034
FXUS63 KLMK 271328
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
928 AM EDT Fri Jun 27 2025

.KEY MESSAGES...

* Heat Advisory continues through this evening.

* Chances for mainly afternoon/evening showers and storms each day
  through Tuesday.

* Less humid conditions arrive next Wednesday and Thursday.

&&

.UPDATE...
Issued at 928 AM EDT Fri Jun 27 2025

A little cooler start to the morning at many sites. GOES sounder
data shows plume of higher precipitable water over western KY, but
with a notch over south central KY right now. This notch shows up in
HREF model forecasts and moist atmosphere should continue over the
area this afternoon. The result should mean scattered to numerous
storm coverage over southern KY. A relative lull, that is, isolated
coverage, looks to be in the LEX/SDF corridor. Once again, no real
shear across the region, so should be a nice day to watch for
microbursts from the taller cores that develop.

Hopefully the last day for the heat advisories across the region.
Rain chances will be higher across the board tomorrow, so that
should limit values to under 100.  Likely will be able to keep
current expiration time as is.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 333 AM EDT Fri Jun 27 2025

Slightly weakened upper ridge remains draped east to west across the
Ohio Valley. Hot and humid air mass remains in place in the low
levels, and we`ll have fairly similar conditions to Thursday,
perhaps with a bit less convective coverage. Still looks like
scattered afternoon thunderstorms, and while shear is too weak to
support organized severe wx, there is plenty of instability for your
typical pulse storm hazards, i.e. gusty or locally damaging winds
and torrential rainfall.

Heat Advisory carries on for one more day, as temps will rise
quickly this morning and crack 90 in many locations before noon.
There is a sufficient window of opportunity for 100+ heat index
values before convective outflow can provide any relief.

Any storms should fade fairly quickly around sunset, leaving behind
another warm and muggy night. Will hang on to a 20 POP in quite a
few spots just because of the tendency for such a juicy air mass to
spark an isolated nighttime storm or two.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 333 AM EDT Fri Jun 27 2025

Unsettled pattern this weekend into early next week with weak zonal
flow aloft and a juicy low-level air mass in place, supporting
mostly diurnally driven thunderstorms each day.

On Saturday, an upper shortwave trof moving east across the Great
Lakes will push a cold front toward the Ohio Valley, but the
boundary will hang up across Illinois and Indiana. Scattered to
numerous showers and storms are possible, but will be mostly garden-
variety convection as shear is too weak to support severe wx, and
the better focus for training and heavy rainfall will be to our
north. Could still see a stray pulse storm that would be capable of
producing gusty, locally damaging winds.

Another peak in precip chances will come Monday and Tuesday as a
sharper upper trof finally drives a cold front solidly into the Ohio
Valley. Expect widespread showers and storms with that system, with
severe risk limited to pulse storm hazards as the stronger wind
fields remain to our north.

Latter half of next week will feature a low-amplitude upper trof
over the Great Lakes and eastern Canada, with NW flow over the Upper
Midwest helping to build a bubble of sfc high pressure into the Ohio
Valley. Wednesday through Friday will have near-normal temperatures,
but manageable dewpoints in the lower to mid 60s. Precip chances
will be limited to isolated diurnal pop-ups, mainly across southern
Kentucky but starting to expand northward on Independence Day.

&&

.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 635 AM EDT Fri Jun 27 2025

Main challenge is timing and impact of scattered thunderstorms this
afternoon and evening, assuming they actually impact each of the
terminals. Brief IFR vis possible with the heaviest rain, but figure
3SM is the lowest that will stick around for any length of time. CB
bases won`t be very low, most likely 3-4K feet. Given the hit-and-
miss nature of expected convection, will handle it with a PROB30
focused mainly on the 20Z to 02Z Sat time frame.

Otherwise expect prevailing VFR conditions with SW winds around 10
kt during the mixy part of the day, diminishing and backing to due
south again once the sun sets.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for
     KYZ023>043-045>049-053>057-061>067-070>078-081-082.
IN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for
     INZ076>079-083-084-089>092.

&&

$$

UPDATE...RJS
SHORT TERM...RAS
LONG TERM...RAS
AVIATION...RAS