536 
FXUS63 KIWX 220420
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1220 AM EDT Tue Sep 22 2026

.KEY MESSAGES...

- A mainly dry weather pattern ahead. Some pockets of light rain
  or drizzle are possible today, with just a low chance (20-40%)
  of light rain showers east of Interstate 69 continuing tonight
  into Wednesday.

- Below normal temperatures through the end of the work week 
  followed by some moderation in temperatures.

- Dangerous swimming conditions are expected on southern Lake
  Michigan beaches today. 

&&

.DISCUSSION...
Issued at 235 PM EDT Mon Sep 21 2026

The transition to a much quieter weather pattern will continue 
this week. Any additional rain chances through the middle of 
the week will have no impact on current river stage/flooding 
situation across the area. Dry weather is expected to continue
for the Thursday through Sunday period.

Upper level flow pattern today is characterized by a cut-off 
negative upper height anomaly ejecting out of the 
Nebraska/South Dakota vicinity with a low amplitude downstream 
character of flow across the southern Great Lakes and Ohio 
Valley. Smaller scale perturbations continue to work through 
this low amplitude flow locally with the more distinct of these 
short waves tracking across far northeast Indiana/northwest Ohio
this afternoon. Some slightly dry mid level air is advecting 
into the region this afternoon which may continue to provide 
some pockets of light rain/drizzle in association with the 
departing short wave into early this evening. Additional 
rainfall amounts generally expected to be one tenth of an inch 
or less, although cannot completely discount possibility of an 
isolated higher amount (south of US 24 across NW Ohio) given 
relatively stalled position of 850 mb front and some lingering 
respectable PWATS of 1.25 to 1.4 inches. However, additional 
rainfall today into tonight is not expected to provide any 
meaningful impact to ongoing river levels and status of 
minor/moderate flooding across portions of Wabash/Maumee basins.

A secondary area of light rain/drizzle today has been across extreme 
NW Indiana into mainly NE Illinois where some inverted troughing has 
been enhanced by lake induced low level thickness ridging across 
western portions of Lake Michigan. Given nature of northeasterly 
flow profiles, higher chances of rain in this forcing pattern should 
stay over the open waters or across northeast Illinois. The pattern 
over the next few days with persistent easterly flow and favoring of 
mid level subsidence will likely keep a frontal inversion in place 
resulting in a likely difficult time eroding low clouds from much of 
the area. 

For temperatures tonight, a weak secondary cool frontal boundary is 
expected to drop across the southern Great Lakes and should 
provide the coolest temperatures to southern Lower Michigan. 
However, possibility that cloud cover could linger for much of 
the area, fairly well mixed near sfc levels, and wind gusts 
remaining above 10 mph overnight, suggest temperatures will not
bottom out too much with expectation of lows from upper 40s to 
lower 50s most areas.

A persistence forecast has been maintained for Tuesday in terms of 
temperatures with thermal advections gradually waning tonight into 
early Tuesday. From a large scale synoptic perspective, the upper 
trough across the Plains will slowly push eastward to the Mid MS 
Valley with an eventual beginning of phasing with secondary negative 
upper height anomaly across Ohio. Any precip should be quite
limited Tue/Tue night with lingering dry mid level air a 
deterrent. Could see scenario again where thermally induced 
thickness ridge over Lake Michigan helps focus a few showers 
across northwest Indiana, and perhaps along/east of I-69 where 
some lingering low level moisture could reside. Have maintained 
some slight chance PoPs these periods.

Looking toward the middle of the week, continued phasing of the two 
negative upper height anomalies should eventually allow low-mid 
level theta-e ridge to wrap back northwestward to the southern Great 
Lakes. This could be enough to yield pockets of light rain showers 
mainly along/east of I-69 Wed but confidence is quite low.

An overall quiet weather regime still looks to maintain its hold 
Thursday to the weekend with eventual departure of this phased upper 
low allowing for mid/upper level height recovery and gradual 
modification of low level temperatures by Saturday and Sunday as low 
level southwesterlies are finally able to develop. Precip prospects 
look low through Monday as any Pacific waves trying to top the 
central CONUS ridge will likely encounter less than ideal moisture 
profiles locally during this period.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1219 AM EDT Tue Sep 22 2026

Somewhat breezy east-northeast low level flow will linger on the
southern fringes of high pressure through the period, with gusts
up to near 20 knots common mid morning into this afternoon.
Slightly drier conditions at KSBN should ensure VFR through much
of the period, while MVFR cigs likely linger at KFWA closer to
an inverted trough. This feature in tandem with an incoming vort
max may allow pockets of light rain to impact KFWA this
afternoon into tonight, though chances remain too low for a
mention at this time. 

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement through late Tuesday night for INZ103.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Marsili
AVIATION...Steinwedel