Damaging Winds and Heavy Rain in Illinois, June 26, 2025

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
629 PM CDT Thu Jun 26 2025

.KEY MESSAGES...

- Chances of showers and t-storms will continue at times tonight
  into Friday.

- After a bit of a reprieve from heat and humidity Saturday
  (especially near the lake), another hot and humid day is
  expected Sunday.

&&

.DISCUSSION...
Issued at 249 PM CDT Thu Jun 26 2025

Another day of hot and humid conditions across the area this
afternoon. Some isolated showers and thunderstorms have brought
some temporary relief to a few places this afternoon, but the
majority of the area is experiencing another day with
temperatures in the 90s and heat index readings near or just
above 100 degrees. Atmosphere is hot, humid, and uncapped, which
has allowed for some "air mass" convection to pop this
afternoon. The threat of these isolated to widely scattered
storms could linger through sunset, but unless we get some
amalgamation of cold pools to force additional storms, coverage
should remain pretty isolated through sunset.

Water vapor imagery shows a well defined shortwave over the
northern Plains moving gradually east to the upper Mississippi
Valley. More organized convection has been developing in
association with this shortwave from southern MN south into
central IA. This convection is expected to continue to shift
gradually eastward toward the MS River the rest of the
afternoon. Stronger shear associated with this shortwave is
north of our latitude, so despite the instability, anticipate
this convection should fall apart after sunset as it crosses the
MS River into northwest IL. Kept the highest pops later this
evening into the early overnight over our northwestern CWA, with
much lower chances for this activity surviving long enough to
bring any organized rain chances over our eastern CWA.

Composite outflow/weak synoptic front is expected to move across
our CWA tomorrow. Strongest forcing associated with the
shortwave trough is expected to pass well north of the area, but
with air mass expected to become moderately to strongly unstable
and uncapped in advance of this boundary tomorrow. Certainly
plausible that scattered thunderstorms could develop ahead of
this front tomorrow afternoon, particularly across NW IN and our
east central IL counties. Slightly drier and more stable
conditions in the wake of the front should result dry weather
over our northwest CWA.

Transient surface high will move across the western Great Lakes
Saturday with lower dewpoints making the still seasonably warm
temperatures more tolerable. The position of the high should
also allow for a prominent lake breeze to move well inland
during the afternoon, providing for nature provided AC for areas
closer to the lake.

That high will scoot off the east of the region Sunday with
southerly winds likely to drag the heat and humidity back north
into the area. Highs on Sunday should top out in the low-mid 90s
with heat indices again near to just over 100 degrees. Southern
flanks of another shortwave trough passing north of the area
Sunday should lead to increasing chances of showers and storms
later Sunday afternoon into Sunday evening. Stronger shear and
better threat for organized convection should remain to our
north, but the air should be very moist and moderately to
strongly unstable again Sunday afternoon, so if convection makes
it into the area, wet microbursts and torrential downpours
would be a threat.

Longwave trough is progged to dig into the Great Lakes Region
early next week with much more comfortable humidity, especially
by Tuesday and Wednesday. Temps will remain seasonably warm
away from the lake, but not as hot as many of the days we've
experienced recently.

- Izzi

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 629 PM CDT Thu Jun 26 2025

Forecast concerns include...

Chance of thunderstorms early this evening.
Chance of thunderstorms northwest IL late this evening.
Possible mvfr cigs Friday morning.

Isolated thunderstorms continue to develop and lift northeast
across the area early this evening and this activity is expected
to continue through sunset. Brief heavy rain and locally gusty
winds will be possible with the strongest storms.

A line of thunderstorms across IA will move into northwest IL
late this evening and are expected to steadily weaken as they
move toward and then past RFD. Have maintain prob thunder for
RFD for this activity but most guidance suggests thunder chances
are decreasing for the Chicago terminals and have removed
thunder. Timing for any lingering showers and a possible
northwest wind shift looks to be later, in the early morning
hours and adjusted timing accordingly.

There is a chance of thunderstorms late Friday morning through
mid afternoon, mainly southeast of the terminals, possibly as
far north at MDW/GYY. Confidence is low for both coverage and
location and maintained a dry forecast for sites on Friday.

