988
FXUS63 KIND 300616
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
216 AM EDT Tue Sep 30 2025

.KEY MESSAGES...

- Dry with unseasonably warm afternoons this week

- Patchy fog possible during the overnights in Wabash River Valley

- Drought persists and worsens across Central Indiana into October

&&

.SHORT TERM (Today and tonight)...
Issued at 215 AM EDT Tue Sep 30 2025

This mundane weather pattern is still expected to continue through
the short term, with a large synoptic ridge along, of which has been
reinforced by emergence of warm-core lows over the atlantic and
strong AVA over the Eastern Canadian Provinces. This large upper
level ridge is the primary culprit for the well above normal
temperatures we have been experiencing. That said, a weak surface
ridge does develop to the south, creating a weak pressure gradient
and NE flow. In response, 850mb temperatures will likely cool a
degree or 2 C, lowering the overall surface heating potential.
Expect highs this afternoon to top off in the mid 80s, with a slight
temperature gradient from east to west.

Also continuing is the diurnal patchy dense fog threat due to the
same dry, clear and calm conditions creating large diurnal curves.
However, without a synoptically induced low level moisture source,
fog should be confined to near rivers and in agricultural areas /
farm fields.

&&

.LONG TERM (Wednesday through Monday)...
Issued at 215 AM EDT Tue Sep 30 2025

Highly amplified and long wave quasi-stacked ridge will be the
dominant feature across the eastern two-thirds of North America for
most of the period.  Highest H500 heights parked over Indiana
through the midweek...will slide to the Mid-Atlantic this weekend,
and most likely to the southeastern CONUS by the end of the long
term.  Very large surface high pressure aligned from eastern Canada
down into the eastern US on Wednesday...will meanwhile shift
southward to the US Eastern Seaboard.

The local region will therefore slide from the center to the western
portions of the stacked ridge...which will provide consistent dry
and rain-free conditions through at least Saturday as any noteworthy
return flow of better deep moisture is directed to our west.  Not
surprisingly, latest guidance is trending slightly greater diurnal
ranges...with low 80s east and now mid-80s expanding from the Wabash
Valley from the mid-week to most western zones Friday and onward.
Overnight lows...which may bring upper 40s northeast Wednesday
night...will be closer to early October normals, exhibiting a slight
upward trend through the 50s into early next week.  The forecast
highs at Indianapolis Friday and Saturday are 84F and 83F
degrees...the corresponding normal high is 71F...the corresponding
record high is 90F both days.

Daily minimum relative humidity values mainly around 30-40 percent
should generally thwart fire weather concerns through the first half
of the period...although moderate afternoon return flow gusts this
weekend, coupled with continued lack of rain, may present marginal
fire weather conditions, especially northwest of Indianapolis. Stray
showers may return to central Indiana at the end of the long term if
a weak disturbance embedded in the ridge can twirl north from the
Gulf coast towards the Ohio Valley.  However, confidence here is too
low to adjust from the Blend`s POPs around 5-10 percent.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 103 AM EDT Tue Sep 30 2025

Impacts:

- Brief MVFR conditions in patchy fog at KBMG, KHUF and KLAF
late tonight

Discussion:

Fairly quiet aviation weather continues to dominate the region.
Mainly VFR conditions should prevail through the period outside of a
period of MVFR visibilities occurring with patchy fog at KBMG, KHUF
and KLAF this morning. Best chance for these conditions will be in
the 10-12z timeframe. The patchy fog will end by 13z with VFR
conditions expected the rest of the day tomorrow with clear skies.

Winds will generally be northeast through the period, with
relatively light winds under 5 kts tonight. Winds tomorrow will
increase during the afternoon but should remain under 10 kts.

&&

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

$$

SHORT TERM...Updike
LONG TERM...AGM
AVIATION...Updike