SPC Convective Outlook Day 1

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740
ACUS01 KWNS 111955
SWODY1
SPC AC 111954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Sat Oct 11 2025

Valid 112000Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE GREAT
BASIN/SOUTHWEST AND COASTAL NORTH CAROLINA...

...SUMMARY...
Isolated severe thunderstorms are possible this afternoon and
evening across the eastern Great Basin and Southwest. A brief
tornado and occasional strong to severe gusts could occur over the
Outer Banks of North Carolina late tonight and early Sunday morning.

...20z Update...
No changes are needed to the current D1 Convective Outlook. Daytime
heating is underway after morning cloud cover with cu development
evident across the high terrain in northern Arizona and much of
Utah. Convection is likely to increase in coverage and intensity
this afternoon with approaching large scale ascent. The marginally
unstable air mass and strong deep layer shear should support a few
stronger storms capable of a few instances of hail and gusty winds.

The Marginal risk continues across coastal North Carolina/Outer
Banks in anticipation of the surface low/warm front approaching
later this evening. Guidance continues to indicate a few rotating
storms may approach the coast by late evening/early morning with
potential for a tornado or gusty winds.

..Thornton.. 10/11/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Oct 11 2025/

...Great Basin/Southwest...
A prominent trough centered over the Pacific Northwest and northern
California early today will shift eastward over the Great Basin and
northern Intermountain region through tonight. This will be
accompanied by considerable height falls/forcing for ascent and
strengthening deep-layer southwesterly flow and an
eastward-advancing cold front. Ahead of this system, a broad fetch
of tropical moisture emanating from the eastern Pacific will
continue to stream northward, with seasonally rich low/mid-level
moisture expected across parts of the Southwest and southern Great
Basin.

As early day cloudiness quickly shifts eastward and abates, stronger
daytime heating is expected, namely across parts of western/central
Utah and central/southern Arizona. Still, mid-level
lapse rates are expected to remain modest across these areas, and
only weak instability is forecast where filtered diurnal heating can
occur.

Current expectations are for a gradual increase in coverage and
intensity of thunderstorms this afternoon and evening across parts
of the eastern Great Basin into the Southwest as large-scale ascent
associated with the upper trough overspreads these areas. Occasional
hail may occur with the stronger cores, as around 30-40 kt of
deep-layer shear (maximized across Utah) supports organized
updrafts. Otherwise, isolated strong to severe gusts should be the
main threat with scattered to numerous thunderstorms that will
spread east-northeastward through the afternoon and evening.

...Coastal North Carolina/Outer Banks...
A surface low and warm front will approach late tonight/early
Sunday, allowing for upper 60s to low 70s surface dewpoints to
approach and potentially advect inland as east-northeasterly
low-level flow strengthens late tonight. While lapse rates aloft
will remain poor, some buoyancy increase is expected. While inland
warm sector development remains uncertain, ample forecast low-level
and deep-layer shear suggest some risk for a tornado and gusty winds
with any supercell that can form in this environment across the
Outer Banks/coastal North Carolina.

...East-central Montana...
A couple of stronger storms with gusty winds could materialize this
afternoon/early evening across the region, but it still seems that
the potential for severe storms will be limited by meager
moisture/buoyancy.

$$

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

069
FLUS43 KLOT 112000
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
300 PM CDT Sat Oct 11 2025

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-122000-
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-
300 PM CDT Sat Oct 11 2025 /400 PM EDT Sat Oct 11 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...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be necessary through tonight.

$$

LMZ740>745-122000-
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-
300 PM CDT Sat Oct 11 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...Sunday through Friday.

Tuesday and Wednesday...
Hazardous conditions for small craft are likely.

$$

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

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164
ACUS02 KWNS 111653
SWODY2
SPC AC 111652

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1152 AM CDT Sat Oct 11 2025

Valid 121200Z - 131200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe-storm risk appears negligible on Sunday into Sunday night.

...East...
A surface cyclone near the coastal Carolinas at 12Z Sunday should
gradually fill as it drifts north, offshore of the Lower
Mid-Atlantic. Convection should primarily segregate into two
corridors of weak elevated activity. One near the quasi-stationary
mid-level low centered in eastern SC and the other in the offshore
low-level warm conveyor that will sustain weakening convection
approaching the Mid-Atlantic to southern New England coast. Largely
poor lapse rates will limit instability/MUCAPE and thunder coverage.

...Northern Plains and Upper Midwest...
Isolated elevated thunderstorms are possible Sunday morning ahead of
the shortwave trough impinging on the northwest ND/far northeast MT
vicinity. Isolated elevated storms are also possible across parts of
the Upper Midwest within the downstream low-level warm conveyor on
Sunday. This will be characterized by weak MUCAPE/mid-level lapse
rates with convection subsiding by Sunday night.

...Southwest...
Scattered afternoon thunderstorms are most probable across southern
AZ into southwest NM. Weak lapse rates above a relatively shallow
mixed boundary layer will limit convective vigor. Isolated elevated
thunderstorms are also possible Sunday night into early morning
Monday both northward to the Four Corners and eastward in the
Southern Plains.

...Pacific Northwest...
A shortwave trough digging south along the Pacific Northwest coast
will aid in sufficient forcing for ascent and steepening of
mid-level lapse rates for an isolated thunderstorm risk on Sunday
afternoon through Sunday night.

..Grams.. 10/11/2025

$$

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

777
ACUS03 KWNS 111920
SWODY3
SPC AC 111919

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0219 PM CDT Sat Oct 11 2025

Valid 131200Z - 141200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not yet forecast on Monday.

...Southwest...
A mid/upper low will move south along the OR to the northern CA
coast through the period. A broadening swath of 50+ kt 500-mb
southwesterlies to westerlies will overspread much of southern CA to
the eastern Great Basin and CO Plateau. Primary area of concern for
a potential level 1-MRGL risk in later outlooks is from the Four
Corners vicinity southward across eastern AZ to southern NM, where
the strengthening deep-layer flow regime would support lower-end
mid-level updraft rotation. But mid-level lapse rates appear likely
to remain weak, limiting MLCAPE. Depending on mesoscale details
related to the degree of diabatic surface heating, in the wake of
lingering overnight/morning clouds/rain, a corridor or two of
low-end severe highlights may become warranted.

...CA...
Guidance consensus indicate an intense mid-level jetlet should
impinge on the southern CA coast Monday night, to the south of the
aforementioned northern CA low. This would foster a conditionally
favorable deep-layer wind profile for updraft rotation. However,
mid-level temperatures should remain warm enough to maintain shallow
convection where hodographs would be enlarged within the low-level
warm conveyor. Isolated, general thunderstorms should be confined
farther north where mid-level lapse rates are much steeper, and
meager buoyancy can still be maintained.

..Grams.. 10/11/2025

$$

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

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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.

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.