Magnet, Indiana Weather Forecast Discussion

718
FXUS63 KLMK 221535
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1135 AM EDT Mon Sep 22 2025
.KEY MESSAGES...
*  Strong to severe storms are possible this afternoon and evening.
   Main impacts are gusty winds, hail, and brief heavy rainfall.
*  Active and unsettled weather pattern sets up over the area for
   next week with daily chances for showers and storms.
*  Multi day rainfall amounts from today to Friday afternoon will
   range between 3 to 4 inches.
&&
.UPDATE...
Issued at 1135 AM EDT Mon Sep 22 2025
A concentrated area of convection has remained over southwest
Indiana and western Kentucky this morning.  Rainfall since midnight
has been in the 1-2 inch range over in far western Kentucky
(Henderson area).  Across the LMK CWA, the highest rainfall has been
in Hancock county with 0.57.  A quick tenth to one quarter has
fallen over parts of central/east-central KY where several bands of
showers have been moving northeast between Frankfort and Lexington.
A relative lull in precipitation is expected across the I-65
corridor for the next hour or two.  However, N/S bands of heavier
convection are developing out in the I-165 corridor.  These will
move northeast and affect areas west of the Louisville Metro within
the next 60-90 min.  Heavy rainfall, gusty winds, and lightning will
be the main threat with this activity.
Moving into the afternoon hours, it appears that we could see two
areas of convection develop. The first may be with the activity
moving northeast along the Ohio River now near Owensboro.  This
activity may intensify as synoptic scale forcing overspreads
southern IN and Ohio ahead of the upper level trough axis.  The
southern end of this may scrape across portions of central/eastern
KY.  A secondary area of convection may develop across
western/southwestern KY later this afternoon and grow upscale after
it crosses the I-65 corridor.  The 06Z MPAS models tend to agree
with  this and have generally handled convection a bit better so far
this morning.
Overall, the forecast for the afternoon remains in good shape.  The
risk for severe weather (damaging winds) continues to be focused
across our eastern sections, generally east of the I-65 corridor.
Issued at 1007 AM EDT Mon Sep 22 2025
A welcome sight on the radar this morning as widespread rains were
noted from western Kentucky into southwest Indiana.  Most of the
convective activity has been out west of I-65.  Heaviest rainfall
has been out western KY southwest of Henderson where 1-1.6 inches of
rain has fallen.  Our western CWA has seen one half inch in our KY
counties, but our southwestern IN counties have likely seen 0.5 to
an inch of rainfall.  Further east, scattered showers and a few
thunderstorms were noted across portions of central and east-central
Kentucky.  These were more scattered in nature and this activity
will move thorugh Frankfort and Lexington through the morning hours.
Heading into the afternoon, a shortwave trough axis over the Mid-
South and lower Ohio Valley is forecast to lift northeastward
through our region this afternoon and evening. Model soundings show
a band of 20-25kt of deep layer shear transversing the region this
afternoon.  While mid-level lapse rates are rather unimpressive, the
low-level lapse rates are a bit better than what models progged
earlier.  These low-level lapse rates combined with some breaks in
the clouds across our eastern counties, should result in adequate
surface based instability to support organized surface based
convection.  Based on the environment, heavy rainfall, lightning,
and gusty winds will be the main threats with activity moving across
central/eastern Kentucky this afternoon.  A few storms that
encounter some localized higher instability areas may get strong
enough to produce a few marginally severe wind gusts.  Back of the
hand calculations suggest 45-50 mph gusts, though a few to 60 mph
can`t be ruled out.  Given the environment east of I-65, SPC felt
confident with going with a slight risk upgrade, mainly for the
damaging wind gust aspects of this afternoon/evening`s convection.
Further west, ongoing convection across NW KY/SW IN will likely
limit overall insolation resulting in lesser amounts of instability.
