988
FXUS63 KIWX 021042
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
642 AM EDT Tue Sep 2 2025

.KEY MESSAGES...

- Dry through Wednesday afternoon. Highs near 80 today and Wednesday.

- 60-80% chances for rain (and maybe a few storms) Wednesday evening
  through early Thursday morning.

- Turning sharply cooler Thursday with highs only in the 60s.

- Briefly warmer on Friday with 20-30% chances for rain, then cooler
  and dry for the upcoming weekend.

- There is a High Swim Risk for southern Lake Michigan beaches
  in La Porte, IN and Berrien County, MI on Thursday. Hazardous
  swimming conditions persist into Friday and Saturday as well,
  with a High Swim Risk for Berrien County, MI and a Moderate
  Swim Risk for La Porte County, IN.

&&

.DISCUSSION...
Issued at 238 AM EDT Tue Sep 2 2025

One more completely dry day today before big changes are in store by
midweek. Expect comfortable humidity levels, mostly sunny skies, and
high temperatures near 80 degrees today. The area of high pressure
that has been over the region over the past several days has started
to move eastward, setting the stage for a potent upper level trough
and attendant strong surface cold front to pivot through the Midwest
and Great Lakes late Wednesday through early Thursday. The morning
and afternoon hours will be dry tomorrow, but the aforementioned
cold front will bring 60-80% chances for rain starting late in
the afternoon in our far northwest. A few embedded
thunderstorms will be possible as well given ~500 J/kg of
surface instability. The cold front will move from the northwest
to southeast, bringing increasing rain chances to the area
Wednesday evening and into the overnight hours. Rain will come
to an end around daybreak Thursday as the cold front is expected
to be well into central Ohio and central Indiana by then. PWAT
values will be around the 75th percentile of normal and with a
strong source of lift via the cold front, a much needed soaking
rainfall is possible for much of the area. At this time, 0.50"
is likely area-wide. Forecast soundings depict tall, skinny CAPE
profiles and a deep warm cloud layer, so if rainfall is
efficient enough, some locations could be looking at 0.75" to 1"
of rain. Severe weather is not expected, however, gusty winds
will likely accompany the rain and potential few thunderstorms.

Strong CAA and northwest flow on Thursday will usher in much cooler
temperatures post-front. A cool Canadian airmass will overspread
much of the Midwest and Great Lakes regions with cooler than normal
temperatures. Highs Thursday will be only in the mid to upper 60s
area-wide, which is about 10 degrees below normal for this time of
year. Overnight lows Thursday into Friday will fall well into the
40s with some areas approaching record cold temperatures. Enjoy the
early fall preview!

Winds shift from the northwest to southwest late Thursday into the
day on Friday, with breezy conditions and WAA boosting temperatures
up into the upper 60s to low 70s on Friday (a few degrees warmer
than previously forecast) A secondary cold front will sweep through
on Friday with 20-30% chances for rain. This second cold front will
reinstate northwest flow and reinforce cooler than normal
temperatures for the weekend. Have kept with the NBM for now in the
long range, which has highs in the low 70s area-wide over the
weekend. Mid to long range model guidance has caught onto this
secondary cold front and has trended towards cooler than normal
temperatures persisting into early next week. Temperatures will
gradually moderate back towards seasonable levels next week.

Additionally, breezy northwest winds on Thursday will generate high
waves over Lake Michigan. Waves will start to increase after sunset
on Wednesday; the strong cold front may create
seiche/meteotsunami activity across southern Lake Michigan that
could intensify wave development. There is a High Swim Risk for
both Berrien County, MI and La Porte County, IN beaches on
Thursday with waves expected in the 4 to 8 feet range. Stay out
of the water and stay off of piers/breakwalls! Strong rip and
structural currents are expected in addition to the high wave
action. Hazardous swimming conditions persist into Friday and
Saturday as well, with a High Swim Risk for Berrien County, MI
and a Moderate Swim Risk for La Porte County, IN.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 642 AM EDT Tue Sep 2 2025

A strong ridge of high pressure and dry/stable airmass will
ensure VFR conditions with light and variable winds for one more
day. A few 4-5 kft diurnal cu are possible this afternoon but
will have no impact.

&&

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

&&

$$

DISCUSSION...Johnson
AVIATION...AGD