318
FXUS63 KLMK 291933
AFDLMK

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

.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 333 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 the 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 /12Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1247 PM EDT Mon Apr 29 2024

Well...flying conditions will be changing by this evening, first
for HNB, then SDF and BWG, and late this evening for LEX and
RGA.

For this afternoon...high based cu and breezy ssw winds of 15 to 20
mph with gusts to 28 kts. Diurnal heating and WAA pattern will
bring isolated shra/tsra in 20-22z range for HNB while all other
sites should be dry.

The overnight weakening ling of convection out by MS River is slowly
reinvigorating.  This is associated with a cold front and will be
the main focus for this evening and tonight. Storms do not have
enough instability or shear to become strong, but follow normal TS
avoidance procedures.

Will continue to mention VCTS at KSDF & KBWG after 22Z. Majority of
CAMs bring best thunder chances at 2330z to 0130z. LEX and RGA best
opportunity for TS chances are in the 02z and 04z timeframe.

Large stratiform precip shield along and behind the actual cold
front will keep mvfr cigs and mvfr to vfr vsbys for 6-9 hrs or
so. Some of the guidance bring cigs close to IFR (800-1200ft
overnight). Precip will continue at LEX and RGA in the morning.

Wind shifts for HNB around 09z, SDF/BWG around 12z, and LEX and RGA
14-15z. Wind gradient behind the front is nearly non existent and
will just keep WNW winds of 7-12 mph for Tue.

Llvl clouds will lift out of HNB by 16z and SDF and BWG 16-18z Tue
and into mid afternoon for LEX/RGA.

&&

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

&&

$$

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