947
FXUS63 KLMK 191734
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
134 PM EDT Sat Sep 19 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Unseasonably hot weather will continue for much of the area
  through at least Sunday. Barring any early day thunderstorms, heat
  indices will top out in the mid 90s to around 105 (highest
  southwest) each afternoon.

* There is a 30-50% chance (highest northeast) for showers and
  storms late this afternoon and evening, with slightly lower
  chances tomorrow. Locally damaging wind gusts and heavy rainfall
  may accompany the strongest storms.

* A weather system will bring higher rain chances (50-70%) Monday
  into Tuesday, followed by a cooldown to more seasonable
  temperatures (highs in the 70s, lows in the 50s) by the second
  half of week.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 310 AM EDT Sat Sep 19 2026

*** HOT WITH SCATTERED PM STORMS (SEVERE?) TODAY ***

Early Saturday morning, a quasistationary front, evident via a
subtle dewpoint gradient, was situated over northern Kentucky and
southern Indiana. In addition, a decaying outflow boundary left in
the wake of last evening`s storms has laid out near the
Kentucky/Tennessee border. The former boundary is slated to lift
northward as a warm front today, while confidence remains lower on
whether the latter (outflow) boundary will fully mix out this
afternoon or serve as a focus for a few storms. Convective allowing
models (CAMs) are certainly more aggressive with thunderstorms along
the warm front, but the ARW, HRRR, and FV3 try to pop a couple cells
further south. Accordingly, we`ve maintained "slight chance" (i.e.,
15-24%) probabilities of precipitation (PoPs) in the forecast across
southern portions of the county warning area (CWA) while boosting
them to 40-60% further northeast where confidence is higher in a
loosely-organized mesoscale convective system (MCS). It is worth
noting that most guidance is hitting areas just north our of local
area (central IN into southwest OH) with the strongest convection,
but given the weakly sheared (0-6km shear ~20-25 kt) environment and
potential storm interaction(s) with the aforementioned outflow
boundary confidence is low in placement. Wherever this potential MCS
sets up, modest buoyancy (MLCAPE 1500-2500 J/kg), PWATs of 1.7-1.9
inches, and notable inverted V on forecast soundings suggests strong
winds will be a concern, particularly with any bowing segments where
wind production may be aided by a rear inflow jet (RIJ). CAM wind
gust output supports this notion, with various CAMs spitting out
splotches of 40-60 mph gusts, and a couple very isolated pockets of
70+ mph apparent in the ensemble max. SPC maintains a level 1 of 5
(marginal) risk for severe weather across areas east of a roughly
French Lick, IN to E-town to Edmonton line, with damaging winds the
primary hazard. Outside of storms it`ll be another unseasonably hot
one with afternoon highs solidly in the 90s for most of the area and
dewpoints, pooling near the warm front, in the upper 60s to low 70s.
This will result in yet another day of heat indices in the upper 90s
to around 105, highest west of the marginal severe weather risk area
where a Heat Advisory is in effect.

*** TOASTY AGAIN, LOWER CHANCE OF A STRAY STORM SUNDAY ***

The axis of the shortwave trough responsible for this evening`s
storms is slated to exit the local area early tomorrow morning,
leaving subsidence in its wake. This should result in a drier
planetary boundary layer (PBL) during the afternoon, when dewpoints
may fall into the lower-mid 60s in many places. Still, it`ll be hot
with forecast high temperatures once again solidly in the 90s area
wide - favoring yet one more day of Moderate to Major HeatRisk
(highest southwest and in urban areas). In addition, we may once
again see a stray shower or storm, with the highest chances in two
separate areas: one along any remnant outflow boundary left in the
wake of this evening`s storms across the Bluegrass and another over
southern Indiana/far northern Kentucky where a weak shortwave trough
is forecast to provide lift during the late afternoon-evening. Shear
is forecast to remain weak while instability is a bit lower compared
to today, suggesting the risk for organized severe storms is low;
even so, we can`t rule out locally gusty winds in any collapsing
taller core. SPC has areas near and north of the I-64 corridor
outlooked in a level 1 of 5 (marginal) risk for severe weather.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 310 AM EDT Sat Sep 19 2026

*** LESS HOT NORTH WITH A FEW STORMS MONDAY ***

The ridge will begin to break down early next work week as yet
another shortwave trough crosses the area Monday evening. This could
spark a few afternoon and evening storms, which may once again carry
some risk for severe weather, though fortunately global models and
their respective ensembles suggest some displacement between the
best shear (north) and most optimal instability (south); the Low
Resolution Ensemble Forecast (LREF) system only gives a 10-30% joint
probability for > 1000 J/kg MUCAPE and > 30 kt 0-6km bulk shear
across western/central Kentucky Monday afternoon (and this may be
inflated due to timing differences among LREF members). Depending on
timing of the trough, cold front, and associated storms, the area
may see quite the gradient in temperatures during the afternoon,
with some locations (most likely southern KY) topping out in the low-
mid 90s and others in the upper 70s.

*** FEELING MORE LIKE FALL BY MID WEEK ***

Behind the front, more seasonable temperatures should overtake the
region with highs in the 70s north and low to mid 80s south by
Tuesday. Wednesday onward, raw (LREF) and calibrated (NBM) guidance
agree temperatures are likely to peak each afternoon in the 70s and
drop each night into the 50s - near to slightly below normal and
certainly much more fall-like. This mild, dry weather is likely to
persist at least through next weekend as the upper level trough
slowly drifts from the Great Lakes into the Northeast, keeping our
area under northerly flow/cool advection.

&&

.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 134 PM EDT Sat Sep 19 2026

VFR conditions are ongoing across the area this afternoon with light
winds generally from the SW. We`ll see clouds increase through this
afternoon and evening from the north, with lower chances for some
scattered storms this afternoon mainly for LEX/RGA. It`s possible
HNB/SDF may need an amendment to mention precip, but confidence is
not high enough to mention any. Otherwise, dry weather expected
tonight with VFR tomorrow.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for
     KYZ023>028-053-061>063-070>076.
IN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for
     INZ083-089.

&&

$$

SHORT TERM...JRB
LONG TERM...JRB
AVIATION...CJP