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

729
FLUS43 KLOT 240845
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
345 AM CDT Tue Jun 24 2025

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-250845-
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-
345 AM CDT Tue Jun 24 2025 /445 AM EDT Tue Jun 24 2025/

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

.DAY ONE...Today and 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 south of I-80.

DISCUSSION...

Scattered thunderstorms are expected this afternoon and evening.
In addition to frequent lightning, the strongest storms may be
capable of localized damaging winds and flooding.

Afternoon heat indices of 100 to 105 degrees are expected again
today in areas south of I-80.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Wednesday and Thursday...
Limited Thunderstorm Risk...with an associated:
Level 1 of 5 Severe Thunderstorm Risk.
Limited Flooding Risk.
Limited Excessive Heat Risk.

Friday...
Limited Thunderstorm Risk.
Limited Excessive Heat Risk.

Saturday through Monday...
Limited Thunderstorm Risk.

DISCUSSION...

Periodic thunderstorm chances will continue through early next
week. The strongest storms may be capable of producing damaging
winds and localized flooding.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed this afternoon and evening.

GENERAL STORM MOTION OF THE DAY:

Moving toward the northeast at 30 mph.

$$

LMZ740>745-250845-
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-
345 AM CDT Tue Jun 24 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...Today and Tonight.

Weather hazards expected...

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

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

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

$$

Petr

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

053
ACUS03 KWNS 240713
SWODY3
SPC AC 240712

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0212 AM CDT Tue Jun 24 2025

Valid 261200Z - 271200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE CENTRAL PLAINS AND MIDWEST...AND OVER MUCH OF THE SOUTHEAST AND
MID ATLANTIC...

...SUMMARY...
Scattered strong storms are possible from the central Plains to
Lower Michigan, over parts of the Southeast, and over parts of
Montana on Thursday. Scattered damaging gusts appears to be the main
concern.

...Synopsis...
On Thursday, a weak upper wave will move eastward across the Great
Lakes, phasing with the larger-scale trough which will be exiting
the Northeast. South of there, a weakening upper low should remain
over FL, providing cool temperatures aloft. Otherwise, winds aloft
over much of the central and eastern CONUS will be weak. To the
west, moderate westerly flow aloft will move across the Pacific
Northwest and into the northern Rockies, with 30-40 kt 500 mb winds
over MT.

At the surface, a large area of moisture and instability will remain
in place from the Plains and Midwest into the Southeast, and this
will continue to support widely scattered thunderstorms, with some
producing severe gusts during the afternoon. Meager moisture return
will occur into eastern MT, in advance of the low-amplitude upper
wave.

...Central Plains into the Midwest...
A surface boundary will provide a focus for daytime redevelopment
from KS IA/MO/IL, with storms becoming numerous by 00Z. Weak shear
and ample moisture should support clusters of storms with primarily
localized strong to damaging gusts.

...Southeast...
Midlevel lapse rates are forecast to weaken on Thursday, but cool
temperatures will still support areas of moderate instability.
Storms should again occur over the Appalachians, and perhaps along
residual outflows from early convection. Isolated damaging gusts
will be possible.

...Eastern MT...
Steep lapse rates will develop, but surface dewpoints are forecast
to be in the 40s F within a pre-frontal trough. Still, the deeply
mixed boundary layer combined with 500-1000 J/kg MUCAPE and modest
westerly flow aloft may support scattered storms capable of locally
strong wind gusts.

..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.

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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No active Non-Precip Statement for DuPage County.

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.

Winter Weather Warnings

No active Winter Weather 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.