LMK issues Area Forecast Discussion (AFD) at Dec 10, 10:57 AM EST546
FXUS63 KLMK 101557
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1057 AM EST Tue Dec 10 2024
.KEY MESSAGES...
* Gray day today with patchy light rain, sprinkles, and drizzle
* Brief period of light snow after midnight tonight. Though any
snow will be very light, damp roads could form slick spots as
temperatures fall to or below freezing.
* Scattered snow showers Wednesday afternoon and evening. Snow
accumulations will be light.
* Colder and blustery conditions for Wednesday and Thursday with
highs in the 30s and wind chills in the 20s.
&&
.UPDATE...
Issued at 1057 AM EST Tue Dec 10 2024
Surface analysis shows the cold front pushing east of the I-65
corridor at this hour. This evident by the shift to northwest winds
behind the front while we still have south to southwest winds out
ahead of the feature. Temperatures were slowly falling in the post
frontal wake with readings in the mid-upper 40s across western KY
with readings still in the upper 50s/lower 60s across portions of
southeast KY (Lake Cumberland region). The cold front will continue
to push eastward this afternoon with a band of post-frontal showers
pushing east-northeast across the area. Rain showers look to
diminish by late afternoon. Highs west of I-65 have already
occurred for the day and temps will continue to slowly fall during
the afternoon. East of I-65, highs in the mid-upper 50s to lower
60s will be seen but temps will fall this afternoon behind the front.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 321 AM EST Tue Dec 10 2024
Low pressure advancing along a surface trough from Nashville to
Pittsburgh will work with high sfc-700mb moisture to produce gray
skies today with patchy light rain, sprinkles, and drizzle. Total
precipitation amounts will be less than 0.20". Winds will be light
and variable this morning as the surface low moves overhead, but
will come in from the northwest this afternoon around 10 mph as the
low pulls away. As a result, today's high temperatures will likely
occur around lunch time with readings dropping slightly this
afternoon.
Tonight the low and its trailing cold front will be off to our east,
however a sharpening 500mb shortwave trough will approach from the
west, arriving in the Mississippi Valley by dawn. Mid-level
frontogenetical forcing ahead of this wave will create a streak of
primarily mid-level clouds from Arkansas to Ohio. Hydrometeors
falling from this cloud deck will initially encounter dry sub-cloud
air and will struggle to reach the surface, especially west of I-65,
where just flurries or brief light snow is expected. Low and mid
levels will steadily moisten through the night and will become
increasingly supportive of snowflakes reaching the ground east of I-
65 to the east of a 170kt upper jet stretching from Louisville to
Montreal. Cooling thermal profiles on soundings and surface
temperatures progged to fall to around the freezing mark support
primarily flurries/light snow (possibly starting as a brief period
of sprinkles light rain). However, due to the light nature of the
snowfall, little if any accumulation is expected. Though roadcasts
suggest pavement temperatures will remain in the mid/upper 30s
overnight tonight, there is still a threat of slick spots where any
residual moisture from today's light rain remains on the roads,
especially west of I-65 where air temperatures are forecast to fall
into the upper 20s. Winds remaining up around 10 mph through the
night may help to dry road surfaces, limiting the threat of
Wednesday morning rush hour slick spots. Something to keep an eye on.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 321 AM EST Tue Dec 10 2024
Wednesday - Thursday Morning... Strong cold air advection will be in
place and continue to filter in from the west-northwest Wednesday
into Wednesday Night. Deep upper-level trough will swing through the
Ohio Valley with a few opportunities for snow showers through the
day. Lingering snow showers and flurries in the wake of the
departing sfc front are possible along and east of the I-75 corridor
Wednesday morning. This activity is expected to quickly come to an
end by mid to late morning. A second wave of snow showers will start
to develop around midday and work eastward across southern IN,
central KY during the afternoon into the early evening. Steep low-
level lapse rates, model soundings showing saturation in the DGZ,
along with lift associated with the trough axis will be enough to
allow for a light accumulation of snow. Temperatures will be in the
mid/upper 30s as these snow showers work across the area; this
should help to limit most impacts from the snow with just minor
accumulations of a coating on elevated and grassy surfaces. With the
possibility of a few snow showers lingering after sunset, especially
from around Louisville over to Lexington, temperatures will fall
quickly to near or even slightly below freezing and that could cause
a few isolated slick spots. Confidence is low on overall impacts
from the snow but something to be mindful of as timing of snow will
be near the late afternoon and evening commute. Winds will also be
breezy with possible gusts of 20-25 mph. Factor this with the chilly
temperatures and wind chill values will be in the mid 20s. Skies
will clear overnight Wednesday into Thursday morning. It will be a
cold morning for Thursday with lows in the upper teens/low 20s.
Thursday - Friday... Sfc high pressure builds in over the region on
Thursday providing more sunshine with clear skies. Temperatures will
still be chilly with highs in the afternoon in the low/mid 30s north
of the parkways and in the upper 30s to the south towards the KY/TN
border. Upper pattern will start to flatten as high pressure works
to the east. Return southerly flow will increase WAA into the region
with highs 10-15 degrees warmer on Friday.
Friday Night into the Weekend... Our next chance of precipitation
will arrive Friday night into the start of the weekend. Another
upper-level trough coming out of the Four Corners on Friday will
develop a sfc low over the Plains Friday. This system is expected to
move to our north and into the Great Lakes by Saturday and Sunday.
Models continue to keep us on the warm side with temperatures in the
low 50s for both Saturday and Sunday and low temperatures in the
upper 30s to low 40s. This will keep the precipitation over the area
as all rain. There continues to remain some timing issues with this
next system with the GFS faster and clearing out the precipitation
on Sunday while the ECMWF is slower with precipitation lagging into
Sunday.
&&
.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 634 AM EST Tue Dec 10 2024
Impacts/Confidence:
- High confidence in sub-VFR ceilings through the daylight hours
(xcp HNB)
- Medium confidence in very light snow after midnight tonight
Discussion...Widespread low clouds will dominate the forecast today
as weak low pressure moves from BNA to around BUF/PIT by this
evening. The deepest moisture and strongest lift will be present
this morning into early afternoon, when there will be the best
chances for light rain, sprinkles, and drizzle. The precipitation
should come to an end by late afternoon/early evening, but a
sharpening 500mb trough advancing into the Mississippi Valley will
bring another chance of precipitation after midnight tonight. While
this precip will be in the form of snow, it will be very light at
the surface at HNB/BWG thanks in part to dry air below 10k'. Snow
chances will be slightly higher at SDF and especially at LEX/RGA as
the lower levels saturate and forcing aloft increases. Right now it
looks like the most likely time for any reduced visibility in -SN at
SDF is during the 08-11Z time frame.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE.......MJ
SHORT TERM...13
LONG TERM....BTN
AVIATION.....13
Source:
LMK issues Area Forecast Discussion (AFD) at Dec 10, 10:57 AM EST---------------
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