SPC Convective Outlook Day 1

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601
ACUS01 KWNS 240535
SWODY1
SPC AC 240533

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1233 AM CDT Tue Jun 24 2025

Valid 241200Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN HIGH PLAINS...

...SUMMARY...
Storms associated with very large hail and severe wind gusts will be
likely this afternoon and evening in parts of the central and
northern High Plains. Marginally severe storms will be possible this
afternoon from part of the central and northern Plains eastward into
the Northeast.

...Central and Northern High Plains...
A mid-level anticyclone will remain in place today across much of
the southeastern third of the nation, as west-northwesterly
mid-level flow continues from the north-central U.S. into the Great
Lakes. At the surface, a post-frontal airmass will be located over
the central and northern High Plains, where surface dewpoints will
be mostly from the mid 50s to the mid 60s F. As surface temperatures
warm during the day, moderate instability will develop across parts
of the region, and scattered convection will initiate in the higher
terrain. These storms will move eastward into the lower elevations
of the High Plains this afternoon.

RAP forecast soundings from eastern Wyoming into northeastern
Colorado at 21Z have 40 to 50 knots of deep-layer shear, with
700-500 mb lapse rates around 8 C/Km. This environment will support
the development of supercells with large hail. Hailstones of greater
than 2 inches in diameter will be possible with supercells that
become particularly intense. In areas where convective coverage is
greatest, the cells could congeal into short line segments capable
of severe gusts. The severe threat should be greatest from late
afternoon to mid evening.

....Central and Northern Plains/Mid to Upper Mississippi
Valley/Lower Great Lakes/Northeast...
The northern edge of a mid-level anticyclone will remain from the
mid Mississippi Valley east-northeastward into the central
Appalachians today. To the north of the anticyclone,
west-southwesterly mid-level flow will be in place. At the surface,
a front will be positioned from the central Plains
east-northeastward into the lower Great Lakes and Northeast. Near
and to the south of the front, surface dewpoints from the mid 60s to
the lower 70s F will contribute to the development of moderate
instability by afternoon. This, along with increasing low-level
convergence near the front, will result in scattered convective
initiation. Several clusters or line segments are expected to
develop and move eastward into the stronger instability. Although
deep-layer shear will remain on the marginal side for organized
storms, low-level lapse rates will become steep in the mid to late
afternoon. This could support a marginal wind-damage threat with the
stronger multicell line segments in areas that heat up the most.

..Broyles/Moore.. 06/24/2025

$$

The "Convective Outlooks" issued by SPC can be thought of as a detailed discussion of the Severe Thunderstorm threat and it's associated risks nationwide. Risk levels range from Marginal to Slight, Enhanced, Moderate, and High and are issued based on the likelihood of 3 major severe weather threats; the risk of tornadoes, damaging winds, and hail. These discussions are often heavily laced meteorological terminology that may be difficult to understand without a background in the field. However understanding these discussions shouldn't be thought of as necessary. Instead, should DuPage county fall under one of these threat levels for severe weather, the response should be to have a heightened level of awareness about the deveoloping weather. Keep an eye on the "Watch County Notification" for any active severe weather watches issued for DuPage county; the "Hazardous Weather Outlook" and "Severe Weather Statement" can also be helpful in explaining the developing risk; additionally, watch for "Active Weather Warnings" and keep an eye on our "Regional Satellite and Radar" products which can be viewed with active watches/warnings or lightning activity.

Hazardous Weather Outlook

See Product Description

737
FLUS43 KLOT 240336
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
1036 PM CDT Mon Jun 23 2025

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-250345-
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-
1036 PM CDT Mon Jun 23 2025 /1136 PM EDT Mon Jun 23 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.
Limited Flooding Risk.

DISCUSSION...

Showers and a few thunderstorms will push across parts of the
region tonight, with the greatest chances across northwest
Illinois. The main threats from the strongest storms and outflow
will be gusty winds to 40 mph and brief heavy rainfall.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Tuesday and Wednesday...
Limited Thunderstorm Risk...with an associated:
Level 1 of 5 Severe Thunderstorm Risk.
Limited Flooding Risk.
Elevated Excessive Heat Risk south of I-80.

Thursday through Sunday...
Limited Thunderstorm Risk.
Limited Excessive Heat Risk.

DISCUSSION...

Periodic thunderstorm chances will exist into the weekend, as
a nearly stationary frontal boundary lingers in the vicinity.
The strongest storms may be capable of producing damaging
wind gusts and localized flooding.

While lower than the past few days, afternoon peak heat indices
near 100 to 105 degrees are expected, mainly south of I-80.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected tonight.

