487
FXUS63 KIWX 141140
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
740 AM EDT Mon Sep 14 2026

.KEY MESSAGES...

- Cooler today with highs in the 70s with comfortable humidity
  levels and sun.

- Turning hot and humid Tuesday and Wednesday. Rain and storms
  possible Tuesday afternoon through Wednesday with 40-80%
  chances.

- There is a marginal risk for isolated severe storms on
  Tuesday. Main threat is damaging winds if storms become
  severe. Confidence is low at this time.

- There is a moderate swim risk for Lake Michigan beaches along
  the Berrien Co, MI shoreline Tuesday. Breaking waves and
  currents expected.

&&

.DISCUSSION...
Issued at 530 AM EDT Mon Sep 14 2026

Cooler and dry today, with calm winds this morning strengthening out
of the east-southeast through the day. Highs will be in the 70s.
Patchy ground fog is possible this morning. Winds shift south-
southwest this evening into Tuesday morning with gusts up to around
25-30 mph on/along Lake MI, so have a small craft advisory for both
of our marine zones. We have a moderate swim risk for beaches along
the Berrien County, MI shoreline on Tuesday as winds shift southwest
and waves build to 2-3 feet (highest further north). A strong
longshore current flowing from south to north along the beaches is
likely, in addition to strong structural currents near piers and
breakwalls (especially the south sides). Rip currents are possible.

Surface high pressure sprawled across the Great Lakes today will
slowly shift eastward to the east coast by Tuesday afternoon. The
upper level ridge will remain anchored over the SE CONUS, extending
northward today into the Great Lakes before taking on a more SW to
NE tilt through Tuesday. Meanwhile, an upper level low and surface
low pressure system drift through the Canadian Prairies/northern
plains and into Quebec/Hudson Bay/James Bay through Tuesday night.
The subsequent upper level trough reaches down into MN/WI/MI by Tue
afternoon, breaking down/shifting our ridge east so we are left with
relatively zonal flow through at least Thursday. At the surface, the
cold front extends down from northern Ontario (Tue AM) into IA/IL/MO
(occluding further north in WI/Upper MI). The warm front is draped
from down from WI through IL/TN/KY at the same time. Return flow
around the exiting surface high will pull up warm, moist air from
the gulf into our forecast area through the morning/afternoon hours.
The cold front arrives on our western doorstep by Tue evening,
shifting east-southeast overnight before becoming stationary/diffuse
Wed AM.  For now, have pops in the 20-50 percent range for late
tonight (far west near Lake MI) and Tuesday morning, expanding
slightly east and lingering on our northern CWA through the
afternoon. Some of the model guidance brings the warm front up and
starts rain showers/isolated storms earlier Tuesday, then we have a
quick break and chances increase again late afternoon/early evening
further west along Lake MI near the cold front. Others keep any warm
front precip further northeast out of our area, so it`s possible Tue
is mostly dry (some of these models also slightly slower with the
front). Have 20-50% chances until the early evening hours (highest
north and west), and then increase chances to 40-80% after that as
the front enters the CWA and stalls out. Severe weather potential
depends on what happens in the earlier part of the day Tue, and then
on the front timing and strength in the evening (some slight height
rises still that could limit intensity, especially further SE). If
we can keep building instability through the day and the cold front
arrives in the late afternoon/early evening, we could see isolated
severe storms with damaging wind gusts. Instability could be as high
as 2000 J/kg (MLCAPE), with 20-30 knots of 0-6 km bulk shear
(slightly higher further north in MI). Confidence is still pretty
low, as mid level lapse rates are pretty crummy (5-6 C/km), there is
potential for mid-level height rises that could limit intensity
(front becomes more diffuse with time), and impacts from earlier
daytime showers or storms (if they happen) could make the
environment less favorable overall. SPC still has our area in a
marginal risk for severe weather occurring. High temperatures on
Tuesday could reach into the upper 80s, low 90s west of I 69 and
further south. A lot will depend on whether we have cloud
debris/morning rain or storms that limit the daytime heating. It
will also be more humid than today.

The front stalls/washes out and we have zonal flow aloft through
Thursday...which makes us susceptible to various shortwaves that
move through. The stationary boundary does lift northward a bit as
warm air advects in from the south again, eventually orienting it
from NE MO into north central IL, NW IN, and southern Lower MI. This
keeps around 30-60% chances for rain and thunderstorm activity until
Thursday. Highs will be in the 70s, low-mid 80s for most days.

Low chances for showers and storms continue through the weekend (20-
30%), with highs in the 70s, low 80s.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 739 AM EDT Mon Sep 14 2026

VFR conditions expected at the terminals through tonight. Light
ESE winds strengthen and shift towards the south late tonight
into Tue AM. Expect increasing high clouds through then, and any
precip chances for KSBN holding off until beyond the TAF
period.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory from 8 PM this evening to 11 AM EDT
     Tuesday for LMZ043-046.

&&

$$

DISCUSSION...MCD
AVIATION...MCD