333
FXUS63 KLMK 282340
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
740 PM EDT Sun Apr 28 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Showers and thunderstorms likely late Monday afternoon through
    Tuesday morning. A few stronger storms capable of gusty winds
    and heavy rainfall will be possible.

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

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 319 PM EDT Sun Apr 28 2024

Visible satellite imagery shows a mix of sun and clouds across
central KY and southern IN this afternoon, with a relative maximum
in cloud cover along the I-65 corridor. Current KY mesonet obs show
temperatures a few degrees cooler in this zone, with temperatures
generally in the upper 70s and lower 80s at this hour. Breezy S/SW
winds are continuing in the presence of a tight pressure gradient;
sustained winds of 10-15 mph with gusts of 20-25 mph are noted in
latest obs. Warm and breezy conditions will continue through the
afternoon and evening hours, with winds gradually weakening around
and after sunset.

Tonight, dry weather is expected to continue in our neck of the
woods, with diurnal cu expected to dissipate and mostly clear skies
returning for the nighttime hours. A large convective complex is
expected to develop across the southern Plains and into the Ozarks
later this afternoon; while it is expected to push east toward the
Mississippi Valley later tonight, it should outrun the best
instability and weaken considerably before it approaches the western
CWA in the immediate pre-dawn hours tomorrow. Still, there is a 20-
30% chance for residual rain showers to reach our western border
communities by around sunrise Monday, with most areas across central
KY and southern IN remaining dry at least through sunrise tomorrow.
Temperatures will be unseasonably mild tonight as warm SSW flow
continues. Lows should range from 60-65 across most areas Monday
morning.

Tomorrow, the upper-level trough which has been responsible for
active weather to our west over the past few days will eject
northeastward into the upper Great Lakes and central Canada,
bringing an associated cold front into our region by tomorrow
afternoon. The trajectory of the upper-level trough is such that
large-scale forcing will be modest at best, with the weakening front
serving as the primary initiation zone for convection tomorrow
afternoon and evening. A tongue of higher boundary layer moisture
along the front will allow for modest amounts of instability, with
12Z HREF mean MLCAPE generally ranging from 200-600 J/kg. With that
being said, the lack of height falls and dry air surging in aloft
will limit overall instability, and wind profiles show fairly
unidirectional deep-layer flow. As a result, while scattered showers
and thunderstorms are expected tomorrow afternoon and evening, the
severe potential is fairly limited, though a gusty shower or storm
would still be possible. The main timing for showers and storms
looks to be after 21Z along the I-65 corridor, with much of the day
remaining dry.

Temperature forecasts are somewhat tricky tomorrow -- while it will
certainly still be warm across the region, exactly how warm it gets
will be determined by how quickly clouds along the front make it
into the region. As such, have bumped temperatures slightly above
NBM guidance east of I-65, where there is greater confidence in
mostly sunny skies through the early afternoon hours on Monday. If
clouds are slower to arrive, temperatures would likely end up a few
degrees warmer than currently advertised.

Last but not least, it will still be breezy tomorrow, with S/SW
winds picking up during the mid-morning hours. Sustained winds will
range from 10-15 mph, with gusts up to 25 mph expected.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 319 PM EDT Sun Apr 28 2024

Upper trof will cross the region Monday night, dragging a weak cold
front through the Ohio Valley with it. Convection developing over
the mid Mississippi Valley on Monday afternoon will push eastward
across Kentucky and Indiana Monday night, with enough convective
character to support embedded thunder, locally gusty winds and at
least brief heavy rainfall. Rainfall totals could exceed 1 inch in
the areas that see the strongest showers and storms.

After the precip slowly departs Tuesday, the middle of the week
looks dry as ridging amplifies over the Deep South and the Ohio
Valley. Unseasonably warm temps will continue with highs pushing
well into the 80s on Thursday, as it looks like showers associated
with the next system could hold off into Thursday night.

A series of upper waves will bring increasing rain chances, possibly
starting as early as Thursday afternoon and continuing through at
least Friday night. Details remain uncertain at this time, but
better model agreement should shed more light in the coming days.
Sfc cold front pushes through Friday night, but can`t rule out post-
frontal precip lingering into Saturday. We`ll carry a 30-40% chance
of precip on Saturday for now, but confidence is low. We can say
with better certainty that temps should continue to run on the high
side of normal for early May.

&&

.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 739 PM EDT Sun Apr 28 2024

There is high confidence in VFR ceilings and visibilities at all
sites tonight into the pre-dawn hours tomorrow. Most lingering low-
mid level cu should dissipate over the next 1-2 hours as we lose
daytime heating, while the nighttime low-level inversion should also
help to reduce wind gusts. The main forecast concern overnight is
LLWS as a 45+ kt LLJ moves across western KY and southwest IN after
06Z. Have included LLWS mention for SDF/HNB/BWG, which will be
closest to the jet core, but marginal WS is also possible at LEX/RGA
between 08-13Z tomorrow.

Just before sunrise tomorrow morning, a decaying band of showers
will approach HNB. There is low-medium confidence that this band of
showers will hold together to make it to HNB, and any impacts from
this area of showers should be minimal. Ceilings will begin to
decrease from west to east during the day on Monday, although
daytime heating should help keep things VFR through sunset tomorrow
night. Winds should also become gusty out of the S/SW during the mid-
morning hours as a cold front continues to slowly move closer to the
region.

A secondary band of showers and storms is expected to develop
tomorrow afternoon and move west to east across local terminals
through the evening and nighttime hours Monday into Tuesday. This
area of showers and storms may bring reduced CIGs and VIS, as well
as gusty winds; however, confidence in TS is too low at this time to
carry anything more than vicinity mention.

&&

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

&&

$$

SHORT TERM...CSG
LONG TERM...RAS
AVIATION...CSG