505
FXUS63 KDVN 181954
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
254 PM CDT Sat Jul 18 2026

.KEY MESSAGES...

- A Heat Advisory is in effect for areas mainly south of I-80
  but also including the Quad Cities metro until 7 PM; expect
  peak heat indices in the lower 100s in this area. A Special
  Weather Statement has been issued just to the north and east
  of the advisory for peak heat indices between 95 to 100
  degrees.

- Isolated to scattered (10-40%) showers and storms are expected
  this afternoon and evening. Isolated severe storms are
  possible, mainly south of I-80 with damaging winds being the
  primary risk.

- A very unstable air mass will develop on Monday with a notable
  increase in humidity compared to Sunday. This setup could
  support severe thunderstorms later in the day as a cold front
  moves in from the northwest. SPC has an Enhanced Risk (level
  3 of 5) for severe storms northwest of the Quad Cities and a
  Slight Risk (level 2 of 5) to the east and south.

- Canadian wildfire smoke is forecast to spread across the area
  tonight through Sunday, which will likely lead to hazy skies
  and potentially to poor air quality.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 245 PM CDT Sat Jul 18 2026

A weak cold front will continue to shift southward through
eastern Iowa and northwest/west-central Illinois this afternoon
and evening, which could provide a focus for development of
isolated showers and storms. Areal coverage of storms through
late evening is anticipated to remain isolated to scattered, and
most favored in counties south of I-80. With a hot and humid
air mass in place there will be plenty of instability to work
with (MLCAPE values reaching 1500-2500+ J/kg), especially along
and south of I-80. Despite weak deep layer shear, a few strong
to severe storms are possible with the main threats being
localized damaging winds and heavy downpours. The main window
for convection will be between 4 PM - 10 PM, with limited
coverage for the rest of the night as a slightly less humid air
mass advects in from the north. Lows tonight will be in the 60s.

For Sunday, expect a less humid day compared to conditions over
the past week. It will still be very warm with highs in the
mid/upper 80s but peak heat indices will only reach the mid 80s
to lower 90s for most of the outlook area. The main story on
Sunday will be the potential for degraded air quality as
Canadian wildfire smoke moves in from the E/NE. Smoke aloft will
result in hazy skies and we do anticipate a period of near
surface smoke, which may lead to minor reductions in visibility
and to poor air quality. An Air Quality Alert has been issued
by the Illinois EPA for all of our Illinois counties from midnight
tonight until midnight Sunday night.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 245 PM CDT Sat Jul 18 2026

Monday/Monday night
Assessment...high (>80%) confidence on hot and humid conditions.

Hot and humid conditions will return again on Monday as southerly
flow brings moisture back into the area ahead of an approaching cold
front. Based on forecasted temperatures, heat indices and WBGT the
probability is high (70-80%) that much of the area will need heat
headlines.

The Storm Prediction Center has an Enhanced Risk (level 3 of 5)
for severe storms northwest of the Quad Cities and Slight Risk
(level 2 of 5) to the east and south. The primary risk looks to
be damaging winds. The ECMWF EFI for CAPE- Shear is showing a
notable signal, compared to mid summer climatology, for
moderate/high instability and wind shear across our northern CWA
(with values between 0.5 - 0.7), providing confidence on an
environment supportive of severe thunderstorms. Timing of
thunderstorms is uncertain at this lead time. There is potential
for scattered activity Monday AM and then a more widespread
round is possible Monday evening and night.

Tuesday through Thursday
Assessment...high (>80%) confidence of a respite from the heat and
humidity

After the passage of the cold front Monday, northwest flow aloft
will dominate resulting in much less humid conditions and
temperatures dropping to or slightly below normal.

There will be weak disturbances in the flow aloft moving through the
area on a daily basis. However, moisture will be lacking so dry
conditions are expected. However, that does not rule out the
possibility of a rogue diurnal shower or storm developing during
peak heating each day. The disturbance on Thursday looks to be the
strongest of the three days. So, if there is sufficient moisture
available, some isolated (10%) diurnal convection would be possible.

Friday
Assessment...low (<25%) confidence on rain chances

On Friday the global models will drag another cool front through the
area. Ahead of the front, return flow will bring moisture back into
the area. The model consensus has a 20 percent chance of rain.
However, the MJO will be stalling due to destructive interference
with the dominate background El Nino state. At the same time the MJO
will be in phase 7 or 8 which correlates to lower than normal
chances for rain.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1258 PM CDT Sat Jul 18 2026

Isolated showers and storms are possible later this afternoon
and evening, mainly south of I-80 with highest chances near BRL.
Confidence remains low on areal coverage and exact timing, so
have continued with PROB30s in the TAFs at MLI and BRL. Brief
MVFR/IFR is possible in the vicinity of any showers/storms.
Winds will turn predominantly to the NW/N this afternoon and
evening.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory until 7 PM CDT this evening for IAZ067-068-
     076>078-087>089-098-099.
IL...Heat Advisory until 7 PM CDT this evening for ILZ015-024>026-
     034-035.
     Air Quality Alert from midnight tonight to midnight CDT Sunday
     night for ILZ001-002-007-009-015>018-024>026-034-035.
MO...Heat Advisory until 7 PM CDT this evening for MOZ009-010.

&&

$$

SHORT TERM...Uttech
LONG TERM...08/ZU
AVIATION...Uttech