SPC Convective Outlook Day 1

See Product Description

804
ACUS01 KWNS 150534
SWODY1
SPC AC 150532

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1232 AM CDT Fri Aug 15 2025

Valid 151200Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe storms are likely over parts of the northern Plains
and Upper Mississippi Valley.

...Northern Plains/Upper MS Valley...

Broad anticyclonic flow is forecast to continue across the
central/southern Plains during the day1 period. Stronger 500mb flow
will extend around the periphery of this feature, extending from the
northern Rockies-northern Plains-upper Great Lakes. While a few
disturbances will eject across the northern Rockies toward the upper
MS Valley, latest model guidance suggests heights will actually rise
much of the period. One such feature currently extends from eastern
WY into northeast CO. Scattered thunderstorms are noted immediately
downstream from the Black Hills into western NE. This disturbance
should advance into central SD by the start of the period, then into
MN by early afternoon. While a few strong storms may be ongoing at
the start of the period, renewed development is expected during the
afternoon across the upper MS Valley. LLJ is forecast to increase a
bit into southwest MN ahead of the short wave, and this should
encourage robust convection along a front that will be draped from
southwest MN-northern WI. Strong buoyancy will be noted south of the
front across much of this region and MLCAPE could exceed 3000 J/kg
from MN/IA into SD/NE. While the short wave should encourage
organized convection, boundary-layer heating will prove instrumental
in thunderstorm development. Forecast soundings suggest CINH weakens
considerably by 19-21z and convection should expand in areal
coverage as convective temperatures are breached. Wind/hail are the
primary risks, though a brief tornado can not be ruled out with any
supercell structures.

Farther west, convective temperatures will be breached across
eastern WY by 22z. Scattered storms will once again develop over the
higher terrain/Plains then spread downstream into western
SD/northwestern NE during the evening. Some consideration was given
to a SLGT risk for this activity but the short-wave trough that
should affect this region will eject across northern AZ into
southwest WY around 16/00z. Timing of this feature suggests stronger
support will not affect this region until well after sunset.

..Darrow/Lyons.. 08/15/2025

$$

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

321
FLUS43 KLOT 142025
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
325 PM CDT Thu Aug 14 2025

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-152030-
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-
325 PM CDT Thu Aug 14 2025 /425 PM EDT Thu Aug 14 2025/

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

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

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

Friday night...
Limited Thunderstorm Risk...with an associated:
Level 1 of 5 Severe Thunderstorm Risk.
Saturday...
Elevated Excessive Heat Risk.
Limited Thunderstorm Risk...with an associated:
Level 1 of 5 Severe Thunderstorm Risk.
Sunday...
Elevated Excessive Heat Risk.
Limited Thunderstorm Risk.
Monday and Tuesday...
Limited Excessive Heat Risk.
Limited Thunderstorm Risk.

DISCUSSION...

Hot and humid conditions will return this weekend, with peak heat
indices over 100 degrees at times. Thunderstorms with gusty winds will
also be possible, especially closer to the Wisconsin state line
late Friday night into Saturday. This could limit the duration
and extent of the hot conditions across portions of northern
Illinois, including near Lake Michigan, on Sunday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be necessary through tonight.

$$

LMZ740>745-152030-
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-
325 PM CDT Thu Aug 14 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.

No hazardous weather is expected at this time.

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

Friday night and Saturday...
Limited Thunderstorm Risk...with an associated:
Level 1 of 5 Severe Thunderstorm Risk.
Sunday through Tuesday...
Limited Thunderstorm Risk at times.

$$

Kluber

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

538
ACUS02 KWNS 150558
SWODY2
SPC AC 150556

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 AM CDT Fri Aug 15 2025

Valid 161200Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE NORTHERN HIGH PLAINS EASTWARD TO THE GREAT LAKES...

...SUMMARY...
Thunderstorms with a potential for isolated severe gusts and hail
will be possible on Saturday from parts of the central and northern
Plains eastward to the Great Lakes.

...Central and Northern Plains...
At mid-levels, a ridge will move across the northern Plains on
Saturday, as southwesterly flow remains from the northern Rockies
into the northern High Plains. At the surface, an upslope flow
regime will remain in place from the Dakotas into eastern Montana.
A surface trough will deepen during the day over the northern High
Plains. Although large-scale ascent will remain weak across the
region, isolated thunderstorms may develop in the afternoon near the
surface trough. Additional isolated storms could develop near and to
the north of a front located across northern Nebraska. To the north
of the front, a moist and unstable airmass is forecast. Moderate
instability will be in place over much of this airmass by afternoon.
Although deep-layer shear will remain near or below 35 knots over
most of this airmass, low to mid-level lapse rates will be steep.
This could be enough for isolated severe gusts and hail with any
cell that can develop and persist in the late afternoon and early
evening.

...Upper Mississippi Valley/Great Lakes...
West-northwesterly mid-level flow will remain in place on Saturday
from the upper Mississippi Valley into the Great Lakes, as a
mid-level ridge moves across the northern Plains. At the surface, a
front is forecast to remain in place from far northern Iowa into
southern Wisconsin. From near the boundary southward, surface
dewpoints are forecast to be in the lower to mid 70s F. This will
contribute to a strongly unstable airmass by afternoon. Although
large-scale ascent will remain weak across the region, isolated
thunderstorms may develop along pre-existing boundaries or along
zones of maximized low-level convergence. NAM forecast soundings
near and to the north of the front across the upper Mississippi
Valley have 0-6 km shear in the 30 to 40 knot range, with 700-500 mb
lapse rates of 7 to 7.5 C/km. This could be enough for isolated
rotating storms with potential for hail and severe wind gusts. A
potential for severe gusts could extend eastward into parts of the
Great Lakes where moderate instability is forecast, but deep-layer
shear will be more modest.

..Broyles.. 08/15/2025

$$

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

199
ACUS03 KWNS 141928
SWODY3
SPC AC 141927

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0227 PM CDT Thu Aug 14 2025

Valid 161200Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
CENTRAL/NORTHERN PLAINS TO LOWER MICHIGAN...

...SUMMARY...
Isolated to scattered strong to severe storms are possible Saturday
from the central/northern Plains to Lower Michigan.

...Discussion...
Thunderstorms may be ongoing Saturday morning along a frontal zone
from the northern Plains to the western Great Lakes. The location
and strength of this morning convection will have significant
impacts on more focused zones of severe weather threat on Saturday.
A MCS may be ongoing across Wisconsin/northern Illinois/western
Michigan on Saturday morning. This MCS or a remnant MCV in its wake,
may provide a focus for severe storms across Lower Michigan Saturday
afternoon. In addition, a MCS may be ongoing across eastern South
Dakota and southwest Minnesota on the nose of the low-level jet. If
the environment downstream of this MCS can destabilize during the
morning, a severe weather threat may materialize as this MCS moves
east along the front. If neither of these solutions occur, the
severe weather threat may be somewhat more isolated. However, very
strong to extreme instability is expected along the frontal zone
with sufficient shear for some storm organization.

Strong heating in the Plains may result in a few isolated high-based
storms from central Nebraska to western South Dakota and potentially
into far southwest Montana with a primary severe wind threat during
the afternoon/early evening.

Convection is expected along most of the frontal zone from eastern
South Dakota to Michigan Saturday night as the low-level jet
strengthens and height falls overspread the region. Isolated large
hail is possible from these storms.

..Bentley.. 08/14/2025

$$

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

See Product Description

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.

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.