JKL issues Area Forecast Discussion (AFD) at Jan 12, 4:52 PM EST067
FXUS63 KJKL 122152
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
452 PM EST Sun Jan 12 2025
.KEY MESSAGES...
- Patchy freezing drizzle and light snow showers are possible
late tonight and into Monday, generally east of I-75.
- Below normal temperatures will persist through Thursday.
- Apparent temperatures could fall to near or below zero for many
locations Monday, Tuesday, and Wednesday nights - primarily
north of the Mountain Parkway.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 452 PM EST SUN JAN 12 2025
Late this afternoon, an upper level low as dropping south near the
Manitoba and Ontario border with troughing extending south and
southeast to the mid MS Valley and also southwest to the Four
Corners and southeast. Shortwave trough was moving from the upper MS
Valley into the Great Lakes while the axis of shortwave ridging was
nearing or moving off the eastern seaboard. Another shortwave trough
was in the Lower Rio Grande to western Gulf of Mexico vicinity while
additional shortwaves were moving around ridging in the eastern
Pacific and south across western and northwestern Canada into the
trough. At the surface, an area of low pressure was tracking in the
vicinity of western Lake Superior with a warm front southeast into
the OH Valley lifting north and northeast and the trailing cold
front into the mid MS valley to eastern TX. Meanwhile sfc high
pressure was centered across the southeast Conus while another ridge
of high pressure was building from Saskatchewan toward eastern MT
and western Dakotas.
This evening and tonight, deeper eastern valleys should decouple and
with snow cover should drop off well into the low to mid 20s during
the late evening to early overnight hours. Temperatures should then
rise late tonight. However, as the shortwave trough continues to
near and the cold front sweeps across western and central KY
moisture will increase ahead of the cold front, with saturation to
cold enough temperatures to have ice crystals being at least
initially marginal/borderline. The system will be moisture starved
and what precipitation that falls will be very light, but at least
patchy light mixed precipitation will be possible in western and
northwestern sections. This could fall as a mixture of flurries and
drizzle or freezing drizzle or perhaps a rain or snow shower. Any
accumulation would be very, very light where temperatures remain at
or below freezing, but slick spots cannot be ruled out on untreated
roads or surfaces. With warm advection on top of the snow cover,
some fog is possible late tonight and into Monday. As the shortwave
trough at 500 mb shifts to the east and northeast of eastern KY on
Monday, the cold front should cross the remainder of the area as 850
mb temperatures fall to -6C or colder.
The patchy light precipitation, if any, should spread into the
southeastern counties around or after daybreak on Monday and there
could be some very, very light accumulation where temperatures are
at or below freezing. However, along and in advance of the front,
temperatures will tend to rise to near or above freezing. This
should occur for most places in the west late tonight to early on
Monday morning, and for Monday morning to midday further east and
southeast with some low to mid 30s ahead of the front. However, the
cold advection should lead to temperatures falling behind the front
to near or below freezing for the western half to two/thirds of the
area by late afternoon. Under uslope flow and with the column
cooling, what precipitation that remains by mid to late afternoon
will probably fall as flurries.
For Monday night, sfc high pressure should briefly build into and
across eastern KY ahead of the next shortwave trough and arctic cold
front to affect the region early in the long term period. Monday
night should be precipitation free with temperatures dropping well
into the low to mid teens, with some single digits not out of the
question in deeper valleys if more significant clearing occurs that
currently forecast.
.LONG TERM...(Monday night through Saturday)
Issued at 359 AM EST SUN JAN 12 2025
Surface high pressure will build back into the region behind an
exiting cold front for Monday evening. However, upper-level height
falls, ahead of an approaching shortwave, will begin to work their
way into the forecast area. As the upper-level trough pivots
southeast into the region, an accompanying surface low will move
southeast with it. The clipper system will move through the region
bringing increased PoP chances (10-30%) for Tuesday night into
Wednesday morning. Did deviate from the NBM and decided to go with
the more robust GFS solution that provided better PoP chances across
the northern portions of the CWA; however, little to no accumulation
is expected with this clipper. Behind the exiting clipper, surface
high pressure will build into the region but CAA will bring some of
the coldest temperatures of the season to eastern Kentucky. Highs
Tuesday and Wednesday are forecast to climb into the low to mid-20s
with overnight lows Tuesday, Wednesday and Thursday mornings will
fall into the negatives to single digits. Another weak trough and
vort max will move through the area overnight Wednesday into
Thursday morning. This will provide enough lift to kick off a few
snow showers (0-30%) for areas mainly along and north of the
Mountain Parkway. Little to no accumulation is expected with this
second round of snow showers that'll linger into late Thursday night.
Models continue to show disagreement for Friday through the end of
the forecast period. The GFS is more robust in potential scenario
where a surface low develops over the southern Plains and ejects
toward the Great Lakes by Friday night. The ECMWF has a surface low
developing over the Gulf and track straight north and come in line
with the GFS solution. With confidence lacking in long-term
deterministic solutions, opted to stick with the NBM solution that
brings PoP into the region Friday afternoon and continues through
the end of the forecast period. Temperatures with this system are
forecast to run well above freezing which would lead to a rainy
solution. However, colder air will filter in behind the exiting
system which will turn rain into snow for all lingering backside
precipitation.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 1206 PM EST SUN JAN 12 2025
Under the influence of sfc and upper level high pressure, VFR was
present across the region at this time. VFR conditions should
persist until 03Z in all areas before some MVFR ceilings are
likely to spread from northwest to southeast through the 11Z to
12Z timeframe in advance as well as behind a cold front. By 09Z to
12Z, further deterioration to IFR is anticipated over the western
and northwestern locations behind the boundary with the IFR
conditions possibly reaching KSYM and KSME by 12Z. The area of
IFR behind the boundary should shift across the eastern and
southeastern sections through the end of the period, while a
return to MVFR may arrive over the west and northwest late. Winds
are expected to south to southwest at generally 5 to 10 KT before
00Z and then become light and variable for valleys overnight
while ridgetop and more open terrain locations south to southwest
at 5 to 10KT. A shift to the west should occur behind the boundary
between 10Z and 18Z. There is some potential for spotty marginal
LLWS between 03Z and 10Z as the NBM suggests, but CONSShort is
more optimistic that it will not occur. With low confidence in
any LLWS occurrence, it will be left out of the 18Z TAF issuance.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JP
LONG TERM...VORST
AVIATION...JP
Source:
JKL issues Area Forecast Discussion (AFD) at Jan 12, 4:52 PM EST---------------
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