SPC Convective Outlook Day 1

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193
ACUS01 KWNS 191953
SWODY1
SPC AC 191952

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Thu Sep 19 2024

Valid 192000Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR
NORTHEAST OKLAHOMA...

...SUMMARY...
Scattered severe thunderstorms are possible this afternoon and
evening across central/eastern Minnesota, Iowa, and western
Wisconsin. A couple of tornadoes, large hail, and damaging winds may
occur across this region. Farther south, an area of locally severe
wind gusts and hail may also develop over parts of eastern Kansas,
southwest Missouri, and northeast Oklahoma.

...20Z Update...
The 18Z observed Minneapolis sounding showed steep mid-level lapse
rates in addition to a long and predominantly straight hodograph.
The expectation remains that a few supercells may initially develop
from north-central Iowa into east-central Minnesota over the next
2-3 hours. These storms would pose the greatest risk for
large/very-large hail. Given weak low-level shear evident on area
VAD data in combination with linear forcing from the cold front,
upscale growth should still occur quickly with a transition to more
of a damaging wind threat. As this is in line with the thinking of
the previous forecast, no changes have been made other than minor
changes to the general thunderstorm area.

See the previous discussion for further details.

..Wendt.. 09/19/2024

.PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/

...Minnesota/Wisconsin/Iowa...
Widely spaced and mainly elevated thunderstorms ongoing late this
morning across parts of IA into eastern MN and western WI should
continue to diminish in coverage over the next couple of hours. In
their wake, daytime heating of a seasonably moist low-level airmass
(surface dewpoints generally in the 60s) and somewhat steep
mid-level lapse rates will contribute to at least moderate
instability by mid afternoon along/ahead of a cold front extending
north to south from western MN into eastern NE and western IA. An
upper low over northern ND and southeast SK/southwest MB will
continue to advance slowly northeastward across south-central Canada
through the period. A belt of 35-50 kt mid-level west-southwesterly
winds on the southern periphery of the upper low will spread
eastward from the northern Plains into the Upper Midwest through
this evening. A veering/strengthening wind profile with height
through mid levels will support around 30-40 kt of deep-layer shear
across the warm sector. This shear will be sufficient for organized
thunderstorms, including the potential for a few supercells.

Current expectations are that scattered thunderstorms will develop
by mid to late afternoon across central/eastern MN into
northern/central IA along or just ahead of the eastward-advancing
cold front. A rather favorable thermodynamic environment will foster
robust updrafts, and any initial supercells should pose a threat for
large to very large hail (around 1.5-2.5 inches in diameter). But, a
fairly quick transition to more linear structures should occur given
the presence of the cold front, with a potentially greater damaging
wind threat evolving with eastward extent through the evening before
convection eventually weakens. South-southwesterly low-level flow
and related shear ahead of the front is not forecast to be overly
strong by most guidance this afternoon. But, some threat for a
couple of tornadoes remains apparent, especially with any sustained
supercells across east-central/southern MN into northern IA late
this afternoon/early evening.

...Eastern Kansas into Missouri and Northeast Oklahoma...
An upper ridge, with rather warm mid-level temperatures, will remain
centered over the southern Plains today. The surface cold front is
forecast to continue moving east-southeastward across the mid MO
Valley and central Plains through late this afternoon. A surface
trough extending southward from this front across the southern High
Plains should also mix eastward through peak daytime heating. Given
weak large-scale ascent and rather warm mid-level temperatures
across this area, there is still a fair amount of uncertainty
regarding how many additional thunderstorms will develop later
today, notwithstanding the ongoing (mainly elevated) convection over
eastern KS and far northwest MO. Still, other surface-based
thunderstorms may develop later this afternoon along/near the
front/dryline intersection in south-central KS/north-central OK, and
along the cold front in eastern KS. While low/mid-level flow should
remain fairly modest, steepened low-level lapse rates and moderate
instability should support a risk for mainly severe/damaging
downdrafts as convection spreads east-southeastward into western MO
and northeast OK through this evening.

$$

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

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837
FLUS43 KLOT 192026
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
326 PM CDT Thu Sep 19 2024

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-202030-
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-
326 PM CDT Thu Sep 19 2024 /426 PM EDT Thu Sep 19 2024/

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

.DAY ONE...Tonight.

Weather hazards expected...

Limited Thunderstorm Risk.

DISCUSSION...

A line of showers and embedded thunderstorms is expected to move
into northern IL after midnight. No severe weather is expected.

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

Friday...
Limited Thunderstorm Risk...with an associated:
Level 1 of 5 Severe Thunderstorm Risk east of Interstate 55.
Saturday though Monday...
Limited Thunderstorm Risk.


DISCUSSION...

Additional showers and thunderstorms are expected to develop
mainly east of I-55 Friday afternoon. The strongest storms may
contain a threat for localized gusty winds up to 60 mph.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be necessary through tonight.

GENERAL STORM MOTION OF THE DAY:

Moving toward the East-southeast at 25 mph.

$$

LMZ740>745-202030-
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-
326 PM CDT Thu Sep 19 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...Tonight.

Weather hazards expected...

Limited Thunderstorm Risk.

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

Friday...
Limited Thunderstorm Risk...with an associated:
Level 1 of 5 Severe Thunderstorm Risk.
Saturday...
Limited Thunderstorm Risk.
Monday...
Hazardous conditions for small craft are likely.
Limited Thunderstorm Risk.

$$

Yack

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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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804
ACUS02 KWNS 191732
SWODY2
SPC AC 191730

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Thu Sep 19 2024

Valid 201200Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
MIDWEST AND ALSO THE SOUTH-CENTRAL PLAINS...

