River Flood Warning 40, NWS Northern Indiana

Area Forecast Discussion
National Weather Service Northern Indiana
825 PM EDT Fri Apr 17 2026

.KEY MESSAGES...

- A line of strong to severe storms is expected to move in
  later this evening and spread east overnight. The greatest
  severe threat will exist west of Interstate 69 with damaging
  winds and possibly a tornado or 2 the main concern.

- Some hydro concerns will exist tonight as locally heavy rain
  accompanies the line of storms. Overall QPF amounts and
  expected duration should limit additional impacts, but some
  areas could see localized flooding issues. Thereafter, no
  additional significant rain chances are expected into next
  week.

- Much cooler temperatures arrive and persist into early next
  week with chances for near or below freezing temps Sunday and
  Monday morning.

- Rain chances may return towards the end of next week.

&&

.DISCUSSION...
Issued at 226 PM EDT Fri Apr 17 2026

Primary forecast focus is on the well advertised strong to
severe storm threat this evening into the overnight hours in
association with a strong cold front and plentiful upper level
support. Dry conditions are expected through the remainder of
the afternoon and most likely to near or just after 00Z. Numerous
thunderstorms are expected to develop upstream (some already
underway from Minnesota to NE Missouri) in a strongly favorable
environment for all modes of severe. As these storms races ENE,
they should congeal into 1 or more lines and most likely
establish strong cold pools as they move across IL and
eventually into portions of Indiana. It remains to be seen just
how strong they are as they arrive later this evening, but
concerns have increased some that they make it roughly half way
through the area before weakening somewhat. This is depicted by
some expansion east of the Slight and Marginal Risk areas in the
DY1 outlook. By this point, hail should not be a concern, with
areas of wind damage (60 to 70 mph) as well as some brief
tornadoes will be the main concern. The main severe threat
should wrap up in the 6-8Z time frame with lingering stratiform
rain behind the main line. Pops have been adjusted for a
somewhat faster trend given the impacts of the cold pool pushing
the line along sooner than previous indications. With regards
to hydro issues, a Flood Watch was contemplated given the
potential for 0.5" to 1" of rain (locally higher possible), but
with the line being so progressive feel the concerns will be
rather limited and can just be handled by Flood Advisories or
Warnings as needed.

The front will stall out some Saturday as another wave moves
along it. The severe threat should remain to our east but some
showers and maybe a storm are still possible in SE areas,
especially early. After that, we enter a less active period into
at least the middle of next week with the only concern being the
monitoring of colder temperatures and frost/freeze potential
Sunday and Monday morning. Will sort that out after we get this
system out of here.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 804 PM EDT Fri Apr 17 2026

VFR conditions should prevail through mid-to-late evening with
BKN to OVC ceilings around 10k feet AGL at both KSBN and KFWA. A
line of showers and thunderstorms will track eastward across the
area overnight, mainly between 04z and 11z Saturday. Occasional
MVFR conditions will likely accompany the heaviest precipitation
cores, along with gusty and erratic surface winds. Showers will
likely linger in the wake of this convection w/ MVFR ceilings at
or below 2500 feet AGL.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 2 AM EDT Sunday for LMZ043-046.

&&

DISCUSSION...Fisher
AVIATION...Hammer

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