SPC Convective Outlook Day 1

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950
ACUS01 KWNS 302004
SWODY1
SPC AC 302002

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0302 PM CDT Mon Jun 30 2025

Valid 302000Z - 011200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS INTO THE MIDWEST AND MID ATLANTIC STATES...AND PARTS
OF THE DESERT SOUTHWEST AND WEST COAST...

...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
southern Plains into the Midwest and the Mid-Atlantic, and in parts
of the Desert Southwest, and also in adjacent parts of southern
Oregon and northern California today.

...20Z Update...
Forecast scenario remains unchanged. See active Mesoscale
Discussions and the prior Outlook discussion below.

..Guyer.. 06/30/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Mon Jun 30 2025/

...Southern OK/Northwest TX...
Morning visible satellite imagery confirms an outflow boundary
extending across central OK. Strong heating to the south of the
boundary will lead to a very unstable air mass with dewpoints in the
mid 70s and MLCAPE values over 3000 J/kg. Scattered thunderstorms
are expected to develop along the boundary by mid-afternoon,
propagating southward into north TX during the evening. Winds aloft
are rather weak in this area, suggesting limited storm organization.
However, the degree of instability and steep low-level lapse rates
will promote a risk of damaging wind in the stronger cells. Hail
will also be possible in the strongest updrafts.

...PA/NY...
A warm and humid air mass is present once again across parts of
NY/PA, where daytime heating will lead to MLCAPE values of 1500-2000
J/kg. Forecast soundings suggest ample mid-level moisture which
will be favorable for considerable coverage of storms, but may limit
the overall severe downdraft potential. Nevertheless, a few strong
to severe cells capable of locally damaging wind gusts are possible.
Refer to MCD #1522 for further details.

...NM/Southeast AZ...
Upper 40s and 50s dewpoints have become established across the
mountains of southern NM into southeast AZ. Full heating will lead
to deep mixing and inverted-v profiles over the region. Scattered
afternoon thunderstorms will likely result in gusty/damaging wind
gusts in some of this activity.

...Upper MI/WI...
A progressive shortwave trough over northern MN will track into the
Great Lakes region today, with cooling mid-level temperatures and
increasing large scale forcing. This will lead to scattered
late-afternoon thunderstorms over parts of WI and the Upper MI.
Locally gusty winds and hail are possible in these storms.

...Northern CA/Southern OR...
Ahead of the weak upper trough immediately west of the CA coast,
southerly flow will aid in increasing mid-level moisture across
parts of northern CA and southern OR. Ample heating coupled with
weak large-scale and orographic ascent will aid in isolated to
scattered high-based thunderstorm development. Very steep lapse
rates will pose a risk of gusty/damaging winds.

$$

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

008
FLUS43 KLOT 302224
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
524 PM CDT Mon Jun 30 2025

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-012230-
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-
524 PM CDT Mon Jun 30 2025 /624 PM EDT Mon Jun 30 2025/

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

.DAY ONE...Tonight.

Limited thunderstorm risk near US-24 through 9 PM.

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

Friday and Saturday...
Limited Thunderstorm Risk
Limited Excessive Heat Risk
Sunday...
Limited Thunderstorm Risk.

DISCUSSION...

Heat and humidity will return for the holiday weekend. The best
chance of storms will hold off until Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be necessary through tonight.

GENERAL STORM MOTION OF THE DAY:

Moving toward the southeast at around 30 mph.

$$

LMZ740>745-012230-
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-
524 PM CDT Mon Jun 30 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...Tuesday through Sunday.

Saturday...
Limited Thunderstorm Risk.

$$

Borchardt

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

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570
ACUS02 KWNS 301731
SWODY2
SPC AC 301729

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 PM CDT Mon Jun 30 2025

Valid 011200Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE MID-ATLANTIC...

...SUMMARY...
Scattered strong to severe storms are possible across parts of the
Mid-Atlantic into the Northeast on Tuesday afternoon/evening. An
isolated severe storm may also occur over parts of the central High
Plains.

