-- Discussion containing changed information from previous version are highlighted. --
670
FXUS63 KLMK 192329
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
729 PM EDT Wed Jun 19 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Some fog development likely overnight. High temperatures well
    into the 90s return for many tomorrow.

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

*   Next chance of rain Sunday into early next week.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 328 PM EDT Wed Jun 19 2024

Elongated upper ridge axis from the mid Mississippi River Valley out
through the mid Atlantic today will center more over our region by
tomorrow. This will keep us in a dry pattern with hot and somewhat
humid conditions continuing.

Considerable upper cloudiness has kept temperatures and resulting
heat indices in check today as temp values are only running in the
mid to upper 80s at this time. With dew points mostly remaining in
the mid and upper 60s, heat indices aren`t all that impressive at
the moment. We`ll "enjoy" this brief reprieve from the more
substantial HI values, as they will begin to be more oppressive
tomorrow and into late week/weekend.

We do expect to lose most of the upper sky cover later this evening
around sunset, and with calm to light and variable winds expected we
should see a pretty decent radiational cooling setup. As a result,
expecting some fog potential especially in our CWA. Have messaged
patchy/areas wording in many spots, and will monitor how well we mix
at peak heating this afternoon for any adjustments to intensity of
fog.

Should see a notable uptick in high temperatures tomorrow as mostly
sunny skies and the upper high pressure centers over our region. H85
temps around 18-20C, with mixing even a bit deeper than that has me
leaning a bit more on the high side of the guidance envelop, which
should put us more solidly in to the low and mid 90s. These temps
combined with dew points in the upper 60s to near 70 in many spots
will yield heat indices peaking back into the mid and upper 90s
tomorrow afternoon. Late week heat has been messaged well so far,
and no plans to change that messaging at this point.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 328 PM EDT Wed Jun 19 2024

Main weather focus remains the heat going into the end of the week
and the start of the weekend. The mid-level ridge will be at its
peak around 600dm Thursday night into Friday as the ridge begins to
weaken and flatten with a more west-east orientation from the Four
Corners towards the Deep South. With more available sunshine due to
less cloud cover, the strong ridging as well as subsidence, highs
will be their hottest on Friday and Saturday approaching the upper
90s with a few locations potentially hitting 100. We could also see
record challenging highs both day for a few locations listed in the
climate section below. It will also be rather muggy with dew point
temperatures in the low 70s but daytime mixing in the afternoon will
help to lower dew points into the upper 60s. Heat index values will
still be just shy of advisory criteria but feeling like they are in
the low 100s each afternoon. While an advisory is not likely,
overnight lows will only fall into the low/mid 70s so a headline may
still be warranted given the lack of relief.

The upper ridge will continue to flatten out with a more zonal flow
over the region as the height anomalies push further south and
slightly weaken. A weak upper trough coming out of Canada and
working along the US/Canada border will push a sfc low and its weak
cold front eastward across the Great Lakes and the Ohio Valley
during the day Sunday. While temperatures will be a few ticks
cooler, heat will remain with highs on Sunday in the low/mid 90s
thanks to increased cloud cover associated with moisture coming up
from the south ahead of the weakening boundary. We could also see a
few showers and thunderstorms out ahead of the boundary but the best
lifting dynamics looks to remain well to our north. Sfc high will
build in behind the parting system to start the week with ridging
expanding back eastward through mid-week. Temperatures will respond
by heating back up from the low 90s on Monday back into the the mid
to even upper 90s for Tuesday and Wednesday. The ridging won`t  be
nearly as strong as it will be for the end of this week but little
relief overall from our extended period of 90+ degree weather. Lows
will also remain mild with lows near 70 with the exception of
Tuesday morning with morning temperatures in the mid/upper 60s.
Another shortwave trough will work along the northern tier of the
ridge and bring another increased chance of showers and storms
associated with a passing boundary by the middle of next week.

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
-- Changed Discussion --
Issued at 729 PM EDT Wed Jun 19 2024

Upcoming TAF period will remain dry with VFR conditions this
evening.  Will have to contend with high level cirrus moving over
the region, but this is expected to dissipate overnight.  Surface
winds this evening will generally be out of the southwest to south
and less than 5 knots.  Overnight, good radiational cooling is
expected which should lead to some patchy fog development.  Will run
some patchy fog in at KHNB/KSDF.  There is a stronger signal in the
data for possibly some IFR fog over at KLEX.  For now, will add a
tempo IFR vsby group between 20/09-12Z for fog.  The outlook for
Thursday calls for VFR conditions at all the terminals.
-- End Changed Discussion --

&&

.CLIMATE...
Issued at 328 PM EDT Wed Jun 19 2024

================== Near-Record Heat This Weekend ==================


               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:       98/100    (2022)

Bowling Green:    97/102    (1901)

Lexington:        97/99     (1988)


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

Louisville:       95/98     (1988)

Bowling Green:    97/104    (1930)

Lexington:        95/96     (1988)


Note 1: Sunday temperatures are highly dependent on the arrival
of an approaching cool front. If the front ends up slower, as
some data suggests, then forecast temperatures will trend
warmer.

Note 2: 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 from midnight tonight to midnight EDT
     Thursday night for KYZ029>031.
IN...Air Quality Alert from midnight EDT /11 PM CDT/ tonight to
     midnight EDT /11 PM CDT/ Thursday night for INZ076>079-
     083-084-089>092.

&&

$$

SHORT TERM...BJS
LONG TERM....BTN
AVIATION.....MJ/REJ
CLIMATE......BTN