Flash Flood Warning 38, NWS Quad Cities, IA

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1242 AM CDT Sat Aug 15 2026

.KEY MESSAGES...

- Another cluster of showers and storms is likely to impact
  portions of the area mid-evening through the overnight period,
  which could initially bring a risk for localized damaging
  winds. Of more concern will be the potential for additional
  episodes of flash flooding (some potentially significant) for
  areas that have been hardest hit over the past few days (receiving
  4" to 6" of rain so far).

- Active weather pattern to continue through 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 SUNDAY/...
Issued at 334 PM CDT Fri Aug 14 2026

After a lull in the thunderstorm activity from late this morning
into early this evening, another wave or remnant MCV currently over
west-central Iowa is expected to reach the western outlook area by
early tonight. CAMs have consistently showed a regeneration of deep
convection along the leading flank of the MCV somewhere in the 5 PM
to 9 PM timeframe across parts of central/south-central Iowa, then
growing upscale into an organized MCS as it rolls eastward into
eastern Iowa and eventually west-central Illinois. Exact north-south
placement is in question; however, the most favored zone is south of
Highway 30 and along/north of Highway 34. This places the tier of
counties just south of I-80 that got hit the hardest with heavy
rainfall and flash flooding last night/early this morning
potentially in the swath of heaviest rainfall again tonight. A very
moist atmosphere with near ~2" PWATs, high freezing levels promoting
efficient warm-rain processes, and relatively slow storm motions are
all supportive of a notable flash flood risk through the overnight
period with peak hourly rain rates between 1-2" possible. WPC has
maintained the Moderate Risk for flash flooding (level 3 of 4) for
most of the area except the far north which is in a Slight Risk
(level 2 of 4).

As for total rainfall amounts, the latest HREF mean has a west-east
axis of 1-3"+ along the I-80 and Highway 34 corridors. The LPMM HREF
has isolated pockets of 4-5"+ south of I-80, which is an indication
of the higher end amounts that could occur on an isolated basis. The
Flood Watch remains in effect into Saturday morning with the
overnight heavy rainfall likely to exacerbate flooding impacts in
poor drainage areas and along creeks, streams, and tributary rivers.

There is also a Slight Risk (level 2 of 5) for severe storms along
and south of Highway 30 late this evening into tonight with
localized damaging winds as the primary threat with any bowing
segments that develop. A few brief QLCS/spin-up tornadoes are also
possible with any balanced bowing segments -- SPC has highlighted a
portion of southeast Iowa with slightly higher tornado probabilities
compared to areas to north and east (5% chance within 25 miles of a
point). Scattered showers and storms will likely linger into the mid
morning hours on Saturday before gradually decreasing in coverage
and shifting off to the east.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 334 PM CDT Fri Aug 14 2026

An active period with brief moments of respite will continue this
week.

Saturday Afternoon and Evening... Saturday afternoon and evening
will be one such brief moment of respite from the constant onslaught
of rain this week. The primary concern would be the need for any
heat headlines as heat and humidity remain in place. The
primary area to watch would be along and south of the HWY 34
corridor, where HREF probabilities of greater than 95 degree
heat indices are 50-90% from north to south. The NBM, which has
had a running warm bias, brings these probabilities (50-90%)
further north to along the HWY 30 corridor. As such, depending
on the evolution of storms through Saturday morning, a heat
headline may be needed.

Saturday night through Tuesday... Another wave moves through late
Saturday night through Sunday morning, bringing yet another round of
rain to the area. Severe risk is unlikely due to low bulk shear, but
there will be enough instability to support embedded thunderstorms.
Rainfall totals will be on the lower side, as seen by NBM
probabilities of 30-50% of exceeding 0.10 inches. CAMs do hint that
locally higher amounts will be possible wherever embedded
thunderstorms occur. Behind these showers, a cold front will bring
cooler temperatures to the region. These will last through midweek
as we remain under the influence of surface high pressure.