...Synopsis...
A mid-level trough will traverse the Northeast as an upper ridge
persists over the central U.S. and a mid-level low meanders over CA
tomorrow (Tuesday). The East Coast mid-level trough will encourage
the eastward advancement of a cold front, which will provide enough
lift for scattered to widespread thunderstorm development across the
Carolinas into the Northeast. Rich low-level moisture preceding the
front will encourage enough buoyancy, amid marginal but adequate
vertical wind shear, to support strong thunderstorms, some of which
could be severe. A couple of strong to severe storms are possible
along the periphery of the upper ridge over parts of the northern
Rockies into the central High Plains.

...Northeast into the Southeast...
As the surface cold front advances eastward across the eastern U.S.,
surface temperatures will warm into the 80s F to near 90 F, amid 70+
F dewpoints from the Southeast to the Mid-Atlantic, boosting SBCAPE
into the 2000-3500 J/kg range by afternoon peak heating. Relatively
poor mid-level lapse rates will limit CAPE to tall/thin profiles.
However, the magnitude of buoyancy, combined with widespread
thunderstorm coverage over a large area, will foster ample
opportunity for at least isolated damaging gusts with wet
downbursts, from the Southeast to New England. A more concentrated
area of damaging gust potential exists over parts of the
Mid_Atlantic, where a Category 2/Slight Risk remains in place. Here,
line segments are expected to organize amid a region of maximum
buoyancy and 30 kts of effective bulk shear, driven by stronger
west-southwesterly mid-level flow grazing the area.

...Portions of the Northern Rockies...
Mid-level monsoonal moisture is forecast to crest the upper ridge
amid modest 500 mb west-southwesterly flow over parts of the
Northern Rockies, where guidance consensus shows PWATs reaching 0.8
inches in spots. High-based thunderstorms will develop by afternoon
peak heating, atop a well-mixed boundary layer extending to 500 mb
via inverted-v thermodynamic profiles. The aforementioned mid-level
moisture, combined with steep tropospheric lapse rates, will support
over 500 J/kg MLCAPE. This buoyancy may support robust enough
updrafts and subsequent storm cores in an environment where ample
evaporative cooling may take place to support isolated severe gusts.

...Central High Plains...
Low-level upslope flow, along with strong diurnal heating, and the
passage of a small impulse embedded in the upper ridge, will all
serve as mechanisms for convective initiation tomorrow afternoon.
Though storms should be isolated, they will develop amid 8 C/km low
and mid-level lapse rates that will boost MLCAPE into the 1500-2500
J/kg range. Modest directional vertical wind shear will support
somewhat curved/elongated hodographs and around 35 kts of effective
bulk shear. As such, a few multicells/transient supercells may
develop and produce isolated severe wind/hail.

..Squitieri.. 06/30/2025

$$

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

032
ACUS03 KWNS 301922
SWODY3
SPC AC 301921

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0221 PM CDT Mon Jun 30 2025

Valid 021200Z - 031200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE NORTHERN ROCKIES...

...SUMMARY...
At least scattered storms are possible across a large portion of the
continental U.S. on Wednesday. A couple of severe gusts may
accompany the stronger storms over portions of the Northern Rockies.

...Synopsis...
A mid-level trough will meander across the Northeast while upper
ridging persists over the central CONUS and a mid-level trough
advances over the Pacific Northwest on Wednesday. Seasonal moisture
and associated diurnal heating will encourage at least scattered
development across most of the CONUS during the afternoon and
evening hours. However, a couple of thunderstorms embedded in the
stronger mid-level flow over the Northern Rockies could become
strong. Given adequate shear and instability in this region, a few
of the stronger storms could become severe.

...Portions of the Northern Rockies...
The periphery of relatively greater mid-level moisture is poised to
traverse the western extent of the upper ridge on Wednesday.
Stronger west-southwesterly mid-level flow will graze the Northern
Rockies due to the approach of the upper trough to the west. Robust
boundary layer heating in this region will boost low-level lapse
rates to 9 C/km over several locales, as 8.5 C/km mid-level lapse
rates overspreads the well-mixed boundary layer. MLCAPE may exceed
1000 J/kg over many areas, and thunderstorms accessing this buoyancy
will be embedded in stronger mid-level flow and 30-40 kts of
effective bulk shear. As such, stronger multicells may produce a mix
of wet and dry downbursts, perhaps inducing a couple of severe
gusts.

..Squitieri.. 06/30/2025

$$

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.