SPC Convective Outlook Day 1

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514
ACUS01 KWNS 231957
SWODY1
SPC AC 231956

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Tue Apr 23 2024

Valid 232000Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHWEST
TEXAS...

...SUMMARY...
Isolated severe thunderstorms capable of producing large hail
(potentially 2+ inch diameter) and gusts to 65 mph will be possible
this afternoon and evening across northwest Texas.

...20Z Update...
Overall forecast outlined in the previous discussion (appended
below) remains valid. As mentioned in recently issued MCD 506, a
supercell or two should develop across a portion of western North
Texas through late afternoon, with large hail of 1.5 to 2.5 inches
in diameter and localized severe gusts of 60-70 mph possible. An
isolated storm or two is also possible farther south in the Texas
Trans Pecos vicinity. Marginally severe hail (i.e. around 1" in
diameter) and damaging gusts are possible here as well.

Farther north, isolated thunderstorms are still anticipated from
northern IL into Lower MI ahead of an approaching shortwave trough
and associated cold front. A few strong to severe storms are
possible with small to marginally severe hail and damaging winds as
the primary hazards (as mentioned in recently issued MCD 507).

...Early tomorrow morning from TX Panhandle into
north-central/central OK...
Elevated thunderstorms may develop from the northeast TX/eastern OK
Panhandles into central/north-central OK within the warm-air
advection regime along the northeastern edge of the returning
low-level moisture. Steep mid-level lapse rates and favorable
cloud-bearing layer shear could support an isolated instance or two
of hail with initial development. However, severe coverage is
currently expected to remain less than 5%, precluding the
introduction of any outlook areas.

..Mosier.. 04/23/2024

.PREV DISCUSSION... /ISSUED 1123 AM CDT Tue Apr 23 2024/

...Northwest TX...
Visible satellite imagery and surface analysis this morning indicate
the initial stage of moisture return is occurring across the
southern Great Plains in the wake of a frontal intrusion into the
Gulf a few days ago. A mid-level ridge will increasingly become
established across the central/southern Rockies and adjacent High
Plains as a Great Lakes disturbance gradually becomes more displaced
from the region. An associated cold front will move southward
across KS/OK before eventually stalling tonight across southeast OK
and northwest TX. Weak lee cyclogenesis will aid in maintaining a
southerly low-level fetch across central into west TX as strong
heating results in a sharpening dryline by late afternoon. Isolated
thunderstorm development will be most probable near the triple point
20-22Z. Steep lapse rates coupled with adequate moisture (1500-2000
J/kg MLCAPE) and veering flow beneath moderate westerlies, will
support an initial supercell mode. Isolated very large hail of
2-2.5 inches in diameter will be the main threat, along with a few
55-65 mph gusts.

...Northern IL/southeast WI/Lower MI late this afternoon/evening...
Have not changed the existing outlook for this region due primarily
to consistency in model data and the forecast conceptual model not
deviating. Water-vapor imagery this morning shows a mid-level
trough over the Upper Midwest and this will continue southeast into
the central Great Lakes by mid evening. An associated surface
trough will likewise move southeastward, and this trough will be
preceded by a band of rain with minimal buoyancy. Behind the rain
band, surface heating with steepening low-level lapse rates and
cooling midlevel temperatures will support weak surface-based
buoyancy just ahead of a secondary frontal surge. Some low-topped
convection will be possible late this afternoon through late evening
from northern IL/southeast WI into Lower MI. The stronger storms
could yield a localized marginal hail/damaging wind threat.

$$

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

996
FLUS43 KLOT 232054
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
354 PM CDT Tue Apr 23 2024

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-242100-
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-
354 PM CDT Tue Apr 23 2024 /454 PM EDT Tue Apr 23 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...with an associated:
Limited Hail Risk...up to quarter size.
Limited Damaging Wind Risk...up to 60 mph.

DISCUSSION...

Scattered thunderstorms are expected across northern Illinois
this afternoon and into northwest Indiana early this evening.
Some of these thunderstorms may be strong to severe with large
hail and localized damaging wind gusts the main severe weather
threats.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Wednesday night...
Significant Frost Risk.
Friday and Saturday...
Limited Flooding Risk.
Elevated Thunderstorm Risk.
Sunday...
Limited Flooding Risk.
Limited Severe Thunderstorm Risk.
Monday...
Limited Thunderstorm Risk.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed this afternoon and early this evening.

