820
FXUS63 KIWX 181958
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
358 PM EDT Fri Sep 18 2026

.KEY MESSAGES...

- Several rounds of rain and embedded thunderstorms expected
  tonight into this weekend, possibly lingering into Monday. A
  flash flood watch is in effect from portions of northern
  Indiana, southern Michigan, and northwest Ohio tonight into
  Sunday morning. 1-3 inches of rain is expected late tonight
  into Sunday morning, greatest totals expected north of US 6.
  Areas further south that received excessive rainfall this past
  week could see an exacerbation to any lingering flooding.

- There is a marginal risk for isolated strong to severe storms
  Saturday. The main threat in severe storms would be damaging
  winds. Confidence is low.

- Cooler and trending drier Tuesday through Friday. Highs in the
  60s, low 70s.

&&

.DISCUSSION...
Issued at 357 PM EDT Fri Sep 18 2026

The active weather pattern continues, with additional heavy rainfall
potential tonight into Sunday morning, possibly lingering into
Monday. WPC has portions of our area in a moderate risk for
excessive rainfall, with the remaining portions of our area in
slight/marginal risk for excessive rainfall. Opted to issue a
flash flood watch for portions of IN/MI and a small part of NW
OH (Van Wert/Paulding Counties, OH). We still remain on the
northern periphery of an upper level ridge/trough to the north,
which keeps us in zonal flow with various shortwaves moving
through. The first arrives late tonight into Saturday, and the
second Saturday night into Sunday morning. The second is
associated with a surface low that drifts from IL into our
forecast area and over to NW OH (or the lower Great Lakes
depending on the model). There is considerable uncertainty with
regards to exact timing, so went broad brush with pops
(likely/categorical). There is also uncertainty as to where
exactly the heaviest rain will fall, but for now it looks like
areas along and north of US 6 will see 2-3 inches of additional
rainfall, while further south around 1-2". Locally higher
amounts are possible where training of storms could occur, and
it`s possible the higher totals shift further south. Given
ongoing impacts with river flooding and water over roads (in the
areas that received 6-10" of rain this week just south of Fort
Wayne/Allen Co, IN)...decided to err on the side of caution and
issue the watch. Areas further north saw around 1-3" (local max
of around 4" near our office), but despite these lower amounts
this may have primed the pump for flooding if we get the higher
amounts as forecast.

Otherwise, highs will be in the 70s, low 80s through Sunday. There
is a marginal risk for isolated strong-severe storms Saturday,
mainly for downburst wind potential (5%) during the day in any
embedded convection. Low confidence.

Additional rain chances with periods of thunder through the week,
becoming drier towards the Wed-Friday time frame. Cooler, with highs
dropping into the 60s, and lows in the upper 40s and 50s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 200 PM EDT Fri Sep 18 2026

A ridge of high pressure across the Great Lakes will provide
easterly flow through this period. This flow regime has allowed
some drier low level air to infiltrate into northern Indiana
with some scattering of VFR cloud deck. Scattered showers have
storms have formed across portions of north central IL along an
instability gradient that has shifted westward this morning. A
small scale convectively enhanced short wave appears to be
interacting with this instability gradient for scattered
convection across northern Illinois. While some advective
forcing appears to be shift eastward with this boundary through
late afternoon, confidence is on the low side whether these
showers can survive into northwest Indiana. Have opted to keep
TAFs dry at this point but may need to monitor KSBN for
potential brief shower potential. During the overnight hours, a
zone of stronger isentropic ascent currently residing across
IA/MN should shift to the western Great Lakes by daybreak. This
increase forcing should allow plume of higher MUCAPEs to lift
northeast into northern Indiana. Did include SHRA at terminals
toward end of this period and may eventually need to include TS
mention once forecast confidence increases. Primarily VFR
conditions are expected this period, but should trend to MVFR
toward end of this period.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Flood Watch from 2 AM EDT /1 AM CDT/ Saturday through Sunday
     morning for INZ005>009-012-014-015-017-018-023>027-
     032>034-103-104-116-203-204-216.
OH...Flood Watch from 2 AM EDT Saturday through Sunday morning for
     OHZ015-024.
MI...Flood Watch from 2 AM EDT Saturday through Sunday morning for
     MIZ078>080-177-277.
MARINE...None.

&&

$$

DISCUSSION...MCD
AVIATION...Marsili