339
FXUS63 KIWX 171757
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
157 PM EDT Thu Sep 17 2026

.KEY MESSAGES...

- Additional storms are possible along and south of US-24
  tonight but confidence is low. Brief heavy rain can be
  anticipated with any storms that develop.

- After dry conditions on Friday, more widespread heavy rain is
  possible over the weekend. Confidence is low on exact timing,
  locations, and amounts but this could bring additional
  flooding.

- Cooler and drier weather returns Tuesday-Thursday.

&&

.DISCUSSION...
Issued at 156 PM EDT Thu Sep 17 2026

Active weather to continue through at least Monday as our area
remains on the dreaded N/NE fringes of large mid/upper level ridge.
Heavy rain this morning is finally ending with a brief break
expected late this afternoon. However, additional storms are
possible later this evening (esp south of US-24) as models indicate
another weak shortwave possibly developing along the sharp
baroclinic zone currently in place. Confidence is low however as
there is relatively high spread among various models (including the
CAM`s) regarding timing, location, and intensity of any convection
that does manage to develop due to incredibly weak/subtle synoptic
forcing overnight. Tend to favor the HRRR here which shows a more
muted convective response focused just south of our area where
remnant outflow boundary likely sets up. The idea that the bulk of
the activity will be focused just to our south has reasonable
agreement from other CAM`s but the HRRR is on the far end of the
spectrum with some models developing storms in our far south late
this evening before quickly pushing into central IN/OH. Will
therefore hold off on another flood watch in our area, but
Huntington, Wells and Adams Counties will be highly sensitive to any
additional rain and will watch those closely tonight.

We get a brief surge of high pressure/dry air advection tomorrow as
the front is shunted south. However, a more robust shortwave arrives
on Sat with another round of strengthening LLJ/theta-e advection. As
expected with this pattern there remains a high degree of
uncertainty where and when the next round of rain falls but do
expect someone in the southern Great Lakes to get heavy rain during
this period given the degree of moisture being pumped into a quasi-
stationary E-W boundary. Multiple rounds of convection are likely
Sat-Sun and may even extend into Mon. Additional flood watches for
this weekend are very possible. Pattern finally shifts a bit by the
middle of next week with drier and cooler conditions expected.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 156 PM EDT Thu Sep 17 2026

Most of the heavier showers and thunderstorms have come to an end
across northern Indiana as a convectively enhanced short wave is
departing to the east. A broader scale longwave trough across
northern Great Lakes will help to push baroclinic zone southward
tonight into Friday morning. This increased frontal forcing may
cause some scattered showers and isolated thunderstorms to develop
generally along and south of the US Route 24 corridor. Confidence at
this time is not high enough to include more than PROB30 shower
mention this evening at KFWA. Some lingering IFR conditions to begin
the period will improve to MVFR this afternoon (or possibly VFR).
Some additional IFR or lower end MVFR cigs are possible late evening
into early Friday morning with preferred location north of sfc
boundary. Lingering MVFR cigs should prove shortly after daybreak
with increased diurnal mixing.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Flood Watch until 2 PM EDT this afternoon for INZ017-018-
     023>027-032>034.
OH...Flood Watch until 2 PM EDT this afternoon for OHZ024-025.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...AGD
AVIATION...Marsili