GENERAL STORM MOTION OF THE DAY:

Moving toward the east southeast at 40 to 45 mph.

$$

LMZ740>745-242100-
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-
354 PM CDT Tue Apr 23 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...

Hazardous conditions for small craft.
Limited Thunderstorm Risk...with an associated:
Limited Hail Risk...up to quarter size.
Limited Thunderstorm Wind Gust Risk...up to 50 knots.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Wednesday...
Hazardous conditions for small craft are likely.
Friday through Sunday...
Hazardous conditions for small craft are likely.
Limited Thunderstorm Risk.
Monday...
Hazardous conditions for small craft are likely.

$$

KMD

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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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781
ACUS02 KWNS 231728
SWODY2
SPC AC 231726

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1226 PM CDT Tue Apr 23 2024

Valid 241200Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM WEST TEXAS
INTO MUCH OF OKLAHOMA...

...SUMMARY...
Strong thunderstorms will be possible on Wednesday across parts of
Oklahoma and west Texas. Isolated hail and severe gusts will be the
primary hazards.

...Synopsis...
Upper pattern is expected to feature a shortwave trough from western
Quebec through western New York early Wednesday, with another
shortwave well off the southern CA Coast. Shortwave ridging is
anticipated between these two troughs. This entire
trough/ridge/trough pattern is forecast to move eastward during the
period, with the eastern shortwave trough moving off the
Northeast/New England coast by Wednesday evening, and the western
shortwave trough making steady eastward progress, likely extending
from southern NV into southwest AZ/far northwest Mexico by early
Thursday morning. Shortwave ridging will be maintained between these
troughs, ending the period over the Great Plains.

At the surface, a cold front associated with the Northeast shortwave
will progress quickly eastward, moving off the Northeast coast by
the late afternoon and off the Mid-Atlantic coast later during the
evening. Farther west, modest lee troughing is anticipated early
Wednesday, with a weak surface low likely over the Texas
Trans-Pecos. Lee troughing is expected to sharpen throughout the
day, with the surface low likely deepening as well. At the same
time, persistent low-level theta-e advection across TX will
contribute to the sharpening of a stalled frontal boundary from the
southeast TX Panhandle across southern OK. By late Wednesday
night/early Thursday morning, this front will likely begin pushing
northward across the eastern TX Panhandle and OK as a warm front.

...Eastern TX/OK Panhandles into central OK early Wednesday...
Elevated thunderstorms may be ongoing early Wednesday morning from
the northeast TX/eastern OK Panhandles into central/north-central OK
within the warm-air advection regime along the northeastern edge of
the returning low-level moisture. Gradually strengthening westerly
flow aloft will support enough vertical shear for organized updrafts
and the potential for some storms strong enough to produce large
hail. Background height rises cast some doubts for overall storm
severity, but thunderstorms will likely persist into the afternoon
as they move generally southeastward.

...TX Panhandle through Permian Basin Wednesday afternoon...
Low-level moisture is forecast to advect northwestward into the
southern High Plains throughout the day. As such, low 60s dewpoints
are expected from the TX Panhandle southward to the Big Bend by the
early afternoon. Even so, mid-level temperatures and associated
capping will likely preclude widespread deep convection. Some
isolated development does appear probable, particularly where
persistent low-level convergence favors multiple attempts at storm
development. Given strong buoyancy and deep-layer vertical shear,
any convection that is maintained and matures should become
supercellular with the potential to produce large to very large hail
and strong, damaging downdrafts.

...TX Panhandle into OK Wednesday night into Thursday morning...
Another round of elevated convection is possible from the southern
TX Panhandle into northwest TX into OK late Wednesday night into
Thursday morning, as low to mid-level moisture spreads northward in
advance of the approaching upper trough. Moderate elevated buoyancy
and sufficient effective shear could support an isolated hail threat
within any more established storms.

...Northern Mid-Atlantic into Southern New England...
Shallow convection is anticipated along and in the wake of the cold
front forecast to move quickly eastward/southeastward across the
region. Shallow nature to the convection should keep lightning
isolated, but a few damaging gusts are still possible as downdrafts
augment the moderate westerly low-level flow in place.

