Schererville, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

458
FXUS63 KLOT 192350
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
650 PM CDT Sat Jul 19 2025

.KEY MESSAGES...

- Next wave of thunderstorms is timed for after 2 am. Overall
  severe threat appears low. However, localized flash flooding
  could develop (10-15% chance)

- Several rounds of thunderstorms may occur early next week,
  with strong/severe thunderstorms possible along with
  torrential rain and localized flash flooding, particularly
  south of I-80.

- Dangerous heat and humidity becoming increasingly likely next
  Wednesday and Thursday.

&&

.DISCUSSION...
Issued at 251 PM CDT Sat Jul 19 2025

Through Sunday Night:

The afternoon complex of storms has primarily shifted east of
the forecast area as of 2 pm, with just a few storms churning on
the south end of Lake Michigan and surrounding land areas. In
the wake of those storms, satellite imagery is depicting some
clearing and sunshine developing from west to east. Nearly all
CAMs are remaining relatively quiet on any redevelopment through
sunset. However, satellite images show some agitated CU in NW
IL, so as sunshine increases SBCAPE values back toward 2,000
J/kg later this afternoon, we can not completely rule out
isolated storms redeveloping on outflow boundaries (10-15%).

Beyond that, the consensus of short-range ensembles are
indicating the next complex of storms will develop in an and
area of low-level isentropic ascent near a stalled frontal
boundary. That wave is already triggering showers and storms in
northeast Nebraska and SE South Dakota. The storms will likely
be elevated when they reach northern Illinois, as low level
stability returns after sunset. The primary focus area for those
storms looks to be the southern half of the CWA, where mid-level
steering flow will guide that activity around the ring of fire.
The airmass will remain primed for heavy rainfall, as PWATs
continue to linger in the 1.8 to 2.0" range through the night
into Sunday. Any slower moving storm could produce localized
flash flooding.

Sunday`s scenario appears to be tied to the lingering frontal
boundary as is shifts southward through the area. The late night
storms will linger into Sunday morning as they progress into the
eastern half of our counties. A couple of latest CAMs indicate
some northward expansion of the showers, north of I-88 in the
late morning to early afternoon time frame, but the better axis
of instability and moisture content will be south of I-80. SPC
continues to paint a Marginal Risk of severe storms in that
area, where damaging winds could develop from any updrafts that
are able to tap into the 3500 J/kg MUCAPE that will develop
along our southern CWA border. WPC has a corridor of Slight Risk
of Excessive Rainfall across the southern half of our CWA, with
ample PWATs for flash flooding still present. After the
morning-early afternoon complex, storm chances will shift
southward into early evening. Yet another complex of storms is
progged for later Sunday night into early Monday, once again
ridge riding on the NW flow into mainly the southern half of the
CWA. Wind damage threat and heavy rainfall will be the
continued hazards.

Shimon

Monday through Saturday:

After that early threat of storms Monday morning, the remainder
of Monday looks to see a break in the rain chances and the front
shifts farther south into central IL.

Then attention turns to the building heat wave as dewpoints make
a slow but steady climb through the 70s by mid to late week.
The highest heat and humidity are continuing to target Wednesday
and Thursday. The forecast guidance may not even be able to
capture the impacts of `corn sweat` from evapotranspiration -
where 3,000-4,000 gallons of water per acre can be released per
acre of corn.

That influx of moisture can cause localized areas of dewpoints
to reach the lower 80s, and nudging heat indices into the heat
advisory (105F) to near extreme heat warning levels (110F+).
The extended guidance is continuing to show a heat dome
developing under an upper level ridge, which will shift east
into Illinois Wed-Thur. High temps will likely reach the 90s
both Wed and Thursday, with heat index readings over 100F in
most areas. A heat headline will need to be considered in future
updates if these forecasts hold. The Chicago urban heat island
effect will likely come into play for that heat wave. Southerly
offshore wind patterns will be unfavorable for some cooler near
the lake conditions.

The upper ridge looks to break down and flatten enough for some
relief from the heat, or at least below heat headline levels.
The extended ensembles are indicating a storm complex will
impact our cwa at some point later Thursday night through Friday
night. We will need to keep an eye out for severe potential as
that heat wave breaks, but with temperature outlooks remaining
above normal into the last week of July, there doesn`t appear to
be a significant cool down in the offing.

Shimon

&&

.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 650 PM CDT Sat Jul 19 2025

Aviation forecast concerns for the 00Z TAFs:

- Wind shift to northeast with cold frontal passage after
  midnight tonight.

- IFR ceilings likely late tonight/Sunday morning.

- Chance of fog early Sunday morning.

- Chance of SHRA/TSRA Sunday morning/midday.

Complex of rain/thunderstorms which moved across the terminals
earlier today has moved well east of the area, leaving stable
conditions across the region this evening. Surface winds have
become light westerly, though a weak lake breeze has moved into
eastern Lake and far northeast Cook counties. TDWR radar trends
indicate this is unlikely to reach the terminals this evening
before washing out.

A cold front, currently drifting southward across central WI, is
expected to reach the terminals predawn Sunday morning, shifting
winds to the northeast and likely resulting in a period of IFR
(and perhaps even brief LIFR, though confidence is fairly low
in that) ceilings and some MVFR visibilities in fog into Sunday
morning. Even prior to the frontal passage, can`t rule out some
MVFR fog at RFD and DPA. Latest model guidance trends suggest
IFR ceilings may linger through midday/early afternoon before
slowly lifting to MVFR, and eventually VFR Sunday evening.

Another round of SHRA/TSRA is expected to develop eastward from
the Plains late tonight and spread across portions of central
and northern IL/IN Sunday morning. Current expectations
(supported by HREF ensemble calibrated TS probabilities <20%)
are that the greatest TS chances will remain south of the
terminals, though perhaps not too far south. Have added a prob30
mention for SHRA during the morning/midday hours along the
northern periphery of this activity except did include TS at
GYY, being the farthest south location.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Beach Hazards Statement from 4 AM CDT Sunday through Monday
     morning for ILZ006-ILZ103-ILZ104.

IN...None.
LM...None.

&&

$$

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