871
FXUS63 KLMK 041435
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1035 AM EDT Mon Aug 4 2025

.KEY MESSAGES...

* Scattered showers and thunderstorms will continue today, with
  locally heavy rainfall possible.

* Additional rounds of afternoon and evening showers and
  thunderstorms are expected through the middle of the week.

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

&&

.UPDATE...
Issued at 1034 AM EDT Mon Aug 4 2025

Surface analysis shows an inverted trough axis over western KY and
southern IN this morning.  A dewpoint axis was noted along the MS
River and then up the Ohio River to about Owensboro.  PWAT values in
this area were in the 1.5-1.6 inch range.  Periods of showers moving
northwest across southern Indiana was noted with somewhat drier
conditions over Kentucky.  Temperatures were in the low-ermiddle 70s
across the region under partly to mostly cloudy skies.

Moving into this afternoon, forecast continues to be on track.  With
some afternoon heating we should be able to get around 1000-1200
J/Kg of MLCAPE and some additional influx of moisture may get our
PWAT values up to near 1.75 inches or so.  Shear through the column
remains very weak with only 15-20kts to work with.  After 18Z,
should start to see some development in/around the I-65 corridor
with scattered showers/storms going up.  The best chances of rain
look to be in an arc from southwest IN down through the Louisville
Metro and then down along the I-65 corridor.  This activity is not
expected to be severe.  However, torrential rainfall, gusty winds,
and lightning would be the main threats.  Localized amounts of 1-2
inches of rain will be possible.  Where storms train over the same
area, localized amounts of 3.5 to perhaps 4 inches could occur in
very localized areas.  The storms look to diminish after sunset with
the loss of heating.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 310 AM EDT Mon Aug 4 2025

The inverted trough is located over western Kentucky and southern
Indiana at this hour. This has allowed for southeasterly flow to set
up over the region. Isolated showers will continue to move across
the western portion of the region near this boundary through
sunrise.

Mid and upper level troughing will move into the region from the
west today. This will bring additional lift to the present moisture
and inverted trough, and will support more scattered showers and
storms. PWATs will be around 1.75 inches again today. MLCAPE will be
around 1000-1200 J/kg, however, shear remains weak around 15-20kts.
Therefore, severe weather is not expected, though a stronger updraft
is possible and could produce heavy rain and frequent lightning. QPF
looks to be mostly along I-65 and west, with some swaths of training
storms bringing up to 3.5 inches (though this will be localized). In
the evening hours, showers and storms will begin to dissipate.
Isolated showers will likely remain overnight, similar to the
previous night.

High temperatures this afternoon will remain mild in the low-to-mid
80s. In the overnight hours, skies will remain broken and winds
light out of the southeast. Low temperatures are expected to be in
the mid-to-upper 60s and urban areas around 70.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 310 AM EDT Mon Aug 4 2025

Upper troughing and surface troughing will remain over the region
through mid week. This will keep daily chances for scattered showers
and storms over the region. PWATs will be around 1.7 inches, shear
will be weak around 15-20kts, and CAPE in the afternoon will be
around 1000 J/kg. Some storms may become strong, but no severe
weather is expected. Heavy rain and frequent lightning are the main
threats. Temperatures will remain below normal in the low-to-mid 80s
for highs and mid-to-upper 60s to around 70 for lows.

The latter half of the work week will feature a slowly departing
trough and amplifying ridge over the southwest CONUS, extending
towards the Mississippi Valley. This ridging will help to bring
temperatures back to near normal in the upper 80s. Depending on how
far east the troughing can move, will determine if daily chances for
showers and storms remain. The greatest chance for showers and
storms would be over the eastern half of the region, and will likely
be isolated to scattered.

Into the weekend and early next week, there is some disagreement
amongst guidance. GFS continues to keep the region under troughing
with deeper troughing swinging through the Great Lakes region on
Sunday. This would bring a cold front south into the lower Ohio
Valley. The ECMWF keeps ridging over the region until mid next week
when the deeper troughing and cold front swings through. Similar
ideas, however, timing is off. The GFS would keep scattered showers
and storms through the weekend and the ECMWF would trend drier for
the weekend. Not much forecast confidence for the weekend, will
continue to monitor trends.

&&

.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 554 AM EDT Mon Aug 4 2025

A few showers are currently near HNB and will continue to push
northwest this morning. Broken stratus around 3-5kft is
overspreading the region. Some guidance wants to bring in MVFR CIGs,
however, this will likely only be brief periods in the morning
through the early afternoon before CIGs lift. Winds will remain
light out of the southeast through the day. Scattered showers and
storms will develop in the mid morning and last through the evening.
PROB30 groups are mentioned in the TAFs to cover this isolated to
scattered chance at each terminal. In the evening, showers and
storms will dissipate and winds will become light and mostly
variable.

&&

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

&&

$$

UPDATE:......MJ
SHORT TERM...SRW
LONG TERM....SRW
AVIATION.....SRW