437
FXUS63 KIWX 301804
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
204 PM EDT Wed Sep 30 2026

.KEY MESSAGES...

- Showers will persist across much of the area into this
  evening, before weakening. Greatest chances (40-80%) will
  remain northwest of US-69.

- Window of dry weather likely late tonight into Thursday
  morning. Chances for showers (50-90%) and an isolated
  thunderstorms return Thursday afternoon into Thursday night.
  Locally heavy rain is possible, but overall flood concerns
  appear low at this time.

- Dry conditions are expected this weekend into early next
  week, with highs in the 60s, low 70s (warmest further south).
  Overnight lows will drop into the 40s.

&&

.DISCUSSION...
Issued at 204 PM EDT Wed Sep 30 2026

Area of weak isentropic lift continues advance across the area,
with light returns (primarily sprinkles or T amounts of precip)
extending east to the I-69 corridor. Steadier rain has remained
in NW parts of the area so far. Models have been showing a
weakening trend over the past several runs, but given current
and upstream radar returns this seems somewhat unrealistic for
at least the next several hours. Pops have been continued into
early evening with a slow taper from southwest to northeast into
the overnight hours. Signs still seem to point towards a small
lull in precip late tonight through at least Thursday morning.

A closed upper low, currently over the Four Corners area, will fight
to work east and eventually northeast along the stubborn SE US
ridge. A weaker northern stream trough will dive in as well. The
southern stream wave will fill and weaken with NE extent as it is
absorbed into the northern stream trough. PWATs will steadily
increase through the day Thursday, peaking in the 1.75" to locally
2" range during the afternoon and evening hours ahead of an eastward
progressing front. Models indicate some weak surface cyclogenesis
that rides along the front mainly Thursday night. All these factors
should lead to the best chances for measurable rainfall with average
amounts of a half to one inch. A low chance exists for thunderstorms
embedded within the area that could aid in locally higher rainfall
amounts, but at this point expected rainfall should not cause
significant impacts to water levels across the area.

Drier air quickly works in from the north Friday as the overall
upper flow becomes semi-zonal and deeper moisture is pushed well
south. Temperatures this weekend into next week will settle back into
the 60s for highs and lows in the 40s with a hint of some upper 30s
possibly coming for Tuesday morning.


&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 122 PM EDT Wed Sep 30 2026

Light rain showers will persist through the afternoon and
evening. However, the boundary layer remains very dry, so cloud
bases are high, and VFR conditions should prevail. Yet if
heavier rain currently over southern Lake Michigan moves into
SBN, MVFR ceilings and visibilities will be possible. Have kept
these lower conditions out of TAFs for now due to uncertainty.
Rain will diminish tonight, but will not completely vacate the
area, and will return later in the day Thursday.

Light south-southwest winds will continue, increasing some on
Thursday. A low-level jet will also kick in tonight, resulting
in southwest wind shear between 02Z and 15Z.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Fisher
AVIATION...Cobb