037
FXUS63 KIWX 191016
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
616 AM EDT Wed Aug 19 2026

.KEY MESSAGES...

- Chances for showers and storms (30-60 percent)this afternoon
  and evening, with the best potential along and south of US 30.
  Heavy rain is possible at times. Severe weather is not
  expected. Patchy to areas of fog this morning.

- Dry conditions with variable cloud cover Thursday into Friday
  before chances for showers and storms return Fri night into
  Saturday, with the best potential (50-70 percent) along and
  east of Interstate 69 Saturday afternoon.

- Hazardous swimming conditions are possible for Lake MI beaches
  along Berrien Co, MI and La Porte County, IN this weekend,
  especially on Sunday. Dangerous currents and waves are
  possible. Monitor the beach forecast for updates.

&&

.DISCUSSION...
Issued at 603 AM EDT Wed Aug 19 2026

Rain showers (isolated thunder/lightning) moved through the CWA
overnight along a pre-frontal trough. The last of these is exiting
Lima, OH as of this writing, and expect dry conditions through mid-
late afternoon. With calm winds and recent rain, fog is being
reported mainly in La Porte/Starke/St Joseph Co, IN are reporting
visibilities of around 1/4 to 1 SM, but with increase in high cloud
cover expect this to improve (especially after sunrise). Have areas
of fog/patchy fog in the forecast through the late morning mainly in
the western half of our CWA. It`s possible we need an SPS if the
visibilities less than 1SM persist or become more widespread in the
next hour or so.

A stationary front drapes from southern Ontario into Southern Lake
MI where a weak sfc low pressure lingers. A cold front (rather
diffuse and continuing to weaken) extends southwestward through
Chicago, IL. We`ll probably see a slight uptick in winds as we head
into the later morning with any movement of this front (which could
help improve visibilities). Where the front ends up is a point of
conflict amongst the model guidance-WPC has the front extending into
SE Lower MI down through White County, IN by 8 pm EDT tonight,
enhanced somewhat by the lake breeze from Lake MI this afternoon and
weak moisture advection from the southwest. Some of the guidance has
the orientation a bit more E-W along US 30 and southward, so that is
where I focused the higher pops/QPF (30-60 percent) late this
afternoon and evening. Aloft, a weak shortwave ripples through
somewhat zonal flow and the broader trough base begins to move in
overnight, shunting everything south and eastward.

South of US 30 there could be potential for heavier showers and
storms that move over the same areas (including many who have seen
flooding), and thus neighboring offices (LOT/IND) have a flood watch
out from this afternoon into tonight-assuming the frontal zone
develops further south and lingers in their area longer. For now,
our area appears to only see the persistent showers and/or storms
for a limited time late this afternoon/early evening before the
boundary moves out. In collaboration with CLE/ILN opted to hold
off on any flood watch at this point given lower confidence in
any impacts-the forecast is a little on the high side (up to
around 0.75-1 inch this afternoon into tonight) of guidance, and
I do not expect that to cause much in the way of impacts flood
wise. Most of the ensembles/guidance has less than 1 inch, with
some of the outliers higher. If the later guidance comes in with
the boundary forming and lingering further north, the day shift
may need to consider issuing a watch in collaboration with
ILN/CLE. WPC has our southern areas in a slight risk for
excessive rainfall for now (marginal outside of that). Severe
weather is not expected today-we have weaker mid level lapse
rates (5-6.5 c/km) and weak forcing. SPC has our area in a
general thunder (marginal risk just to our south). We do have
decent sfc cape/incoming moisture especially in the south and
west, along with around 30 knots of 0-6 km bulk shear. However
winds up to around 700 mb are fairly light-so think our risk of
any strong winds is pretty limited.

Thursday into Friday will be dry, with highs in the 70s, low 80s.
Chances for rain showers and storms (20-50 percent) return Friday
night into Saturday as a cold front moves through from west to east
during the period. There are higher chances of 50 to 70 percent
Saturday afternoon-mainly east of I 69. However, it`s dependent on
the location of the front by the late afternoon/evening. Some of the
guidance has convection really developing between 21-00z just east
of our CWA border, others keep it further west to start. At this
point, severe weather is not expected.

Mostly dry for Sunday/Mon as an upper level low drops into the Great
Lakes (could be further north in Ontario, depends on model). Cooler
northwest flow across Lake MI will bring waves up to around 2-3 feet
for Saturday afternoon and up to around 3-5 feet for Sunday. There
is a moderate/high swim risk forecast for Berrien/La Porte county
beaches, worst conditions on Sunday.


&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 603 AM EDT Wed Aug 19 2026

Predominantly VFR conditions at the terminals this period,
except this morning at KSBN where LIFR/IFR ceilings/visibility
persist as of this writing. Have tempo down to 1/4SM FG with
VV001 until 13z for now. Its possible that conditions improve to
closer to 1SM just after 12z with sunrise/slight uptick in
westerly winds behind a diffuse cold front, and incoming cloud
cover. Otherwise, showers and storms are possible this
afternoon/evening, mainly at KFWA. Have prob 30 group to
account for this.

&&

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

&&

$$

DISCUSSION...MCD
AVIATION...MCD