SPC Convective Outlook Day 1

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230
ACUS01 KWNS 171236
SWODY1
SPC AC 171234

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0634 AM CST Mon Nov 17 2025

Valid 171300Z - 181200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Scattered thunderstorms should occur this evening and overnight
across parts of the northern/central Plains into the Ozarks and mid
Mississippi Valley. Isolated thunderstorms are also possible across
the Southwest and central California. A few strong thunderstorms may
occur across parts of Missouri and southern Illinois late tonight,
but organized severe thunderstorm potential appears low.

...Synopsis...
A pair of upper troughs/lows will impact the CONUS today. The
leading upper trough/low will progress eastward over the central
Plains though this evening, eventually reaching the mid MS Valley
late tonight. Farther west, a separate upper trough/low will develop
slowly southward across coastal CA through the period. With
seasonably cool temperatures and modestly steepened lapse rates
aloft associated with the western U.S. trough/low, isolated
thunderstorms may occur across parts of CA and the lower CO River
Valley/AZ. Meager instability across these areas should limit the
threat for organized severe thunderstorms. Father east, isolated to
scattered thunderstorms should develop this evening/overnight from
portions of the northern/central Plains into the MO and mid MS
Valleys. The bulk of this activity is expected to remain elevated,
with minimal severe potential.

...Ozarks into the Mid Mississippi Valley...
Low-level moisture will continue to stream northward across the
southern Plains and lower/mid MS Valley ahead of a weak surface low
and cold front related to the lead upper trough/low. Latest NAM/RAP
forecast soundings across the surface warm sector this
afternoon/evening continue to show a substantial cap in place, which
combined with negligible large-scale ascent should act to inhibit
surface-based convective development. Low-level warm/moist advection
is expected to increase this evening/overnight as a southwesterly
low-level jet strengthens over the Ozarks/mid MS Valley. Most
guidance shows weak MUCAPE (around 500-1000 J/kg) with modest
mid-level lapse rates present. This should tend to limit the updraft
strength of scattered elevated convection that is forecast develop
tonight across MO into parts of southern IL, even in the presence of
moderate to strong deep-layer shear. While small/sub-severe hail may
occur with the stronger cores, the threat for severe hail appears
too limited to include low probabilities with this update.

..Gleason/Broyles.. 11/17/2025

$$

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

442
FLUS43 KLOT 170940
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
340 AM CST Mon Nov 17 2025

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-180945-
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-
340 AM CST Mon Nov 17 2025 /440 AM EST Mon Nov 17 2025/

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

.DAY ONE...Today and Tonight.

No hazardous weather is expected at this time.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be necessary through tonight.

$$

LMZ740>745-180945-
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-
340 AM CST Mon Nov 17 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...

Hazardous conditions for small craft east of Gary this morning.

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

Tuesday...
Hazardous conditions for small craft are likely.
Friday and Saturday...
Hazardous conditions for small craft are likely.

$$

- Izzi

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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233
ACUS02 KWNS 170608
SWODY2
SPC AC 170606

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1206 AM CST Mon Nov 17 2025

Valid 181200Z - 191200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms are possible across portions of the Middle Mississippi
and Lower Ohio Valleys on Tuesday, additional isolated thunderstorms
are expected across parts of the Southwest. Severe potential appears
limited at this time.

...Ohio Valley Vicinity...

An upper shortwave trough over the Mid/Lower MO Valley will develop
east across the Ohio Valley through Tuesday evening, before arriving
over the Mid-Atlantic coast by Wednesday morning. A belt of enhanced
westerly flow will overspread the region as this occurs. At the
surface, a weak low over the Ozark Plateau early in the day will
weaken, with little surface cyclogenesis tied to the upper trough.
Building high pressure over the Great Lakes will allow for a weak
cold front to develop south/southeast across the Mid-South/Lower
Ohio Valley through the period, and will limit northward progression
of any deeper boundary-layer moisture.

Most forecast guidance suggests convection will be ongoing Tuesday
morning. This activity will occur on the nose a southwesterly
low-level jet within a broad warm advection regime. This elevated
convection may produce small hail in stronger updrafts, but overall
severe potential is expected to remain limited as convection
develops east of the better instability/moist axis. During the late
afternoon or evening, additional storms may develop along the
surface boundary. Surface-based instability is expected to remain
minimal given convection earlier in the day, modest boundary layer
moisture, and increasing inhibition with loss of daytime heating.
Low to midlevel flow also will veer during the evening as the upper
trough passes to the north and east. Small hail could once again
accompany the strongest storms, but overall severe potential appears
low.

...Southwest...

Isolated thunderstorms are possible as an upper low moves southeast
across southern CA/northern Baja. Modest midlevel moisture within a
warm advection regime ahead of this system will support enough
instability for occasional thunderstorms across portions of the
Lower CO Valley/southern NV/much of AZ. Severe storms are not
expected.

..Leitman.. 11/17/2025

$$

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

589
ACUS03 KWNS 170739
SWODY3
SPC AC 170738

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0138 AM CST Mon Nov 17 2025

Valid 191200Z - 201200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms are possible across parts of the Southwest into the
southern Plains vicinity Wednesday into early Thursday.

...Southern Plains...

An upper trough is expected to be oriented from the western Great
Basin toward southern CA/northern Baja Wednesday morning, and track
slowly eastward toward the Four Corners/southern Rockies by Thursday
morning. Forecast guidance has trended slowly with the eastward
ejection of the upper trough. As a result, stronger southwesterly
flow, and a strengthening low-level jet are not expected to develop
over portions of the southern Rockies into OK/TX until after 00-06z.
This will also delay any stronger forcing for ascent until late in
the forecast period.

At the surface, southerly low-level flow will transport Gulf
moisture northward across TX/OK and the south-central states.
Forecast soundings suggest capping in the 850-700 mb layer will
persist for much of the diurnal period. Given nebulous forcing,
outside of persistent, modest warm advection, it is unclear if/how
much convection may develop across the warm sector during the day.
The 00z RRFS suggests elevated convection may develop near the
moisture gradient/surface trough across west-central TX and toward
the Red River in southwest OK by late afternoon. While vertical
shear would support at least loosely organized convection, low to
midlevel flow will be somewhat weak, and elevated instability modest
(generally less than 1000 J/kg). Later in the period (after 06z),
large-scale ascent will increase and a modest southerly low-level
jet should intensify as the upper trough approaches NM. Additional
convection may develop late Wednesday night into early Thursday
morning amid a stronger mass response.

Some risk for marginal hail could accompany stronger convection.
However, confidence is low regarding coverage, intensity and timing
of any more organized/stronger storm development, especially given
the trend toward a more slowly/later ejecting trough. Will hold off
introducing severe probabilities at this time, but probs could
become necessary with later updates.

..Leitman.. 11/17/2025

$$

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.