GENERAL STORM MOTION OF THE DAY:

Moving toward the east-northeast at 20 to 30 mph.

$$

LMZ740>745-250345-
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-
1036 PM CDT Mon Jun 23 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.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Tuesday and Wednesday...
Limited Thunderstorm Risk...with an associated:
Level 1 of 5 Severe Thunderstorm Risk.
Thursday through Sunday...
Limited Thunderstorm Risk.

$$

Carlaw

Visit us at www.weather.gov/chicago

The "Hazardous Weather Outlook" contains information regarding any and all weather expected to occur within the region that could be hazardous to travel, life or property. This is one of our most highly recommended products to check on a daily basis, and it some cases multiple times per day should significant weather be expected to affect DuPage county.

SPC Convective Outlook Day 2

See Product Description

129
ACUS02 KWNS 240606
SWODY2
SPC AC 240605

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0105 AM CDT Tue Jun 24 2025

Valid 251200Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CAROLINAS
INTO PARTS OF THE FLORIDA PANHANDLE...SOUTHERN ALABAMA AND
GEORGIA...

...SUMMARY...
Severe wind gusts are possible over much of the Southeast, with
widely scattered strong to severe storms possible from the northern
High Plains eastward toward the Mid Atlantic.

...Synopsis...
A positive-tilt shortwave trough will weaken on Wednesday as it
lifts out of the Great Basin and across the northern Plains.
Meanwhile, an upper high over the OH/TN Valleys will also weaken.
Areas of 30 kt midlevel winds will remain over parts of the northern
Plains and Great Lakes around the northern periphery of the upper
ridge, aiding movement of storms clusters throughout the period.

At the surface, high pressure over Ontario and Quebec will result in
cool/dry trajectories across the Great Lakes, with a boundary
roughly from a low over NE eastward toward southern Lower MI and
continuing into southern New England. A very moist air mass will
remain south of this front, with 2000 J/kg MUCAPE common.

South of the upper high, a low-latitude upper low is forecast to
move across FL, with -10 C at 500 mb over FL, AL, GA and SC. This
will boost instability further, exceeding 3000 J/kg in those areas
with steepened midlevel lapse rates.

...Southeast...
Strong instability will develop during the afternoon over much of
the region, with 2000-3000 J/kg MLCAPE common. Of note will be
midlevel lapse rates greater than 7.0 C/km, suggesting robust
convection is likely. Storms are expected to form around 21Z over
the high terrain, and within a surface trough during peak heating
over the central Carolinas. Slow moving at first, storms will form
into clusters, with erratic motions possible. However, a general
southerly trends is expected. The high PWAT content, steep lapse
rates, and favorable time of day all suggest areas of damaging
microbursts will develop. As such, the area has been upgraded to a
Slight Risk.

Scattered storms are expected farther south into GA, AL, and the FL
Panhandle as well, within a southwest extension of the surface
trough, and, possibly with the sea breeze. Forecast soundings in
this region similarly show very strong instability, with
west/southwest moving storm clusters likely producing damaging wind
gusts.

...Parts of the northern Plains...
Areas of storms will be ongoing early in the day from NE eastward
into IL/IN/OH, in a zone of warm advection around the periphery of
the ridge. While moist and unstable, lapse rates will not be
particularly steep aloft, but substantial moisture will continue to
fuel bouts of storms redeveloping during the day from NE into
SD/IA/southern MN, and some of this activity could produce marginal
hail or wind.

To the west, cells will develop during the late afternoon from over
the northern to central High Plains, with hail potential as
temperatures aloft will remain cool.

..Jewell.. 06/24/2025

$$

The "Convective Outlooks" issued by SPC can be thought of as a detailed discussion of the Severe Thunderstorm threat and it's associated risks nationwide. Risk levels range from Marginal to Slight, Enhanced, Moderate, and High and are issued based on the likelihood of 3 major severe weather threats; the risk of tornadoes, damaging winds, and hail. These discussions are often heavily laced meteorological terminology that may be difficult to understand without a background in the field. However understanding these discussions shouldn't be thought of as necessary. Instead, should DuPage county fall under one of these threat levels for severe weather, the response should be to have a heightened level of awareness about the deveoloping weather. Keep an eye on the "Watch County Notification" for any active severe weather watches issued for DuPage county; the "Hazardous Weather Outlook" and "Severe Weather Statement" can also be helpful in explaining the developing risk; additionally, watch for "Active Weather Warnings" and keep an eye on our "Regional Satellite and Radar" products which can be viewed with active watches/warnings or lightning activity.

SPC Convective Outlook Day 3

See Product Description

130
ACUS03 KWNS 231931
SWODY3
SPC AC 231930

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 PM CDT Mon Jun 23 2025

Valid 251200Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
NORTHERN/CENTRAL HIGH PLAINS TO THE MIDWEST...GREAT LAKES AND THE
MID-ATLANTIC...SOUTHWARD ACROSS THE SOUTHEAST AND INTO FLORIDA...

