180
FXUS63 KDVN 270829
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
329 AM CDT Mon Jul 27 2026

.KEY MESSAGES...

- Oppressively hot and humid through this evening, with heat
  indices in many locations peaking around 105-115 degrees.

- Organized thunderstorms are possible this afternoon into this
  evening in northwest Illinois, though there remains some
  uncertainty due to capping and the track. Some of these storms
  may be strong to severe with damaging winds if well-
  organized. An Enhanced (level 3 of 5) risk of severe
  thunderstorms is in effect for northwest Illinois.

- Some midweek relief comes behind a cold front tonight,
  although smoke from Northwest U.S. and Canadian fires may
  spread over the area that could continue through Tuesday.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 301 AM CDT Mon Jul 27 2026

A complicated forecast is in store for Monday, but amidst the many
different ways today could play out, there is one consistent factor:
it will be oppressively hot and humid. Early morning
temperatures remain quite warm in the upper 70s to low 80s, with
dew points not far behind. Combined with weak surface winds,
this warm and humid airmass has allowed for the development of
patchy areas of fog and low stratus north of Interstate 80. This
also includes areas of dense fog east of the Quad Cities metro.
Diurnal heating and quickly increasing temperatures will allow
any fog to burn off by mid-morning.

Once the fog clears out, the surface will quickly heat up, leading
to yet another oppressively hot and humid day. Highs are forecast in
the low to mid 90s, with some areas in the far south reaching
into the upper 90s. Dew points are once again expected to reach
into the lower 80s today, leading to heat indices as high as
105 to 115 degrees. An Extreme Heat Warning is in effect area-
wide. However, there is a potential limiter in how hot we can
get today: thunderstorms.

Guidance remains keen on a potential MCS moving through parts of
northern Illinois today, though there is quite the range of
solutions, including a some that have no storms at all. This is
likely due to the strong environment that will be in place: 30-40
kts of shear, high instability from a hot and humid airmass, and
ample moisture with PWATS near 2 inches. Given this potent
environment, SPC has an Enhanced (level 3 of 5) in place for
northwest Illinois and a Slight (level 2 of 5) to the Interstate
380/Highway 218 corridor. However, forecast confidence is quite
low, with the most likely scenario being low storm coverage.
This is due to a number of factors, with perhaps the greatest of
these being warm temperatures aloft. While capping will be weak
with 850mb temperatures around 20-25 degC, it could suppress
any convection, such as was seen yesterday. If storms do
develop, there are still a few scenarios that could play out.

Scenario 1: Storms develop across Wisconsin and move south-
southeastward as an MCS. This MCS matures prior to reaching
Illinois early to mid afternoon, allowing for it to produce
swaths of damaging winds and torrential rainfall as it moves
through northern Illinois. In this scenario, the MCS tracks to
the east of our CWA. While the fringes of the MCS could still
impact parts of our CWA across northwest Illinois, damaging
winds would have a lower probability but still be an area of
concern.

Scenario 2: Similar to Scenario 1, storms develop across
Wisconsin, with the main difference being a more westward track.
This would result in the MCS tracking over our CWA`s northwest
Illinois counties, and slight shifts could result in parts of
eastern Iowa along the Mississippi River seeing a few storms. In
this scenario, the potential for damaging winds, including
significant winds, is higher. The primary impacts would be
focused in northwest and north-central Illinois.

By evening, the cold front will begin making its way through the
CWA, slowly pushing southward. While this may not offer immediate
relief in temperatures, it will help reduce heat indices and the
chances for heat headlines in the coming days.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 301 AM CDT Mon Jul 27 2026

Once the front passes through, Tuesday will feel much cooler as
more seasonable temperatures return. One note for behind the
front is the potential for smoke in the air, possibly even
reduced air quality at the surface. GOES Geocolor satellite
Sunday afternoon indicated widespread smoke over the northern
CONUS Rockies into the western Dakotas. RAP and HRRR extended
smoke forecasts indicate this being steered southward behind the
front over our area. This is still too far out to tell if it
would mix to near- surface, but at least some smoky sky tonight
into early Tuesday looks probable.

After quiet and near to slightly warmer than seasonable
temperatures Wednesday and into the day Thursday, a slow moving
and fairly well-defined short wave is indicated by guidance to
pass over the area late Thursday night into Friday. This looks
like the next chance of rain.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1249 AM CDT Mon Jul 27 2026

Current satellite imagery shows the development of a low stratus
deck from the Mississippi River eastward into northwest Illinois,
along with mid to high clouds moving southward. Clear skies and high
humidity tonight will support the development of areas of shallow
patchy fog, as seen already at DBQ. This could lead to temporary
MVFR to IFR VSBYs through daybreak.

Of note is great uncertainty in convective potential through the TAF
period. Guidance has been quite mixed in how storms are to develop
and evolve this morning, including time of arrival being pushed back
with each run. As such, the PROB30s for DBQ/MLI have been removed
from this issuance due to high uncertainty in when and where storms
may occur. Towards afternoon(27/18-23Z), there is increasing
confidence in isolated to scattered showers and storms in southern
Iowa. Uncertainty in eastward extent has kept any PROB30 mention
from BRL at this time.

Winds will be light and variable overnight before strengthening and
becoming gusty and southwesterly through the day. Towards the end of
the period, winds will turn northwesterly with the passage of a
front.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Extreme Heat Warning until 10 PM CDT this evening for
     IAZ040>042-051>054-063>068-076>078-087>089-098-099.
IL...Extreme Heat Warning until 10 PM CDT this evening for ILZ001-
     002-007-009-015>018-024>026-034-035.
MO...Extreme Heat Warning until 10 PM CDT this evening for MOZ009-
     010.

&&

$$

SHORT TERM...Ellingworth
LONG TERM...Ellingworth/Friedlein
AVIATION...Ellingworth