Hazard Report Provided By forecast.weather.gov

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
244 PM CDT Sat Aug 15 2026

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-161945-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
244 PM CDT Sat Aug 15 2026 /344 PM EDT Sat Aug 15 2026/

This Hazardous Weather Outlook is for portions of north central
Illinois...northeast Illinois and northwest Indiana.

.DAY ONE...Tonight.

Weather hazards expected...

  Limited Thunderstorm Risk...with an associated:
     Level 1 of 5 Damaging Wind Risk...up to 60 mph.
  Elevated Flooding Risk, mainly south of I-80.

DISCUSSION...

Another wave of heavy rain producing showers and thunderstorms is
expected ahead of a cold front tonight into Sunday morning. These
storms will produce torrential downpours and locally gusty winds.
Flash flooding may result in areas where multiple storms move over
the same areas.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Sunday...
  Limited Flooding Risk.
  Limited Thunderstorm Risk...with an associated:
     Level 1 of 5 Severe Thunderstorm Risk.
Tuesday Night...
  Elevated Flooding Risk.
  Limited Thunderstorm Risk.
Wednesday...
  Limited Thunderstorm Risk.
  High Swim Risk Lake Michigan Beaches.


DISCUSSION...

Additional storm chances are expected late Tuesday into Tuesday night.

.SPOTTER INFORMATION STATEMENT...

  Spotters may be needed tonight for flash flooding reports.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the east at 20 to 30 mph.

$$

Flood Statement
National Weather Service Chicago IL
847 PM CDT Sat Aug 15 2026

...The Flood Warning is extended for the following rivers in
Illinois...

  Thorn Creek at Thornton affecting Cook County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Warning means water levels above flood stage are imminent or
may already be occurring. Persons along rivers and streams in the
warned area should take immediate precautions to protect life and
property.

These forecasts are based on observed precipitation as well as
forecast precipitation 24 hours into the future. Changes to the
rainfall forecast, or any additional rainfall after 24 hours, may
cause changes to these river forecasts.

Additional information is available at www.weather.gov.

The next statement will be issued by Sunday afternoon.

&&

ILC031-162000-
/O.EXT.KLOT.FL.W.0069.000000T0000Z-260817T1400Z/
/THNI2.1.ER.260814T1522Z.260815T0145Z.260815T0725Z.NO/
847 PM CDT Sat Aug 15 2026

...FLOOD WARNING NOW IN EFFECT UNTIL MONDAY MORNING...

* WHAT...Minor flooding is forecast.

* WHERE...Thorn Creek from Near Glenwood downstream to confluence
  with Little Calumet River, including the Thornton gauge.

* WHEN...Until Monday morning.

* IMPACTS...At 9.0 feet, Water begins to be diverted through Thorn
  Creek Diversion Tunnel.

* ADDITIONAL DETAILS...
  - At 8:30 PM CDT Saturday the stage was 7.4 feet.
  - Forecast...The river is expected to rise to a crest of 8.6 feet
    tomorrow evening.
  - Flood stage is 9.0 feet.
  - http://www.weather.gov/safety/flood

&&

LAT...LON 4161 8760 4158 8754 4151 8760 4154 8767


$$

Yack

Hazard Report Provided By forecast.weather.gov