498
FXUS63 KLMK 200527
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
127 AM EDT Thu Jun 20 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.

&&

.UPDATE...
Issued at 947 PM EDT Wed Jun 19 2024

Current satellite and observations show clear to partly cloudy skies
across the area. Temperatures range from the low to mid 70s across
the area with the urban areas still in the lower 80s. Current
forecast remains in good shape. Skies are expected to clear out
overnight with patchy river fog developing. Overnight lows are
expected to be in the upper 60s to around 70s. With mid 70s in he
urban areas.

&&

.SHORT TERM /THROUGH FRIDAY/...
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 /FRIDAY 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 /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 125 AM EDT Thu Jun 20 2024

Impacts/Confidence:
- Medium confidence in MVFR VIS this morning due to light fog
- Low confidence in IFR VIS at LEX and RGA

Discussion...Surface high pressure moving across the region will
maintain VFR conditions and light, variable winds for this TAF
period. Only exception will be a brief chance of MVFR visibilities
towards sunrise at some terminals. Current surface observations
indicate saturation with reducing visibilities across the Bluegrass.
Satellite imagery reveals dissipating cirrus deck in central KY,
given way to additional radiational cooling and potentially
development/maintenance of fog at BWG,LEX,HNB, and RGA. Fog
development at SDF is lower confidence given the current dewpoint
depression.

Extended Outlook...Another fog event is possible tonight with
MVFR/IFR visibilities.

&&

.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 until midnight EDT tonight for KYZ029>031.
IN...Air Quality Alert until midnight EDT /11 PM CDT/ tonight for
     INZ076>079-083-084-089>092.

&&

$$

UPDATE...REJ
SHORT TERM...BJS
LONG TERM...BTN
AVIATION...ALL
CLIMATE...BTN