363
FXUS63 KIND 241040
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
640 AM EDT Thu Sep 24 2026

.KEY MESSAGES...

- Cooler than average conditions persist today with mostly cloudy
  skies.

- Drizzle and light rain showers this morning.

- Clearing skies with a warming trend this weekend.

- Showers and thunderstorms possible late Tuesday through early
  Thursday.

&&

.DISCUSSION (Today through Wednesday)...
Issued at 253 AM EDT Thu Sep 24 2026

Surface high pressure, centered over southeastern Canada, has been
in place for the past few days. An upper-level low passed overhead
yesterday, allowing for the surface wind field to gain cyclonic
curvature. This has lead to weak lift within the boundary layer,
causing stratus trapped beneath an inversion to produce widespread
drizzle. Drizzle continues as of this writing (2am), and is expected
to persist through the morning hours today.

The upper-level low has moved southeastward towards the Mid-
Atlantic, and surface high pressure is beginning to nudge southward
in its place. Broad subsidence and dry air is expected to return,
causing the low stratus to finally begin to dissipate. This process
is likely to be slow, with mainly cloudy skies expected for most of
the day today. Due to this, we went below guidance for high
temperatures today. Clearing ramps up after sunset, especially east
of a Lafayette to Terre Haute line.

Winds become light and variable at times tonight, with perhaps a
dominant northeasterly component. Some patchy fog is possible given
the moist boundary layer, but renewed dry air advection may mitigate
this potential. With clearing skies and light winds, the main effect
will be much cooler lows than previous nights. Temperatures in the
40s are possible where clearing is most widespread. In urban areas,
lows near 50 are more probable. Along the Illinois state line, cloud
cover could persist long enough to keep lows in the 50s.

FRIDAY THROUGH SUNDAY

By Friday, low cloud cover will be gone only to be replaced by high
cirrus arriving from the northwest. A frontal system over the plains
is expected to generate convection from Texas to North Dakota.
Though precipitation remains far to our west, debris cirrus could
become quite thick at times Friday as it spreads eastward...thick
enough to keep high temperatures suppressed a few degrees. High
temperatures returning to the 70s is still the most likely outcome,
though we did nudge the forecast down a degree or two from guidance.

High pressure strengthens its grip over the region this weekend,
providing enough of a buffer to keep thick cirrus at bay. Some thin
cirrus may still try to creep into our western counties, however.
Winds retain an east to northeast direction through the weekend, so
a rapid warm up is not expected. Nevertheless, increasing sunshine
should help temperatures gradually warm both Saturday and Sunday.
Highs in the 70s are likely both days.

NEXT WEEK

Guidance is beginning to hint at a potent system developing over the
Plains around the Tuesday timeframe. Current ensemble suite
generally brings the low center to our northwest, with the trailing
cold front passing through Indiana. Uncertainty remains regarding
the strength and track of the low, but enough of a signal is present
to justify higher PoPs Tuesday night through early Thursday.
Thunderstorms are also possible, but deep warm moist advection
appears limited despite the system`s potential strength. For now,
most members of guidance show only low amounts of MLCAPE (under 500
J/Kg). This system resembles a cold-season synoptic low with minimal
instability and high shear. So, despite the low MLCAPE, this system
still bears watching from a severe weather standpoint.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 640 AM EDT Thu Sep 24 2026

Impacts:

- MVFR/IFR ceilings through 00z, clearing overnight.

- Patchy drizzle and light rain showers this morning.

Discussion:

Widespread IFR/MVFR stratus with drizzle continues across central
Indiana. These conditions are expected to persist through the
morning hours, with improvement during the afternoon. Despite the
gradual improvement, MVFR ceilings likely remain through 00z.

Surface high pressure builds in from the northeast this evening,
which brings large-scale subsidence and dry air back into the
region. As such, clearing is expected after 00z. Stratus may persist
a bit longer from LAF to HUF since the dry air is arriving from the
northeast. Skies become mostly clear for a time tonight before
cirrus from a storm system over the Great Plains increases after
about 12z Friday.

Winds will be lighter than previous days between 5 to 10 knots as
high pressure settles in. A period of light and variable winds is
possible overnight.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

AVIATION...Eckhoff
DISCUSSION...Eckhoff