185
FXUS63 KLMK 090555
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
155 AM EDT Wed Jul 9 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Isolated to scattered thunderstorms could produce locally gusty
  winds and brief torrential rainfall this afternoon. Storm coverage
  will diminish by this evening.

* Warm and humid all week, with scattered showers and thunderstorms
  expected each day. Organized severe weather is not expected.

&&

.UPDATE...
Issued at 943 PM EDT Tue Jul 8 2025

Area radars are quiet at this hour as the nearest convection resides
across southern TN and northern AL. A convective complex over the
mid-Miss. valley has weakened over the past few hours, in line with
this afternoon`s HRRR guidance. Would expect the rest of this area
of showers and storms to fall apart with the loss of heating over
the next few hours.

For the rest of tonight into Wednesday morning, mostly dry
conditions are expected. Baggy mid-level troughing is in place just
NW of the area, and 10-15 kt low-level SW flow will persist across
the southeastern half of the CWA. This may be just enough to set off
a few showers early Wednesday morning; however, these should be
fairly isolated. Convective debris clouds will drift overhead from
the south and west overnight. While this may limit widespread fog
development, patchy fog is still likely near bodies of water and in
areas which received rain today. Otherwise, another seasonably mild
night is expected, with lows falling into the upper 60s and lower
70s.

For this update, just freshened overnight PoPs and temperatures to
match latest hi-res trends. The forecast remains on track.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 319 PM EDT Tue Jul 8 2025

Weak sfc boundary is along the Ohio River today, with sfc temps in
the upper 80s and low 90s across the forecast area, and dewpoints in
the upper 60s and lower 70s. A cluster of thunderstorms is noted
across western KY, being driven by a pocket of deep moisture
convergence and upper level divergence. Despite marginal
instability, little to no wind shear is keeping any convection
unorganized. PWATs above 1.5" will support some heavy rain rates
near the BWG area. Overall, this cluster of storms is expected to
continue to weaken as it pushes east this afternoon. CAMs have
performed poorly today, so confidence in additional precip outside
of this cluster remains low.

By this evening, the loss of daytime heating will promote a decease
in precip activity. Overnight, mid-level clouds will linger overhead
as we remain under the influence of general troughiness and the weak
frontal boundary. Before sunrise, some patchy fog may develop,
especially in our valleys and any areas that do pick up some rain
this afternoon.

For tomorrow, the weak boundary is expected to dissipate, though we
will remain in a warm and muggy airmass. Stacked shortwave energy is
supporting a sfc low over the Great Lakes, with a trailing cold
front through the Midwest. This front will shift southeastward by
tomorrow, and will be cutting across central IN and IL by the end of
the day. The combination of warm daytime heating and muggy airmass,
along with marginal instability ahead of the front, will support
additional isolated to scattered shower and storm development across
the region tomorrow, especially in the afternoon. Model soundings
suggest PWATS to be above 1.7", suggesting heavy rain possible. Wind
shear will be weak, leading to another day of messy garden variety
storms, with slower storm motions.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 319 PM EDT Tue Jul 8 2025

Upper level troughing will remain over the region for Wednesday
night and into Thursday, with upper ridging centered over the
southwestern US. A second weak cold front will be shifting southward
through the upper Ohio Valley on Thursday, driven by a sfc low
passing over the Great Lakes. Additional showers and storms will be
possible Wednesday night and Thursday as we remain in a warm and
humid airmass. The front is not expected to pass through the
forecast area, likely getting stalled out north of the Ohio River on
Thursday and Friday. This will keep our forecast area in the warm
side of the boundary, with muggy dewpoints and above average PWATs
available for afternoon destabilization as we warm into the upper
80s and lower 90s. Diurnally-driven storms will fire off in a
marginally unstable environment, but weak flow in the column will
keep wind shear weak. This will promote storms to be unorganized,
though should be capable of producing heavy downpours and gusty
winds.

As we get into the weekend, the frontal boundary will lift north of
the region, though additional shortwave energy will lead to another
sfc low to track across the Great Lakes, and trail an associated
cold front through the Midwest. We will remain warm and muggy, with
highs both Saturday and Sunday in the upper 80s and lower 90s, and
dewpoints in the lower 70s during peak heating. Shower and storm
chances will continue each afternoon for the weekend and into early
next week. Precip coverage is expected to diminish into the
nighttime hours as we lose heating each day.

&&

.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 151 AM EDT Wed Jul 9 2025

The rest of the overnight remains quiet and mainly VFR flight
categories. As was mentioned in the previous discussion, brief MVFR
CIGs are possible right around the start of the day depending on how
much mixing occurs before the cu field develops. Otherwise, the main
thing to look out for will be isolated TSRA during the afternoon and
evening hours as has been the main issue the last few days. Went
ahead and added a PROB30 to SDF thinking there is a little better
chance this afternoon for a shower or storm then the activity
diminishes with the setting sun.

&&

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

&&

$$

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