River Flood Warning 39, NWS Quad Cities, IA

Area Forecast Discussion
National Weather Service Quad Cities IA IL
634 AM CDT Thu Jun 11 2026

...Updated for 12z Aviation...

.KEY MESSAGES...

- Today will see more severe storms. There is an Enhanced, level
  3 out of 5, risk for severe storms that look to occur in two
  rounds. All modes of severe weather will be possible.

- Storms will be moving at 50-60 mph so there will be less time
  than normal to react when a storm approaches. Additionally,
  storms will be prolific heavy rain producers that may cause
  flash flooding.

- Strong gradient winds of 30 mph with gusts to 45 mph will be
  seen today ahead of the front. Behind the front winds may gust
  up to 50 mph for a period of a few hours.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 241 AM CDT Thu Jun 11 2026

The next 24 hours will consist of multi-faceted weather risks with
several having the potential of being high impact. That being severe
storms, fast moving storms, flash flooding and non-thunderstorm
winds.

Headlines changes...

The flash flood watch has been extended to the entire area and
extended until 7 PM.

Discussion...

The LLJ and moisture transport will continue to strengthen through
sunrise. This will allow elevated storms to develop from southeast
Nebraska into southwest Iowa and possibly northwest Missouri. The
very short term models show this growing upscale into an organized
MCS that will move east across Iowa. The arrival in eastern Iowa
will be after sunrise and the MCS will begin a transition from
elevated to surface based.

Like yesterday there will be a risk of damaging winds this morning
through about mid-day. The very short term models differ on when the
complex becomes surface based but it will be across eastern Iowa.

Initially the damaging winds may be limited to 55 to 65 mph with
large hail. However, once the complex becomes surface based, much
higher severe winds become more likely. Indeed, some of the CAMs are
starting to suggest small corridors of 70 to 80+ mph winds as the
system bows out (indicating the system is surface based). At the
same time, brief spin-up tornadoes would also be possible.

Normally the severe risk would go down after the atmosphere gets
worked over so thoroughly in the morning.

However, the LLJ will increase through late morning and into the
afternoon with the approach of the surface low. Integrated Vapor
Transport is progged to increase to over 1200 kg/m/s. The very
strong IVT combined with an upper jet of 100+ knots will result in
rapid recovery of the atmosphere behind the departing morning storm
complex and also promote broad lift for new storm development.

The passage of the surface low from late morning through mid-
afternoon will be the time when the tornado risk will be the highest.

All the CAMs develop supercells by mid-day and continue that through
mid-afternoon. The position of the warm front across the area will
maximize low level turning in the atmosphere and will be key as to
where the greatest tornado risk will be located. Any storm riding on
or near the warm front will be most at risk for producing tornadoes.

During the supercell phase the primary severe risks will be very
large hail and tornadoes. The CAMs are indicting upscale growth
occurring into a broken line of storms. One CAM solution suggests
two broken lines of storms; one along the cold front and the other
along a pre-frontal trof. Once the upscale growth into lines occurs,
the severe risk will transition to damaging winds and spin-up
tornadoes.

On top of all this, storms will be moving at 50-60 mph so there will
be less time that normal to react when a storm approaches. In spite
of the fast storm movement, high atmospheric moisture means storms
will be prolific heavy rain producers. If storms stall or repeat
over the same area due to fronts or boundary interactions, high
rainfall rates will create flash flooding due to already wet ground.

In addition to the severe risk will be strong gradient winds. Model
soundings are showing 35-40 knots through the mixed layer with 50-55
knots on top. This suggests the potential for sustained gradient
winds during the late morning and afternoon of around 30 mph with
gusts up to 45 mph...on the cusp of wind advisory. Likewise, the
models are showing several hours of wind gusts approaching 50 mph
behind the front.

The cold front and severe storms will clear areas east of the
Mississippi by mid-evening. The strong gradient winds will slowly
decrease the remainder of the night resulting in much cooler and
quieter conditions.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 248 PM CDT Wed Jun 10 2026

Quick look at the longer range, a quiet, cooler and tranquil Friday
looks in store, then another frontal system takes aim at the region
on Saturday with potentially enough forcing to support some strong
storms. After that, a well needed reprieve as the storm track gets
shunted south and below normal temps infiltrate the area for highs
in the 70s Sunday and into early next week. Will have to watch for
nuisance clipper like systems for spotty precip chances in the
northwesterly steering flow next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 625 AM CDT Thu Jun 11 2026

Thunderstorms will impact terminal operations today. Two rounds
of storm are anticipated; the first one is high confidence
this morning, the other round is slated for the afternoon to
early evening but offers some uncertainty due to potential
impacts of vigorous morning activity on atmospheric recovery.
Numerous TSRA will be seen. The morning storms will produce
wind gusts of 35 to 50 knots with swaths of 60-70 kt possible
along with embedded tornadoes possible; the afternoon storms
may see wind gusts well over 50 knots, a threat for tornadoes
and hail. Conditions will be IFR to lower MVFR in the storms.
Outside of the storms, some IFR/LIFR stratus and patchy fog will
begin the period. Winds outside of storms today and tonight
could gust 35-45 kt ahead and behind a cold front. Cold front
is progged to be along the Mississippi by 00z/12 with rapidly
improving conditions behind it and slowly decreasing winds.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flood Watch through this evening for IAZ040>042-051>054-
     063>068-076>078-087>089-098-099.
IL...Flood Watch through this evening for ILZ001-002-007-009-
     015>018-024>026-034-035.
MO...Flood Watch through this evening for MOZ009-010.

&&

SHORT TERM...08
LONG TERM...12
AVIATION...McClure

Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
315 AM CDT Thu Jun 11 2026

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-120815-
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-
315 AM CDT Thu Jun 11 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

Two rounds of storms will be seen today; the first in the morning
and the second in the afternoon and early evening. The Storm
Prediction Center has an Enhanced, level 3 out of 5, risk for the
area.

All modes of severe weather will be possible. Individual
supercells will be capable of very large hail and tornadoes. The
tornado risk will be highest during the passage of strong low
pressure this afternoon.

Additionally, storms will be moving at over 50 mph leaving less
time to react as storms approach.

Individual storms will grow upscale into lines both this morning
and afternoon. Lines that evolve into bowing segments may produce
damaging winds of 70 to 80 plus mph in the strongest storms.

Heavy rainfall will be a risk today due to an already wet ground.
If storms repeat over the same areas, flash flooding will be
possible.

An additional risk will be strong gradient winds. Winds may gust
up to 45 mph ahead of the cold front. Behind the cold front winds
may gust up to 50 mph late this afternoon and early evening.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

Thunderstorms are expected Saturday afternoon and evening across
the area, some of which may be severe. The Storm Prediction Center
has a slight, level 2 out of 5, risk for parts of the area.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will be needed today.

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
848 AM CDT Thu Jun 11 2026

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

0847 AM     Rain             5 NW Industry           40.38N 90.67W
06/11/2026  U3.60 Inch       McDonough          IL   Trained Spotter

            Rain fell between 5pm and 9pm last evening.

&&

MJB