267
FXUS63 KIWX 131912
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
312 PM EDT Thu Aug 13 2026

.KEY MESSAGES...

- This afternoon light to moderate rain showers expected with a
  few embedded thunderstorms for most areas this afternoon. The
  better chances for thunderstorms will be the far southern
  portions of the area including White and Cass Counties in
  Indiana. A few of the storms may become strong but severe
  storms are not expected at this time.

- More widespread, heavy rain is possible late tonight into
  early Friday morning, especially south of US-30 where a lot of
  rain has already fallen. A flood watch remains in effect there
  through Friday morning.

- More chances for rain/storms are possible over the weekend
  but the potential for heavy rain and flooding will be lower.

&&

.DISCUSSION...
Issued at 224 PM EDT Thu Aug 13 2026

A MCS has again developed over central IA this morning and has
been making its way eastward. The stronger convective
circulation has been pushing southeastward along the stubborn
quasi-stationary boundary that has hung around the area the last
several days and current radar imagery shows the stronger
storms pushing just south of our CWA along this boundary over
the next couple of hours. The rest of the area will see a weaker
convective band with light to moderate rainfall push in from the
west with a few embedded thunderstorms possible but storms are
expected to remain weak with the better instability and moisture
further south.

Later tonight the main concern becomes the potential for heavy
rainfall with the boundary slightly shifting northward and
become orientated northwest to southeast across the center of
the CWA once again. A northward surge of moisture and forcing
along the boundary will envelop the area and bring a resurgence
of a band of convective thunderstorms and rainfall across the
area. With the general westerly to easterly flow training of
cells will bring moderate to heavy rainfall for areas directly
underneath where the band sets up and this includes areas where
recent rains in the previous days have made soils quite moist.
Current guidance does show this band setting up from the US-30
corridor and southward however the models have had a horrendous
time with this "ring of fire" pattern in place and is likely to
continue to struggle with such a stagnant pattern in place.
Therefore, confidence is low in the exact placement of the band
but does seem to make sense that the band will set up along the
boundary and more northern areas are more stable.

Starting to sound like a broken record but for the longer term
there is still considerable uncertainty with this very stagnant
pattern that models struggle resolving since this is not a
normal pattern and the models tend to be more progressive which
is the norm. But all indications look to be a continued zonal
pattern with periods of showers and thunderstorms parading over
the area, however there is some hints into the ridge over the
south trying to push northward this weekend which may push the
rainfall activity further northward which would be welcome as
our southern parts of our CWA and areas over IND CWA have been
drenched and can hardly take any more.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 133 PM EDT Thu Aug 13 2026

A complex of thunderstorms persists this afternoon over central
Illinois. Satellite and radar trends indicate the strongest
portion of this storm will pass well south of KSBN, yet
lightning on the northern end lends confidence to include TSRA.
Some maintenance of this complex appears favorable by the time
it would reach KFWA, though on its current trajectory, the
strongest part of the line appears on track to pass south of
KFWA, yet lightning will still be a concern.

Tonight offers little certainty as redevelopment of heavy rain
is favored in the vicinity of KSBN. Given the current complex
of storms, I suspect the axis of redevelopment will be south of
the terminal, but spilling over to KFWA. Stratus is favored to
develop outside of any heavy rainfall, so that too offers
uncertainty.

Leaning heavily on ensemble guidance, have offered a period of
-SHRA at KFWA where confidence is slightly higher; in contrast
 to a TEMPO for overnight -SHRA at KSBN. MVFR to IFR ceilings
 could be a problem overnight depending where rain sets up.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Flood Watch through Friday morning for INZ012>015-017-018-020-
     022>027-032>034-116-203-216.
OH...Flood Watch through Friday morning for OHZ024-025.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Andersen
AVIATION...Brown