891
FXUS63 KILX 191127
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
627 AM CDT Sun Jul 19 2026

.KEY MESSAGES...

- Wildfire Smoke and Poor Air Quality Today: Thick wildfire
  smoke will bring widespread hazy skies and degraded air
  quality through midnight tonight. Visibility will be
  diminished as air quality reaches to unhealthy levels for
  sensitive groups.

- Severe Weather Risk Monday Night: While the higher threat for
  severe storms will be northwest of central Illinois, areas
  north of I-72 will have a threat for damaging downburst winds
  and locally heavy rainfall Monday evening.

- Dry and Cooler Late Week: A strong high-pressure system will
  bring a return to quiet weather from Wednesday through Friday.
  Expect dry conditions with comfortable, slightly below-normal
  temperatures in the upper 70s to lower 80s.

&&

.DISCUSSION...
Issued at 252 AM CDT Sun Jul 19 2026

Synopsis...
The surface cold front responsible for last evenings convective
activity has progressed southward to near the I-72 corridor as
of 06z (1 AM CDT). While post-frontal airmass modification has
been sluggish initially, a robust Canadian high-pressure system
will build southward over the Upper Midwest today. This feature
will effectively drive the boundary south of the forecast area,
delivering a temporary period of cooler, but noticeably hazy
conditions. The primary near-term concern centers around a
significant plume of near-surface wildfire smoke accompanying
this high. Looking ahead, the frontal boundary will lift back
northward as a warm front on Monday, setting the stage for a
volatile thermodynamic environment and a growing threat for
organized severe weather late Monday into Monday night. Quieter,
cooler, and highly comfortable conditions return by mid-to-late
week.

Today and Tonight: Wildfire Smoke & Air Quality Impacts.
The main story for today is the incoming surge of vertically
integrated and near-surface smoke originating from Canadian
wildfires. Upstream observations across northern Illinois have
already noted visibility restrictions dropping into the 2 to
5-mile range.

High-resolution smoke transport modeling (HRRR and RRFS)
bring this thick smoke plume southwestward across central
Illinois through the morning and afternoon hours. While some
discrepancies exist regarding concentrations with the HRRR
exhibiting a lower impacts compared to the more aggressive
RRFS. Our forecast leans toward a more pessimistic, smoke-laden
outcome. This aligns closely with recent upstream trends.
Expect widespread hazy skies and degraded air quality capable of
reaching Unhealthy for Sensitive Groups (USG) thresholds.
Consequently, the Air Quality Alert remains in effect for the
entire CWA through midnight tonight.

Otherwise, expect a dry day with high temperatures held in the
low to mid-80s due to a mix of weak cold advection and solar
attenuation from the smoke layer. Smoke concentrations should
gradually decrease overnight as the surface high slides
eastward.

Monday Severe Weather Potential...
On Monday, the upstream pattern shifts rapidly as a potent
shortwave trough ejects across the Northern Plains, forcing the
stalled surface front to lift back northward as a warm front.
Deep southerly to south-westerly flow will re-establish in its
wake, transporting a highly unstable airmass characterized by
upper 80s to lower 90s surface temperatures and pooling
dewpoints in the low 70s.

Confidence is steadily increasing in a multi-hazard severe weather
episode late Monday afternoon into Monday night, with a higher
potential in NW IL and points NW of there. As a strong cold
front approaches from the northwest, intense destabilization
combined with 3545 knots of mid-level westerly flow will
provide sufficient deep-layer shear to organize convection.
Initial discrete or semi-discrete development along and ahead
of the front west of Illinois will likely upscale into a
forward-propagating mesoscale convective system (MCS) or squall
line as it sweeps southeastward into our region.

Primary Hazards: Damaging straight-line winds look to be the
predominant threat given steep low-level lapse rates and high
DCAPE potential. However, large hail and a few tornadoes cannot
be ruled out, particularly with any initial discrete structures
or along the QLCS.

Heavy Rainfall: Precipitable Water (PWAT) values climbing near or
above 2.0 inches will support highly efficient rainfall rates.
Locally heavy rain could lead to localized flash flooding,
especially in areas seeing repeated convective tracks.

By Wednesday, a sprawling, high-amplitude Canadian high-
pressure system will anchor itself over the Great Lakes and
Midwest regions. This will usher in an extended period of
exceptionally quiet and comfortable weather. Deep north-to-
northeasterly flow will reinforce a dry airmass, dropping
dewpoints back into the more comfortable 50s. High temperatures
from Wednesday through Friday will average slightly below
normal, comfortably topping out in the upper 70s to mid-80s
under mostly clear skies. This beautiful mid-summer stretch
looks to persist well into the upcoming weekend before the high
begins to shift eastward.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 627 AM CDT Sun Jul 19 2026

Smoke has moved into the area and will likely remain until
Tuesday morning. Band of broken to overcast CU/SC remains over
the central part affecting SPI, DEC, and CMI. However, do not
believe this will last all day so scatter them out around 15z.
BMI and CMI have dropped to 2sm, but believe this evening, they
both will improve to 3sm. Though not at SPI yet, believe they
will see vis drop very soon, so have PIA, SPI, and DEC at 3sm
through the period. Winds will be easterly at 10kts or less
through the day and then becoming light and variable this
evening.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Air Quality Alert until midnight CDT tonight for ILZ027>031-
036>038-040>057-061>063-066>068-071>073.

&&

$$

KEY MESSAGES...Shimon
DISCUSSION...Shimon
AVIATION...Auten