700
FXUS63 KLMK 201754
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
154 PM EDT Sat Jul 20 2024

.KEY MESSAGES...

*   Gradual warm up this weekend with increasing mugginess by early
    next week.

*   Shower and storm chances increase across southern KY this
    weekend, then everywhere else by next week.

*   Locally heavy rainfall possible with any of these showers and
    storms.

&&

.UPDATE...
Issued at 1038 AM EDT Sat Jul 20 2024

The current forecast remains on track this morning into the
afternoon. Rain showers from earlier this morning over the Blue
Grass have worked off to the east and we have seen some clearing on
Satellite imagery with additional cloud cover across western KY. All
of this is associated with an inverted sfc trough that will work
across parts of central/southern KY this afternoon. Think the
current thinking on shower/storm chances for this afternoon from the
previous discussion look good so no forecast/grid changes are
expected at this time.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 323 AM EDT Sat Jul 20 2024

At this hour, regional radars show an area of light rain showers
extending from just north of Burkesville to just south of Stanford.
This area of precipitation appears to be associated with the leading
edge of a low-to-mid level moisture surge from the Tennessee Valley,
with greater amounts of low clouds showing up across western KY and
much of TN on current nighttime microphysics satellite imagery. A
pronounced gradient in low-level moisture is observed in current
dewpoints, which range from the upper 60s to near 70 across southern
KY to the upper 50s across southern IN and northern KY. As we head
toward sunrise this morning, a few additional showers will be
possible, mainly across southern and southeast KY, though a sprinkle
or two will also be possible farther to the NW, close to the Ohio
River where the current band of low-mid clouds is starting to
develop.

Today, a subtle mid-level trough will swing through the Ohio Valley
and lower Midwest, providing just enough forcing to increase shower
and storm chances. At the surface, an inverted pressure trough
currently just south of the area will lift north toward to Ohio
River later today. This pressure trough should serve as a pretty
good divide between the less humid air to the NW and the more humid
air to the SE. The higher near-sfc dewpoints will lead to greater
amounts of instability south of this boundary, with 1000-2000 J/kg
SBCAPE expected along and south of the western KY/Bluegrass
Parkways. Wind shear will be seasonably weak given only 10-15 kt mid-
level flow, and although the sfc pressure trough may serve as a
boundary for low-level convergence, it will be quite subtle, so any
convection which does form should be quite disorganized. Can`t rule
out a gusty thunderstorm here or there, but generally expect
isolated to scattered garden-variety thunderstorms, with coverage
increasing the farther south and east you go in the CWA. High
temperatures will be near to slightly below normals, with most areas
reaching the mid-to-upper 80s this afternoon.

Late this evening and tonight, the loss of diurnal heating will
bring a decrease in coverage of showers and storms, leaving most
with partly cloudy skies. The weak pressure gradient over the region
should allow many areas to go calm quickly after sunset, combining
with ample low-level moisture along and south of the Parkways to
provide favorable conditions for fog development. Otherwise,
temperatures should fall into the 60s for most, with the milder
urban centers only falling into the low 70s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 323 AM EDT Sat Jul 20 2024

A weak cutoff low will slowly wobble around the lower Missouri River
Valley to end the weekend. Meanwhile, strong upper ridging will be
in place across the western Atlantic. We`ll find ourselves
sandwiched between these two features, with a steady plume of Gulf
of Mexico moisture squeezed out across a broad baroclinic zone from
the western Gulf Coast through the mid Atlantic. This pattern is
expected to persist through much of the week, bringing rounds of
showers and storms capable of locally heavy rainfall. The signal has
been consistent that the best coverage and overall heaviest rainfall
totals will be south and east of our CWA, however we will be on the
northern fringes of the enhanced PWAT plume, so fully expect
efficient rainfall rates combined with slow movement up here as
well. Overall, deep layer shear is unimpressive in the presence of
modest to moderate instability values. Severe threat would be low in
this environment, with the main concern focusing on the heavy rain
potential. Gusty winds and small hail would be secondary threats
with the strongest storms. Like the WPC Marginal Risks for Excessive
Rainfall, and it could be a scenario where some upgrades may be
needed the deeper into the week we get once rainfall totals start to
add up in spots.

Will continue the same forecast theme we have been going with as
scattered to numerous showers and storms are expected each afternoon
and evening. Best coverage should still be across southern and
eastern portions of the CWA, but the whole CWA gets in the game by
Sunday night into Monday. These should mainly be diurnally driven,
however there will likely be a few embedded waves at times that
could enhance coverage at any time of the day.

Sunday should be the warmest day with highs topping out in the 85 to
90 degree range. Most of this day should be dry across our north,
but slight chances will creep up near the Ohio River by the evening.
The rest of the work week will be slightly below normal with highs
ranging in the low and mid 80s. Temperatures will be highly
dependent on storm/cloud activity each day.

&&

.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 154 PM EDT Sat Jul 20 2024

Forecast continues to call for VFR flight categories for most of the
locations through the period. The only exception would be the
potential for fog development overnight into tomorrow morning for
RGA and BWG. Sfc boundary has worked northward as a warm front into
southern KY. SCT to BKN clouds between 5000-10000Ft will be around
and there is a chance of a few isolated to potentially scattered
showers or storms this afternoon or evening. The other feature we
will monitor will be an upper level wave pushing in from the Upper
Midwest. There is plenty of moisture ahead of this so increased
mid/upper clouds and he potential for increased precipitation
tomorrow morning into he afternoon.

&&

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

&&

$$

UPDATE...BTN
SHORT TERM...CSG
LONG TERM...BJS
AVIATION...BTN