Severe Thunderstorm Warning 207, NWS Quad Cities, IA

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1243 PM CDT Sun Jun 28 2026

.KEY MESSAGES...

- Semi-organized, lightning-heavy thunderstorms (70-90%
  coverage) will impact at least locations along and north of
  U.S. Highway 30 through mid afternoon, with a "worst case"
  scenario being scattered severe as they do.

- A prolonged period of hot and very humid conditions will be
  seen starting this afternoon (in the south) and lasting
  through much of the work week, with peak heat index values
  upwards to 105 degrees or higher. Extreme Heat Warnings
  continue for this upcoming hot spell.

- Precipitation chances will remain limited through midweek,
  increasing each day from Thursday onward. The chance for
  showers/storms and resultant cloud cover may have an impact on
  forecast high temperatures as we approach the July 4th
  weekend.

&&

.UPDATE...
Issued at 900 AM CDT Sun Jun 28 2026

Persistent MCS from late last night that is approaching
northeast Iowa as of mid-morning is our current focus. Radar
and 1-minute satellite imagery indicate the most organized and
balanced part of this MCS is near the Mason City area as of 9
AM. Motion has generally been due east, although as eluded to
in the early morning AFD, the instability gradient does slope
east-southeast. In addition, the 40-45 kt low-level jet
supporting this as sampled by recent DMX VWP data should
continue new storm development and/or festering of existing
storms on the southern portion of the MCS. Deep layer shear
values of 40-50 kt and MUCAPE of 1,500-2,500 J/kg certainly are
enough for a severe threat, but at least some sizable inhibition
does exist that may thwart a continuing mature MCS wind threat.
That would mean a more isolated wind and hail threat.

So confidence has increased in at least semi-organized /
multicell storms in our Iowa CWA north of U.S. Highway 30
between 11 AM and 2 PM. Confidence is lower for south of there,
such as toward I-80, as well as into northwest Illinois for
early this afternoon. The forecast warm advection near 800 mb
remains stout and even with daytime heating, the capping from
that warm nose may limit the ability for any new boundary-layer
rooted updrafts by early afternoon. That's especially true with
the convective debris cloud ahead of this limiting full daytime
heating. We'll keep a close eye on it, and have updated PoPs,
and some messaging soon for these slight refinements.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 235 AM CDT Sun Jun 28 2026

Ongoing MCS acrs southeast SD and far northeast NE looks like it may
be going to be a fcst buster for today for at least portions of the
local area. Several MCS maintenance parameters and instability/THTA-E
gradients bend southeastward and tighten from northwest IA into
southeastern to east central IA as the morning progresses. A warm
front trying to retreat as well acrs IA all spell trouble with
regards to a portion of the MCS propagating east-southeastwrad
enough to impact the DVN CWA from late morning into mid afternoon,
especially along and north of the I-80 corridor. The extent of shear
and building thermodynamic energy support damaging winds to 70 MPH
and large hail even if partially elevated. If a sfc root becomes
established, LLVL shear/southeast BL flow supports some meso-vortice
spin up tornadoes. But all this will be encountering an upper level
ridge trying to amplify right acrs the MS RVR Valley as well as
building EML between H8-H7 MB which could act as a storm "eater".
Several of the latest CAM runs continue to be bullish in maintaining
the MCS into our area either along and north of I-80, Hwy 30, or Hwy
20. This while some CAMs and favored deterministic 00z run ECMWF and
GFS erode this convection as it arrives or deflects it north of the
area in an elevated state.

Have to think/bet on that some of this is going to make it and
walked a swath of 20-30 POPs acrs the north half of the DVN CWA from
after 15z to 21z or so. Will also go with a NW-to-SE  oriented
narrow POP swath to account for a connecting elevated warm air
advection wing of a linear stripe of broken to isolated showers and
possible thunder connecting to the incoming lift of associated MCV.

