-- Discussion containing changed information from previous version are highlighted. --
142
FXUS63 KLMK 211729
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
129 PM EDT Fri Jun 21 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Heat continues for the end of the week into the weekend with
    near-record highs for some locations today and Saturday.

*   Scattered showers and storms possible Sunday, and again by the
    middle of next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 257 AM EDT Fri Jun 21 2024

Synopsis...Strong mid-level ridge will slowly weaken and move south
of the Lower Ohio Valley as a Pacific shortwave trough ejects to the
north-central US. At the surface, stagnant high pressure will
continue promoting dry and hot conditions.

Today...Latest satellite imagery reveals mostly clear skies over the
forecast area with a few mid-level clouds to the west. The resultant
radiational cooling in combination with light winds have allowed
saturated conditions at several stations, with some already
experiencing visibility reductions due to developing fog. Based on a
well-mixed boundary layer yesterday afternoon and current relative
humidity inversion profiles from the KY Mesonet, most instances of
fog should be light, shallow and mostly focus on river valleys and
close to bodies of water. Rest of today will be characterized by
hotter temperatures (relative to yesterday) and comparably humid
conditions. Therefore, peak heat index values this afternoon will
range anywhere from 96 to 102 degF, prompting recommendations to
stay hydrated and cool while limiting sun exposure. There is even a
chance of tying or breaking record highs at SDF and LEX (see Climate
section below for more information). Otherwise, winds will remain
light and variable accompany by fair weather cumuli.

Tonight...Mostly clear skies are anticipated after sunset with winds
starting off calm or light and variable, but a light southwest flow
could could kick off the second half of the night as the high
pressure moves to the south and the Pacific trough advances across
the west. The aforementioned wind change and the well above-average
temperature trend increased confidence to raise lows, by several
degrees, to the point that some warm min records could be in
jeopardy.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 257 AM EDT Fri Jun 21 2024

Hot and dry weather will continue into Saturday as the region
remains under the influence of a strong, elongated upper level ridge
that stretches across much of the southern CONUS. Highs Saturday and
Sunday will likely climb into the 92-97 degree range, and with
dewpoints in the mid 60s to right around 70, this will result in
heat indices peaking around 97-102 degrees. The core of this upper
level ridge will begin to retrograde westward Sunday as low-
amplitude upper level trough swings from the Plains into the Great
Lakes region. Our region will receive a glancing blow from it as
most of the better forcing and lift stay off to our north, but it
will provide some chances for much needed rainfall in the form of
scattered showers/storms during the day Sunday.

Our upper level trough will begin to deepen over the eastern CONUS
on Monday, but elongated ridging centered over the Desert SW and
southern Plains will try to nudge back toward the Tennessee and Ohio
Valleys. As a result, we really won`t see much in the way of a drop
in temperatures with the passage of this trough, and temperatures by
Tuesday may even climb back into the mid/upper 90s. One slight piece
of good news with the warmup early next week is that dewpoints
should drop well into the 60s behind the upper trough with only a
gradual build up to higher values by midweek. This will help to off-
set the heat indices from getting too terribly high above the air
temperatures on Monday and Tuesday. Additionally, by late Tuesday
into Wednesday of next week, we may see another upper trough swing
into the region and bring scattered showers/storms along with clouds
to keep temperatures closer to climo normals.

&&

.AVIATION /18Z TAFS THROUGH 00Z SUNDAY/...
-- Changed Discussion --
Issued at 128 PM EDT Fri Jun 21 2024

The forecast will continue to feature VFR flight categories through
the period. Combination of large upper ridge and sfc high pressure
across the region has lead to mainly fair weather over the region.
Current visible satellite imagery shows mainly scattered Cu over
Kentucky and southern IN. This should continue through the afternoon
with CIGs with the Cu field around 5000 ft. Wind are calm to light
and variable. Skies should become mostly clear with the loss of
daytime heating but with the warm temperatures overnight fog may be
less of an issue than it has been over the last couple of mornings.
An approaching storm system tomorrow will start to tighten the
pressure gradient over western KY and southwestern IN during the
afternoon. Winds will slowly increase to around 10kts out of the
southwest near the end of the period with mostly clear skies once
again.
-- End Changed Discussion --

&&

.CLIMATE...
Issued at 257 AM EDT Fri Jun 21 2024

** Near-Record Heat Potential Mainly for Today and Saturday **


               Friday 6/21/2024
          Max T Fcst/Record (Year)

Louisville:       98/98     (1988)

Bowling Green:    97/102    (1933)

Lexington:        97/97     (1988)


             Saturday 6/22/2024
          Max T Fcst/Record (Year)

Louisville:       97/100    (2022)

Bowling Green:    97/102    (1901)

Lexington:        96/99     (1988)


               Sunday 6/23/2024
          Max T Fcst/Record (Year)

Louisville:       92/98     (1988)

Bowling Green:    93/104    (1930)

Lexington:        91/96     (1988)


Some records may have occurred in multiple years. The latest year
the record was tied is displayed.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Air Quality Alert until 1 AM EDT Saturday for KYZ029>031.
IN...Air Quality Alert until 1 AM EDT /midnight CDT/ Saturday for
     INZ076>079-083-084-089>092.

&&

$$

SHORT TERM...ALL
LONG TERM...DM
AVIATION...BTN
CLIMATE...DM