Flash Flood and Hail in Illinois, April 15, 2026

Area Forecast Discussion
National Weather Service Quad Cities IA IL
151 PM CDT Wed Apr 15 2026

.KEY MESSAGES...

- Isolated-scattered showers/storms are expected through the
  afternoon, with a line of strong/severe storms set to come
  through this evening. Severe weather is possible, with a
  Slight Risk (level 2/5) for severe weather.

- A seasonally strong storm system will impact our area Friday
  afternoon and evening, where the SPC has highlighted much of
  our area in an Enhanced Risk (level 3/5) for severe weather.

- Much cooler airmass moves in this weekend behind a cold front,
  bringing unseasonally cool temperatures back to the area.
  Temperatures in the 30s through the nighttime hours will bring
  the potential for frost/freeze, especially in our north.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 126 PM CDT Wed Apr 15 2026

Seasonally strong shortwave trof currently located over central
Nebraska will continue to track east through Iowa this
afternoon/evening. A surface low pressure will pass southwest to
northeast just northwest of our area, dragging a cold front through
our area this evening/tonight. While we already have ongoing showers
and storms, we are expecting another round of storms as the cold
front moves through the area this evening/tonight. Ahead of that, we
will have a stationary/warm front draped over the area, which will
be another focus for convective initiation ahead of the main line of
convection. This is currently located between the Highway 30 and
Highway 34 corridors. Thus, a few rounds of storms are expected
today, where flash flooding is possible. A Flood Watch remains for
those areas at greatest risk, owing to heavy rainfall yesterday. The
SPC has our whole area outlooked in a Slight Risk (level 2/5) for
severe weather today, where our best chances for severe weather
will be with the line of storms progged to come through with
the cold front this evening. Isolated severe storms are possible
ahead of this through the afternoon, but confidence is low on
coverage and severity.

Looking at model soundings, we can expect another day of mixed-mode
convection. Early-Mid afternoon, we are likely to continue to see
scattered showers and storms. Given a lot of cloud cover and higher
coverage of showers/storms in our north, the severe threat
should remain relatively low into mid-afternoon. Although, areas
south of Interstate 80 will have seen more sun peeking through,
which has allowed more instability to build. Thus, there will
be a little more of a severe threat in our south, generally in
the form of semi- discrete supercells. Confidence is low on this
at this time, but will further get monitored for the potential
through mesoscale analysis this afternoon. This convection will
generally be seen between the hours of 12-4 PM. Going into late
afternoon and evening, we will see a line (possibly disconnected
line of supercells) moving into our area from west to east,
with some leading semi-discrete cells as well. The leading cells
could be supercellular, which are currently looking to develop
between the Highway 30 and Highway 34 corridors. These
supercells may form just ahead of the line, generally between
4-6 PM, and then get absorbed into the main line. As we get
towards the evening hours, the aforementioned line (QLCS- like
with embedded supercells) will move through the area from west
to east. Timing-Wise, this is expected to move into our west
around 5-7 PM, and move out of our area by midnight local time.
The best severe threat will be in the late afternoon/evening
hours, but gradually decreasing after sunset.

Now a look into the environment in place. The AM convection and
resultant cloud cover has delayed our surface heating a bit, but
clearing skies have been seen. This may limit the overall
instability, but will still be sufficient. We are still looking at
the potential for CAPE around 2000-3000+, collocated with shear
around 50-60+ KTs, with little/no cap seen in forecast soundings.
Thus, we have the necessary CAPE/Shear balance to favor supercells
today. Although, with strong forcing moving in this afternoon and
evening, upscale growth is expected. As was mentioned, this could be
in the form of a disconnected line with embedded supercells. Lapse
rates are once again favorable for hail in the midlevels, collocated
with a fat CAPE profile in the hail growth layer. SPC highlights
parts of our area in the potential for significant hail (2"+), which
is possible. Otherwise, all hazards are in play today, with the
primary threat being winds and embedded tornadoes when the line of
convection comes through this evening. We are especially
focusing on counties along the Interstate 80 corridor, as this
is generally where the stalled out boundary will be. This will
serve as a focus point for severe weather (some significant
severe weather possible), with the increased tornado threat.

