217
FXUS63 KIND 201049
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
649 AM EDT Sun Sep 20 2026

.KEY MESSAGES...

- Scattered to numerous showers and storms will be around at times
  today and tonight.

- An isolated severe storm with damaging winds is possible this
  afternoon. Locally heavy rain remains a threat.

- Rain chances continue early this week, then dry weather should
  return. Temperatures will be much cooler after today.

&&

.DISCUSSION (Today through Saturday)...
Issued at 248 AM EDT Sun Sep 20 2026

Early This Morning...

Some upper energy along with the old surface front were generating
some scattered showers across the northeastern half of the forecast
area.

As an associated surface low across western Illinois moves east and
the initial upper energy departs, the scattered showers should push
east and north. Most of central Indiana should be dry by 12Z.

Today and Tonight...

Another upper wave will move east and provide forcing this
afternoon. Meanwhile, the surface low will move southeast across
the area.

With little or weak forcing across the area this morning, will only
have some low PoPs across the far north where the front will start
out.

During the afternoon, as the surface low moves through, forcing will
increase. The low will drag the front south. Thus, expect scattered
to numerous showers and thunderstorms to develop.

Interestingly, some drier air will get advected into the southern
forecast area ahead of the surface low. This may limit convection
development there until the surface front gets closer toward 00Z.

CAMs show a variety of solutions, while other guidance focuses rain
north, near and behind the front. Given all the above, will go
likely PoPs in the far north mid to late afternoon, tapering to
slight chance in the far south. Confidence isn`t great as mesoscale
influences as well as the aforementioned dry air could change things.

If enough instability builds, cannot rule out an isolated severe
storm with damaging winds ahead of the front. Locally heavy rain
remains a threat with precipitable water values near 2 inches.

Rain chances will continue tonight as the front continues to trek
south and additional upper energy moves through. Overall though
forcing doesn`t look great, so will keep PoPs no higher than chance
category.

A strong temperature gradient will exist again today as the front
moves south. Trimmed blended guidance far north given the expected
location of the front and clouds/rain chances. Went near 80 far
north to the lower 90s south.

Monday and Tuesday...

Upper waves on Monday followed by an approaching upper low on
Tuesday will keep chances for rain around. The hot air will finally
be south of the area. Highs will be in the upper 60s to near 80 on
Monday with only mid 60s to lower 70s Tuesday.

Wednesday and beyond...

The far east may see an isolated shower Wednesday as the upper low
exits. Otherwise, high pressure will provide dry weather into next
weekend. Temperatures will start out below normal, but they will
return to closer to normal next weekend.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 649 AM EDT Sun Sep 20 2026

Impacts:

- Scattered convection mainly later this afternoon and tonight.
- MVFR conditions along with a wind shift move north to south
  late this afternoon into the evening. IFR possible.

Discussion:

Can`t rule out some brief MVFR fog at 12Z at KHUF and KBMG. An
outflow boundary should put KLAF back to VFR by 12Z.

A low pressure system and cold front will trigger more
scattered convection mainly late this afternoon and evening, but
much uncertainty remains on how this plays out. Will just use a VCSH
mention for now, but thunder is certainty possible.

Behind the front, winds will become north and northeast, and
ceilings will drop into MVFR a while after the wind shift. IFR
ceilings cannot be ruled out tonight, especially at KLAF.

&&

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

$$

AVIATION...50
DISCUSSION...50