LMK issues Area Forecast Discussion (AFD) at Aug 28, 3:45 AM EDT073
FXUS63 KLMK 280745
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
345 AM EDT Thu Aug 28 2025
.KEY MESSAGES...
* Dry weather with below normal temperatures will continue into the
Labor Day weekend. There is a very low (<10%) chance for a shower
this afternoon and Friday afternoon.
* Isolated to scattered daytime shower/storm chances will return for
Labor Day into early next week, though significant rainfall
amounts appear unlikely at this time.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 344 AM EDT Thu Aug 28 2025
This morning, sfc high pressure is centered over West Virginia and
is starting to be squeezed off to the east by two separate low
pressure systems. On the western flank, a Colorado low supported by
a mid-level shortwave will slide from the Ozarks across the lower
Miss. Valley later today. On the northern flank, a cold front
supported by an upper level trough will pivot from the St. Lawrence
valley and into the northeast US over the next 24 hours, with the
southern edge of the trough extending into the Midwest.
Today, much of our area will be in between the two above-mentioned
features, with subtle ridging swinging across the area. This should
keep most of the measurable precipitation chances to our northeast,
though a stray shower can't be ruled out along and northeast of a
line from Scottsburg, IN to Winchester, KY. However, given that the
sfc-850 mb layer will remain very dry, the likelihood and expected
coverage of any precipitation will be low enough to keep a dry
forecast going. A mix of sun and clouds is expected across the area
today, with mainly high clouds expected across southern KY while a
mid-level cu field is more likely along and north of I-64. Since mid-
level moisture will be increasing ahead of the cold front to our
north, dry air mixdown might not be as strong as on Wednesday.
Still, minimum RH values this afternoon could still reach the upper
20s and lower 30, especially south of I-64. Highs should be 2-3
degrees warmer than on Wednesday given thickness trends, with a
range from 78-84 across the forecast area.
Tonight, the cold front to our north will continue to saunter
southward, losing upper-level support as troughing aloft pivots
toward upstate NY. Some high-res guidance tries to bring a band of
low-to-mid level clouds across northern portions of the forecast
area, along with a few sprinkles. If clouds are more prevalent,
overnight cooling may be limited, keeping lows a bit milder for
Friday morning. For this forecast, have a range between the low-to-
mid 50s in rural areas to around 60 in the Louisville metro.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 344 AM EDT Thu Aug 28 2025
On Friday, a dissipating cold front is expected to extend from WNW
to ESE across the region, slowly pushing south through the day.
Since the upper-level trough which initially supported this front
will be pivoting across the northeast US and southeast Canada, the
disturbance will have little to no forcing to help generate
precipitation. With that being said, there are a few CAM/global
model solutions which generate isolated showers Friday afternoon
along the front (e.g., NAM 3km and ECMWF). Soundings from these
models do show a small layer of instability between 850-700 mb, and
this, along with convergence along the front, is likely what is
forcing these showers. It should also be noted that the NAM's usual
llvl moisture bias may be playing a role in generating additional
showers. In contrast, dry-bias models like the HRRR/RAP/GFS show
little to no shower activity. In any case, the overall lack of deep-
layer moisture and forcing keeps me from going with a mentionable
PoP; however, wouldn't be surprised if we see an isolated shower
Friday afternoon. Highs on Friday should be closer to climo than in
recent days, ranging from the low-to-mid 80s across the area.
Over the weekend, the above-mentioned cold front should wash out
near or just south of the forecast area, with drier and slightly
cooler air filtering in from the northeast behind the front. With
the air mass behind the front not entirely pushing into the area,
there should be a decent temperature gradient across the region
Saturday and Sunday. Highs should reach the low-to-mid 80s across
southern KY over the weekend, while remaining in the upper 70s to
around 80 across north central KY and southern IN. All in all, it
should be a lovely Labor Day weekend, with dry northeasterly breezes
continuing to squash precipitation chances.
By Labor Day into early next week, medium-range guidance suggests
that an east coast CAD event may try to set up over the Carolinas,
with inverted troughing extending from the Tennessee valley
northeastward across our area. If this setup occurs, we would start
to see moisture return to the area, sufficient for at least isolated
afternoon and evening showers and thunderstorms, particularly across
southern and southeastern KY. By Tuesday, moisture return is looking
to be sufficient that most of the area will have at least a slight
chance for an afternoon/evening shower or storm. Diurnal temperature
ranges should decrease somewhat early next week, though overall,
below normal temperatures are favored to continue. Highs are
expected to be in the upper 70s and low-to-mid 80s with lows in the
mid-to-upper 50s and low 60s.
There is increasing agreement that a stronger system will descend
into the region next Wednesday into Thursday. This would bring a
more widespread chance for rain ahead of a cold front, along with
another drop in temperatures/humidity behind the front.
&&
.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 127 AM EDT Thu Aug 28 2025
The main potential impact over the next few hours would be the
development of shallow fog at HNB given that latest obs already show
saturation. Otherwise, VFR conditions and light and variable winds
are expected through late morning, with mainly high clouds streaming
overhead. Later this morning, mid-level moisture will increase from
the north, and this may be sufficient for a SCT-BKN cloud layer
around 7-10 kft this afternoon and evening. While wind speeds should
again be less than 10 kt during peak mixing this afternoon, wind
direction is a bit uncertain given a messy pressure field over the
region. In general, would expect SW winds veering to NW through the
afternoon before becoming light/variable again tonight.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
SHORT TERM...CSG
LONG TERM...CSG
AVIATION...CSG
Source:
LMK issues Area Forecast Discussion (AFD) at Aug 28, 3:45 AM EDT---------------
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