...SUMMARY...
Strong to potentially severe storms are possible Wednesday in a
corridor from the northern High Plains into the Midwest and
Northeast, and also along and east of the Appalachians into the
Southeast and much of Florida

...Synopsis...
Upper-level ridging across the eastern CONUS will start to weaken on
Wednesday. A weak low will move west across the Florida Peninsula
during the period. A strong mid-level jet streak will extend along
the northeastern periphery of the ridge from northern Ontario to the
Northeast. The trough across the western CONUS will deamplify
through the period with a weak shortwave trough ejecting into the
Plains.

...Northern/Central High Plains and adjacent Plains...
A deepening surface low will develop across northeast
Colorado/northwest Kansas, and southwest Nebraska on Wednesday as a
mid-level trough ejects over the Plains. Moderate instability is
expected to develop south of the front which will extend east from
this surface low across Nebraska and into Iowa. Isolated to
scattered storms are expected along this front and near the
intersection with the dryline/surface low. While mid-level flow is
forecast to be somewhat weak, stronger upper-level flow may provide
sufficient upper-level venting/deep-layer shear for some supercell
organization.

Stronger flow will be present farther north across northeast Wyoming
and southeast Montana. A few supercells are possible if low 60s
dewpoints can advect into the region with moderate instability.

...Midwest to the Mid Atlantic...
Thunderstorms will likely be ongoing at the beginning of the period
from the central Plains to the Great Lakes. These thunderstorms and
their composite outflow will likely reinforce the boundary across
the area. South of this boundary, a very moist airmass with moderate
instability will be in place. Very weak shear will be the primary
limiting factor to severe weather, but numerous thunderstorms in a
moderately unstable and very moist environment should support some
threat for wet microbursts and damaging wind gusts.

...Mid-Atlantic to the Southeast and Florida...
Steep mid-level lapse rates are expected across much of the eastern
CONUS on Wednesday as the upper-level ridge weakens. Strong heating
in a very moist environment should result in moderate to strong
instability from Virginia southward into Florida. The highest
confidence for storms will be along the sea breeze and the higher
terrain. However, additional thunderstorms are also possible during
the afternoon, particularly where any remnant outflow boundaries may
remain from Tuesday night thunderstorm activity. Strengthening
northeasterly flow across the region may provide enough shear for a
few strong to severe multicell clusters capable of mostly damaging
wind gusts.

..Bentley.. 06/23/2025

$$

The "Convective Outlooks" issued by SPC can be thought of as a detailed discussion of the Severe Thunderstorm threat and it's associated risks nationwide. Risk levels range from Marginal to Slight, Enhanced, Moderate, and High and are issued based on the likelihood of 3 major severe weather threats; the risk of tornadoes, damaging winds, and hail. These discussions are often heavily laced meteorological terminology that may be difficult to understand without a background in the field. However understanding these discussions shouldn't be thought of as necessary. Instead, should DuPage county fall under one of these threat levels for severe weather, the response should be to have a heightened level of awareness about the deveoloping weather. Keep an eye on the "Watch County Notification" for any active severe weather watches issued for DuPage county; the "Hazardous Weather Outlook" and "Severe Weather Statement" can also be helpful in explaining the developing risk; additionally, watch for "Active Weather Warnings" and keep an eye on our "Regional Satellite and Radar" products which can be viewed with active watches/warnings or lightning activity.

Special Weather Statement

See Product Description

No active Special Weather Statement for DuPage County.

The "Special Weather Statement" details notable weather either occuring or expected to occur, but does not necessarily have to be considered severe or hazardous. This is a supplementary product issued by the National Weather Service to help describe noteworthy weather. It's terminology should be reasonably easy to understand by the general public.

Watch County Notification

See Product Description

No active Watch County Notification for DuPage County.

The "Watch County Notification" will contain updates regarding active severe weather watches that pertain to DuPage county. This may be for a newly issued watch, or the cancelation of an existing watch. Severe weather watches come in two forms; Severe Thunderstorm and Tornado, and it should be noted that a Severe Thunderstorm Watch does NOT rule out the possibility of tornadoes occuring. It generally means that the tornado threat is minimal while damaging winds and hail are still likely. See our "Watch, Warning, and Advisory Criteria" for more detailed information on the differences and critera for watches, warnings and advisory for all forms of weather.

Winter Weather Statement

See Product Description

No active Winter Weather Statement for DuPage County.

The "Winter Weather Statement" is a product aimed at the general public that will discuss impacts caused by winter weather. This may include information about watches, warnings and advisories as well as details about impactful winter weather that may not warrant the issuance of a watch, warning or advisory.

