Severe Thunderstorm Warning 263, NWS Quad Cities, IA

Area Forecast Discussion
National Weather Service Quad Cities IA IL
633 AM CDT Wed Aug 12 2026

.KEY MESSAGES...

- There is a Slight (level 2 out of 5) risk for severe storms
  this morning and early afternoon. Damaging wind up to the 70
  mph and heavy rain will be the primary threats. Some embedded
  tornadoes will also be possible.

- There is a Marginal (level 1 out of 5) risk for severe storms
  Thursday afternoon and evening. Damaging wind and heavy rain
  will be the primary threats. Some localized flash flooding is
  also possible for areas that see repeating storms.

- There will be a near daily risk of shower/storms through the
  remainder of the week and into the weekend, However, there
  will also be many hours of dry weather.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 250 AM CDT Wed Aug 12 2026

Another repeat of yesterday? Same llvl thermal and moisture gradient
alignment from the northern/central plains over to Indiana, with the
local area stuck in the middle. Water vapor imagery showing a
seasonably robust short wave probably convectively enhanced, acrs
central SD and an associated strong cluster of storms pushing
southeast into far north central NE ATTM. This may be the "player"
as it continues to evolve and develop a cold pool for propagation
mechanics acrs IA and through the local area this morning. Current
trends would have it dive further southeast than what most CAMs
suggest it will and then hammer the far southern CWA and MO. But
these areas are covered by a strong EML, and more prime LLJ feed and
ongoing MCS maintenance parameters align right along I-80 into
northern IL. Thus would expect more north/northeastward flank
development of the current storm cluster as it comes acrs and much
of the DVN CWA except maybe the far north will be at risk of the
wrath of another severe QLCS with damaging winds and embedded
tornadoes this morning.

If the current 3500 J/kg MLCAPE pool can hang on during storm
arrival, there appears to be enough kinematics again to fuel wind
gusts of 70 to 85 MPH with a bow utilizing cold pool mechanics and
mix down. The ongoing quasi-stationary LLVL boundary undulating acrs
NE over to northern IL will also be a focus. The storms will also be
producing rainfall at rates of 1-2 inches an hour, but hopefully the
progressive nature will limit flash flooding potential unless some
re-generation of a few storms on the wake outflow left behind
lingers longer into early afternoon on areas hit hard earlier.

High temperatures may vary quite a bit with convective debris and
outflow boundaries all over the place. But with storm system exit
and most the afternoon to recover, looks like another sultry day
with high humidity. Went ahead and issued another Heat Advisory for
the southern third of the fcst area which is expected remain south
of the main boundary and in the land of sfc DPTs in the upper 70s to
around 80. Some chance that a further south MCS track and lingering
wake clouds/perculating precip may ruin the ambient temp heat up
potential even in the south.

Tonight...Signs of another bout of short wave upper ridging and LLJ
re-focus back off to the west may make the later afternoon and most
of the night precip free again...with the ongoing chance for a rogue
elevated shower or storm with nocturnal LLJ WAA processes. This as
yet another short wave or MCV lurks upstream off to the west to ruin
the day Thursday. Like having to watch for this early Wednesday
morning, there may be some fog development in spots Thu morning
especially along and north of the quasi-stationary boundary. NBM low
temps ranging from the upper 60s to low 70s look on target.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 250 AM CDT Wed Aug 12 2026

Thursday...This could be a day were the rounds of heavy rainfall add
up and the flooding potential increases especially by late Thu
night. After we may have yet another strong to severe MCS or storm
cluster move acrs the area during the day, there are synoptic scale
signals that the LLVL west-to-east boundary gets enhanced and is a
focus point of LLJ convergence and moisture feed, fueling more
thunderstorms possibly in a back-building scenario as Thu night
progresses. Where this west-to-east line of convection lays out
still uncertain of course at this juncture of the game but CAM
ensembles are hinting along to a county or two north of the I-80
corridor. Depending on what occurs rainfall-wise leading up to this
scenario, could see the eventual need for a flood watch for Thu or
Thu night.

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 /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 633 AM CDT Wed Aug 12 2026

Another round of showers and thunderstorms is moving through the
area this morning, bringing a mixture of IFR/MVFR conditions in
-TSRA. Storms may brush just south of KDBQ, but LIFR ceilings
 along with MVFR visibilities are likely to linger for several
 more hours. This is just the first wave of two rounds of
 showers and storms this morning, with another wave just a few
 hours behind the first. This round is affecting KCID/KMLI/KDBQ
 the most, with KCID/KMLI/KBRL more likely to be affected by
 the second round. Thunderstorm activity should move out of all
 terminals by 19z today, with conditions returning to VFR. Fog
 may develop late tonight bringing MVFR visibilities. There may
 be another round of showers and storms after 09z tonight, and
 have included PROB30 groups for now.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory from noon today to 8 PM CDT this evening for
     IAZ087>089-098-099.
IL...Heat Advisory from noon today to 8 PM CDT this evening for
     ILZ025-026-034-035.
MO...Heat Advisory from noon today to 8 PM CDT this evening for
     MOZ009-010.

&&

SHORT TERM...12
LONG TERM...12
AVIATION...LE

Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
425 AM CDT Wed Aug 12 2026

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-131100-
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-
425 AM CDT Wed Aug 12 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

A strong to severe storm system will move in from the west and
impact much of the Outlook Area this morning. Damaging winds,
potentially up to 70 mph, will be the primary risk. Brief spin-
up tornadoes will be a secondary risk. Much of the area is in a
Slight, level 2 out of 5, Risk for severe storms today. Locally
heavy rainfall and flooding will also be a concern

A Heat Advisory is in effect this afternoon and evening for areas
generally along and south of an Ottumwa, Iowa to Galesburg,
Illinois line. Heat Index readings will range from 100 to 105
degrees in these areas.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

Rounds of strong to severe storms will again be possible Thursday
and Friday as the area continues to lay under an active storm
track. There is a Marginal, level 1 out of 5, Risk for severe
weather for the portions of the Outlook Area both days. Locally
heavy rain and flooding will also be a concern, especially
Thursday night when there will be the potentially for
thunderstorms moving repeatedly over the same areas.

There will continue to be an almost daily chance for thunderstorms
through the upcoming weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is likely today.

12

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
706 AM CDT Wed Aug 12 2026

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

0704 AM     Tstm Wnd Gst     Davenport Municipality  41.62N 90.58W
08/12/2026  M59 MPH          Scott              IA   ASOS

            ASOS.

&&

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
712 AM CDT Wed Aug 12 2026

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

0709 AM     Tstm Wnd Dmg     2 N Davenport           41.58N 90.61W
08/12/2026                   Scott              IA   Trained Spotter

            1-2 inch branches down, very heavy rain and
            heavy winds.

&&

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
713 AM CDT Wed Aug 12 2026

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

0712 AM     Tstm Wnd Dmg     2 NNE Rock Island       41.50N 90.57W
08/12/2026                   Rock Island        IL   Trained Spotter

            6 inch branches down. Water over roads.

&&

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
717 AM CDT Wed Aug 12 2026

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

0716 AM     Rain             Belle Plaine            41.90N 92.27W
08/12/2026  M2.50 Inch       Benton             IA   Public

            So far.

&&

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