761
FXUS63 KDVN 112352
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
652 PM CDT Tue Aug 11 2026

.KEY MESSAGES...

- Strong to severe storms will be possible late tonight into
  Wednesday morning. The entire area is under a Marginal, level
  1 out of 5, Risk for severe storms. The primary risk is
  damaging winds.

- There will be a near daily risk of rain through the remainder
  of the week as disturbances continue to move around the edge
  of the heat dome. However, there will be many hours of dry
  weather.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 133 PM CDT Tue Aug 11 2026

Through sunset isolated to low end scattered (10-25%) showers and
thunderstorms will be seen. While a severe storm cannot be ruled
out, it would be very localized with damaging wind being the primary
risk.

Overnight, muggy conditions will be seen across the area. There may
or may not be some isolated showers or storms that develop. The
overall forcing is very weak if not non-existent. However, there are
areas of steep lapse rates which may allow isolated nocturnal
showers or even a thunderstorm to occur. For 95 percent of the area,
no rain is expected.

Wednesday has the potential to be interesting.

Internally, the models are pointing to yet another storm complex
developing during the night and generally moving east. The LLJ
support is very weak ahead of the potential complex but does
increase behind it. This may or may not be convective feedback in
the various models.

The models suggest a weakly organized storm complex moving east or
east southeast from the Plains as it rides the edge of the heat
dome. Overall timing suggests that it would arrive in eastern Iowa
shortly after sunrise and continue east southeast into Illinois and
the Ohio Valley.

If this scenario is correct then two things are known; 1) the better
rain chances will be during the morning and early afternoon and 2)
the storm cluster should be further south than the Tuesday morning
complex.

Boundaries from this complex will then provide the focus for
additional diurnal development Wednesday afternoon.

Given the weaker nature of the upper level support, the overall
severe risk would be conditional on Wednesday. Progged lapse rates
aloft are very steep so if severe storms would develop the primary
risk would be damaging winds.

The rain Wednesday morning into early afternoon would suppress
temperatures and resultant heat indices for much if not all of
the area. The overall situation will need to be watched and a
tactical heat advisory may or may not be issued Wednesday
morning.

It appears there be a brief lull Wednesday night between the diurnal
convection in the afternoon and the arrival of the next system late
Wednesday night. This system gives the appearance of producing a
more wide-spread rain for the northern two thirds of the area.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 245 AM CDT Tue Aug 11 2026

Thursday through Monday...If the currently extrapolated short wave
train along the edge of the heat dome is in the ballpark, we may
have another MCS moving into the local area Thu morning with severe
weather and heavy rain risks. The temperature battle will continue
as well with LLVL baroclinicity and thermal ribbon wavering acrs the
region for high heat or not so bad depending on the daily flux.
Rainfall amounts may really add up by the weekend and early next
week on the northern fringe of the heat dome from the west central
plains, acrs IA/IL, and curving down acrs the eastern OH RVR Valley.
Will have to watch the Thu through Friday period for heavy rain and
back building MCS potential depending on LLVL boundary and
convergent flow axis`s lay out if long range 2 inch PWAT feed
indicators are accurate.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 652 PM CDT Tue Aug 11 2026

General VFR conditions are expected through this evening before
the next disturbance moves in from the northwest. There is a low
chance (20-40%) for isolated to scattered showers and
thunderstorms along and north of I-80 tonight before a more
broad round of storms moves in from the west during the morning
hours and early afternoon. With any storm, reduction in
visibility is likely to MVFR to IFR conditions, but ceilings
should stay VFR outside a brief period possibly (30-50% chance)
at DBQ. Conditions should return to VFR conditions by the late
afternoon as skies scatter out behind the morning round of
storms. There is also a medium probability (40-70%) that wind
gusts exceed 20 knots at any given time during the morning round
of storms, but the uncertainty in timing and duration led to
their exclusion from this TAF issuance.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory until 8 PM CDT this evening for IAZ076>078-
     087>089-098-099.
IL...Heat Advisory until 8 PM CDT this evening for ILZ024>026-034-
     035.
MO...Heat Advisory until 8 PM CDT this evening for MOZ009-010.

&&

$$

SHORT TERM...08
LONG TERM...12
AVIATION...Delaune