231
FXUS63 KDVN 210648
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
148 AM CDT Fri Aug 21 2026

.KEY MESSAGES...

- Another system to pass through the area, bringing the chance
  for afternoon showers/storms along a passing cold front. A few
  storms may be strong to severe.

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

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 140 AM CDT Fri Aug 21 2026

Shortwave trof to pass overhead today, dragging a cold front
through the area from northwest-southeast this afternoon and
evening. Prior to frontal passage, a pre-frontal wave will pass
through this morning. This will bring along low-end chances for
showers/storms (15-30% in our north), but coverage should
largely remain isolated-scattered. Severe weather is not
expected with this initial round of showers this AM. The chance
for strong to severe storms will be focused along and ahead of
the passing cold front this afternoon/evening. Although,
uncertainty does exist on this threat. Compared to previous
forecast packages, the front may come through a little earlier.
This would generally put the timing of frontal passage between
12-8 PM locally. The earlier the front moves through may limit
some of the destabilization, along with any residual cloud cover
from decaying AM convection. Favored areas for storms will be
along and east of the Mississippi River, with better chances
over western Illinois.

Destabilization will be important for convective initiation,
especially since shear is lacking (around 30 KTs deep layer shear).
Short term guidance would favor 2000-3000 CAPE building by mid
afternoon, which would be sufficient for some stronger storms, with
sufficient lapse rates present. If strong to severe storms develop,
damaging wind gusts would be the main concern, with large hail being
secondary. There will also be a low-end tornado threat, largely for
areas east of the Mississippi River, where low level hodographs have
sufficient curvature to support it. Although, this should be a
relatively isolated threat, coverage-wise. SPC continues to
highlight much of the area in a Marginal Risk, level 1/5, for severe
weather. Although, they have upgraded all locations along/east of
the Mississippi River to a Slight Risk, or level 2/5 risk. While
higher confidence exists on the potential for scattered
showers/storms, especially east of the Mississippi River, much
uncertainty remains on the overall severe threat and coverage.
Thorough mesoscale analysis through the day will provide a
better idea on the scope of the severe threat.

Post-frontal airmass will kick in tonight, with mostly clear skies
and light northwesterly winds. Temperatures will remain in the 60s
throughout, with decreasing humidity and dry conditions for the rest
of the night.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 140 AM CDT Fri Aug 21 2026

Through the remainder of the forecast period, we will remain
dominated by upper level northwest flow. This will continue to usher
shortwaves through the area, which will help dampen the ridge that
is forecast to set up over the Rockies. Although, this pattern is
not favorable for much moisture return. Thus, precipitation chances
will remain limited through this timeframe, with passing clouds and
shifting winds being the main signs of the passing waves.
Temperatures will remain seasonal and hover around 80 degrees, with
low humidity to make it quite pleasant. After Friday night, our
precipitation chances will be quite limited. Some global models
skirt our south with precipitation chances from a passing system on
Monday, and then more widespread PoPs midweek, albeit low. Overall,
chances for precipitation with both of these systems generally fall
between 20-40%.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1225 AM CDT Fri Aug 21 2026

VFR conditions will prevail through much of the TAF period.
Between 12-18z this morning, we may see a round of isolated-
scattered showers passing through our north, possibly
impacting DBQ. Visibility reductions will be the main concern
with these showers, with infrequent lightning possible. After
18z, we will see the development of scattered showers/storms
along a passing cold front. Best chances will be at DBQ/MLI, but
there remains some uncertainty on coverage and timing. Thus,
opted to message in TAFs with PROB30 groups at this time, with
minor vis/cig reductions. Winds will increase out of the
southwest after 12z throughout, becoming west-northwesterly
after the cold front passes through this afternoon and evening.

&&

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

&&

$$

SHORT TERM...Gunkel
LONG TERM...Gunkel
AVIATION...Gunkel