JKL issues Area Forecast Discussion (AFD) at Feb 19, 7:30 PM EST689
FXUS63 KJKL 200030 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
730 PM EST Wed Feb 19 2025
.KEY MESSAGES...
- Another round of steady snow is expected overnight before
tapering to flurries and snow showers Thursday.
- Single-digit wind chill and/or air temperatures are expected
tonight into Thursday morning, and again Thursday night into
Friday morning.
- High temperatures return to near to above normal during the
first half of next week.
&&
.UPDATE...
Issued at 645 PM EST WED FEB 19 2025
23Z sfc analysis shows a cold air mass pushing deeper into eastern
Kentucky with cyclonic air flow around a low pressure system off
the Carolina coast. An upper level wave and sfc clipper moves
through the area tonight - renewing the snow fall for much of the
area. This, combined with the refreezing wet roads and icy
conditions tonight, will keep the winter storm warning going until
early Thursday morning, at the least. Currently, the snow is in a
lull with just some flurries around through the first part of the
evening - under mostly cloudy skies. Temperatures are already
quite cold out there with readings ranging from the upper teens
north to the low and mid 20s south. Meanwhile, amid northerly
winds of 5 or so mph, dewpoints are generally in the mid teens.
Have updated the forecast to fine tune the PoPs and snow chances
through the night per the latest CAMs guidance. Did also include
the current obs and trends for the T/Td/Sky grids. These
adjustments have been sent to the NDFD and web servers along with
a freshening of the zones and SAFs.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 325 PM EST WED FEB 19 2025
Models are in good agreement in depicting a deep upper low moving
east from the Ohio River Valley tonight before quickly moving out
into the Atlantic by Thursday night. Strongly confluent flow aloft
on the upstream side of the upper low then persists through the
remainder of the short-term ending Friday morning.
An upper-level jet streak will strengthen as the upper level low
approaches eastern Kentucky tonight, with the forecast area falling
under an impressive area of shear vorticity aloft in the left exit
region of the attendant strengthening upper-level jet stream,
indicative of a brief yet fairly decent area of upward motion (i.e.,
lift). Would thus expect that the atmosphere will be efficient in
squeezing out a 1- to 2-hour period of more intense snow as this
feature moves quickly across the area tonight.
After the transitory upper low and strongest curvature/shear
vorticity aloft departs, the area then resides in a cold advection
upslope regime that is quite common for our area this time of year,
with snow showers and flurries continuing through the remainder of
the period as high pressure builds into the area under the strong
upper level confluence.
The big story in addition to the snow will be the bitter cold.
Record low high temperatures will be threatened for Thursday, with
highs only in the lower to mid 20s. With the western and
southwestern counties at least partially if not fully clearing out
overnight Thursday night, lows will plummet into the single digits,
with the potential for a reading near zero degrees in any sheltered
valley locations, especially areas along and southwest of US Highway
421. The Cold Weather Advisory stands a good chance of being
extended through Thursday into Thursday night, but will defer one
more forecast package for now.
Though the majority of the snow with this two-pronged winter storm
has fallen, will keep the Winter Weather Advisory and Winter Storm
Warning areas and expiration times as-is.
.LONG TERM...(Friday through Wednesday)
Issued at 405 PM EST WED FEB 19 2025
A progressive long wave pattern will be in place through the
middle of next week. Several short wave troughs will be moving
through the west northwest flow that will be set up across the
CONUS, with some amplification taking place towards the end of the
period. 500 mb heights will be on the uptick across the Ohio and
Tennessee valleys Friday, with surface high pressure building in
across the region. A weak short wave trough will brush by the area
Saturday and Saturday night, with the GFS now showing a weaker
solution compared to yesterday. As such, an increase in mid and
high level cloudiness will likely be the extent of the influence
from this feature, with dry weather expected. Meanwhile, high
pressure will be weakening and shifting off to our east and
southeast with time, allowing for warmer low level return flow.
The next weaker system that will take aim at the area will arrive
Monday night, although PoPs continue to look low (20-30%), given
the more shallow nature of the moisture. Another more substantial
system will follow towards the end of the period, with the better
chance PoPs arriving in from the west just beyond the forecast
period.
Plenty of cold air will be entrenched across the area Friday
morning; however, the building 500 mb heights and clearing skies
should support highs in the 30s. One more particularly cold night
in the valleys will occur Friday night, with mostly clear skies,
calm winds, and a lingering snowpack will allow for the threat of
more single digit readings. Temperatures will gradually moderate
into early next week, but have kept the overnight low temperatures
warming more conservatively each successive night, given the only
gradually eroding snowpack and favorable decoupling. Next week,
temperatures will be averaging above normal, with highs well into
the 50s and lows mainly in the 30s by Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 730 PM EST WED FEB 19 2025
A lull in the snow is holding into the first part of the evening
with only a few flurries around, amid MVFR to low VFR CIGs
prevailing. Conditions will deteriorate towards and after 06Z to
around 09Z continuing through 12Z as this latest Ohio Valley
clipper system crosses the area, with MVFR conditions prevailing
and brief intermittent periods of IFR possible in the heaviest of
the snow. As snow becomes increasingly confined along and just
upstream of the high terrain of far southeastern Kentucky between
12Z and 18Z, expect MVFR cigs to persist at most TAF sites before
some clearing starts to arrive late in the afternoon from the
west. Winds will continue out of the north at around 5 kts
through the night with a tilt more northwesterly at 5 to 10 kts on
Thursday.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon EST Thursday for KYZ044.
Cold Weather Advisory from 1 AM to 11 AM EST Thursday for KYZ044-
050>052-058>060-068-069-079-080-083>088-104-106>120.
Winter Storm Warning until noon EST Thursday for KYZ050>052-
058>060-068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...GREIF
SHORT TERM...CMC
LONG TERM...JKL
AVIATION...CMC/GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Feb 19, 7:30 PM EST---------------
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