If this MCS can make it acrs if even in a decaying form, cloud
cover/debris/cool outflow looks like it will move acrs at least the
Extreme Heat Watch areas. And new Heat Index values for today are
marginal in the mid to upper 90s in those areas. Thus have cancelled
the EH watch for today and tonight in those areas, and replaced it
with an upgrade to an Extreme Heat Warning starting at 17z Monday.
More confidence in dry hot conditions with high DPTs to make warning
criteria on Monday so as why to make this move now. The rest of the
Warning continues as is for now for multi-day Heat Index's of 100-
110, with later shifts assessing the need to extend into the mid or
even late week. This depends on cloud debris and edging closer to
the western edge of the thermal ridge and ring of fire as early
as late Tue and growing in potential Wed through Thu/Fri.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
Issued at 235 AM CDT Sun Jun 28 2026

Thursday onward through the holiday weekend, we will start to see
the strong ridge over the Central CONUS break down a little and
start to shift east. This easterly shift will result in upper waves
tracking closer/over our area, leading to increasing precipitation
chances. Thus, there are uncertainties in the temperature forecast
as we approach the July 4th weekend. Overall, we are expected to
remain hot and humid. If we avoid the storm track, it is possible
that the oppressive heat will continue, but if we fall under the
storm track, temperatures may be lower than currently forecast.
Currently, precipitation chances are not very high, but we do have
20-40% PoPs each day Thursday onward. Forecast would favor the
potential for diurnally driven storms with such hot and humid
conditions, with the chance for overnight ring of fire convection
that may result in convective debris into the daytime. This
convective debris would be a limiting factor on the high temperature
forecast.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1240 PM CDT Sun Jun 28 2026

Primary concerns with the TAFs are MVFR ceilings and nearby
thunderstorms through mid afternoon, gusty southeast winds at
times this afternoon, and potential for LLWS tonight.

Semi-orgnized thunderstorms will continue to move east-southeast
over portions of eastern Iowa and eventually into northwest
Illinois through mid-afternoon. While DBQ will see some
effects, it is less certain at MLI. If they occur at MLI, they
would likely be between 1930-21Z, and probably have some gusts
25-35 kt. Apart from storms, areas of MVFR ceilings are present
and will be slow to depart through mid-afternoon. DBQ could even
hold onto them through the entirety of the daytime hours.

For winds, east to southeast winds will have regular gusts this
afternoon. There are likely to be what we call "wake low"
effects at DBQ and possibly CID, which even gustier east-
southeast non-thunderstorm winds that occur in the wake of a
persistent area of storms. These could result in temporary (~1
hr) gusts to 30-40 kt, but confidence in that is low.

While gusts abate after sunset, sustained winds should hold
around 10 kt, maybe higher at times. The setup also favors a
35-40 kt low-level jet AOA 1.5 kft, and that is borderline for
true LLWS development given those sustained surface winds. If it
occurs atop area airports, 03Z-09Z is the most favored time.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Extreme Heat Warning from noon Monday to 9 PM CDT Tuesday for
     IAZ040>042-051>054-066.
     Extreme Heat Warning until 9 PM CDT Tuesday for IAZ063>065-067-
     068-076>078-087>089-098-099.
IL...Extreme Heat Warning from noon Monday to 9 PM CDT Tuesday for
     ILZ001-002-007-009-016>018.
     Extreme Heat Warning until 9 PM CDT Tuesday for ILZ015-024>026-
     034-035.
MO...Extreme Heat Warning until 9 PM CDT Tuesday for MOZ009-010.

&&

UPDATE...Friedlein
SHORT TERM...12
LONG TERM...Gunkel
AVIATION...Friedlein

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Special Weather Statement
National Weather Service Quad Cities IA/IL
1146 AM CDT Sun Jun 28 2026

IAZ040-041-051>053-281730-
Linn IA-Buchanan IA-Delaware IA-Benton IA-Jones IA-
1146 AM CDT Sun Jun 28 2026

...Strong thunderstorms will impact portions of northern Linn,
Buchanan, Delaware, northeastern Benton and northwestern Jones
Counties through 1230 PM CDT...

At 1146 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Stanley to near Winthrop to near Urbana.
Movement was east at 35 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Strong winds could break small tree limbs and blow around
         unsecured objects.

