255
FXUS63 KLMK 071047
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
647 AM EDT Tue Oct 7 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

*  Widespread soaking moderate rain, with a few embedded
   thunderstorms, continue throughout today. Widespread rainfall
   amounts of 1 to 3" are expected. Localized swaths of 3-5+" may
   lead to minor flooding issues.

*  Conditional low-end severe threat possible along KY/TN border
   this afternoon, but confidence remains low.

*  Cooler and more seasonal temperatures arrive by late week, with
   a mostly dry forecast anticipated.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 339 AM EDT Tue Oct 7 2025

===== Early Morning Discussion =====

Early this morning, the initial round of light rain that occurred
yesterday evening has shifted northward over the past few hours,
with a lull in precip activity currently across a large portion of
the forecast area. KY Mesonet and other obs generally show a range
of 0.25-0.50" of rainfall in the last 24 hours across the region,
though a few outliers in the 0.75-1.0" range are noted as well.
Temps have been fairly steady over the past few hours thanks to the
cloud cover and rain, with upper 60s to right near 70F this morning.
Sfc analysis early this morning depicts a rich plume of moisture
extending into western KY from an enhanced 850-925mb moisture
transport axis, with PWATs exceeding 1.5" for our entire area. The
sfc low is also exiting northeast Arkansas and beginning to enter
western TN, and is a bullseye of PWATs over 2 inches as a result of
better low level moisture convergence and 40kt 850mb jet core. Off
to the northwest, the elongated sfc cold front is stretching from
northern Illinois through central Missouri, which is located under a
positive tilted upper trough that is shifting across the central US.
For the rest of the pre-dawn hours, we`ll see the rain shield expand
from southwest to northeast as the low level jet ramps up across our
area.


===== Moderate to Heavy Rain Today =====

The mid-Mississippi Valley sfc low is drawing quite a moisture fetch
up into the TN and OH valleys today, and will combine with an
approaching sfc cold front to provide widespread moderate to heavy
rain to the region throughout the daylight hours. Deep southerly
flow ahead of the cold front will continue to provide a rich
moisture plume into the area, with PWATs over 1.5" expected. HREF PW
probs suggest a 75% chance of exceeding 2" PWAT values in our
southwestern CWA late morning, but it`ll be a 50/50 chance for the
rest of the counties mainly along and south of the KY Pkwys today.
North of the Pkwys, the chances decrease the further north you go.

With the help of the approaching cold front today, the sfc low will
take on a more eastward trajectory across north-central TN today.
This will set up our precip axis to mainly be from southwest to
northeast, with the greatest QPF axis following the KY Pkwys across
the Commonwealth. Forecast confidence remains high on seeing a
widespread 1-3" of rainfall today as multiple bands of soaking
moderate to heavy rainfall spread across the area. However, given
the potential convective nature of the precip, we very well may see
some locally high amounts that could lead to some localized flooding
issues. The 00z HREF 24-hr LPMM QPF shows a general 1 to 3 inches
across the area today, though some locally 3-5+ inch amounts can`t
be ruled out. Our experimental Probabilistic Precip Portal agrees,
with generally a 70-80% chance of exceeding 2 inches of rain, and 40-
50% chance for exceeding 3 inches.

There was consideration for a Flood Watch for today, but given the
current drought status and Flash Flood guidance, continued without a
headline at this time. OHRFC Flash Flood guidance depicts 1-hr FFG
around 3 inches, 3-hr FFG around 4 inches, and 6-hr FFG around 5
inches. Regardless of the drought status or FFGs, this amount of
rainfall will still likely lead to several flood advisories and
maybe a few localized Flash Flood Warnings.


===== Conditional Low-End Severe Threat =====

Other than the widespread rain threat today, there is a conditional
low-end severe threat worth at least mentioning in the forecast.
With the sfc low tracking across TN today, and ahead of the cold
front, our low level helicity and shear values along the TN border
will increase this afternoon for a brief period, which would create
a somewhat favorable hodograph with a veering low level wind profile
and south-southeast sfc flow. The main limiting factor will be
instability, as it remains uncertain if we will be able to realize
any SBCAPE given the cloud cover and precip expected. Regardless, hi-
res guidance is picking up on the potential for our 0-1km SRH values
to increase to nearly 150-200 m2/s2 along with deep-layer shear
exceeding 35kts across our southern row of counties this afternoon
as the sfc low pivots. Wouldn`t be surprised if SPC did draw in a
Marginal risk later today, but again the main concern will be how
much instability will be available.


===== Drier Trend Arrives Tonight =====

FROPA will take place later on this afternoon or evening, leading to
a sharp wind shift to northerly flow. We may have a thin line of
post-frontal precip to deal with before the drier air arrives, but
eventually a drier trend will settle in. Additionally, we`ll see
clearing skycover, and much cooler temps to follow. Temps will
likely range from northwest to southeast due to the front and cloud
cover. As such, our southern IN counties could see upper 40s
tonight, though our Lake Cumberland area will remain closer to 60.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 339 AM EDT Tue Oct 7 2025

===== Wednesday - Friday =====

The cold front will be sliding east of the Appalachians by Wednesday
morning, leaving a much drier trend for the second half of the work
week. Upper clouds could linger in our south and east through the
Wednesday morning time frame as the upper trough axis pivots east of
the I-65 corridor, but increasing sunshine is to be expected through
the day as sfc high pressure builds across the Great Lakes region.
If you`re looking for fall, you`ll like the temperature forecast for
the long term. Highs on Wednesday are expected to remain in the
upper 60s to low 70s, with decreasing humidity. Wednesday night will
feature clear skycover and light winds, which will support good
radiation cooling combined with CAA regime from the sfc high to our
north. We`ll likely see temps drop into the 40s region-wide
Wednesday night into Thursday morning.

Beautiful weather continues for Thursday and Friday, with additional
sunshine and cooler temps. Highs for Thursday are forecast to be
upper 60s and low 70s again. By Friday, the sfc high will be
shifting to the east of the Great Lakes, which will support slightly
warmer temps with highs in the low to mid 70s. A weak shortwave
ejecting southward from Canada may push across the region, leading
to a slight increase in cloud cover for Friday. However, current
guidance keeps fairly dry air in place, so no rain chances at this
time.


===== Next Weekend =====

Upper level ridging amplifies over the central US for the weekend,
which will expand sfc high pressure over the region. Dry weather is
expected to continue, with a slight warming trend over the weekend
and into early next week. We could see the aforementioned upper
shortwave eventually deepen into a closed low over the southeastern
US, though any moisture associated with that system is currently
expected to remain east of the Appalachians. Temps creep back into
the mid 70s for the weekend, though morning lows in the 40s will be
a nice touch for those looking for fall weather.

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 646 AM EDT Tue Oct 7 2025

MVFR and IFR conditions are beginning to settle in this morning as
moderate to heavy showers spread across the region. Expect impacts
to flight cats throughout today as widespread showers and embedded
storms continue. Restrictions to MVFR or IFR cigs and vis are
expected at every terminal through at least this morning, but will
begin to see slow and gradual improvements through this afternoon
and evening at HNB, SDF, and BWG. LEX and RGA are expected to see
IFR through the end of the forecast period as low stratus along the
front lingers into tomorrow morning. Otherwise, we will see our
winds shift from a southerly flow today to a northerly flow behind
the cold front later on tonight.

&&

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

&&

$$

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