744
FXUS63 KDVN 251129
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
629 AM CDT Sat Jul 25 2026

.KEY MESSAGES...

- Heat and humidity returns this weekend and into early next
  week. Heat indices around or exceeding 100 degrees are
  becoming increasingly likely Sunday and Monday. A Heat
  Advisory in northwest Illinois and an Extreme Heat Warning for
  the rest of the area have been issued for Sunday. An Extreme
  Heat Watch is in effect for all areas for Monday.

- Thunderstorms are possible (10-40% chance) Sunday night into
  Monday and may be strong to severe. The SPC has issued a
  Marginal-to-Slight Risk (Level 1 to 2 out of 5) for severe
  weather with damaging winds being the primary hazard.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 251 AM CDT Sat Jul 25 2026

Satellite imagery early this morning shows a thick deck of
stratocumulus stretching from Minnesota to southern Illinois. Across
parts of eastern Iowa, western Illinois, and northeast Missouri,
this low cloud deck will help keep lows slightly warmer this morning
in the upper 60s. By mid-day, clouds will lift out as they move
east, lingering into the early afternoon in far eastern Iowa and
northwest Illinois. This will help limit highs in these areas to the
low to mid-80s, with areas to the west reaching the mid- to upper
80s.

Saturday night into Sunday, lows will drop into the low 70s. A
feature of particular note in many of the 00Z CAMs is a cluster of
showers and storms across parts of western and central Iowa. This
cluster is associated with a vort max that rides along the edge of
the upper-level ridge. Many CAMs suggest that remnants of this
cluster will reach eastern Iowa by Sunday morning and decay shortly
afterward. If this were to happen, lingering cloud cover could help
temper high temperatures slightly on Sunday, though a hot day with
temperatures in the low to mid-90s will still be in store due to a
near continuous stream of WAA. Combined with very humid conditions,
this will support heat indices in the 100s and potentially exceed
105 degrees (50-90% chance north to south). An Extreme Heat Warning
is in effect for eastern Iowa, west- central Illinois, and northeast
Missouri and a Heat Advisory is in effect for northwest Illinois on
Sunday afternoon.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 251 AM CDT Sat Jul 25 2026

Sunday Night through Monday Night
Sunday night, the question turns from heat to storm potential
as a shortwave moves through. While decent shear of 25-35 kts
and instability will be in place, it is possible that the
environment remains capped due to warm temperatures at 850 and
700 mb. Without strong forcing to break this cap, it is possible
that no storms occur. Any storms that do develop will be able
to take advantage of the shear and instability, with the primary
threat being damaging winds. Due to this risk, SPC has a Slight
(level 2 of 5) risk for severe thunderstorms for the Highway 20
corridor and a Marginal (level 1 of 5) risk for the remainder
of the area.

Heat and humidity are expected with warm lows in the mid-70s Monday
morning, which will help temperatures reach into the low to mid-90s
and heat indices in the 100s. The primary limiting factor to this
would be storms lingering from overnight through Monday morning,
though uncertainty in storm initiation and evolution limits the
confidence in whether temperatures will be lower. As such, an
Extreme Heat Watch remains in effect for the entire area through
Monday evening.

Another round of storms is possible Monday afternoon and evening as
a cold front pushes through the region. Shear will remain similar to
Sunday, though with the greatest shear now being to the east across
northeast Illinois. This could help limit the number of storms
across our region, as greater shear could allow for the development
of an organized cluster of storms to our east.

Tuesday through Friday
Following the passage of storms with the cold front overnight
into Tuesday, high pressure will build in on the northeast
periphery of the upper level ridge. The cold front will help
slightly lower heat indices into the mid-90s with the
introduction of a drier airmass, though this heat will remain
through both Tuesday and Wednesday as we remain under the
influence of the ridge.

By midweek, the greatest question is when the ridge retrogrades and
brings us back into the summertime storm track and grants us a
reprieve from the heat.The majority of the guidance has this change
towards the end of the period around Thursday and Friday, though
there a few outliers that have it as early as Wednesday. With this
return to the storm track, there is the potential for another system
to pass through as soon as Friday, though changes in speed could
have it arrive earlier.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 620 AM CDT Sat Jul 25 2026

MVFR/IFR ceilings and visibilities are anticipated this morning due
to extensive low clouds across the Upper Mississippi Valley
region and pockets of fog mainly west/northwest of MLI. A return
to VFR is expected this afternoon with light winds continuing
through the period.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Extreme Heat Warning from 11 AM to 9 PM CDT Sunday for
     IAZ040>042-051>054-063>068-076>078-087>089-098-099.
     Extreme Heat Watch from Sunday evening through Monday evening
     for IAZ040>042-051>054-063>068-076>078-087>089-098-099.
IL...Extreme Heat Warning from 11 AM to 9 PM CDT Sunday for ILZ009-
     015>018-024>026-034-035.
     Extreme Heat Watch from Sunday evening through Monday evening
     for ILZ001-002-007-009-015>018-024>026-034-035.
     Heat Advisory from 11 AM to 9 PM CDT Sunday for ILZ001-002-007.
MO...Extreme Heat Warning from 11 AM to 9 PM CDT Sunday for MOZ009-
     010.
     Extreme Heat Watch from Sunday evening through Monday evening
     for MOZ009-010.

&&

$$

SHORT TERM...Ellingworth
LONG TERM...Ellingworth
AVIATION...Uttech