560
FXUS63 KDVN 210515
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1215 AM CDT Tue Jul 21 2026

.KEY MESSAGES...

- Smoke from Canadian wildfires is forecast to keep hazy skies
  and poor quality across the area through tonight. Smoke may
  linger through the day on Tuesday as winds turn more northerly
  at the surface.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 149 PM CDT Mon Jul 20 2026

Convection continues to exit into northern Missouri and central
Illinois early this afternoon. Clouds are exiting the area from
northwest to southeast. An outflow boundary is evident on radar
and satellite imagery stretching into Clark County and
northwestward toward Ottumwa and Newton. Another area of storms
is currently evident on radar and satellite across western
Wisconsin into southern Minnesota and far northern Iowa.

Airmass recovery is underway in the wake of earlier convection
with areas north of Highway 20 warming into the mid 80s with
dewpoints in the mid to upper 70s. This airmass will allow
storms currently in southern Minnesota to intensify as they
move southeastward. CAMs have shown that this area of storms is
expected to intensify with some becoming supercellular as shown
with potential intense updraft helicity swaths across the area.
This is supported by model soundings as well as hodographs
which show strong curvature at least in the 0 to 3 km layer.
Additionally, if these storms anchor on the expected retreating
outflow boundary from earlier storms, this will lead to
increased tornado risk with the potential for strong tornadoes.
Additionally, these storms will be capable of large hail
damaging winds. Think that the primary threat for severe weather
will be from 4 PM to 10 PM. Heavy rain and localized flash
flooding will also be possible with PWATs near 2.00 inches.

For later tonight, an unusually strong 500 mb trough and
associated 125 knot jet streak will dig into the area tonight.
This forcing for ascent is unusually strong for late July and
will lead to another round of storm development this evening
that will sink southward across the area. The main question is
how much instability will this increasing lift have to work with
across the area. This could at least lead to rain developing
across the area with thunderstorms possible and potentially
severe if any instability remains. The potential is there for
damaging wind gusts as well as heavy rain overnight although
lower instability will lead to more isolated severe potential.

Model consensus has the cool front exiting the area by 12 UTC
on Tuesday. The HRRR surface smoke and RRFS show some smoke
moving into the area behind the front for Tuesday but with lower
concentrations than on Sunday and today.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 149 PM CDT Mon Jul 20 2026

Tuesday onward, the 500 MB pattern will yield troughing in the
Great Lakes and Ridging across the western CONUS through the
reminder of the week. Little has changed in the forecast
thinking from the previous shift. Therefore the previous long
term is included below.

Tuesday through Thursday...some lingering early morning showers or
storms are possible in the far south as the cold front moves into
southern Missouri. Humid conditions will be seen Tuesday until a
secondary front moves through. Once this front moves through much
less humid conditions and cooler temperatures will be seen Wednesday
and Thursday.

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

The model consensus is narrowing the time frame for rain to late
Thursday night into Friday morning. Rain chances have increased
slightly (20-35%) mainly south of I-80 but this appears to be an
anomaly tied to one specific model.

The weak low and associated fronts are progged to be across Missouri
so the better rain chances will be associated with the higher
moisture and stronger forcing. Indeed, a dprog/Dt of the various
models shows a southward shift to the moisture/wind convergence;
closer to the frontal boundary. This adds support that the uptick in
rain chances is an anomaly. I suspect rain chances will slowly
decrease as the week progresses.

Friday night through Sunday
Assessment...a certainty (>98%) of slowly rising humidity levels

All models show southerly flow redeveloping over next weekend as the
heat dome builds north in the Plains. Dew points in the 50s Friday
night will slowly climb into the low to mid 60s Saturday with mid to
upper 60s dew points by Sunday. The increasing temperatures and
moisture will slowly push heat indices into the 90s by Sunday.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1212 AM CDT Tue Jul 21 2026

Cold front to sweep through eastern Iowa and northern Illinois
through 15z/21. Prior to 12z/21 SHRA or even a TSRA will be
possible but coverage will be 10-30 percent. After 15z/21 deep
mixing will allow wind gusts up to 25 knots to occur. The winds
will subside with sunset as the boundary layer stabilizes and
high pressure builds into the Midwest.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...Cousins
LONG TERM...08
AVIATION...08