Shepherdsville, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

640
FXUS63 KLMK 170004
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
804 PM EDT Thu Jul 16 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Scattered (20-40% coverage) thunderstorms will pose a risk for
  cloud to ground lightning and heavy rainfall leading to localized
  flooding through around 9pm EDT this evening. Additional
  thunderstorms are forecast during the afternoon and evening Friday.

* Outside of storms, heat indices will peak in the 97-103 degree
  range each afternoon through Saturday. This will favor moderate
  heat risk, suggesting an increased chance for heat illness,
  especially among vulnerable populations.

* There is another chance (40-60%) for thunderstorms Saturday
  evening into early Sunday morning. Cloud to ground lightning,
  gusty winds, and locally heavy rainfall may accompany the
  strongest storms.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 256 PM EDT Thu Jul 16 2026

***** MUGGY, SCATTERED PM HEAVY STORMS THROUGH FRIDAY *****

Early Thursday afternoon, temperatures across central Kentucky and
southern Indiana were in the upper 80s and dewpoints in the low to
mid 70s - resulting in heat indices in the upper 90s. RAP
mesoanalysis revealed 1500-3000 J/kg of MLCAPE, which, despite high
pressure over the region, is already fueling a few
thunderstorms this afternoon and evening as convective
temperatures (around 85-88 degF) have been reached. The greatest
coverage (30-40%) of showers and thunderstorms should be across
areas near and west of the I-65 corridor where deep layer
moisture is most pronounced and the remnants of a decaying mid-
level low favor weak synoptic-scale lift. PWATs upwards of
1.9-2.0 inches in this area, "tall, skinny" CAPE profiles on
forecast soundings, and a deep (>13 kft) warm cloud layer
suggest these storms will be efficient rain-producers, and with
less than 10 kt of deep layer shear they`ll also be very slow-
moving. Fortunately, this lack of shear will also limit the
duration of individual storms, so, in the absence of training
cells forming on preceding storms` outflow boundaries, the
duration of heavy rainfall in any given area should be
relatively short (<2 hours). Nonetheless, the ensemble max in
both the High Resolution Ensemble Forecast (HREF) system and
Rapid Ensemble Forecast System (REFS) have a handful of 1-hour
precip bullseyes that exceed 2 inches, suggesting at least a low
risk of localized flash flooding beneath the tallest cores;
WPC`s level 1 of 4 (marginal) risk for excessive rainfall seems
appropriate.

Storms should dissipate between 8-10pm EDT this evening with the
loss of diurnally-driven instability, then refire again early
tomorrow afternoon when convective temperatures are once again
reached. A disorganized mid level disturbance lifting into the area
from the Deep South should spread the higher-moisture airmass that`s
west of I-65 today further east to encompass the entire county
warning area (CWA), resulting in higher coverage of storms (50-65%)
across the Bluegrass State. Given the environment will be similar to
today, locally heavy rainfall and flash flooding are again concerns,
and in addition the merging cells apparent in various convective
allowing models (CAMS) suggests some potential for dropping
precipitation-laden cores ("wet downbursts"), which can occasionally
result in locally damaging winds. Like today, those storms should
gradually diminish with waning instability after 8-9pm EDT. Outside
of storms, conditions will remain seasonably muggy and uncomfortably
warm during the afternoons both today and tomorrow, with daily peak
heat indices near 100 degrees each day; accordingly, moderate heat
risk suggests an increased chance of heat-related illness primarily
among vulnerable populations.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 256 PM EDT Thu Jul 16 2026

***** FEW STORMS, SEVERE RISK(?) SATURDAY NIGHT *****

A seasonably potent upper level trough will dig southeastward across
the Great Lakes and into New England Saturday into Sunday. The
associated trailing cold front will eventually enter our area, but
global model guidance suggests that`s not going to happen until late
Saturday night or early Sunday morning, by which time diurnal
instability will be waning and optimal dynamics (forcing/shear) will
be displaced well off towards the northeast. However, the NAMNest
shows a pre-frontal trough triggering thunderstorms well ahead of
the cold front during the mid-late afternoon timeframe. This
solution would favor scattered to widespread (60-80% coverage)
thunderstorms and a risk for severe weather Saturday afternoon-
evening, while remaining guidance suggests we`ll be dry during the
evening and have only a low (20-40%) chance of a thunderstorm
overnight into Sunday morning. The Storm Prediction Center (SPC) has
our area outlooked in a level 1 of 5 (marginal) risk for severe
weather, which seems reasonable given the uncertainty.

***** SEVERE RISK(?) TUESDAY, TURNING MILDER MID-WEEK *****

The front washes out over our area and high pressure builds in from
the west on Sunday. This should favor drier weather, though we can`t
rule out (20-30% chance) a pop-up shower or storm along any remnant
boundary during the afternoon and evening. Conditions will turn
slightly less humid behind the front late Sunday into Monday, but
then a stronger push of moisture and warmth will overspread the Ohio
Valley ahead of a seasonably strong upper level low by Tuesday. The
Low Resolution Ensemble Forecast (LREF) system depicts a 40-60%
joint probability of 0-6km bulk wind shear > 30 kt and > 2000 J/kg
MUCAPE Tuesday afternoon and evening, which suggests this system
will bear watching for organized and potentially severe storms. In
addition, several machine learning programs are advertising at least
low (15%+) probabilities for severe weather across the local area
during this time. However, lots can change between now and then, so
stay tuned. Of higher confidence will be milder temperatures and
lower humidity (dewpoints in the 60s) by Wednesday, when the
National Blend of Models` (NBM`s) 75th percentile for high
temperatures are in the mid 80s. (This means there is a 75%
probability that high temperatures will be lower than around 85
degrees.)

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 803 PM EDT Thu Jul 16 2026

Isolated SHRA/TSRA will gradually diminish over the next hour.
Mainly dry conditions are forecast overnight, with scattered high
clouds and very light winds. Fog appears likely at HNB given their
higher crossover temperature and much lower dewpoint depression at
this time. MVFR vsbys is likely at HNB between 06-12Z and tempo IFR
conditions are possible (lower confidence).

Scattered convection will blossom over the region once again Friday
afternoon and evening, so decided to introduce PROB30 groups for
TSRA at all terminals.

&&

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

&&

$$

SHORT TERM...JRB
LONG TERM...JRB
AVIATION...EBW