Severe Weather Statement

See Product Description

No active Severe Weather Statement for DuPage County.

The "Severe Weather Statement" is a product aimed at the general public that will discuss impacts caused by severe thunderstorms. This may include information about watches and warnings as well as details about impactful "sub-severe" weather that may not warrant the issuance of a watch or warning which sometimes may come when a watch or warning has been canceled.

Non-Precip Statement

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907
WWUS73 KLOT 240309
NPWLOT

URGENT - WEATHER MESSAGE
National Weather Service Chicago IL
1009 PM CDT Mon Jun 23 2025

ILZ103>105-240415-
/O.CAN.KLOT.XH.W.0001.000000T0000Z-250624T0500Z/
Northern Cook-Central Cook-Southern Cook-
Including the cities of Calumet City, Oak Lawn, Orland Park, Oak
Park, Cicero, Northbrook, Des Plaines, Palatine, Schaumburg,
Evanston, Chicago, Oak Forest, Lemont, La Grange, and Park Forest
1009 PM CDT Mon Jun 23 2025

...EXTREME HEAT WARNING IS CANCELLED...

$$

ILZ003>006-008-010>013-019>021-106>108-INZ001-002-240415-
/O.CAN.KLOT.HT.Y.0001.000000T0000Z-250624T0500Z/
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-La
Salle-Kendall-Grundy-Northern Will-Southern Will-Eastern Will-
Lake IN-Porter-
Including the cities of Belvidere, Ottawa, Bolingbrook, Rockford,
Hammond, Naperville, Crete, Buffalo Grove, Channahon, Peotone,
Waukegan, Mendota, DeKalb, Plano, Woodstock, Manhattan, Portage,
Minooka, Valparaiso, Oswego, Algonquin, Elgin, Wilmington,
Gurnee, Byron, Morris, Mundelein, Yorkville, Sycamore,
Plainfield, La Salle, Carol Stream, Marseilles, Coal City,
Crystal Lake, Streator, Oregon, Aurora, Gary, Joliet, Wheaton,
McHenry, Mokena, Lombard, Dixon, Downers Grove, Rochelle,
Merrillville, Chesterton, and Beecher
1009 PM CDT Mon Jun 23 2025

...HEAT ADVISORY IS CANCELLED...

$$

ILZ023-032-033-039-INZ010-011-019-241315-
/O.CON.KLOT.HT.Y.0001.000000T0000Z-250625T0000Z/
Kankakee-Livingston-Iroquois-Ford-Newton-Jasper-Benton-
Including the cities of Gibson City, Dwight, Gilman, Paxton,
Rensselaer, Oxford, Bradley, Watseka, Fairbury, Fowler,
Bourbonnais, Morocco, Kentland, Pontiac, DeMotte, Roselawn, and
Kankakee
1009 PM CDT Mon Jun 23 2025 /1109 PM EDT Mon Jun 23 2025/

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT /8 PM EDT/
TUESDAY...

* WHAT...Peak afternoon heat indices of 100 to 105 degrees expected
on Tuesday.

* WHERE...In Illinois, Livingston, Ford, Iroquois, and Kankakee
Counties. In Indiana, Benton, Jasper, and Newton Counties.

* WHEN...Until 7 PM CDT /8 PM EDT/ Tuesday.

* IMPACTS...Hot temperatures and high humidity may cause heat
illnesses.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of
the sun, and check up on relatives and neighbors.

&&

$$

The "Non-Precip Statement" is aimed at the general public and will detail notable weather that is either occuring or expected to occur, but does not relate to any form of precipitation. These would include but are not limited to high winds, reduced visibility or extreme temperatures.

Active Weather Warnings

Tornado Warnings

No active Tornado Warnings.

Severe Thunderstorm Warnings

No active Severe Thunderstorm Warnings.

Flood Warnings

No active Flood Warnings.

General Tornado/Severe Weather Safety

1. A Tornado or Severe Thunderstorm Warning is issued when it has been reported, or when it has been detected via National Weather Service radar. It is to be interpreted that this event is occuring and is expected to affect all warned areas. Those within the warning need to take action immediately.
2. If under a warning remain calm and if it is necessary to seek shelter. Students and Employees should head to their nearest designated shelter area. The route to these shelter areas are posted in all rooms on campus and signs are placed in the hallways to direct you to the nearest shelter area. Review these instructions and be familiar with where your nearest shelter is. Stay indoors, away from windows and large unsupported ceilings. Faculty should account for their students and Supervisors should account for their areas employees.
3. If outside, take shelter in the nearest building.
4. After the storm has passed, dial Police at 911 to report any injuries or damage to buildings.
5. If the building is severely damaged, evacuate the building as soon as possible after the storm has passed.