453
FXUS63 KDVN 132356
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
656 PM CDT Thu Aug 13 2026

.KEY MESSAGES...

- Training storms tonight into early Friday morning with flash
  flooding more in the spotlight, with an isolated severe threat
  of primarily localized winds. Uncertainty on the zone of
  heaviest rain location.

- Active weather pattern continues into the weekend, with
  greatest storm coverage at night into the morning. Due to
  successive rainfall events, additional totals of 2 to 4 inches
  by Saturday morning are favored with localized higher values likely
  (70%), continuing the flash flood threat.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 310 PM CDT Thu Aug 13 2026

In the wake of the earlier MCS, we remain in a somewhat "worked
over" environment. The 850 mb temperature and moisture gradients
remain draped west to east generally near the I-80 to U.S.
Highway 30 corridors. As gradual but persistent warm air
advection (WAA) continues along that and taps into 500-1000 J/kg
of MUCAPE, festering scattered showers and storms (~30%
coverage) should continue in or near that zone through the rest
of the daytime hours. Severe potential is limited through that
time with very marginal mid-level lapse rates.

For this evening through early Saturday morning, this is when
the convective coverage should be higher, expected to peak late
evening and overnight. This will be driven by that continued
warm air advection and moisture transport in the low-level jet
layer, impressively high moisture (PWATs around or slightly over
two inches), as well as a couple low amplitude short wave
impulses. These attributes favor a west-to-east training setup
but with uncertainty on the latitude, as well as how early it
ramps up, with a wide breadth in CAM solutions from mid-evening
through very late tonight. But with the environment, one to
three inches are highly likely in that zone that is to be a
couple counties wide from north-to-south, supported by HREF and
REFS probability matched mean QPF solutions (account for
uncertainty in CAM exact locations). Basically 20-40% of CAMs
show some narrow swaths of three plus inch amounts in the zone
from near Highway 30 to just south of I-80. These amounts, and
especially rates with this high PWAT environment, may be enough
on wet ground to result in flash flooding, hence the watch. It
was expanded to include the Iowa U.S. Highway 20 corridor due to
the north being within the envelope of uncertainty.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 310 PM CDT Thu Aug 13 2026

Friday Evening onward...Convective coverage should be diurnally
waning into the midday. Boundary placement should make for high
temperature variance from north to south. Timing the next
ridge-riding short wave will be likely late day into the
evening. The convective mode and coverage for Friday night is
highly uncertain, with some CAM signal of a forward-propagating
MCS, which would bring at least a scattered damaging wind
threat. Regardless of mode, heavy rain to a water sensitive CWA
resulted in us extending the Flood Watch.

Saturday through Wednesday...Latest ensemble and upper jet trends
suggest the upper ridge and heat dome to get pressed eastward
temporarily maintaining the ring of fire for the weekend with the local
area precariously near the periphery through at least Sunday.
Storm chances will continue as well with high dew point air,
but then some signs early next week of upper ridge retrogrades,
allowing for more of a northwest flow push down the upper
Mississippi River Valley. A resultant drier and cooler Monday
would be much welcome by then.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 656 PM CDT Thu Aug 13 2026

A mix of VFR to MVFR ceilings were seen across the area early
this evening. We are watching a line of showers and storms that
have developed between CID and DBQ as of TAF issuance, but it
appears likely this will have limited impacts to the terminals
there for the time being. However, we will be watching for the
potential for more widespread storms to develop this evening
through the overnight hours along a frontal boundary that`s
found along the I-80 corridor. Confidence in the exact timing of
these storms remains low due to differences among the high-res
models, but confidence is high that should this activity go over
a local airport terminal, expect IFR/LIFR visibilities and
ceilings along with ~25 knot gusts and VRB wind directions.
Conditions are expected to gradually improve during the daylight
hours Friday.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch through Saturday morning for IAZ040>042-051>054-
     063>068.
     Flood Watch through Saturday morning for IAZ076>078-087>089-
     098-099.
IL...Flood Watch through Saturday morning for ILZ007-009-015>018.
     Flood Watch through Saturday morning for ILZ024>026-034-035.
MO...Flood Watch through Saturday morning for MOZ009-010.

&&

$$

SHORT TERM...Friedlein
LONG TERM...Friedlein/12
AVIATION...Schultz

NWS DVN Office Area Forecast Discussion