316
FXUS63 KLMK 031939
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
339 PM EDT Sun Aug 3 2025

.KEY MESSAGES...

* Scattered showers and thunderstorms will continue tonight into
  Monday, with locally heavy rainfall and localized flash flooding
  possible.

* Additional rounds of afternoon and evening showers and
  thunderstorms are expected through the middle of the week. Drier
  conditions are expected late week into early next weekend.

* Below normal temperatures continue today through the first half of
  the week, with temperatures warming to around normal levels by
  late week.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 339 PM EDT Sun Aug 3 2025

Across the region this afternoon, visible satellite imagery shows an
expansive field of stratus and stratocumulus clouds, with a weak
cyclonic spin noted within the stratocu layer. This coincides with
the developing inverted pressure trough which will slowly move to
the west across the area over the next 24 hours. SPC mesoanalysis
shows an area of deep moisture convergence across south central KY
this afternoon, with an area of 1.7+" PWATs stretching from near
Lake Cumberland into east TN. Within this area of moisture
convergence, slow-moving showers and thunderstorms have lingered
through the morning and into the early afternoon hours, producing
between 1 and 4" of rain. Given that the axis of moisture
convergence is starting to lift north, think that hi-res model
guidance is generally correct in having this area of rain weaken,
with new development expected between the WK/BG Parkways and I-64.
With storm motions being fairly slow, additional heavy rainfall
swaths and localized minor flooding will be possible through this
evening.

Tonight, showers and storms should become more isolated after sunset
as instability diminishes. With moisture continuing to advect across
the region from the south and east, expecting mostly cloudy to
overcast skies across much of the area overnight. With the extra
moisture and low cloud cover, temperatures should be milder than the
past few nights, with lows expected to range between the mid 60s and
70 Monday morning.

In the pre-dawn hours on Monday, the axis of the inverted trough
will move into western KY, with winds becoming more southerly in the
925-700 mb layer. This will allow for a weak LLJ to develop, which
should re-ignite isolated to scattered showers and storms over the
area. While an exact location where shower/storm development is
expected is difficult to pin down, model consensus favors areas
along and west of the I-65 corridor, with more coverage expected
over southern IN along the leading edge of the LLJ. Scattered
showers and thunderstorms should continue into Monday afternoon and
evening, again with the greatest coverage expected near the leading
edge of the higher moisture axis.

While there will be moderate amounts of instability available (1000-
1500 J/kg MLCAPE), soundings show a tall, skinny CAPE profile.
Additionally, deep-layer shear is on the order of 15-20 kt, which
should generally be too weak to support severe convection. However,
warm cloud depths should be fairly deep (~12 kft), with heavy
rainfall and lightning continuing to be the main threat with
thunderstorms. 12Z HREF does show a few swaths of 2-4" of 6-hr LPMM
QPF, suggesting the potential for localized minor flooding where
training of storms occurs.

Otherwise, Monday should be another day with below normal high
temperatures. Warmer temperatures are expected along the I-75
corridor, where more periods of sunshine are likely. In general,
expect highs in the low-to-mid 80s.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 339 PM EDT Sun Aug 3 2025

No major changes were noted in the long term forecast period from
the 00Z to the 12Z guidance. Low-amplitude upper troughing will
continue across the Mississippi Valley through the middle of the
upcoming week, with weak moisture advection sustaining elevated PW
values between 1.6-1.7". Although the inverted sfc trough should
gradually dissipate, weak mid-level CVA combined with sufficient
moisture should combined for scattered afternoon and evening showers
and thunderstorms Tuesday and Wednesday. High temperatures should
gradually warm, but should remain in the low-to-mid 80s through
Wednesday. Low temperatures through Wednesday night should range
from the mid 60s to around 70 degrees in most locations.

For the end of the upcoming week into next weekend, there are minor
disagreements in the medium range guidance, with model divergence
increasing as we head into the second half of the weekend and early
next week. The GFS solution keeps a deeper upper trough/low over the
Tennessee valley into next weekend, while the ECMWF solution weakens
the upper low, spreading upper ridging from the southwest US across
the central Plains. There is fairly good agreement that afternoon
shower/storm chances should become more isolated, with many
locations remaining dry from Thursday into the beginning of the
weekend. Confidence is also fairly high in temperatures returning to
near normal levels for early August, with highs back in the upper
80s and lower 90s by next weekend.

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 155 PM EDT Sun Aug 3 2025

An area of low pressure has developed on the west side of the
Appalachians, with low-level moisture spilling northward into the
area this morning. MVFR ceilings have developed at BWG and RGA,
though it is expected that there should be just enough mixing to
lift these to low VFR levels later this afternoon. Showers and
thunderstorms over southern KY will try to lift northward this
afternoon, with the best chance to see TSRA at BWG. Winds are
expected to remain out of the east at 5-10 kt this afternoon, with a
few 15+ kt gusts possible at SDF and LEX.

Tonight, forecast confidence is fairly low as model guidance varies
on where additional showers and low ceilings will try to develop.
The best chance for IFR/MVFR ceilings will spread toward SDF and HNB
Monday morning, though any site could see lower ceilings. Given low
confidence in where SHRA will set up Monday morning, we`ll keep a
dry forecast going for now.

&&

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

&&

$$

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