Wednesday through Friday... By midweek, midlevel flow will
transition from zonal to northwesterly flow. This will help
sustain the cooler temperatures established earlier in the week.
Additionally, signals are in place for waves to move through
the flow, bringing chances for more active weather.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1240 AM CDT Sat Aug 15 2026

Shower and thunderstorm activity remains steady in the south
through the overnight hours with a slow northward progression in
shower/storm reach towards MLI and possibly CID. A few gusty
winds will be possible at southernmost sites, such as BRL. In
the north, fog and/or low ceilings should develop with IFR to
LIFR conditions, while the stormy south has more intermittent
IFR to LIFR potential. Shower activity diminishes early morning
with cigs slowly lifting. VFR conditions are possible in the
south during the afternoon. Another chance of showers/storms is
forecast towards the end of the TAF period.

&&

.HYDROLOGY...
Issued at 1122 AM CDT Fri Aug 14 2026

Rainfall ranging from 3 to 6 inches, with locally higher amounts
occurred last night across parts of the area. The area was
generally two counties wide, running from Keokuk County Iowa
into southern Henry County Illinois in the north, and Highway 34
in the south.

More heavy rainfall, potentially another 3 to 6 inches with
locally higher amounts, is expected tonight into Saturday
morning. Some models are indicating the same areas that were hit
last night would get hit again. Other models are slightly
further south.

Regardless of the location, soils across the area run from moist
to saturated. Heavy rainfall tonight has a high probability of
resulting in more flash flooding that may be considerable.

The persistent rounds of rain are causing a slow rise on area
rivers.

Based on rainfall through tonight, most rivers are projected to
only see within bank rises. However, slight changes in the
amount each basin receives over the next two days may cause some
rivers to go into flood, especially tributary rivers.

A better way to look at this is to look at the probabilities of
reaching minor and moderate flood stages using an ensemble spread
of precipitation over the next 10 days.

For the following rivers there is a 30-50 percent probability of
achieving minor flood stage through August 24th;

English and Iowa Rivers. Cedar River south of I-80

These rivers also have a 20-30 percent probability of achieving
moderate flood stage.

For the Skunk River, the probability of achieving minor flood
stage is 30 percent, and 20 percent for moderate flood stage.

For the Wapsipinicon River, the probabilities vary considerably.
Anamosa has a 37 percent change of reaching minor flood stage
while near DeWitt the probability is 83 percent.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch until 10 AM CDT this morning for IAZ051>054-
     063>068-076>078-087>089-098-099.
IL...Flood Watch until 10 AM CDT this morning for ILZ007-009-
     015>018-024>026-034-035.
MO...Flood Watch until 10 AM CDT this morning for MOZ009-010.

&&

SHORT TERM...Uttech
LONG TERM...Ellingworth
AVIATION...NWS
HYDROLOGY...08

Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
249 PM CDT Fri Aug 14 2026

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-152000-
Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson-
Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson-
Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll-
Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson-
Warren-Hancock-McDonough-Scotland-Clark-
249 PM CDT Fri Aug 14 2026

This Hazardous Weather Outlook is for portions of north central
Illinois...northwest Illinois...west central Illinois...east
central Iowa...northeast Iowa...southeast Iowa and northeast
Missouri.

.DAY ONE...THIS AFTERNOON AND TONIGHT

Rounds of heavy rain producing storms are expected again tonight.
There is a chance for severe storms, especially this evening. All
hazards will be possible, but the primary concern will be
damaging winds and embedded brief tornadoes in southeast Iowa.
Very heavy rainfall and flash flooding will also be a primary
concern, especially where storms move repeatedly affect the same
area. Significant flash flooding is possible tonight, in urban
areas and in counties that saw excessive amounts of rain last
night. Several area rivers will be on the rise and have the
potential to reach bankfull or even flood stage over the weekend
and into early next week.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

More episodes of thunderstorms are expected over the weekend,
mainly at night and into the mornings, though there is
uncertainty on area and coverage with each successive round.
Flash flooding will continue to be a concern, especially Saturday
night into Sunday morning if storms move across areas already
soaked from Friday's storms. Isolated to scattered damaging wind
threats will continue through Saturday night, depending on how
organized storms become.

Between the episodes of storms, high heat and humidity may
produce dangerous Heat Index readings over 100 degrees Saturday
afternoon.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is likely through tonight. Reports of flooding
would also be appreciated.

ERVIN

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
1231 AM CDT Sat Aug 15 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1139 PM     Tstm Wnd Dmg     1 NNW Montrose          40.54N 91.43W
08/14/2026                   Lee                IA   Public

            3 inch diameter tree limbs downed.

&&