143
FXUS63 KLMK 300009
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
809 PM EDT Mon Apr 29 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Showers and scattered thunderstorms will be possible later this
    afternoon before coming to an end tomorrow.

*   Dry and warm Midweek with highs in the mid to upper 80s

*   Additional showers and thunderstorms possible late in the week,
    though confidence in exact timing remains low.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 808 PM EDT Mon Apr 29 2024

Currently, a low pressure system is over the Minnesota/Wisconsin
border. To the south, a cold front extends from the surface low and
runs through Chicago and sweeps to the southwest towards the Ozarks.
Satellite imagery shows dense cloud cover ahead of the front with
clear skies behind it. It`s in this cloudy area that low level flow,
wrapping around high pressure over the Southeast, is bringing
moisture north from the Gulf of Mexico. Precipitable water values
are climbing to around 1.5" ahead of the front.

As we head through the afternoon and evening hours, precipitation
chances will begin increasing from west to east over southern
Indiana and central Kentucky. Even though the area of precipitation
isn`t all that wide, the system is moving fairly slowly, so by
sunset, many in the Bluegrass and Lake Cumberland regions will
likely remain dry. For the areas in the western part of the CWA,
model soundings show a decent amount of dry air near the surface
with high LCLs over 1 km. MLCAPE could reach a few hundred J/kg, so
some thunder could develop. Overall, not expected severe weather.

Tonight, sounding profiles quickly become stable with moist profiles
saturating the low level dry layer, so the chance of thunder will
lessen as the rain moves east across the rest of the CWA. The
majority of the CWA will see the majority of their rainfall during
the overnight hours. Dubois County, IN could be the exception with
most of their rainfall coming prior to 0z Tuesday (8 PM EDT this
evening). Lows are expected to fall into the low 60s.

The cold front should begin to work into our southern Indiana
counties around 10-11z in the morning, and by the afternoon it
should be through central Kentucky. Behind the front, winds will
flip to the northwest, but they will be light, around 5-10 mph.
Skies will quickly clear behind the front. Temperatures will warm
into the 70s. Along the eastern side of the CWA, rain may take
awhile to come to an end. This will help keep temperatures a little
cooler in the low 70s while along and west of Interstate 65,
temperatures will likely reach the mid and upper 70s. For most,
rainfall totals are expected to range from around half of an inch to
around 1.5 inches.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 333 PM EDT Mon Apr 29 2024

Midweek will feature dry and warm conditions as ridging builds in
over the Ohio Valley. Southerly winds will increase WAA over the
area pushing afternoon temperatures into the 80s Wednesday with
warmest day Thursday and highs in the mid/upper 80s.

As the upper ridge continues to become more amplified over the
eastern third of the US, an upper trough will become more negatively
tilted late Thu into Fri as a sfc slow deepens over the Upper
Midwest into western Ontario, Canada. This will push a weak cold
front into the Ohio Valley increasing the shower/thunderstorm threat
for the end of the week. While the 00z CIPS has a shaded 10 percent
probability of severe weather across the eastern half of KY on Fri,
the Machine Learning outlook from the same time keeps the better
chance of severe off to the southwest over the Lower Mississippi
Valley. Models continue to show a couple hundreds J/Kg of SCAPE with
a little shear. While not impressed with the threat of severe, still
wouldn`t rule out the possibility of some thunderstorms during the
day Friday. Timing of the boundary could play a role, as the 12z GFS
is a bit faster moving the boundary through during the morning while
the ECMWF is slower bringing the boundary and activity through
towards the afternoon.

Weak area of sfc high pressure will push in over the Great Lakes
late Friday into early Saturday ahead of a second cold front that
will work in from the northwest out Central Plains on Sunday. Return
flow out of the south will advect low-level moistures from the south
with increased instability for Saturday. NBM has increased PoPs
Saturday from around 30 to now closer to 40/50. Given the latest 12z
of the GFS and ECMWF, personally feel this is too high. There
continues to be in inconsistency run to run in the models which
leads to lower confidence on current rain chances for the start of
the weekend.

Pattern looks to remain active from the second half of the week into
early next week. Ridging looks to build in over the eastern two-
thirds of the CONUS for the start of the week. Low 80s and increased
dew points into the low 60s will keep instability around each
afternoon/evening. Think 30 to 40 PoP seems reasonable at this time.

&&

.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 808 PM EDT Mon Apr 29 2024

Ahead of an approaching cold front, showers with some very isolated
thunder is beginning to enter the region from the west, and as the
sun sets, chances of thunder will continue to decrease. An isolated
rumble of thunder or two will remain through the night, but
expecting mostly rain at area TAF sites. Ceilings are expected to
drop into MVFR levels as rainfall becomes more widespread later
tonight. A few places could see IFR ceilings for a short time, but
the best chances for IFR ceilings currently look to be towards the
west, over southwest Indiana and western Kentucky, starting around
10z. This could impact HNB, but believe BWG will remain far enough
east to not be impacted. This is as the front begins to work through
the area from the northwest. Skies behind the front will begin
clearing as winds veer towards the northwest and north.

&&

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

&&

$$

SHORT TERM...KDW
LONG TERM...BTN
AVIATION...KDW