St. Matthews, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

143
FXUS63 KLMK 180542
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1242 AM EST Sat Jan 18 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

*  Precipitation returns tonight as light to moderate rain. Rain
   will mix with and change to snow and/or drizzle Saturday
   afternoon as temperatures tumble.

*  Scattered light snow showers could produce minor fluffy
   accumulations Saturday night through Sunday.

*  Frigid temperatures are expected late in the weekend into the
   middle of next week. Lows will be in the single digits, with wind
   chills below 0 at times. High temperatures Monday and Tuesday
   will only reach the teens to low 20s.

&&

.UPDATE...
Issued at 929 PM EST Fri Jan 17 2025

Light rain showers are currently featured along and west of I-65.
Moderate showers are moving northeast through western Kentucky and
will arrive to our western counties around midnight. Temperatures
are sitting in the mid-upper 40s in the northern half (snow-covered)
of the region and low-mid 50s in the southern half of the region.
With temperatures well above freezing, we are still melting the snow
pack and incoming rain will also help the melting process along.
Rain showers will become isolated to scattered over most of the area
by mid-morning as the cold front begins to move through. QPF from
overnight rain will be 0.3-0.6 inches. This QPF along with snowpack
melt, with snow cores between 0.4-0.9 inches, will allow for ample
soil saturation.

The previous forecast remains on track.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 334 PM EST Fri Jan 17 2025

Mostly sunny skies continue across the area this afternoon, though
high clouds are starting to move into the area from the southwest
ahead of the next system. Temperatures have surged today, as we have
warmed into the mid-to-upper 50s across snow-free southern KY while
north central KY and southern IN has made it into the mid 40s to
around 50. Winds have picked up out of the south and southeast as
the sfc pressure gradient has tightened ahead of an approaching cold
front over the central Plains and upper Mississippi Valley.

This afternoon into tonight, a complex upper pattern with two
unphased waves will move from the Plains across the Mississippi
Valley. With mid-level cyclonic vorticity advection taking place
over the Ohio and TN valleys ahead of the southern stream wave,
dynamics will support broad ascent. Meanwhile, a seasonally strong
LLJ core on the order of 45-50 kt will pull warm and moist air into
the region from the southwest, which when combined with the support
from the upper dynamics as well as the approaching low-level front,
should assist in developing precipitation over the region. Hi-res
guidance tries to bring a leading band of showers into the region
between 8-10 pm EST this evening, though soundings show lacking
saturation in the low levels, so much of this may not reach the
ground. However, as a low-level theta-E surge overspreads the region
late this evening, the main surge of moderate rain will move across
the area between 11 pm and 5 am EST. Mild temperatures in the
presence of S/SW flow should keep precipitation as all rain tonight,
with total precipitation amounts between 0.25-0.50" expected.
Temperatures should be fairly steady in the upper 30s and low 40s
tonight into Saturday morning.

By sunrise tomorrow, the main area of rain showers will move to the
east of the area as the best forcing moves east of the Appalachians.
The surface cold front is expected to cross the area during the
early-to-mid morning hours, with winds veering around from S/SW to
the NW through the day. As the wind direction shifts, cold advection
will begin to spread across the area from the northwest, and
temperatures should fall through the daytime hours after reaching a
high during the early-to-mid morning. As temperatures fall, thermal
profiles will eventually become favorable for rain to mix with and
eventually change to snow. The question will be how long we can hang
on to deep enough saturation to generate snow aloft, especially
along and north of the Ohio River. Where shallower moisture exists,
a period of mist and drizzle would be expected tomorrow afternoon,
with intermittent light rain and snow showers occurring in pockets
of saturation into the DGZ. No significant snow accumulation is
expected during the daytime tomorrow, with the better chance for
accumulating snow arriving Saturday night into Sunday morning. All
in all, Saturday should be a dreary, raw day across southern IN and
central KY with low clouds and light precipitation.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 334 PM EST Fri Jan 17 2025

Saturday Night - Sunday...

