ILN issues Area Forecast Discussion (AFD) at Jan 18, 10:07 PM EST401
FXUS61 KILN 190307
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
1007 PM EST Sat Jan 18 2025
.SYNOPSIS...
Snow will develop late tonight along and south of the Ohio
River as low pressure organizes across the southern Appalachians.
Snow and some heavier snow showers are expected on Sunday ahead
of an Arctic front that will reach the area by the afternoon
and evening hours. Bitterly cold conditions will then be in
place Sunday night through Wednesday morning.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Updates this evening include adjusting hourly temperatures and
the forecast low tonight as CAA has been a little slower
filtering south behind a cold front. We are still expecting snow
to develop along and south of the Ohio River late tonight as
low to mid level frontogenesis develops in response to an
embedded mid level disturbances in the southwest flow aloft. We
could see around a half inch of snow where the current Winter
Weather Advisory is in effect by sunrise Sunday. Have adjusted
overall QPF into Sunday, which will give snow total amounts of 2
to 3 inches by early Sunday afternoon in the advisory area.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
The weather setup for Sunday remains a bit complicated and
potentially impactful. As mentioned in the near term, a
disturbance will pass by to the southeast during the morning
hours which should result in some light snowfall in parts of
northern Kentucky and southern Ohio east of Cincinnati. Forecast
snowfall amounts are fairly low since the best forcing and
moisture remains shunted to the southeast. However, slick spots
and some travel difficulties are likely where snow falls in the
morning since temperatures will be cold enough to support
accumulations.
On Sunday afternoon and evening, an arctic front will dive into
the Ohio Valley from the northwest. Snow showers, and possibly
some snow squalls, are forecast to occur just ahead of the
arctic boundary. These snow showers/squalls have the potential
for travel impacts since they could be heavy and surface
temperatures will be well below freezing and dropping. If
traveling during the afternoon/evening, please monitor the
forecast for updates since there could be rapidly changing road
conditions. There is fairly good model guidance indicating
moderate ascent through a saturated DGZ ahead of the front which
suggests squall potential does indeed exist.
For Sunday night, snow showers come to an end behind the front
as arctic air rushes in. Forecast lows drop to near or below
zero for all locations with wind chills reaching -5 to -20 by
Monday morning. Precautions for very cold air should to be taken
for anyone venturing outside late Sunday night/Monday morning.
An Extreme Cold Watch remains in place since forecast
temperatures are too close to warning vs advisory criteria for a
decision to be made this early. More data for the
warning/advisory decision is needed in the upcoming model runs.
Either way, the key message is very cold conditions are on the
way.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
A dry forecast is in store for this period.
Exceedingly cold temperatures from Monday through Wednesday are
the focus of this forecast. An arctic air mass will remain in
place over the region with one surface high pressure situated
nearby on Monday, and a second becoming established over the
region Tuesday night and early Wednesday. The radiative heat
release under the high pressure centers will be notable. An
extreme cold watch has been issued and will continue this
afternoon, in effect from overnight Sunday to Wednesday morning.
A fly in the ointment occurs on Tuesday as a weak boundary
crosses the region, warming temperatures slightly and pushing
them above what would be expected to be found in a warning for
excessive cold. This warming should not be enough to change the
messaging of the cold air through these three days, hence the
continuation of the watch as additional factors remain in play.
The criteria and expected low end apparent temperatures will be
the lowest on Monday morning, with slightly "warmer" readings
found Wednesday morning. Apparent temperatures in the north will
drop to or below -20, and in the south at or below -15. While
much of these northern and southern groupings may be slightly
warmer than the threshold values, messaging the threat will
likely trump these minor differences on Sun night/Mon morning
and again Tues night/Wed morning. In addition, only minor
temperature/wind changes could result in a large apparent T
swing for any locations during this time.
Confidence is high that this period will feature large impacts
due to the cold, though confidence is only medium in specific
values -- particularly when dealing with wind chills (apparent
temperatures) due to those values being dependent on two other
elements (temperatures and wind speeds). The other source of
uncertainty is the state of the snow pack, which will definitely
be modified by above-freezing temperatures and rain today
(Saturday), and may be modified by additional snow on Sunday.
Wherever the snow pack remains robust and/or freshly added, that
will drive where the coldest temperatures reside this coming
week.
As of now, it appears that a very slight warm up could occur
for later in the week. By later Wednesday the departing surface
high will permit flow to turn southerly, bringing in warmer air.
A stronger signal for warming is showing up for Thursday and
Friday, when temperatures should be able make a run into the 20s
and 30s. Possibly more notable is that single digit lows will
rise into the teens for the overnight periods Thursday and
Friday.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
For tonight, CAA will be ongoing in the wake of a cold front.
This will keep mainly MVFR ceilings (1500 to 2500 feet) across
the region. Winds will be from the north between 8 and 12 knots.
Toward morning, mid level energy rippling through a long wave
trough will perturb a wave of low pressure across the southern
Appalachians. For the Ohio Valley, large scale ascent and some
low to mid level frontogenesis will spread snow across the
southern part of our forecast area. This will likely affect the
KCVG/KLUK/KILN terminals with a period of MVFR/IFR conditions
during the morning.
By Sunday afternoon, the large scale forcing associated with
the embedded mid level energy will be exiting off to the
northeast. An Arctic cold front will then be waiting in the
wings, and will push east across the forecast area during the
afternoon and evening. There will at least be scattered snow
showers, some heavier in intensity associated with the Arctic
front. For now, just have a VCSH mentioned, but as confidence
increases on timing and coverage, this might have to be covered
with at least by a TEMPO group. MVFR ceilings will remain.
However, IFR or lower visibilities will be possible in the snow
showers. Winds will shift to a more northwest direction with the
passage of the front, sustained around 15 knots with gusts
around 25 knots.
OUTLOOK...MVFR ceilings to linger into early Sunday morning.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Extreme Cold Watch from late Sunday night through Wednesday
morning for OHZ026-034-035-042>046-051>056-060>065-
070>074-077>082-088.
Winter Weather Advisory from 1 AM to 1 PM EST Sunday for
OHZ073-074-079-081-082-088.
KY...Extreme Cold Watch from late Sunday night through Wednesday
morning for KYZ089>100.
Winter Weather Advisory from 1 AM to 1 PM EST Sunday for
KYZ089-090-094>100.
IN...Extreme Cold Watch from late Sunday night through Wednesday
morning for INZ050-058-059-066-073>075-080.
&&
$$
SYNOPSIS...Campbell/Hickman
NEAR TERM...Campbell/Hickman
SHORT TERM...Campbell
LONG TERM...Franks
AVIATION...Hickman
Source:
ILN issues Area Forecast Discussion (AFD) at Jan 18, 10:07 PM EST---------------
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