220
FXUS64 KHUN 080324
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
924 PM CST Tue Jan 7 2025

...New NEAR TERM...

.NEAR TERM...
(Rest of tonight)
Issued at 924 PM CST Tue Jan 7 2025

A very cold airmass remains over the Tennessee Valley as current
temperatures range from the mid 20s to lower 30s. A persistent low
stratus deck can be seen over much of north AL and southern middle
TN, with the only clearing over far northeast AL. Have seen a
slight eastward expansion of the cloud deck recently, and expect
little change in this overnight. Minor changes were made to the
cloud cover forecast to better match satellite trends, but
otherwise no changes were needed during the evening update.
Overnight lows will drop to the low to mid 20s with light
northerly winds. Be sure to bundle up when headed outdoors in the
morning!

&&

.SHORT TERM...
(Wednesday through Friday)
Issued at 211 PM CST Tue Jan 7 2025

Cold air advection continues to reinforce this arctic air mass,
reinforcing the well-below normal temperatures across the TN
Valley (highs in the mid-upper 30s and lows in the mid Teens to
lower 20s). Surface high pressure continues to build in on
Wednesday and Thursday, allowing for the colder airmass to
continue settling in. The good news is that both days should
feature wall- to-wall sunshine across the entire area, with a few
isolated cirrus from time to time. With any wind, wind chill
values can easily drop into the single digits to teens. Given the
cold air in place, this is looking to set the tone for a
significant winter storm set up on Friday.

Mid-range guidance is coming into better focus regarding the
synoptic-level features Thursday night into Friday that will drive
the evolution of the aforementioned winter storms. A deepening
upper-level trough over the northern Plains and Great lakes will
phase with an upper low over Baja California that will be shifting
into central Mexico. In response, a surface area of low pressure
is progged to develop along LA/MS Gulf Coast Thursday night and
deepen as it tracks ENE into the FL Panhandle and SW Georgia
during the day on Friday. Strong synoptic and frontogentic forcing
will help generate a broad area of precipitation that will push
northward from the Gulf region Thursday night into central Alabama
and the Tennessee Valley during the predawn hours early Friday
morning -- and then overspread the entire region from Friday
morning through Friday evening, before tapering off after Midnight
Friday night into Saturday morning.

Subfreezing temperatures will precede the onset of precipitation
early Friday morning and given the depth of moisture and colder
air aloft, this precipitation will fall as all snow. Given the
cold surfaces, significant travel impacts will begin immediately
once snow begins to accumulate. In short, be where you need to be
by 12 AM Friday -- as treacherous travel conditions may already
be in place by the 6-9 AM time period Friday morning. Heavier
bands of wintry conditions will develop through much of the day,
with accumulating snowfall likely across the entire region. The
recent trends with both QPF trending higher and ensemble guidance
trending a little cooler with profiles aloft, gives confidence to
an uptick in snowfall totals. Our current most likely scenario is
that 3-6 inches storm total snowfall will fall across northern
Alabama and southern middle Tennessee -- though it should be
mentioned that these totals could be a touch lower if a heavier,
wetter snowfall occurs. An additional caveat will be the vertical
temperature profile over southern portions of the area, where a
brief transition to sleet and or rain occurs during the event.
Given the slightly colder trend with the guidance, still think
snowfall will be the more favored outcome, but lighter amounts
were forecast south of the Tennessee River in part because of this
uncertainty.

A Winter Storm Watch will likely be needed within the next 12-24
hours for the entire area. We cannot stress this enough: we have
very high confidence in a significant winter storm that will cause
widespread societal impacts Friday, Friday night and into the day
on Saturday regardless of what the specific amounts add up to be
for each location. It is important now to prepare for the
potential for widespread accumulations of wintry precipitation and
bitter cold temperatures during this timeframe.

&&

.LONG TERM...
(Saturday through Monday)
Issued at 153 AM CST Tue Jan 7 2025

Wintry precipitation ends from west to east on Saturday morning as
the surface low rapidly ejects up towards the Northeast. Cloud
cover on the backside of the system is likely to remain in place on
Saturday, but temperatures should barely rise above freezing.
Keep in mind if we get a bigger snowpack than expected this may be
overdone. With the upper level pattern becoming more zonal
towards the second half of the weekend, temperatures begin to
moderate with expected highs in the upper 30s to lower 40s on
Sunday. Combined with some sunshine, this should help melt some of
the snow. Conditions remain cooler than climatological normals
heading into the start of next week.

&&

.AVIATION...
(00Z TAFS)
Issued at 620 PM CST Tue Jan 7 2025

MVFR conditions will prevail this evening, as a nearly stagnant
stratus deck persists over north central and northwest AL.
Confidence in regards to clearing and a return to MVFR cigs is
low, and amendments may be needed this evening if the cloud deck
dissipates earlier than expected. Northerly winds will back to
the northwest tomorrow afternoon, and gusts will increase to near
15kts.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.
&&

$$

NEAR TERM...25
SHORT TERM....Serre
LONG TERM....GH
AVIATION...25