314
FXUS63 KDVN 160659
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
159 AM CDT Wed Sep 16 2026

.KEY MESSAGES...

- An active weather pattern continues through the weekend with
  rounds of rain, heavy at times. There will be brief dry
  periods between each round.

- Additional rainfall of 2-3 inches through Monday is becoming
  likely (50-80%) across eastern Iowa and northwest Illinois,
  keeping a risk of flash flooding around. Localized areas of
  5+ inches remain possible (5-15%) which could lead to sharp
  rises in small streams and creeks.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 159 AM CDT Wed Sep 16 2026

A stationary front across northern Missouri and central
Illinois will keep scattered showers (50-70% coverage) along and
south of I-80, supported by an area of shear vorticity left
behind from Tuesday`s trough passage. While the severe threat is
very low (less than 5%), heavy rainfall remains the primary
hazard, especially south of Highway 34 where some locations
already received over 3 inches of rain already. There should a
break this afternoon/evening before a second weak shortwave
invigorates more showers and storms (50-80% coverage) along and
north of I-80 that will last into Thursday morning. Latest CAM
guidance is hinting towards a narrow band of 1-3 inches near the
I-80 corridor, but this is prone to shift with future model
runs. While portions of our western counties along and south of
I-80 is now primed for flash flooding, opted not to issue a
Flood Watch at this time given the uncertainty in the heavy rain
axis tonight. The WPC has a Slight (level 2 of 4) risk for
excessive rainfall for areas along and south of Hwy 20.

Another notable feature is a lobe of mid-level vorticity being
pulled northward from the subtropical Pacific by a shortwave
trough over the western CONUS. Surface cyclogenesis is expected
along the leeward side of the Rockies in Colorado tonight into
Thursday in response to the new forcing, and this new low will
play a key role in the generation of more storms heading into
the weekend.

Outside of Thursday morning though, mostly dry conditions are
in the cards for Thursday afternoon and night as there is little
support aloft for showers. Northeasterly flow and cloud cover
should keep highs seasonable in the mid-70s to low 80s and lows
in the 60s areawide.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 159 AM CDT Wed Sep 16 2026

Friday-Saturday...The low pressure over Colorado will move
northward into the Dakotas and Minnesota and produce a WAA wing
across eastern Iowa in association with a warm front. Scattered
showers and storms (40-80% coverage) are likely to form along
this boundary and move northeastward into Wisconsin. Overnight
Friday, the mid-level trough finally reaches the northern edge
of the ridge over the south-central CONUS and is ejected
eastward, pulling the low pressure into northern Iowa. With the
enhanced surface convergence and a sufficiently moist air mass
(PWATs near 2 inches), widespread storms (60-80% coverage) are
expected across the region through Saturday afternoon. Muggy
conditions are favored to return with dew points in the upper
60s to low 70s (60-90% chance).

Sunday-Tuesday...A surface pressure over Ontario pushes the low
pressure over Iowa southward into Missouri as the shortwave
over the western CONUS finally propagates eastward. Mid-level
CVA from the trough should support storm development north of
the low pressure Sunday into Monday before the system moves into
Illinois and Indiana. CAA to kick in as the trough swings
through the area, leading to a decrease in PoPs Tuesday and
allowing cooler, drier air to move in.

With nearly daily PoPS through Monday and unseasonably high
PWATs, additional rainfall of 2-3 inches is likely (50-80%)
across portions of eastern Iowa and northwest Illinois with
localized areas of 5+ inches possible (5-15%). With most of the
CWA already receiving 1-3+ inches over the last 48 hours, the
flash flooding threat will become more elevated after each round
of heavy rain, and small creeks and tributaries could see sharp
rises in short periods of time.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1243 AM CDT Wed Sep 16 2026

Widespread showers with isolated embedded thunderstorms are
moving across our southeastern CWA and will impact BRL and MLI
over the next few hours. Brief periods of MVFR visibilities are
possible in heavier showers. After sunrise, another round of
showers could impact BRL and MLI as an MVFR cloud deck moves in
from the south, eventually reaching CID and DBQ in the
afternoon. Ceilings will generally stay between 1500 and 2500
feet with occasional reductions to IFR conditions (30-40%
chance) near BRL and MLI. Towards the end of the TAF period,
there is a small chance (10-20%) that an isolated thunderstorm
develops near CID, but a PROB30 was not included with this
issuance.

&&

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

&&

$$

SHORT TERM...Delaune
LONG TERM...Delaune
AVIATION...Delaune