Most guidance brings an mvfr deck into at least northwest IL in
the predawn hours with it persisting through mid morning and
have included mvfr cigs at RFD. Further east, confidence is low
with the expectation that the precipitation will weaken and
possibly dissipate. Some mvfr level cloud cover is possible at
the Chicago terminals Friday morning and trends will need to be
monitored.

A lake breeze is slowly moving northeast, back toward the lake
currently. This wind shift is not expected to reach ORD/MDW with
south/southwest winds continuing through sunset. However,
prevailing winds may become southerly or briefly south/southeast
for a few hours later this evening, before turning back to the
southwest overnight. Winds will turn west/southwest Friday
morning with gusts into the lower 20kt range possible. Winds
will diminish with sunset Friday evening and turn to the
northwest. Winds may shift to the north or northeast late Friday
evening for the Chicago terminals. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

Visit us at weather.gov/chicago

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
257 PM CDT Thu Jun 26 2025

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-272000-
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-
257 PM CDT Thu Jun 26 2025 /357 PM EDT Thu Jun 26 2025/

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.
  Limited Flooding Risk.
  Elevated Excessive Heat Risk.

DISCUSSION...

The threat of widely scattered thunderstorms will continue
through the evening hours. Conditions are not favorable for
organized or widespread severe weather, however there is a very
low risk that an isolated storm could produce very isolated
marginally damaging wind gusts. In addition, thunderstorms will be
capable of producing torrential downpours.

Heat indices will remain around 100 degrees until sunset.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...
  Limited Flooding Risk.
  Limited Thunderstorm Risk.
Sunday...
  Elevated Excessive Heat Risk.
  Limited Flooding Risk.
  Limited Thunderstorm Risk.
Monday...
  Elevated Thunderstorm Risk.
  Limited Flooding Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation is not expected tonight.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the northeast at around 20 mph.

LMZ740>745-272000-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
257 PM CDT Thu Jun 26 2025

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Tonight.

Weather hazards expected...

  Limited Thunderstorm Risk...with an associated:
     Level 1 of 5 Thunderstorm Wind Gust Risk...up to 50 kt.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...
  Limited Thunderstorm Risk.
Sunday and Monday...
  Limited Thunderstorm Risk.

- Izzi

Visit us at www.weather.gov/chicago

Preliminary Local Storm Report
National Weather Service Chicago IL
250 PM CDT Thu Jun 26 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0702 PM     Tstm Wnd Dmg     1 ESE South Beloit      42.49N 89.02W
06/25/2025                   Winnebago          IL   Emergency Mngr

            Trees downed, multiple large tree branches
            snapped, and roof shingles peeled. Time
            estimated from radar.

&&

RO

Preliminary Local Storm Report
National Weather Service Chicago IL
302 PM CDT Thu Jun 26 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0703 PM     Tstm Wnd Dmg     2 ESE South Beloit      42.49N 89.00W
06/25/2025                   Winnebago          IL   Public

            Photos shared on social media showing an
            unattached semi-trailer rolled onto its side
            and flattened corn crops on the east side of
            South Beloit. Time estimated from radar.

&&

RO

Special Weather Statement
National Weather Service Chicago/Romeoville
615 PM CDT Thu Jun 26 2025

ILZ011-012-020-270000-
Kane IL-De Kalb IL-Kendall IL-
615 PM CDT Thu Jun 26 2025

...GUSTY THUNDERSTORMS WILL IMPACT KENDALL...SOUTHEASTERN DE KALB
AND SOUTHERN KANE COUNTIES THROUGH 700 PM CDT...

At 614 PM CDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line from Leland to Somonauk to Millbrook,
Movement was northeast at 25 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Oswego, Somonauk, Montgomery, Millbrook, North Aurora, Boulder Hill,
Big Rock, Sandwich, Aurora, Hinckley, Bristol, Sugar Grove,
Yorkville, Little Rock, Plano, Kaneville, Waterman, Batavia, and
Plainfield.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4183 8872 4183 8826 4160 8826 4153 8848
      4154 8855 4158 8860 4163 8860 4163 8884
TIME...MOT...LOC 2314Z 221DEG 20KT 4167 8880 4162 8862 4157 8852 4151
8847

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

Borchardt