645
FXUS63 KDVN 130016
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
716 PM CDT Wed Aug 12 2026

.KEY MESSAGES...

- There is a Marginal (level 1 out of 5) Risk for severe storms
  Thursday and Friday for the entire area. Damaging winds and
  heavy rain are the primary risks.

- There is a Slight (level 2 out of 4) Risk for excessive
  rainfall Thursday and Friday. If storms repeat over the same
  areas, flash flooding is possible.

- The active weather pattern will bring a daily risk of showers
  and thunderstorms through the weekend. HOWEVER, there will be
  many hours of dry weather each day.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 209 PM CDT Wed Aug 12 2026

The morning MCS partially worked over the atmosphere. Since the
atmosphere was not completely worked over, isolated to scattered (15-
40%) showers and some thunderstorms will be possible into early
evening.

A break in the rain is possible during the evening. However, a weak
LLJ develops after midnight with yet another thunderstorm complex,
possibly in the form of an MCS, developing that moves into eastern
Iowa in the pre-dawn hours. A localized severe storm is possible.
Heavy rainfall is a given with the high moisture levels in the
atmosphere.

The weak frontal boundary will vacillate across the area Thursday
into Thursday night. Where the boundary is located will dictate
where the organized storm clusters will develop/track. Outflow
boundaries from the storm clusters will then provide additional foci
for diurnal development on Thursday or allowing low end convection
to persist.

Although the overall severe risk is low, the CAPE built up in the
atmosphere will allow some severe storms to develop. The primary
risk with any severe storm will be damaging winds and heavy
rainfall. Hail is a secondary risk.

Although the overall rain chances are quite high, there will be
hours of dry weather Thursday and Thursday night.

Given the potential for cloud cover and persistent showers/storms no
heat advisory for Thursday will be issued at this time. If a heat
advisory is needed for Thursday, it will be a tactical issuance
based on trends in shower/storm coverage and evolution.

One area that is a concern is the continued heavy rainfall. If
storms repeat over areas where the ground is quite moist, then
flooding would be possible. Area waterways will see rises occur but
there is no clear signal if any flooding would occur.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 250 AM CDT Wed Aug 12 2026

Friday through Tuesday...Latest ensemble and upper jet trends
suggest the upper ridge and heat dome to get presses eastward
again with some amplitude thrust up the mid to upper MS RVR
Valley with west coast L/W troffiness establishment. This could
make for another heat and storm track battle zone on Friday for
the region, until the track then gets shunted more to the north
acrs MN and WI while we heat up again. Still on the southern
fringe, couldn`t rule out MCS seepage down this far south into
the local at times over the weekend as well. The action may last
into early next week with longer range signs of upper ridge
dampening and flattening to get us back under the influence of
ring of fire periphery.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 716 PM CDT Wed Aug 12 2026

After brief periods of BKN MVFR cloud ceilings this evening, VFR
conditions should prevail through most of the night. Closer to
sunrise, patchy fog could develop near DBQ, MLI, and BRL with
MVFR visibilities (40-70% chance) for 1-3 hours. Another round
of showers and storms is likely tomorrow morning and early
afternoon (14 UTC to 19 UTC) with a medium chance (40-60%) of
lightning being observed during the period. With the heavier
storms, ceilings and visibility could drop below IFR conditions
briefly. The bulk of the precipitation should exit all TAF sites
by the early afternoon with general VFR conditions returning.
Isolated showers and storms could develop in the mid-to-late
afternoon. PROB30s for these storms were utilized, but most
sites should stay dry. In terms of wind gusts, there is a
20-40% chance of gusts exceeding 30 knots, but this percentage
could increase depending on the organization of the storms in
the morning.

&&

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

&&

$$

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