...SUMMARY...
Isolated strong to severe thunderstorms are possible in the late
afternoon Friday in parts of Illinois, Indiana, and southwest Lower
Michigan. Isolated strong to severe storms are also possible across
parts of the south-central Plains.

...Midwest...
A low-amplitude shortwave trough will pass across the Upper to
central Great Lakes during the first half of the period. This will
outpace a cold front that trails from a cyclone shifting northeast
in MB, yielding a largely weakening to stalling front by Friday
evening. Most guidance suggests at least isolated thunderstorms
should form within a low-level warm conveyor ahead of the front,
generally focused on a moderate buoyancy plume emanating northeast
from parts of MO/AR. A fast westerly upper jet will further impinge
on this portion of the front as well, favorably timed with peak
boundary-layer heating. A few marginally severe storms may develop
within this regime. Despite weak mid-level lapse rates, elongation
of the mid to upper hodograph should support a threat for 1-1.5 inch
hail, along with strong to marginally severe gusts from 45-60 mph.
These threats should diminish quickly after sunset.

...Southern KS/northern OK vicinity...
A mid/upper-level shortwave trough is forecast to move slowly
eastward across the Southwest on Friday. Farther east, a surface
boundary initially draped from the lower MO Valley into southern
KS/northern OK is forecast to lift northward as a warm front.
Large-scale ascent across much of the Plains may remain relatively
limited, outside of low-level warm advection near/north of the
front. However, relatively strong heating along the western/northern
periphery of returning low-level moisture could support thunderstorm
development during the afternoon somewhere in the vicinity of
southwest KS/northwest OK. Effective shear of 30-40 kt will support
potential for somewhat organized convection. Strong to localized
severe gusts may be the most likely hazard, but hail cannot be ruled
out if any more discrete storms can move into an environment of
greater moisture/instability.

...New Mexico...
Scattered thunderstorms will be possible across much of NM on
Friday, in closer proximity to the approaching shortwave trough.
While deep-layer shear will be rather strong, generally weak
midlevel lapse rates and buoyancy may tend to limit the potential
for more robust storms. If confidence increases regarding sufficient
heating/destabilization, then severe probabilities may eventually be
needed for parts of the region.

...Central Plains into the lower MO Valley...
Guidance continues to vary regarding the potential for robust
elevated convection Friday night into Saturday morning, within a
low-level warm advection regime. Increasing elevated buoyancy and
sufficient mid/upper-level flow could support a few stronger storms
with hail potential, but confidence in sufficient coverage and a
favored region for this potential is too low for probabilities at
this time.

..Dean.. 09/19/2024

$$

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

919
ACUS03 KWNS 191941
SWODY3
SPC AC 191940

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0240 PM CDT Thu Sep 19 2024

Valid 211200Z - 221200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF NM INTO
THE SOUTHERN HIGH PLAINS...PARTS OF THE UPPER MIDWEST INTO THE
CENTRAL PLAINS...CENTRAL APPALACHIANS VICINITY...

...SUMMARY...
Isolated severe thunderstorms are possible on Saturday afternoon to
early evening in New Mexico and the southern High Plains, mid
Missouri Valley to upper Mississippi Valley, and central
Appalachians region.

...Southern High Plains...
In advance of a southern-stream shortwave trough reaching the Four
Corners, a strong midlevel jet is forecast to eject over NM by early
evening Saturday. This will yield favorable deep-layer shear for
organized storms across NM into parts of northwest TX. Strengthening
large-scale ascent within a low-level warm/moist conveyor should
overspread this region by Saturday morning. This should yield
early-period convection and renders moderate uncertainty over the
degree of destabilization by afternoon.

Still, with ample boundary-layer heating to the south of early-day
activity, a plume of at least weak-surface based buoyancy should
develop. Renewed afternoon to early evening thunderstorms could
become severe. Steep mid-level lapse rates should be confined along
and west of the Sangre de Cristo Mountains, rendering further
uncertainty over the intensity and coverage of the severe threat.
The eastern extent of the threat should be limited by the confined
buoyancy plume and decreasing instability deeper into TX/OK.

...Central Plains and Lower/Mid-MO Valley to the Upper MS Valley...
A relatively complex and uncertain evolution to convective potential
remains evident on Saturday afternoon/evening. This region will
largely remain within a low-amplitude mid-level ridge. This may
flatten somewhat in between a southern-stream shortwave trough in
the Southwest and a northern-stream trough over the southern Prairie
Provinces to along the ND/MN international border. In association
with the latter wave, a surface cold front should push southeast in
the north-central states. Guidance varies with the degree of
destabilization ahead of it, and especially with the spatial extent
of afternoon/evening convection. There is sufficient confidence in
destabilization and storm coverage to introduce a 5% area from the
mid MO Valley to the upper MS Valley, though uncertainty remains
rather high.

...Parts of the Northeast/Mid Atlantic...
A low-amplitude midlevel shortwave trough is forecast to move
through northwesterly flow aloft across parts of the upper Ohio
Valley into the Mid Atlantic on Saturday. Isolated to scattered
thunderstorm development will be possible across the region during
the afternoon. Veering wind profiles within the northwesterly flow
regime will support effective shear for some storm organization,
though it remains somewhat uncertain if instability will become
sufficient to support an organized severe threat. Guidance has
trended toward somewhat greater instability and storm coverage, and
a small Marginal Risk has been included where confidence is
currently highest in some severe threat.

..Dean.. 09/19/2024

$$

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.