Tonight and through Thursday, weak ridging moves in, with a surface
high pressure quickly passing through. Thus, after any residual
showers move out Thursday AM, we should remain dry for the remainder
of the day. Clouds will also decrease through the day, with light
winds and temperatures increasing into the mid-upper 70s. Thus, we
are in for a beautiful day.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 126 PM CDT Wed Apr 15 2026

Friday will be another day of concern, as a potent shortwave tracks
off of the Rockies and towards the Upper Midwest. This wave will
develop a seasonally strong low pressure system, progged to drag a
strong cold front through the area. Ahead of this, we will have an
environment favorable for organized convection that can become
strong to severe. Uncertainty remains with regards to timing, which
can lead to impacts on the overall severe threat. Guidance has been
hinting at this moving through Friday evening/night. Ahead of that,
we will see a mix of clouds/sun, which will help build instability.
According to model soundings, we may have CAPE values upwards
to 2000-3000+, with shear around 35-45 KTs. The shear is a
little lower than we have seen with the recent events, but
sufficient for organized convection. Although, this would lead
me to believe that we will largely be dealing with a line of
strong/severe convection, but some initial isolated-scattered
storms cannot be ruled out. More details are to come, as more
short term hi-res CAMs start rolling in over the next 24-36
hours. The SPC has highlighted much of our area in an Enhanced
Risk (level 3/5) for severe weather, with a Slight Risk (level
2/5) for areas east of the Mississippi River. Continue to
monitor the forecast for future updates.

This weekend, upper level flow becomes northwesterly behind the
aforementioned shortwave. Modest cold advection will kick in,
bringing much cooler air to the area. Daytime temperatures are set
to be in the upper 40s to 50s through the weekend, which is quite
the change to the 70s and 80s we have been seeing. Overnight lows
will be in the 30s, with areas north of Interstate 80 seeing lows
approaching freezing. Thus, our north will have the chance to
see a frost/freeze during this timeframe. Although, confidence
is lower on this now, as temperatures have trended upwards a few
degrees since the last forecast package. Dry conditions are
expected through the weekend, with mostly clear skies. While
cooler, it should be a relatively pleasant weekend.

Going into next week, it looks like the upper level pattern becomes
active again. There remains many differences amongst guidance, but
precipitation chances return to the area by midweek, along
with increasing temperatures.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1238 PM CDT Wed Apr 15 2026

The main focus of this TAF issuance is on the shower and
thunderstorm potential this afternoon and evening. The first
wave of showers and a couple lightning strikes are lifting
northeastward and are expected to pass out of the TAF sites in
the next couple hours. Another line of storms is expected to
develop around or after 22Z, then traverse the TAF sites through
about 04Z. Tried to adjust the timing a bit with the latest
guidance to start/end the storm potential from west to east.
MVFR ceilings and visibilities are possible with any storm that
develops with visibilities possibly dropping lower in heavier
precipitation. Erratic wind gusts may exceed 35-30kts as the
main line of storms passes through the TAF sites. Conditions
will improve from west to east after overnight into Thursday
morning.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch until midnight CDT tonight for IAZ040>042-051>054.
IL...Flood Watch until midnight CDT tonight for ILZ001-002-007.
MO...None.

&&

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

Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
423 AM CDT Wed Apr 15 2026

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-160930-
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-
423 AM CDT Wed Apr 15 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...TODAY AND TONIGHT

There is a Slight Risk, or level 2 of 5 risk, for severe weather
across the Outlook area this afternoon and evening. Damaging
winds, large hail and a few tornadoes are all possible. In
addition, there is the potential for flash flooding in any areas
that see multiple rounds of heavy rain producing storms. The
greater risk for flash flooding will be north of Highway 30 where
the ground is saturated from recent heavy rainfall of 1 to 3
inches.

Area rivers are experiencing flooding. Please see the latest
Flood Statements and Flood Warnings for details.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

There is an Enhanced Risk (Level 3 of 5) for severe weather across
much of the area late Friday afternoon and Friday night. Damaging
winds and tornadoes are the primary threats.

Much colder air will bring the potential for frost and freeze
conditions to parts of the area Saturday night and Sunday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
233 PM CDT Wed Apr 15 2026

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

0537 PM     Hail             Packwood                41.13N 92.08W
04/14/2026  E2.00 Inch       Jefferson          IA   Public

            Time estimated using radar.

&&

MTF

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
540 PM CDT Wed Apr 15 2026

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

0531 PM     Hail             3 S Vinton              42.12N 92.03W
04/15/2026  M1.00 Inch       Benton             IA   Emergency Mngr

&&

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
613 PM CDT Wed Apr 15 2026

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

0605 PM     Hail             Belle Plaine            41.90N 92.28W
04/15/2026  M0.25 Inch       Benton             IA   Trained Spotter

&&

DC