SPC Convective Outlook Day 1

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176
ACUS01 KWNS 151629
SWODY1
SPC AC 151628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Sun Sep 15 2024

Valid 151630Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL PLAINS...

...SUMMARY...
Thunderstorms capable of producing isolated severe gusts and hail
may occur today and tonight across parts of the northern/central
Plains.

...Northern/Central Plains...
An amplified upper trough along/near the West Coast this morning
will further evolve into a closed upper low over northern CA and
vicinity by late tonight. Ahead of this feature, modestly enhanced
south-southwesterly mid-level flow will be in place over much of the
western states and Rockies through the period. Although low-level
moisture is expected to remain limited over much of this region,
isolated strong to severe gusts may occur with any thunderstorms
that can develop in a deeply mixed boundary layer favorable for
gusty downdraft winds.

Latest guidance continues to suggest that a relatively greater
concentration of severe potential will be focused across parts of
the northern/central Plains late this afternoon through tonight.
Across this area, a weak surface lee trough and greater low-level
moisture to its east should support weak to moderate instability
with daytime heating. Steep mid-level lapse rates should also aid
updraft accelerations/intensities, with around 20-30 kt of
deep-layer shear supporting modest thunderstorm organization.
Isolated severe hail may occur with initially more discrete
convection, but a tendency for clustering should lead to a
relatively greater wind threat with time as convection spreads
generally east-northeastward through the evening. Regardless, the
overall severe threat from northeast CO into western NE/SD and
vicinity should remain fairly isolated/marginal given the modest
deep-layer shear.

Low-level warm advection is forecast to increase across much of the
northern/central Plains tonight as a southerly low-level jet
strengthens. A surface warm front is also expected to lift northward
over ND late tonight into early Monday morning. With steepening
mid-level lapse rates overspreading the northern Plains in tandem
with increasing low-level moisture, ample MUCAPE should be
available. Most guidance shows at least isolated convection
developing across parts of ND tonight in this favorable
thermodynamic environment. Although deep-layer shear may remain
fairly modest, it may still be sufficient for updraft organization
and an isolated threat for severe hail with any elevated convection
that can form. Have therefore expanded the Marginal Risk northward
to account for this potential.

...Coastal Carolinas...
Latest NHC forecast continues to indicate some potential for
sub-tropical or tropical development of a surface low currently off
the SC Coast. Regardless of development, it still appears that the
more moist/tropical low-level airmass over the Gulf Stream will
struggle to advance inland over coastal portions of NC/SC through
the end of the Day 1 forecast period early Monday morning (16/12Z).
Accordingly, tornado potential with any low-topped supercells on the
north to northeast periphery of the surface low should tend to
remain offshore until Day 2/Monday (after 16/12Z).

..Gleason/Moore.. 09/15/2024

$$

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

907
FLUS43 KLOT 150803
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
303 AM CDT Sun Sep 15 2024

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-160815-
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-
303 AM CDT Sun Sep 15 2024 /403 AM EDT Sun Sep 15 2024/

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...Monday through Saturday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be necessary through tonight.

$$

LMZ740>745-160815-
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-
303 AM CDT Sun Sep 15 2024

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.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

No hazardous weather is expected at this time.

$$

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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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746
ACUS02 KWNS 151727
SWODY2
SPC AC 151725

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1225 PM CDT Sun Sep 15 2024

Valid 161200Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN
GREAT BASIN INTO THE FOUR CORNERS REGION...ND INTO NORTHWEST
MN...EASTERN NC AND VICINITY...

...SUMMARY...
On Monday, sporadic severe gusts and hail will be possible during
the afternoon to early evening across parts of the eastern Great
Basin to Four Corners. Isolated severe storms are possible over
eastern North Dakota into northwest Minnesota. Some tornado threat
may develop over eastern North Carolina and vicinity.

...Eastern Great Basin to the Four Corners...
A seasonably strong mid-level low initially near San Francisco Bay
Monday morning should move east during the day, before curling
northeast Monday night towards the NV/UT/ID border area. This will
occur in response to a strong mid-level jet translating through the
basal portion of the large-scale trough across the Desert Southwest
into the eastern Great Basin.

Convection will likely be ongoing at the start of the forecast
period near the midlevel low, and also farther east toward the Four
Corners region, within the warm/moist conveyor. Relatively strong
heating will be possible between these two regimes, from eastern NV
into parts of UT. While buoyancy will likely remain quite weak
within this warmer and more well-mixed regime, high-based convection
will be possible during the afternoon and evening as the midlevel
low approaches the region, with increasing meridional flow and a
deeply mixed boundary layer supporting isolated severe gusts.

