890
FXUS63 KDVN 181809
AFDDVN

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

.KEY MESSAGES...

- Hot and humid conditions will be seen today with peak heat
  indices of 95 to 100. A heat advisory has been issued for most
  areas south of I-80 until 7 PM where heat indices have a
  60-80% chance of exceeding 100 degrees.

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

- A cold front on Monday poses a severe weather threat, with SPC
  issuing a Slight Risk (Level 2 out of 5) for potential
  damaging winds.

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

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 136 AM CDT Sat Jul 18 2026

Very warm and humid conditions continue today with heat indices of
95 to 100 for much of the area. Based on forecasted heat indices,
Wet Bulb Globe Temperatures and expected pooling of moisture near
the front, the heat headlines will be extended another tier of
counties north but will also include Muscatine, Scott and Rock
Island counties as well.

Convection this afternoon will be isolated to low end scattered (10-
30%). Diurnal heating will drive the convection and based on the
timing of the front, areas along/south of I-80 have the relatively
better chances of seeing rain. Where rain does occur there will be
relief from the heat and humidity.

Diurnal convection will continue into the evening hours before
dissipating. By 10 PM the area should be rain free for the remainder
of the night with dew points slowly falling. Northerly winds are
expected to bring some wildfire smoke down into northwest
Illinois.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 136 AM CDT Sat Jul 18 2026

Sunday/Sunday night
Assessment...high (>80%) confidence on dry and slighly less
humid conditions

Canadian high pressure and northerly winds will bring a brief
respite to the hot and humid conditions Sunday into Sunday night.
However, the northerly winds will increase the prospects of bringing
Canadian wildfire smoke into the area. A majority of the smoke will
be aloft and create hazy skies. However, reductions in air quality
are possible across northwest Illinois.

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.

Based on the timing of the front (afternoon/evening), the Storm
Prediction Center has a slight, level 2 out of 5, risk for severe
storms across the entire area. The primary risk looks to be damaging
winds.

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...08
LONG TERM...08
AVIATION...Uttech