664
FXUS63 KJKL 081800
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
100 PM EST Wed Jan 8 2025

.KEY MESSAGES...

- Below normal temperatures will persist through the next week.

- Apparent temperatures (wind chills) will likely bottom out near
  or below zero around dawn Thursday for locations near and north of
  the Mountain Parkway.

- Confidence is increasing for a storm system to bring light to
  moderate snow accumulations Friday into early Saturday.

&&

.UPDATE...
Issued at 1123 AM EST WED JAN 8 2025

Tricky temperature forecast is unfolding for tonight. Lingering low
clouds should keep a majority of the forecast area in the teens
tonight. However, indications from the RAP13 and GFS20 suggest
that low-level CAA will cease a few to several hours before
sunrise near and north of the Mountain Parkway. If this occurs,
skies should clear over the northern counties. Additionally, the
fluffy inch or two of new snow accumulation from today and this
evening will serve as an extremely efficient insulative blanket
atop the existing ground/snow cover. Confidence in reaching Cold
Weather Advisory criteria (-5F or colder apparent temperature)
was highest from Elliott to Montgomery Counties. While the
official forecast is for temperatures to fall to near 0F, it is
worth noting that the colder end of guidance is between -5F to
-10F which could be realized if clearing occurs earlier than
anticipated. Further south, a Cold Weather Advisory has been
issued for the Mountain Parkway/US-460 corridor from Powell over
to Johnson Counties (mainly areas impacted by heavy icing in the
recent winter storm). Confidence in reaching the standard Cold
Weather Advisory criteria is much lower here as skies may struggle
to clear before sunrise, especially in Magoffin and Johnson
Counties. However, given the lingering power outages due to icing
as well as temperatures likely dropping into the single digits, we
have included Powell, Menifee, Wolfe, Morgan, Magoffin, and
Johnson Counties in an "impact-based" Cold Weather Advisory.
Additionally, if skies clear more quickly than expected, air
temperatures could easily dip to near or even below 0 in these
counties as well.

UPDATE Issued at 811 AM EST WED JAN 8 2025

Major update to the forecast this morning. Persistent snow showers
expanded in coverage and intensified overnight into early this
morning. To the point that the snow over that past few hours has
been accumulation 1 to 2 inches at a number of locations. Roads
around the forecast area have become snow covered and slick, and
it appears that these snow showers will continue throughout the
day. Therefore, a winter weather advisory was issued to account
for the snow and its impacts. The forecast grids were update to
reflect higher qpf, snow fall amounts, and PoPs. The updated zones
have been issued and the hazardous weather outlook has also been
updated to add the winter weather advisory.

&&

.SHORT TERM...(Today through Thursday)
Issued at 632 AM EST WED JAN 8 2025

The large scale flow pattern aloft across the country will feature
the following: A large and vigorous trough of low pressure centered
just off the coast of southeastern Canada. Another trough of low
pressure will be centered over the northern Baja peninsula, with
yet another storm system moving onshore in the Pacific Northwest.
Between the series of troughs is extensive ridging over the northern
Rocky`s, eastward across the Great Plains and finally over the Great
Lakes and Ohio and Tennessee Valleys.

Generally quiet weather will continue across eastern Kentucky today
through Thursday night, as high pressure remains in place over the
region. We will, however, see widespread low level cloud cover and
rounds of snow flurries and light showers continue across the area
today into tonight, due to moist northwest flow aloft and very cold
air that is in place. The snow should taper off this evening, and
finally come to an end by late this evening. Very light
accumulations will be possible with this snow. Light winds and
single digit temperatures could lead to wind chills around zero late
tonight into early Thursday morning.

.LONG TERM...(Thursday night through Tuesday)
Issued at 632 AM EST WED JAN 8 2025

Surface high pressure over the area to start the period will
depart to the east Thursday night as ridging aloft passes over.
This will bring mainly clear skies and light winds to start
the night. Temperatures should readily drop in the evening,
probably quite precipitously in valleys with snow cover. High
clouds spilling through the upper ridge will begin to lower and
thicken during the night. This will eventually halt the falling
temperatures. How long this takes to happen will determine our
lows for the night. Best estimate at this time is that our
northeast valleys will reach lower single digits, while our
southwestern counties which have clouds come in earliest will only
reach the teens. After clouds thicken and radiating largely stops,
light winds on the backs side of the high should begin to stir and
temperatures are expected to begin climbing before dawn.

The increasing clouds will be a harbinger of the next weather
system quickly moving in. An closed upper low currently over the
north end of the Gulf of California will open and get picked up by
northern stream trough currently dropping southeast over the
northern plains and central Rockies. This will support a surface
low which will track along the Gulf Coast, sending moisture
northward and getting picked up ahead of the advancing full
latitude upper trough. Models are consistent in this set-up
bringing snow to our area Friday into Friday night. It seems to be
a question of how much. A model blend currently suggests
somewhere from 3-5 inches for most of the area, with the greatest
amounts in our southern and southeastern counties. Warning
criteria being 4 inches, this barely meets or exceeds that.
Considering that the system is still 5th period and beyond and
forecast changes may happen, would have preferred to wait on
issuing a watch and handle it in the Hazardous Weather Outlook
again in this forecast cycle. However, surrounding offices decided
to go ahead with watches instead, and JKL needed to follow suit.

The surface low will reach the NC coast and depart early Saturday
and the upper trough will advance to our east, putting an end to
the event here. While somewhat colder air will move back in behind
the system, there won`t be a great surge of colder air. As a
result, a return of at least partial sun on Sunday might be able
push temperatures a little above freezing for most of the area.
Any chance at further warming will be cut off as another upper
level wave and its associated cold front pass on Monday and more
arctic air flows in.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 100 PM EST WED JAN 8 2025

MVFR/low VFR ceilings are expected to hold through most of
tonight due to persistent upslope flow and a shallow layer of low-
level moisture. Look for ongoing light snow/flurries to gradually
diminish from west-to-east this evening. The ceilings should
gradually breakup late tonight and Thursday morning. Winds will
remain westerly to variable around 5 kts or less through Thursday
morning.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 7 PM EST this evening for KYZ044-
050>052-058>060-069-088-104-106>115-117>120.

Cold Weather Advisory from 1 AM to 10 AM EST Thursday for KYZ044-
050>052-059-060-104-106>109.

Winter Storm Watch from Friday morning through Saturday morning
for KYZ068-069-079-080-083>088-114>118.

&&

$$

UPDATE...GEERTSON
SHORT TERM...AR
LONG TERM...HAL
AVIATION...GEERTSON