LMK issues Area Forecast Discussion (AFD) at Jan 20, 11:54 AM EST ...Updated Aviation Discussion...595
FXUS63 KLMK 201654
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1154 AM EST Mon Jan 20 2025
...Updated Aviation Discussion...
.KEY MESSAGES...
* Gelid today with temperatures in the single digits and wind
chills below zero this morning. Highs this afternoon will only
reach 15-20 degrees.
* Frigid temperatures are expected through the middle of the week
with single-digit lows and below-freezing highs Tuesday and
Wednesday. Gradual warming towards the weekend.
* Mostly dry this week with spotty flurries Tuesday and
Thursday into Friday. Rain chances returning on Sunday.
&&
.UPDATE...
Issued at 1054 AM EST Mon Jan 20 2025
Despite the plentiful sunshine, temperatures have been struggling
this morning as a frigid Canadian high continues to build into the
region. At the time of this writing all of southern Indiana and most
of central Kentucky are still in the single digits. Decreased
afternoon MaxT 1-3 degrees, especially in areas with snow on the
ground.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 349 AM EST Mon Jan 20 2025
Conditions are very cold and quiet early this morning. Strong sfc
high pressure continues to build in from the west. Skies are mostly
clear to partly cloudy, with some lingering low clouds mostly east
of I-65. Temperatures are in the single digits early this morning,
with wind chills between 0 and -11. Temperatures will slowly fall
from current readings until just after sunrise. Wind speeds will
also gradually lower during that time. Expect wind chills below
zero, mainly between -2 and -12, through mid to late morning.
With high pressure in place and a dry column, we'll see plenty of
deceptive sunshine today. From their lows around 0-5 degrees above
zero this morning, sfc temperatures will only top out in the 15-20
degree range this afternoon. Westerly winds around 5 mph will keep
wind chills in the single digits to teens this afternoon.
Tonight, upper level troughing develops southeast toward the region.
Moistening mid-levels will produce mostly cloudy conditions after
midnight, which will produce stable but still frigid temperatures
early Tuesday morning. Lows will range from the single digits to
lower teens. With the cold high in place, the lower levels will stay
quite dry most of the night. However, as the column tries to moisten
ahead of the approaching upper level wave, a chance for flurries
develops after 09Z Tuesday. A weak sfc trough embedded within
broader ridging will sink into the area from the northwest early Tue
morning. Winds will be very light early Tue morning, but from a
prevailing SW direction ahead of the trough.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 349 AM EST Mon Jan 20 2025
Synopsis...Deep upper-low over the Hudson Bay in combination with
blocking ridge stretching across the Gulf of Alaska will drive a
longwave trough over the CONUS. The amplified large-scale pattern
will favor periodic shortwave intrusion with persistent cold air
advection and spotty light snow episodes for the Ohio Valley
throughout the week. Then, increasing precipitation chances and
warming temperatures are likely this weekend as ridging builds over
the Southeast US and a cut-off low develops over the Dessert
Southwest. That being said, uncertainty remains fairly high
regarding the large-scale evolution during the weekend, potentially
causing large swings in the forecast.
Model Evaluation/Confidence...Confidence in temperature and wind
chill forecast through midweek remains high. On the other hand,
lower confidence exists on light precipitation chances with
associated shortwave troughs Tuesday and Thursday night into Friday.
ECMWF p-type meteograms continue indicate around 10-20%
probabilities of light snow/flurries both days. Based on past
experiences with that guidance on similar situations, decided to
start mentioning that slight-chance scenario. Finally, model
disagreement persists during the weekend and thereafter. Differences
arise on the interaction of the Gulf of Alaska ridge with Canadian
shortwave energy and the cut-off low to the south. Still, rain
chances focus on Sunday with growing discrepancies in precipitation
duration and temperature fluctuations early next week.
Tuesday - Friday...Arctic high pressure approaching the Ohio Valley
from the west will favor cold air advection and bitterly cold
temperatures both Tuesday and especially Wednesday morning when the
surface high moves overhead. Due to the fast transition of the high
pressure early in the evening, there might be enough wind Wednesday
morning to yield slightly negative wind chills at sunrise. First of
a series of shortwave troughs swings by the forecast area on Tuesday
and although shallow saturated layer will be rooted slightly above
the DGZ, there will be enough lifting to potentially generate spotty
flurries along the OH River and northward. Next chance of
precipitation comes Thursday into Friday as the second shortwave
approaches the region. Have decided to mention another round of
spotty flurries but GFS/ECMWF forecast soundings and GFDL 1-hr
precip field favor the potential for heavier snow rates. Definitely
something to watch over the coming days. As for temperatures,
warming trend will start the second half of the week with above-
freezing highs Thursday and Friday.
Weekend...Building mid-level ridge and surface high pressure over
the Southeast US will promote warmer temperatures over the weekend
while also pumping weak moisture under southwest low-level flow.
Saturday will be mostly dry with increasing upper cloud cover ahead
of another shortwave. Isentropic lifting and enhanced warm advection
will promote rain chances Saturday night into Sunday morning. Steady
light to occasional moderate rainfall will persist through Sunday
with decreasing chances towards the evening. It is worth noting that
the aforementioned scenario is based on a blend of main
deterministic guidance and forecast confidence remains low at the
moment.
&&
.AVIATION /12Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1153 AM EST Mon Jan 20 2025
Strato cu have developed over eastern Kentucky, and at 1615Z RGA
acquired a broken MVFR ceiling at 2200'. However, satellite images
show RGA on the very western edge of the cloud field, the Madison
County Kentucky Mesonet camera shows just some scattered small
clouds overhead, and the RGA AWOS went back to SCT by 1635Z. So,
will keep low clouds scattered in the RGA TAF.
Clouds over the central and southern Plains this morning will stream
eastward ahead of a digging upper trough, replacing today's mostly
sunny skies with mostly cloudy, but VFR, conditions tonight. High
pressure at the surface will keep winds light today and nearly calm
tonight. Tomorrow the mid-level clouds will push off to the east
though there may be some scattered lower level clouds lingering into
the afternoon.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Cold Weather Advisory until 1 PM EST /noon CST/ this afternoon
for KYZ023>043-045>049-053>057-061>067-070>078-081-082.
IN...Cold Weather Advisory until 1 PM EST /noon CST/ this afternoon
for INZ076>079-083-084-089>092.
&&
$$
UPDATE...13
SHORT TERM...EBW
LONG TERM...ALL
AVIATION...13
Source:
LMK issues Area Forecast Discussion (AFD) at Jan 20, 11:54 AM EST ...Updated Aviation Discussion...---------------
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