372
FXUS63 KLMK 060057
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
857 PM EDT Wed Jun 5 2024

.KEY MESSAGES...

*   Scattered showers and storms likely this afternoon and evening.
    A few strong to severe storms are possible. Gusty winds and
    torrential rainfall will be the main threats.

*   Drier weather and cooler temperatures are favored late week into
    the first half of this coming weekend.

&&

.UPDATE...
Issued at 857 PM EDT Wed Jun 5 2024

Moderate to heavy rain showers ahead of an approaching cold front
currently working into western IN will continue to work across the
area this evening and overnight. There were a few isolated storms,
mainly across Hardin and into Nelson Counties this evening that took
advantage of better effective shear (30 kts) and higher MLCAPE 1000-
1500 J/Kg but more recent analysis shows CAPE values dropping as we
continue to lose the daytime heating. As the activity continues to
move more to the east slowly this evening, we may see convection
become more elevated. PWAT values remain between 1.70" to 1.90"
ahead of the boundary thanks to good moisture pooling ahead of the
boundary. This makes heavy rain and some localized flooding the main
concern with any storms that form later this evening and overnight.

Given some of the uncertainty of where activity would fire this
evening, previous forecast had a wide swath of 50-60 PoPs across the
CWA. Now that we see how activity has been developing, went ahead
and cleaned up some of the PoPs to better reflect the ongoing
situation across our CWA with higher PoPs across southern IN and
along the OH with lower PoPs right now to the south and east. Then
we increase PoPs towards the east and south as the boundary works
closer and we see more development overnight. Other than that, not
other changes have been made to the forecast and updated product
will be pushed out here shortly.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 333 PM EDT Wed Jun 5 2024

Afternoon satellite imagery shows partly to mostly cloudy skies
across the region.  Earlier MCV over southern KY continues to churn
eastward helping firing convection over mainly eastern KY.  In the
wake of the MCV, some partial clearing is trying to take place
across portions of central KY (I-65 corridor) ahead of an
approaching cold front.  Afternoon temperatures were generally in
the low-mid 70s in the cloud cover.  In areas that had partially
cleared, temps had warmed back into the upper 70s to around 80. Some
low-mid 80s were located down in the Pennyrile region of western KY.

Mesoscale analysis shows instability building across the central
part of the region with MLCAPE values in the 800-1200 J/kg range
with about 30kts of bulk shear.  Low and mid-level lapse rates were
still quite meager with rates running around 6 C/km.  PWAT values
were quite high with widespread 1.7 to 1.8" values, so we have
plenty of primo juice to work with.

For the remainder of the afternoon, additional forcing for
convection remains rather nebulous in the wake of the passing MCV.
Frontal forcing remains well to our northwest for now.  Some
additional insolation may result in an uptick of convection along
differential heating boundaries, so will keep isolated/scattered PoP
coverage going into the evening hours.  Any strong storm will be
capable of producing torrential rainfall, gusty winds, and frequent
lightning.  Localized flash flooding will be a threat, especially in
areas that have seen recent rainfall.

Moving into the evening hours, surface frontal boundary to our
northwest will sink southward into the region.  Majority of the 12Z
CAMs suggested an uptick in convection along and just ahead of the
front and we`re already seeing the start of that across
central/southern IL.  Early evening coverage looks to be most
concentrated across southern IN back into southwest KY.  This
activity should then drop southward into north-central/east-central
KY this evening while weakening as we loose heating/instability. The
storms this evening could be on the strong side with torrential
rainfall, gusty winds, and frequent lightning being the main
threats.  We`ll have to be on guard for some localized flash
flooding given that these storms should be efficient rain producers.
The risk of flooding will be highest where storms tend to train over
the same locations.  Overnight, the front will continue to push
south/southeastward with rain chances ending from NW to SE.
Overnight lows will cool into the lower 60s over southern IN and
in the mid-upper 60s over much of central/eastern KY.

For Thursday, overnight cold front will continue to push southeast
during the morning hours.  We`ll have some lingering low-level
moisture that will be in place during the morning hours.  A
secondary frontal boundary will drop into the region during the
afternoon and may spark an isolated shower or two, mainly across our
far eastern counties.  Highs for Thursday will be near normal with
lower-middle 80s expected.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 333 PM EDT Wed Jun 5 2024

Thursday Night through Friday Night...

A sfc cold front will be well southeast of the area by Thursday
night, with northwesterly flow at all levels. Cooler, drier air
filters into the region Thursday night with temperatures falling
into the mid/upper 50s. Dry NW flow continues through Friday with
high pressure centered over the southern Plains and Lower MS Valley.
Expect sunny skies and lower humidity (sfc dewpoints in the lower
50s). Afternoon highs will reach the 75-80 degree range. It will be
a bit breezy with NW winds of 10-15 mph, gusting to 20-30 mph.
Friday night temperatures will be on the cool side of normal with
lows in the 50s.

This Weekend into Early Next Week...

The upper level pattern deamplifies a bit Saturday with ridging
aloft now centered over the western Gulf Coast. An upper level
shortwave trough is forecast to rotate southeast over the Upper
Midwest and Great Lakes. Weak low pressure spinning up over the
southern Plains will also help lead to strengthening SW return flow
from the southern Plains east across the Mid-MS and Lower OH
Valleys. This will result in modest moisture advection into the OH
Valley, but the atmosphere looks to remain rather stable. We could
see some weakening convection attempt to push into central or
southern KY by evening, but a largely dry day appears likely at this
time. Afternoon highs will be in the mid/upper 70s in most areas.

The upper level trough over the Great Lakes deepens as it drops
south late in the weekend, and a weak sfc cold front is forecast to
drop south through southern IN and central KY. Rainfall chances tick
upward late Saturday night into Sunday, especially across southern
KY. However, rainfall totals are forecast to be relatively light
(generally a quarter-inch or less). Some areas across southern IN
and north-central KY may not see much rain at all during this time
frame.

Another push of cool, dry air advection from the north will likely
yield fair weather heading into early next week. Highs in the
mid/upper 70s look likely for Monday, perhaps with a couple spots
near 80 F. Most areas will approach 80 degrees by Tuesday.

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 843 PM EDT Wed Jun 5 2024

Area of showers and a few isolated thunderstorms are located mainly
north or along the Ohio River with just a few showers/storms forming
to the south. Winds have not been that gusty and the environment is
not great for a lot of convection but enough for a few isolated
storms. The best chance for this will towards LEX later this evening
and overnight as a cold front currently working across central
pushes into the area later this evening and overnight. This will
push the showers through. Again some of these showers could have
heavy rain with brief period of IFR conditions but so far haven`t
seem much of that this afternoon or evening. Generally left it out
of the TAFs.

Once the front moves through we could see some MVFR and a brief
period of IFR conditions for BWG-LEX-RGA in the earl morning hours.
Once the front clears for SDF/HNB likely going to see clearing then
a wind shift more out of the west. Expect clearing near or shortly
after sunrise for BWG-LEX-RGA with improvement to VFR. Winds will
also pick up behind the front with gust during the day tomorrow out
of the west around 20-25 Kts.

&&

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

&&

$$

UPDATE...BTN
SHORT TERM...MJ
LONG TERM...EBW
AVIATION...BTN