Only potential change is that I could see the slight risk being
expanded back to the southwest a little bit (mainly back toward the
Bowling Green area) where insolation may be a bit more
overachieving this afternoon.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 328 AM EDT Mon Sep 22 2025
A 25-30kt LLJ is developed over the lower Ohio Valley and is helping
to promote a cluster of showers and embedded storms over western
Kentucky and a few isolated storms along the TN border. This cluster
of showers/storms will continue to push NE through the morning
hours.
The main trough axis will swing through the region during the day
today. This feature will bring better forcing to an already moist
and uninhibited environment. Looking to see multiple rounds of
scattered showers and storms today. Modest CAPE around 1500 J/kg, 20-
25kts of deep-layer shear, and modest low-level lapse rates will
allow for some storms to become strong. Main hazards being gusty
winds, heavy rainfall, and lightning. High-Res guidance is still not
handing convection well, so exact timing and coverage is low
confidence.
Otherwise, winds will pick up out of the SW around 8-12mph and
gusting up to 20mph outside of storms. Temperatures will likely be
in the low-to-mid 80s, though convection placement and timing will
have a large impact on temperatures today.
In the overnight hours, the trough axis will continue to swing
through the region. A 25-30kt LLJ will once again develop over the
lower Ohio Valley. These features and elevated instability will help
to keep rounds of showers and storms overnight. We should see
tapering chances towards sunrise.
Given how dry it has been over the last several weeks, we most
definitely welcome the rain. Although HREF LPMMs show a few swaths
of 2-3 inches and some bullseyes of 3-4 inches through the Tuesday
morning. Therefore, a will keep an eye on any flooding
concerns today.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 328 AM EDT Mon Sep 22 2025
Tuesday - Tuesday Night...
The shortwave trough will exit to the east by Tuesday morning and
flow aloft will become more zonal. Broader troughing will remain
over the northeastern CONUS and extend through the upper Midwest and
into the high Plains, where a closed upper low will attempt to
develop. We will likely see a break in precip over most of the
region from Tuesday morning through much of the day. Though a
lingering weak LLJ over the southeastern portion of the region and a
continued stream of vorticity may help to bring some showers and
storms along the TN border. With ample instability and weak shear,
we could some stronger storms capable of gusty winds, heavy
rainfall, and lightning. Best timing is Tuesday afternoon through
the evening.
Tuesday night, we could see continued showers and storms given a
developing LLJ, continued vorticity stream, and elevated instability.
Wednesday - End of the Week...
The closed low over the High Plains will begin to travel east and
interact with broader troughing over the northeastern CONUS. This
will bring cyclogenesis over the mid-Mississippi Valley. The low
will track over the Ohio Valley bringing a cold front through the
region later in the week. During this time, showers and storms will
remain in the forecast each day until the cold front passes through.
The weekend is trending drier, though some guidance keeps a closed
low over the southeastern CONUS, which may bring showers and storms
back into the forecast by late weekend.
QPF Forecast...
Forecast still shows a widespread 2.5-3.5 inches of rainfall, with
some areas over 4 inches. Due to the convective nature of this QPF
forecast, locally higher and lower amounts are possible. HREF LPMMs
show a few bullseyes of higher values for today. Backbuilding
convection is possible on Tuesday. Could see some flooding concerns
these days.
&&
.AVIATION /12Z TAFS THROUGH 18Z TUESDAY/...
Issued at 651 AM EDT Mon Sep 22 2025
Showers and some embedded thunder is pushing NE into the region this
morning. This will bring -SHRA VCTS to most of the region through
the afternoon. In the afternoon, winds will pick up from the SW
around 8-12kts and gusting up to 20kts. A line of showers and storms
is expected to push through bringing -TSRA to most of the region.
These windows are outlined with PROB30 groups right now. In the
evening, the western terminals will begin to dry and CIGs will
lower. A LLJ will develop in the morning, spawning showers in the
early morning.
Timing and coverage of thunder is low confidence. Other elements of
the forecast has higher confidence
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE.......MJ
SHORT TERM...SRW
LONG TERM....SRW
AVIATION.....SRW

NWS LMK Office Area Forecast Discussion