Farther southeast into eastern UT and the Four Corners vicinity,
increasing southwesterly flow aloft and strengthening deep-layer
shear will become conditionally supportive of organized convection.
Warmer midlevel temperatures may limit buoyancy to some extent,
though sufficient moisture will support afternoon MLCAPE of 500-1000
J/kg. A few supercells will be possible within this regime, with an
attendant threat of isolated severe gusts and hail.

...Parts of ND into northern MN...
With the primary upper-level trough displaced well to the west,
deep-layer shear will remain weak across much of the Great Plains.
However, most guidance suggests an MCV will emanate out of central
High Plains convection on D1/Sunday and gradually progress northeast
towards the Red River Valley during the day on Monday. In
conjunction with a strengthening low-level jet, this MCV may help to
support relatively vigorous storm redevelopment within a moderately
unstable environment during the afternoon and evening.

Stronger midlevel flow attendant to the MCV could support some storm
organization, and a couple supercells and/or stronger clusters will
be possible, with a threat of isolated hail and damaging wind.
Somewhat favorable low-level shear/SRH could also support a tornado
threat, if a surface-based supercell can be sustained. Uncertainty
remains regarding the strength/timing of any MCV moving across the
region, along with the most favored corridor for diurnal storm
development.

...Eastern NC and vicinity...
Guidance generally suggests that an initially offshore surface low
will move northward or northwestward from later on D1/Sunday into
D2/Monday and D3/Tuesday, and eventually move inland across some
part of the Carolinas. However, uncertainty remains regarding the
timing, track, and intensity of this low, along with the extent to
which it acquires any tropical or subtropical characteristics.

If a deepening low does move onshore, then a higher theta-e airmass
may move inland, accompanied by increasing low-level shear/SRH
along/north of the low track. While the general scenario supports
some potential for low-topped supercells, the magnitude of any
tornado threat will be dependent on the extent of intensification
that occurs with the low (and its attendant wind fields) prior to
landfall. The Marginal Risk has been expanded somewhat across
eastern NC and vicinity, in response to the various uncertainties.

..Dean.. 09/15/2024

$$

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

425
ACUS03 KWNS 150731
SWODY3
SPC AC 150730

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Sun Sep 15 2024

Valid 171200Z - 181200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE HIGH
PLAINS...

...SUMMARY...
Isolated severe thunderstorms will be possible across a large swath
of the High Plains region, mainly from Tuesday late afternoon into
the evening. Severe gusts should be the primary hazard.

...High Plains...
A shortwave trough over the eastern Great Basin at 12Z Tuesday
should take on a negative tilt as it advances towards the northern
High Plains. This process will yield a separation of the strong
upper-level jet surrounding the trough, from a meridional component
shifting north into eastern WY and a zonal component holding over
AZ/NM. Guidance has oscillated southward with the evolution of the
meridional component relative to yesterday's guidance. Deep lee
cyclogenesis is expected over northeast WY/southeast MT. This low
will advance north towards the MT/SK border area by 12Z Wednesday.

Large-scale ascent will be pronounced within this synoptic regime,
with favorable upper-level difluence, mid-level height falls, and
low-level convergence. But weak buoyancy and modest mid-level lapse
rates will characterized much of the environment. The bulk of
convective development will occur over the higher terrain, likely
aided by the subtropical moisture plume over the Southwest.
High-based storms should progress into a well-mixed boundary layer
that may initially be devoid of appreciable CAPE. This lack of
greater buoyancy during the late afternoon to early evening, outside
of northeast MT into the Dakotas, yields substantial uncertainty in
the degree of strong versus severe storms. But with scattered to
widespread convection likely into the evening, sporadic severe gusts
may occur.

...Eastern NC and southeast VA...
The poor predictability of offshore cyclogenesis amplitude and
inland progression on Monday renders minimal confidence in
delineating a severe area on Tuesday. Slower and more aggressive
ensemble members suggest an adequate SRH/buoyancy combination for
low-topped tornado potential may linger over eastern NC early in the
period and shift into parts of southeast VA. But overall trends
indicate a generalized weakening low-level wind field may occur
during the day.

..Grams.. 09/15/2024

$$

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.