..Mosier.. 04/23/2024

$$

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

225
ACUS03 KWNS 231831
SWODY3
SPC AC 231831

Day 3 Convective Outlook AMEND 1
NWS Storm Prediction Center Norman OK
0131 PM CDT Tue Apr 23 2024

Valid 251200Z - 261200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE
EASTERN TX PANHANDLE AND WESTERN OK INTO SOUTHWEST/SOUTH-CENTRAL
KS...

AMENDED TO UPDATE FORECAST

...SUMMARY...
Severe thunderstorms are likely from late Thursday afternoon into
Thursday night across parts of the central and southern Great
Plains. Very large hail, severe wind gusts, and strong tornadoes
will all be possible.

Guidance continues to suggest strong buoyancy will be in place ahead
of a negatively tilted shortwave trough ejecting across the southern
High Plains. General forecast expressed in the previous outlook
remains valid, but confidence in an area of greater severe-weather
potential has become more apparent with the most recent guidance.
Late afternoon development is anticipated across the TX Panhandle,
with these storms quickly becoming severe and capable of large to
very large hail up to 3" in diameter. Low-level moisture may be
later to arrive in west-central/southwest KS, delaying convective
initiation to a few hours later than farther south. Large to very
large hail is anticipated with initial development across
west-central/southwest KS as well.

In both of these areas, storms are expected to move
east-northeastward off the dryline, encountering strengthening
low-level southerly flow and environment that is increasingly
favorable for tornadoes. Low-level shear will continue to
strengthening into the early evening, and the overall environment
supports the potential for strong to intense tornadoes if a discrete
mode can be maintained.

--- Previous Discussion issued at 0230 AM CDT Tue Apr 23 2024 ---

...Synopsis...
A shortwave trough initially over the Southwest is forecast to take
on an increasingly negative tilt as it moves eastward towards the
central/southern Plains by Thursday night into Friday morning. In
response, a surface low will consolidate and deepen across the
central High Plains through the day, before moving northeastward
toward northwest KS/southwest NE by Friday morning. An initially
stationary surface boundary will move northward as a warm front
across the central Plains through the day. Along/south of the warm
front, relatively rich low-level moisture will stream northward to
the east of a dryline that will become established from the eastern
TX Panhandle into western KS and eastern CO.

...Southern/central Great Plains...
Coverage of the severe-thunderstorm threat remains somewhat
uncertain, but a couple intense supercells are possible by Thursday
evening near the dryline from western KS into western OK and the
TX/OK Panhandles. Another round of overnight convection will
potentially bring the severe threat eastward into a larger portion
of the central/southern Plains.

The warm sector of the deepening cyclone will likely remain capped
for much of the day, though elevated convection may persist from
parts of central/eastern KS into eastern OK, to the north of the
effective warm front. Increasing moisture beneath steep midlevel
lapse rates will support MLCAPE in excess of 2000 J/kg along/east of
the dryline, as deep-layer shear strengthens across the region
through the day.

Ascent attendant to the approaching shortwave trough will begin to
impinge upon the warm sector by late afternoon, with isolated
supercell development possible near the surface low across southwest
KS and southward down the dryline into the TX Panhandle. Very large
hail (potentially 2-3 inches in diameter) will likely be the primary
initial hazard. A notable increase in low-level flow/shear near and
after 00Z will also support a tornado threat with any supercells
that can persist into the evening across parts of western KS/OK.

While any initial dryline storms may weaken by mid/late evening due
to increasing MLCINH with eastward extent, renewed storm development
is possible overnight along the Pacific cold front from southwest TX
into western/central KS/OK as stronger large-scale ascent
overspreads the region. Steep midlevel lapse rates, moderate
buoyancy, and strong low-level and deep-layer shear will
conditionally support a severe threat with overnight convection
across the warm sector, though storm mode may become complex and
tend toward a linear evolution with time. Severe wind gusts may
become an increasing threat with the nocturnal convection, though
hail and a couple tornadoes will also be possible if semi-discrete
or embedded supercells can be maintained.

...NE/WY border region into northeast CO...
Low-level southeasterly flow will support modest moisture return
into parts of northeast CO, southeast WY, and western NE, to the
north of the deepening cyclone. Thunderstorm development will be
possible near and to the cool side of the effective warm front
during the afternoon. While deep-layer shear will be weaker compared
to areas farther southeast, steep midlevel lapse rates will support
an isolated hail threat. A tornado also cannot be ruled out, if
surface-based storms can be maintained within this regime.

..Mosier.. 04/23/2024

$$

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

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

See Product Description

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.