulbing processes will lock in temps at or below freezing
during the day. Then with clearing skies tomorrow night,
radiational cooling over cold ground and snow will push low
temperatures into the teens, and possibly below 10 degrees in the
coldest of areas near any snow pack. /NF/
&&
.DISCUSSION...
Issued at 251 PM CST Mon Jan 20 2025
Tonight through Tuesday night: Snow is still expected across the
southern half of the area Tuesday followed by bitter cold
temperatures Tuesday night. Mid afternoon surface analysis had a
>10136mb high centered over western Tennessee, a >1042mb high
centered over the central Plains and an inverted trough along the
southeast Texas coast. Mid afternoon satellite imagery/RAP analysis
showed a northern stream large amplitude shortwave dropping over the
central CONUS and a southern stream disturbance tracking east across
old Mexico. The northern stream trough will swing across our region
Tuesday and Tuesday night helping the >1042mb high spread southeast
over our CWA. The southern stream disturbance will help develop a
surface low off the southeast Texas coast track east across the
northern Gulf through Tuesday night. Together these features will
result in clouds increasing across our CWA this evening from the
southwest. Light snow is expected to develop and move into the
southwest portions of our CWA. This area of snow is expected to
increase in coverage across the southern portions of our CWA. This
will lead to accumulations from a dusting along the Interstate 20
corridor to several inches along and south of Highway 84. The area
south of Interstate 20 has been placed in a Winter Weather Advisory
and the area along the Highway 84 corridor has been placed in a
Winter Storm Warning. The Winter Storm Watch was canceled for the
along and north of Interstate 20 as forecast snowfall amounts there
will be less than one inch but a few roads may become slick there
Tuesday morning. Models have come in faster in ending the snow by
evening. As a reimbursing shot of arctic air is drawn south across
our CWA temperatures will plummet and bottom out from 11F to 18F.
WInd chill temperatures will be in the single digits. Tuesday night
is expected to be the coldest night of the week and a Cold Weather
Advisory remains inn effect for the whole CWA. /22/
Wednesday through next Monday:
Wednesday will remain chilly as afternoon temps reach the upper 30s
to near 40 degrees across the area on Wednesday; however overnight
lows will remain dangerously cold with as temps drops to the teens
and lower 20. Temperatures aren`t expected to be as cold on Thursday
as afternoon highs reach the mid 40s; overnight lows will continue
to be in the mid 20s. Surface ridging will begin to move towards the
area Thursday and Friday, resulting in temperatures gradually
warming and increasing moisture (due to southerly/southeasterly
return flow) through the weekend. Rain chances return late Saturday
afternoon and is expected to linger into next Monday as a few
shortwave disturbances traverse the area. Showers and an isolated
thunderstorm can`t be ruled out will be possible. Although rain
chances are expected, afternoon temps are expected to range from the
upper 50 to into the 60s by the end of the forecast period. /SW/
&&
.AVIATION...
(06Z TAFS)
Issued at 1136 PM CST Mon Jan 20 2025
VFR conditions prevail through the period under 5k-8k ft ceilings.
-SN is expected at HEZ, JAN, HKS, MEI, HBG and PIB, tapering off
this afternoon. Winds will prevail from the north around 8 to
11kts, diminishing this evening./SAS/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 37 24 32 13 / 0 20 40 0
Meridian 37 23 31 12 / 0 20 50 0
Vicksburg 37 24 33 13 / 0 20 30 0
Hattiesburg 40 25 32 13 / 0 20 90 0
Natchez 37 24 32 13 / 0 40 60 0
Greenville 32 22 30 17 / 0 10 10 0
Greenwood 37 21 31 14 / 0 10 10 0
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Winter Weather Advisory until midnight CST Tuesday night for
MSZ053>059.
Winter Storm Warning until midnight CST Tuesday night for
MSZ060>066-072>074.
LA...Winter Weather Advisory until midnight CST Tuesday night for
LAZ023>025.
Winter Storm Warning until midnight CST Tuesday night for LAZ026.
AR...None.
&&
$$
22/SW/SAS20
NWS JAN Office Area Forecast Discussion
Mt Washington Wx CAM
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