Ferdinand, Indiana Weather Forecast Discussion

402
FXUS63 KLMK 231040
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
640 AM EDT Tue Sep 23 2025
...Updated Aviation Discussion...
.KEY MESSAGES...
*  Fog expected across southern Indiana this morning,
   locally dense north of I-64. Lingering showers and a few storms
   this morning into the afternoon, mainly across KY.
*  A few strong storms and locally heavy rainfall expected mainly
   late tonight into Wednesday.
*  Additional rainfall amounts should range between 1.5 to 3 inches
   for most, although locally higher amounts are possible through
   late Thursday.
*  Dry and increasingly warm this weekend.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 302 AM EDT Tue Sep 23 2025
Active weather continues early this week as rounds of showers and
thunderstorms bring both a localized strong/severe threat in
addition to localized heavy rainfall concerns. Currently, scattered
to numerous showers and a few storms reside where the low level jet
component is the strongest (20-25 knots). The better coverage is
mainly southern and eastern KY, with only isolated coverage north of
the Ohio River. As we move through the morning hours, the strongest
low level jetting will continue to slowly slide eastward and
gradually weaken, and as a result, the best coverage will move out
of our CWA. Will have to hold onto some pops across our far south
and east, but overall chances will be lower this morning into the
early afternoon.
Another concern for this morning is for some dense fog building in
across our northern tier of counties in the pre-dawn hours to around
sunrise. Model data has consistently suggested that this will be a
close call for our northern counties, and this area lines up
perfectly with where the low level jet tapers below 10 knots, and
low level moisture goes better toward fog production than low
stratus. Will look for deteriorating conditions up there toward
dawn, and may need a short NPW if this does indeed develop.
PAH/IND/ILN already have a headline out for areas that are already
seeing reduced vis, but so far HNB obs are good. Will continue to
monitor.
For much of today, we will be in the subsident wake of that lead
shortwave, and with low level jetting minimized later this morning
through the afternoon, don`t expect a whole lot of coverage of
showers and storms. Temps should warm to the low and mid 80s for
most. We`ll take advantage of this relative lull in activity to
recover in a few spots that saw some heavy rain last night. For
instance, sections of eastern Clark, Trimble, and Oldham counties
saw 3-5" late last evening. FFG values will still be quite strong
for many areas today, but some spots will start being less
receptive with repeated rounds of rain going into mid week.
As we move into tonight, expect another plume of deep moisture to
overspread the area ahead of a shortwave and strengthening surface
low ejecting into to the mid Mississippi River Valley. We`ll start
to see a warm front develop and strengthen over our area in response
to the upstream cyclogenesis, and we`ll see the low level jet
respond up around 25 knots once again across our SW CWA. This warm
frontal position, and the low level jet will provide enough deep
layer shear for perhaps a few stronger storms. SPC has the Marginal
risk placed in our SW CWA to account for this threat up until 12z.
Thereafter, it overspreads our entire CWA. In addition to the
Marginal severe threat, some heavy rain may set up along/near the
warm front, especially with the aid of the strengthened low level
jet and its deep moisture transport. Still only a localized threat
expected, so no real confidence to place a Flood Watch that would be
more indicative of a widespread flood threat. WPC extended a Slight
Risk for Excessive rainfall along the Ohio River Valley to account
for warm frontal position, and an axis of heavier rain that fell in
the past 24 hours.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 302 AM EDT Tue Sep 23 2025
Wednesday through Friday Night...
The upper pattern by mid week will feature two distinct shortwaves
over the eastern half of the CONUS. The first height anomaly will be
in the form of a closed low over the Great Lakes region, which will
wobble and remain nearly stationary until Thursday afternoon. The
second shortwave ejects out of the eastern Plains into the mid
Mississippi River Valley later Wednesday into Wednesday night, with
a notable surface low developing ahead of this feature and likely
moving into our CWA. It is also worth noting that we will see a
coupled jet structure at 300 mb, which does suggest why the surface
low strengthens a good amount thanks to good upper level divergence.
Overall, the upper pattern does add confidence that the models
likely have the surface low handled properly, and that at least some
warm sector and/or triple point will be in our region Wed PM.
Overall, looks to be a decent severe weather setup given
sufficiently strong deep layer shear combined with what should be at
least modest to moderate instability developing inside of where the
warm sector does set up. This instability is conditional upon
getting some breaks in the rain/clouds, which is a limiting factor
in confidence for the moment. Right now, the best destabilization
looks to be along and south of the Ohio River, with the main focus
across southern KY. One piece of the puzzle that does seem to be
lacking is stronger H85 flow. Only seeing about 15-20 knots in that
layer by afternoon, however the strongest values do appear to be
across southern KY where the best chances for instability should
also reside. Overall, this should mainly be a wind threat, however
given the triple point in the area, and perhaps just enough low
level shear from a weak LLJ, can`t rule out a small tornado threat
at this point.
We`ll also have to keep an eye on where precipitation totals end up
by this time, as several rounds will occur ahead of this and some
localized rainfall amounts may begin to add up. Will keep mention of
a localized flood threat going through this time. WPC Slight Risk
for Excessive Rainfall seems reasonable given the several rounds of
rain leading up to another healthy deep moisture surge.
As we move through Wednesday night into Thursday, the two shortwaves
phase into a larger trough trough axis that will be slow to move
through our area. This will create continued shower and storm
chances, although these will likely not carry a severe threat and
don`t look overly heavy at this point. The best coverage should be
over southern and eastern KY by Thursday. A few showers may linger
into Thursday night, but overall a drying trend is expected for
Thursday night into Friday. Temperatures mid to late should
generally range in the mid to upper 70s. Some 80 degree readings are
possible across southern KY Wednesday where that warm sector sets up.
Saturday - Monday...
The weekend currently appears to be a dry and increasingly warm
stretch of weather as upper ridging builds into our area. Models are
suggesting the shortwave that passed through our area late week may
close off into a nearly stationary closed low to our south or
southeast through this period. It is possible this occurs, and could
gradually bring some deeper Atlantic moisture back into our area on
an E or SE deep layer flow. Models do sometimes overdo this type of
moisture feed into our area, especially if you get downsloping off
the Appalachians. Nevertheless, something to watch for before we can
be 100% confident in a dry/warm stretch going into early next week.
Look for temps rebounding at least into the low 80s, if not the mid
80s, if this current pattern does look to hold with upper ridging in
place.
&&
.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 639 AM EDT Tue Sep 23 2025
Active and complex setup for the next TAF cycle as we deal with some
fog/low ceiling concerns across our northern TAF sites this morning,
in addition to continued rounds of showers and storms. HNB is the
most pessimistic forecast as it is already down below minimums in
dense fog. This should continue until mid morning before
improvement. Elsewhere, it will mostly be MVFR or brief IFR ceilings
across the other northern TAF sites (KSDF/KLEX/KRGA). BWG is
expected to stay VFR.
Overall, expecting a relative lull in precipitation activity from
late morning through much of the afternoon, however showers and
storms are expected to once again move in during the evening into
the overnight hours later tonight into Wed morning. Have some
prob30s to cover that threat. Surface winds will mostly be steady
out of the SW through this period, although may end up seeing light
SE winds late in this cycle.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
SHORT TERM...BJS
LONG TERM...BJS
AVIATION...BJS

NWS LMK Office Area Forecast Discussion