467
FXUS63 KDVN 202333
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
633 PM CDT Thu Aug 20 2026

.KEY MESSAGES...

- Shower and storm chances (30-70%) return Friday for areas
  mainly north of I-80 and some of the storms may become strong
  to severe.

- A stretch of quiet and mostly dry weather will be seen this
  weekend into early next week, with seasonal temperatures.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 1225 PM CDT Thu Aug 20 2026

Surface high pressure will remain in place through the rest of today
which should lead to a quiet weather day. Temperatures once
again will remain near average, with afternoon highs reaching
the upper 70s to low 80s across the region. The winds the rest
of the day will be fairly light as well, which will lead to a
very pleasant afternoon across the forecast area! Mostly sunny
skies are forecast for today, but that will change as we go into
tonight as positive H700 theta-e advection moves in out ahead
of a very weak shortwave trough. Even though there will be lift
provided by the shortwave, confidence in any light rain showers
developing tonight is very low as there is quite a bit of dry
air below 10k ft agl tonight.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 1225 PM CDT Thu Aug 20 2026

The potential for rain showers and thunderstorms will increase on
Friday, especially during the afternoon into the evening time frame.
Another shortwave will move southeast from the Northern High Plains
towards the Midwest during the day. This wave will usher in a cold
front which will move over the forecast area on Friday. Given the
low confidence in any showers during the morning, plenty of
instability should be able to build during the day as temperatures
rise into the 80s and dew points quickly climb. Forecast soundings
continue to depict MLCAPE values rising up to 3000 J/kg out ahead of
the front tomorrow afternoon. Deep layer shear is not all that
impressive out ahead of this system, with model guidance showing
values around 30 kts, but they are sufficient enough to at least
attempt to build organized convection along the front. Any storms
that are able to form in this environment will have the potential to
become strong to severe, with the most likely hazard being damaging
wind gusts as a linear complex may develop along the front. If
any storms can remain discrete, some large hail cannot be ruled
out. Storms should be relatively quick moving along the front
and should be out of the area by late evening.

After that system departs to the east, the region looks to be
under mainly northwest flow for much of the remainder of this
forecast period. This is in part to troughing over the
northeastern US with a ridge of high pressure building over the
Rockies into the Great Plains. Very mild conditions are likely
this weekend through the start of the next work week with
afternoon highs in the 70s to low 80s. Upper level high pressure
over the southern High Plains may retreat back west during the
middle of next week which would increase the potential for
moisture return over the Midwest. However, that is still nearly
a week out so any slight change in the pattern could occur so
confidence is low at this time.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 633 PM CDT Thu Aug 20 2026

VFR conditions are expected to continue through much of the TAF
period. High pressure and dry low-level air should help maintain
high ceilings tonight, along with light and variable winds.
Eventually, winds will turn from the southwest around sunrise
Friday and strengthen to around 10 knots.

The main focus for this TAF set will be on increasing chances
of showers/storms (40-70%) Friday afternoon. There may be some
light showers prior to this time during the late morning at DBQ,
but impacts from this should be pretty minimal. Any storms that
develop Friday afternoon could become severe, packing locally
strong wind gusts and heavy rainfall, leading to reduced
visibility. At this time, confidence in the exact
coverage/location of storms is very low. However, areas most
likely to see these storms include DBQ and MLI (although MLI
might see storms closer to 00z Saturday/7 PM Friday).

&&

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

&&

$$

SHORT TERM...NWS
LONG TERM...NWS
AVIATION...Schultz