Locations impacted include...
Independence, Manchester, Center Point, Urbana, Central City,
Edgewood, Winthrop, Earlville, Walker, Alburnett, Coggon, Quasqueton,
Lamont, Delhi, Ryan, Rowley, Greeley, Aurora, Prairieburg, and
Dundee.

This includes Interstate 380 between mile markers 39 and 49.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is occurring and may lead to localized flooding.
Do not drive your vehicle through flooded roadways.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4241 9123 4212 9148 4224 9202 4249 9186
      4264 9190 4264 9125
TIME...MOT...LOC 1646Z 287DEG 31KT 4268 9184 4247 9179 4229 9191

MAX HAIL SIZE...<0.75 IN
MAX WIND GUST...50 MPH

Ervin

Special Weather Statement
National Weather Service Quad Cities IA/IL
1222 PM CDT Sun Jun 28 2026

IAZ041-042-052>054-281815-
Linn IA-Delaware IA-Jackson IA-Dubuque IA-Jones IA-
1222 PM CDT Sun Jun 28 2026

...Strong thunderstorms will impact portions of northeastern Linn,
Delaware, west central Jackson, Dubuque and northern Jones Counties
through 115 PM CDT...

At 1221 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Edgewood to Manchester to Central City.
Movement was east at 30 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Strong winds could break small tree limbs and blow around
         unsecured objects.

Locations impacted include...
Anamosa, Manchester, Dyersville, Monticello, Cascade, Epworth,
Farley, Peosta, Central City, Edgewood, Earlville, Coggon, Hopkinton,
Delhi, New Vienna, Colesburg, Worthington, Holy Cross, Ryan, and
Greeley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is occurring and may lead to localized flooding.
Do not drive your vehicle through flooded roadways.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4267 9087 4239 9078 4207 9098 4217 9170
      4230 9159 4264 9160 4265 9090 4268 9090
TIME...MOT...LOC 1721Z 276DEG 25KT 4265 9147 4246 9144 4220 9154

MAX HAIL SIZE...<0.75 IN
MAX WIND GUST...50 MPH

Ervin

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
1244 PM CDT Sun Jun 28 2026

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

1244 PM     Rain             2 ENE Hazleton          42.63N 91.86W
06/28/2026  M1.36 Inch       Buchanan           IA   CO-OP Observer

            rainfall past 2 hrs.

&&

GROSS

Special Weather Statement
National Weather Service Quad Cities IA/IL
1253 PM CDT Sun Jun 28 2026

IAZ041-042-053-054-065-066-281845-
Clinton IA-Delaware IA-Jackson IA-Dubuque IA-Cedar IA-Jones IA-
1253 PM CDT Sun Jun 28 2026

...Strong thunderstorms will impact portions of northwestern Clinton,
southeastern Delaware, western Jackson, southwestern Dubuque,
northeastern Cedar and Jones Counties through 145 PM CDT...

At 1252 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Dyersville to near Monticello to near
Martelle. Movement was southeast at 35 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Strong winds could break small tree limbs and blow around
         unsecured objects.

Locations impacted include...
Maquoketa, Anamosa, Dyersville, Monticello, Cascade, Epworth, Farley,
Peosta, Lowden, Olin, Hopkinton, Wyoming, Oxford Junction, Lost
Nation, Worthington, Martelle, Onslow, Monmouth, Toronto, and Morley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is occurring and may lead to localized flooding.
Do not drive your vehicle through flooded roadways.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4243 9068 4206 9063 4183 9086 4199 9137
      4226 9137 4237 9130 4254 9124
TIME...MOT...LOC 1752Z 299DEG 31KT 4245 9117 4230 9114 4205 9133

MAX HAIL SIZE...<0.75 IN
MAX WIND GUST...50 MPH

Ervin

Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
125 PM CDT Sun Jun 28 2026

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

0125 PM     Rain             2 ESE Fairview          42.08N 91.30W
06/28/2026  M0.48 Inch       Jones              IA   CO-OP Observer

            rain fell in 15 min.

&&

GROSS

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