697
FXUS63 KIWX 211157
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
757 AM EDT Thu Aug 21 2025

.KEY MESSAGES...

- Seasonable and less humid this week. High confidence in fall-
  like weather arriving late in the weekend into early next
  week. Highs in the low to mid 70s and lows in the 40s are
  likely.

- Mainly dry aside from a slight chance (20%-30%) for rain on
  Saturday. Lake effect rain showers possible near Lake Michigan
  late Sunday into Monday.

- Dangerous swimming conditions for southeast Lake Michigan
  beaches today and then again on Sunday and Monday. A beach
  hazards statement is in effect for La Porte County, IN and
  Southern Berrien County, MI through this afternoon.

&&

.DISCUSSION...
Issued at 310 AM EDT Thu Aug 21 2025

A few areas of light to moderate drizzle will be possible in
northwest Ohio this morning as northeasterly flow off of Lake Erie
pushes moisture inland. Forecast soundings in the vicinity of Lima,
OH show a favorable atmospheric profile for drizzle through
daybreak. Drizzle will taper off in northwest Ohio and area-wide,
clouds will slowly diminish throughout the afternoon. Diurnally-
driven northeast winds will gust to 15 to 20 mph this afternoons and
evening (especially east of I-69) before subsiding after sunset.
Surface high pressure over the upper Great Lakes region will allow
for seasonable temperatures and mainly dry conditions to persist
across the area this week.

Rain chances will be few and far between over the next 7 days as a
mainly dry pattern persists with dominant north/northwest flow. A
large area of low pressure will move over the upper Great Lakes
region over the weekend, bringing low chances (20-30%) for
rain/storms during the day on Saturday with the attendant cold
front. Uncertainties remain as to how much moisture accompanies this
front. There does appear to be (per RAP and GFS soundings), decent
instability and speed shear on Saturday with the front. It will
likely be breezy over the weekend near Lake Michigan as well. A
trough pivots through late Sunday into Monday, with potential
for lake effect showers and waterspouts over southern Lake
Michigan. Soundings show favorable profiles near the
southeastern Lake Michigan lakeshore with cyclonic low level
flow, saturated low to mid levels, and inversion heights of 7-8
km near South Bend. This is a very typical pattern in late
summer into fall with cold air behind Saturday`s cold front that
will be moving over the relatively warm waters of Lake
Michigan. Upper level temperatures will be on the low end of
climatological normals during this timeframe and lake
temperatures are still in the low 60s.

After the cold front comes through Saturday, much cooler air filters
in to end the weekend and begin the new work week. There is high
confidence that this will be a taste of true fall-like weather;
temperatures will be 10+ degrees below normal. Highs in the low to
mid 70s and lows in the 40s are likely for several days next week!
Some locations closer to Lake Michigan may struggle to even reach 70
degrees on Monday and Tuesday. With cooler temperatures and
persistent northwest flow, this bodes well for the dry pattern to
continue next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 733 AM EDT Thu Aug 21 2025

Predominantly MVFR/VFR conditions at the taf sites, with the
exception of KSBN who is hovering at the edge of VLIFR/LIFR
with a 200-400 ft cloud deck (KEKM just to the east is at
OVC002ft). The 11:31z observation at KSBN just came in with
400ft ceilings and 4SM BR reported. Clouds are quickly scouring
out to the south-southeast and I suspect that this will be
short lived, so only have a tempo until 13z. Outside of that
we`ll improve to MVFR through the morning and then VFR shortly
after that. KFWA is currently VFR but upstream we still see some
1500-2500 ft ceilings that are moving southwest--arriving (if
they stay MVFR) around the 13-16z period. Some of the guidance
builds them back to around 3500 ft before arriving, and it
seems quite variable so just have a tempo for 2kft to cover at
this point. With light/variable winds and mostly clear skies
tonight expect we`ll see some ground fog/BR towards the 9-12z
time frame at both sites, so have 4SM BR in that period.

&&

.MARINE...
Issued at 507 AM EDT Thu Aug 21 2025

Extended the small craft advisory for the southern most
marine zone (MI City-New Buffalo) through around 8 am. Also
extended the beach hazards statement for La Porte County, IN
beaches (2 pm EDT) and S. Berrien County, MI (11 am EDT) as
waves this morning still linger around 4-5 feet at Michigan
City, IN; around 3-4 feet at the Cook Nuclear Buoy near
Stevensville, MI; and 2-3 feet at South Haven, MI. Wave periods
are running around 5-6 seconds, with wave angles of approach
generally in the 40-90 degree range, which favors stronger
currents (especially further south at New Buffalo/Mi City).

Expect waves to diminish through the day as flow temporarily
shifts more E-NE, with waves eventually dropping as low as 1-2
feet by late afternoon. Winds shift north and strengthen
slightly towards evening, possibly climbing to 2 to 3 feet
around sunset or shortly after. The highest waves will be
further south near New Buffalo, MI and Michigan city.

A strong southward flowing longshore current is likely to
persist through the day, in addition to life-threatening
structural currents near piers and breakwalls (particularly on
the north side). Strong rip currents are expected through the
early afternoon as well (especially further south), but will be
less likely as waves subside and flow becomes more E-NE
(offshore/shore parallel) this afternoon.

Have a high swim risk for the morning and early afternoon with
the beach hazards statement. For northern Berrien county,
moderate swim risk conditions will last through morning with 2-3
ft waves, then become low risk in the early-mid afternoon.
Moderate to strong structural currents are still likely to
persist on north sides of piers/breakwalls, despite lower wave
heights. It`s possible moderate risk conditions return with the
evening increase, but waves look to be about 2 ft through sunset
(marginal).

High swim risk conditions are likely for all of Berrien County
Sunday into Monday, and La Porte County, IN on Monday behind a
cold front that will bring W-NW flow and waves of 3-5 feet. La
Porte will likely be moderate on sunday, with waves around 2-3
feet at peak.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement until 1 PM CDT this afternoon for
     INZ103.
OH...None.
MI...Beach Hazards Statement until 11 AM EDT this morning for
 MIZ277.

&&

$$

DISCUSSION...Johnson
AVIATION...MCD
MARINE...MCD