We`ll be post-frontal by Saturday evening, with a notable 850-500mb
dry slot working through our area. This will cut off the more
widespread precipitation, however a good amount of 1000-850mb
moisture lingers beneath the dry slot. In addition, we`ll have
pretty strong cold advection ongoing by this time. There could be a
period where we may have some patches of freezing drizzle late
Saturday evening when temps fall below freezing and low level
moisture may be just sufficient enough. The window for this should
be fairly short as cold advection through the low levels eventually
allows for ice reintroduction as -8 to -10C temps coincide with the
low level moist layer by late Saturday night into Sunday morning.
Here, we could pick up some light accumulations on snow, especially
east of I-65 where accums could end up warranting a Winter Weather
Advisory. Right now, we have a dusting to 2" generally east of I-65,
especially as you near I-75. This would be the most likely location
for a future headline. Along and west of I-65, looks like a dusting
to 1" where a Winter Weather Advisory is a little less likely. Given
the cold air promoting higher SLRs 15:1 late Sat Night trending
toward 20:1 by Sunday morning, and the potential for a bit of low
level moisture enhancement from Great Lakes origin trajectories do
think that snow showers and light accums could cause some minor
impacts through Sunday. Something to watch.

In addition to the snow chances, temperatures/wind chills will be
down right nasty with highs not making it out of the 20s and wind
chills in the single digits to teens. We will also have to watch out
for some black ice/slick spots Saturday night in case any lingering
wet surface re-freeze with the falling temps.

Sunday Night - Wednesday...

Arctic high pressure really starts to build in by Sunday night, so
will go dry by this time. The big story will be the cold as lows dip
into the single digits by Monday morning. Corresponding wind chill
values are expected to dip into the -5 to 5 above range, which may
flirt with Cold Weather Advisory criteria. Monday highs only reach
into the teens to low 20s, with Monday night lows again in the
single digits to low teens. Wind chills won`t be quite as bad by
Tuesday morning, but still looking at values in the 0 to 10 above
range. One favorable thing about the impacts of the Sunday/Monday
snow/cold will be the holiday on Monday. May not have as much
traffic for Monday morning which could limit impacts a bit from the
coldest air and slick spots from snow. Small win there.

The cold temperatures continue Tuesday and Wednesday with highs
trending from the teens to the 20s and another cold night in the
single digits between the two. Dry conditions continue during this
stretch with Arctic high pressure in place at the surface. Could
have an impactful storm ongoing across the SE CONUS during this
time, but right now looks to stay suppressed from us. Will be
continuing to monitor.

Wednesday Night - Friday...

Lower confidence for the end of the work week, however there is some
hope for a bit of recover on the temps. Still looking at cold nights
with lows likely in the teens, but some better optimism about
getting a bit above freezing each afternoon. For the moment, most of
the precipitation activity looks to stay south of the CWA, however
confidence is lower with some member suggesting the alternative.
Will keep some small chances in for now.

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 1241 AM EST Sat Jan 18 2025

Confidence/Impacts:
- Medium to high confidence in MVFR/IFR ceilings this morning
- Medium confidence in periods of MVFR/IFR VIS with showers
- Medium confidence in light snowfall accumulations Sat night

Discussion...Deteriorating flight conditions this morning as a wave
of rainfall moves in ahead of a cold front located over the Midwest.
Radar imagery shows extensive coverage of light-to-moderate showers
under SW flow. There could also be a brief period of gusty winds at
the beginning of the TAF period before the heavier rainfall sets in.
Ceilings are expected to become predominantly MVFR before sunrise
and fall into IFR threshold by midmorning. On the other hand, VIS
will mainly stay MVFR, but strongest shower activity could yield
periods of IFR. No lightning is anticipated. Rain will let down by
13-14Z with probably drizzle/mist thereafter. Winds will gradually
shift to the NW as the cold front sweeps through the area in the
morning. Finally, there is a signal for light snow showers after
19/0Z with overall minor accumulations.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.

&&

$$

UPDATE...SRM
SHORT TERM...CSG
LONG TERM...BJS
AVIATION...ALL