Hazard Report Provided By forecast.weather.gov

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
433 AM CDT Fri Apr 17 2026

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-180945-
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-
433 AM CDT Fri Apr 17 2026 /533 AM EDT Fri Apr 17 2026/

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

.DAY ONE...Today and Tonight.

Weather hazards expected...

  Significant Thunderstorm Risk...with an associated:
 Level 3 of 5 Damaging Wind Risk...up to 70 mph.
     Level 2 of 5 Tornado Risk.
     Level 1 of 5 Large Hail Risk...up to one inch in diameter.
  Elevated Flooding Risk.
  Significant Fog Risk early this morning.

DISCUSSION...

Dense fog around the Chicago metro area and near Lake Michigan
will improve by early to mid-morning. Fog may linger later into
the morning along the Lake Michigan shoreline.

A line of thunderstorms is expected to work across northern
Illinois this evening. Thunderstorms may be severe with damaging
wind gusts, hail, and perhaps a few tornadoes. Heavy rain may
also lead to instances of flash flooding.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Saturday Night into Sunday Morning...
  Elevated Frost and Freeze Risk.
Sunday Night into Monday Morning...
  Significant Frost and Freeze Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotters will likely be needed this evening.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the east at 45 mph.

$$

URGENT - WEATHER MESSAGE
National Weather Service Chicago IL
601 AM CDT Fri Apr 17 2026

ILZ005-006-012-013-103-INZ002-171500-
/O.CON.KLOT.FG.Y.0010.000000T0000Z-260417T1500Z/
McHenry-Lake IL-Kane-DuPage-Northern Cook-Porter-
Including the cities of Des Plaines, Evanston, Algonquin,
Naperville, Downers Grove, Woodstock, Aurora, Crystal Lake,
Buffalo Grove, Palatine, Gurnee, Portage, Northbrook, Lombard,
Schaumburg, McHenry, Valparaiso, Carol Stream, Waukegan,
Mundelein, Chesterton, Elgin, and Wheaton
601 AM CDT Fri Apr 17 2026

...DENSE FOG ADVISORY REMAINS IN EFFECT UNTIL 10 AM CDT THIS
MORNING...

* WHAT...Visibility one quarter mile or less in dense fog.

* WHERE...In Illinois, DuPage, Kane, Lake IL, McHenry, and Northern
  Cook Counties. In Indiana, Porter County.

* WHEN...Until 10 AM CDT this morning.

* IMPACTS...Low visibility could make driving conditions hazardous.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If driving, slow down, use your headlights, and leave plenty of
distance ahead of you.

&&

$$

Doom

Hydrologic Outlook
ILC007-031-037-043-053-063-075-089-091-093-097-099-103-105-111-
141-197-201-INC007-073-089-111-127-172100-

Hydrologic Outlook
National Weather Service Chicago IL
357 AM CDT Fri Apr 17 2026 /457 AM EDT Fri Apr 17 2026/

...Another round of thunderstorms expected Friday afternoon and
Friday night...

Additional thunderstorms are expected Friday afternoon and Friday
night across northern Illinois and northwest Indiana. Atmospheric
conditions are favorable for some of these storms to produce
locally heavy rainfall.

Many rivers across northern Illinois and northwest Indiana remain
elevated. Soil moisture also remains elevated in many areas,
especially in northern Illinois along the Wisconsin border. Thus,
any heavy rainfall that occurs could lead to flooding of rivers,
creeks, urban and low-lying areas. Rivers such as the Rock, Fox
and Des Plaines which are already in flood in some locations, may
be especially prone to rainfall which could exacerbate ongoing
flooding.

This outlook means that elevated water levels and potential
impacts are possible, but not yet certain. Persons should closely
monitor forecasts including the possibility of flood watches,
warnings, and advisories.

This outlook will be updated by Friday afternoon.

$$

Hazard Report Provided By forecast.weather.gov