LMK issues Area Forecast Discussion (AFD) at Oct 20, 3:50 AM EDT956
FXUS63 KLMK 200750
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
350 AM EDT Mon Oct 20 2025
.KEY MESSAGES...
* Drier and cooler weather is expected for much of the upcoming
week.
* Another cold front will bring a small chance for a shower late
tonight into Tuesday morning. Breezy west winds are expected
Tuesday and Wednesday.
* Widespread frost looks increasingly likely Thursday morning and
Friday morning.
* Unsettled weather is likely to return by the weekend.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 350 AM EDT Mon Oct 20 2025
Early this morning, satellite imagery reveals clear skies across the
lower and middle Ohio Valley. River valley fog is noted over much of
eastern KY, including in the Cumberland and portions of the Kentucky
River valley. Latest RAP sfc analysis shows high pressure centered
over the Tennessee Valley as the pressure gradient has weakened
considerably since yesterday afternoon. Light west-southwest winds
have been observed, allowing temperatures to cool into the upper 30s
and low-to-mid 40s. Through sunrise, no significant weather is
expected aside from ongoing river valley fog. Temperatures should
settle into the upper 30s and low 40s around sunrise.
Today, fairly flat upper ridging will quickly slide across the
region as another trough descends across the central CONUS. Sunny
skies are expected, which will help temperatures warm after a chilly
start this morning. Also assisting temperatures will be warm
advection as sfc winds should become south-southwesterly and
increase in strength later today as high pressure slides off the
southeast US coast. High temperatures should range from the mid 60s
across the Bluegrass region to the low 70s along and SW of I-165.
Tonight, a sfc cold front associated with a leading upper shortwave
amidst broader upper troughing will move across the Mississippi
Valley and into the Ohio Valley. A strengthening height gradient
aloft should support the development of a 50 kt LLJ overnight;
however, the moisture advection with this jet will be much less than
the previous system, with PW values only rising to around 0.8-1"
immediately ahead of the front. As a result, hi-res guidance shows
most areas remaining dry even with FROPA early Tuesday morning.
However, we'll advertise a slight chance PoP for an isolated
showers, mainly across southern IN and the Bluegrass region. With
southerly winds staying up overnight ahead of the front,
temperatures will be milder tonight, with lows only falling into the
mid-to-upper 40s and low 50s.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 350 AM EDT Mon Oct 20 2025
Tuesday through Thursday Night...
During the day on Tuesday, an anomalous upper low will be settling
across the Great Lakes. The initial sfc cold front associated with
the upper low will be moving across the area at the beginning of the
period. Behind the front, a setup typical of occluding systems will
be present over the Ohio Valley, with several smaller pressure
troughs sliding across the region Tuesday into Tuesday night. A
strong pressure gradient will support breezy conditions through the
day on Tuesday, and steep low-level lapse rates in the post-frontal
air mass should help stronger winds aloft get down to the sfc.
Sustained west winds of 10-20 mph with gusts of 20-30 mph are
expected on Tuesday. While the best chance for a shower will be with
the initial cold front early Tuesday morning, a stray shower will be
possible along across the northern half of the forecast area through
the day on Tuesday, though most will remain dry. Highs should range
from the mid-to-upper 60s across northern KY and southern IN to
around 70 in southern KY.
Tuesday night into Wednesday, the upper low will pivot over the
Great Lakes, with cyclonic flow aloft gradually transitioning to NW
flow. Cold advection will continue during this period, though
persistent winds Tuesday night will likely limit radiational
cooling. Lows should fall into the upper 30s and low-to-mid 40s
Wednesday morning. Breezy conditions will continue into the day on
Wednesday, and the proximity of the H85 thermal trough should result
in the coolest high temperatures of the week. Highs should range
from the upper 50s across southern IN and northern KY to the mid 60s
across southern KY.
The upper trough will very gradually lift to the NE Wednesday night
into Thursday, with high pressure moving into the TN Valley by
Thursday morning. This will allow winds to relax and temperatures to
tumble, with lows Thursday morning falling into the mid-to-upper 30s
in most locations, though the typical warm spots may stay in the low
40s. After another cool and dry day on Thursday with temperatures
only a few degrees warmer than Wednesday, Thursday night may feature
some of the coldest temperatures in the next 7 days, particularly
across the northeastern half of the forecast area. Widespread mid-to-
upper 30s are expected Friday morning, with a few of the cooler
spots across the Bluegrass and southern IN likely making a run at
freezing. This would support another chance for widespread frost.
Friday through Next Weekend...
For Friday into next weekend, the main focus will be on a cutoff low
which is expected to eject from the Four Corners region across the
southern Plains and into the Ohio Valley. Ahead of this system,
southerly flow will tap into Gulf moisture, with an axis of water
vapor transport extending into the Ohio Valley. Over the past few
model runs, this system has trended slower in its eastward
progression, making it more likely that Friday remains dry over our
area, with high clouds increasing during the period.
Precipitation chances will increase Friday night into the day on
Saturday, with confidence increasing in off and on periods of rain
next weekend. At this time, modest forcing and moisture will support
modest precipitation amounts, with most likely QPF ranging from 0.25-
1". However, high-end ensemble amounts of 2-3" are noted, so there
is an outside chance for more significant rainfall. With clouds and
rain lingering over the region through the weekend, diurnal
temperature ranges will be suppressed, with highs generally in the
60s and lows in the upper 40s and 50s.
&&
.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 123 AM EDT Mon Oct 20 2025
Through mid-morning, light SW winds and clear skies are expected
across the area. Later today, winds will back toward the south-
southwest, increasing to around 10 kt during the late morning and
early afternoon hours. A few wind gusts of 15-18 kt are possible
during peak mixing. VFR conditions will continue through the current
forecast period, with a mid-level deck expected to move across the
region late Monday night in association with a cold front.
Immediately ahead of the front, a LLJ will bring the potential for
LLWS, with sfc winds veering from SSE to SW toward the end of the
current forecast period.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
SHORT TERM...CSG
LONG TERM...CSG
AVIATION...CSG
Source:
LMK issues Area Forecast Discussion (AFD) at Oct 20, 3:50 AM EDT---------------
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