270
FXUS63 KLMK 182346
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
746 PM EDT Wed Sep 18 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*  One or two showers are possible this evening, with lingering
   moisture contributing to the development of fog Thursday morning.

*  Mainly dry and hot weather tomorrow through Sunday with highs
   each day around 90 degrees.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 304 PM EDT Wed Sep 18 2024

This afternoon, the remnant mid-level low from the tropical system
earlier this week is centered over the upstate of South Carolina.
Greater sfc-700 mb moisture in the vicinity of this mid-level low
has allowed for the development of a broken stratocumulus cloud
layer this afternoon, with the thickest cloud cover currently being
observed south and east of a line extending from Munfordville to
Mount Sterling. With a fairly deep layer of near saturation present,
an isolated rain shower will be possible this afternoon into the
early evening hours, particularly along and east of US 127. At this
hour, temperatures range from the mid-70s to the mid-80s depending
on cloud cover, and it`s expected that we`ll add another few degrees
area-wide for highs this afternoon.

This evening into tonight, the mid-level low is expected to pivot to
the east, allowing drier air in the mid-troposphere to be drawn into
the area from the north. Once we lose daytime heating, much of the
stratocu field is expected to dissipate, and clearing skies are
expected into the overnight hours. With boundary layer mixing this
afternoon limited by the extra cloud cover, ample near-sfc moisture
will remain over much of the area into Thursday morning. With a weak
pressure gradient keeping winds calm or light/variable overnight,
conditions will be favorable for fog across the area early Thursday
morning. One uncertain factor is whether or not a few low-mid clouds
will linger overnight, potentially limiting sfc decoupling. Given
the signal, will go ahead and advertise patchy and/or areas of fog
in this forecast.

On Thursday, any lingering fog should burn off quickly after sunrise
as sunshine allows drier air aloft to mix down to the surface.
Increasing heights and thicknesses aloft will promote a continued
warming trend, and drier mid-level air should also lead to less
diurnally-enhanced cloud cover tomorrow in the late morning and
afternoon hours, though extra clouds will still be expected in
eastern and southeastern portions of the FA. Light north winds and
high temperatures ranging from the mid 80s to the low 90s are
expected on Thursday, starting a stretch of multiple unseasonably
warm and dry days in a row.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 304 PM EDT Wed Sep 18 2024

Thursday Night - Friday Night...

Upper ridge axis holds over our area to end the work week, keeping
us dry and above normal for high temps. Plenty of sunshine and H85
temps nearing 20C will allow for highs in the upper 80s and lower
90s. Quite a bit of spread among MAV/MET guidance, however like
something close to the NBM which pretty much splits the difference.
Lows should mostly be in the low and mid 60s.

Saturday - Sunday Night...

By early Saturday morning, a weak frontal boundary trailing from a
northern Manitoba surface low will work into our area, and likely
stall through the weekend. This feature is expected to be very weak
and lacking in overall deep moisture. As a result, don`t expect a
whole lot out of it other than some increased mid to upper sky
cover. There are some models that are hinting at a few very isolated
showers over the northern half of the CWA. Not sure coverage would
be enough to justify a 20% mention at this time, and anticipate a
bit of a drying trend in the data by then given how the moisture
profile looks on soundings/time heights. Warm temperatures in the
upper 80s and low 90s continue through the weekend.

Monday - Wednesday...

A much stronger area of low pressure wobbles over southern Canada
with mid level troughing overspreading the central CONUS into the
Great Lakes/Ohio River Valley region by early next week. This will
drag another and stronger cold front into our region, bringing
chances for showers and a few storms through mid week. Overall,
temperatures should be cooler during this stretch, falling back into
the 80s for highs, and even upper 70s and low 80s by the Wednesday.

Looking beyond the current forecast window, a potential tropical
system coming out of the Gulf may need to be monitored if it
develops, and depending on its eventual track. The aforementioned
upper trough (prevailing westerlies) would ultimately play a role in
whether that potential tropical system decides to take a more
easterly route.

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 745 PM EDT Wed Sep 18 2024

SCT stratocu at 5-6 kft continues to thin and dissipate this
evening, which will leave us with mostly clear skies at the start of
this TAF period. SCT thin cirrus will drift overhead from west to
east late tonight into early Thursday.

However, the primary aviation impact will likely be fog between 06-
13Z Thu. MVFR and at least brief IFR/LIFR vsbys appear likely in fog
at all of our terminals, except for SDF. Impactful fog looks
unlikely at SDF, but temperatures early Thursday should easily meet
or sink below crossover temperatures. Impactful dense fog will be
possible between 08-12Z at BWG/RGA/HNB. Fog will clear by mid-
morning, with VFR conditions and light winds the rest of the day.

&&

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

&&

$$

SHORT TERM...CSG
LONG TERM...BJS
AVIATION...EBW