A line of showers and embedded thunderstorms moved across northwest Indiana during the late morning and early afternoon of April 27th. On the back side of this precipitation, a wake low developed, producing wind gusts between as high as 60 mph, which blew down trees, tree limbs and power lines.
Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS LOT wrote it up.
A line of showers and embedded thunderstorms moved across northwest Indiana during the late morning and early afternoon of April 27th. On the back side of this precipitation, a wake low developed, producing wind gusts between as high as 60 mph, which blew down trees, tree limbs and power lines. Scattered thunderstorms moved across west central Indiana during the evening of April 27th producing isolated wind damage.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Chicago, IL wrote its last area forecast discussion before the first event at Apr 27, 12:09 PM CST, 36 minutes earlier. Its key messages:
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
109 PM CDT Mon Apr 27 2026
.KEY MESSAGES...
- Strong to locally damaging non-thunderstorm wind gusts near
and north of the Illinois and Kankakee Rivers through mid
afternoon.
- There is a threat for severe weather later today, primarily
between 4 and 11 PM this evening. The main threats are
damaging winds and damaging hail.
- A transition toward a cooler and drier pattern will commence
by midweek.
&&
.UPDATE...
Issued at 109 PM CDT Mon Apr 27 2026
The rapidly advancing wake low winds have been intensifying with
eastward extent into northeast Illinois, with observed gusts of
55-70 mph, including 49 kt at KDKB and 58 kt at KARR. Opted for
a short-fused High Wind Warning for locations near and north of
I-88/290, including the city of Chicago. The Wind Advisory
issued earlier remains in effect southward to the IL and
Kankakee River Valleys. The wind headlines are in effect until 4
PM for now. Will adjust as needed based on observational trends.
Castro
Previous Update Issued at 1215 PM CDT Mon Apr 27 2026
A Wind Advisory is in effect for locations near and north of the
Illinois and Kankakee Rivers until 4 PM this afternoon due to
strong wake low winds. Observed wind gusts west of the
stratiform rain with embedded thunderstorms quickly advancing
east have been in the 40-50+ mph range from the southeast, most
recently 45 kt at DBQ and FEP. Forecast soundings and high
resolution model output suggest brief localized gusts up to 60
mph are possible, which would enhance wind damage and power
outage potential if/where this occurs.
The thunderstorm driven severe wind threat with the ongoing MCS
will likely continue to focus just south of our far southern
counties over the next 1-2 hours.
It's highly uncertain to what extent and how far north air mass
recovery will occur later this afternoon into this evening
regarding any renewed severe threat later on. This will be
detailed with the full afternoon forecast issuance and
discussion once we have a better handle on trends.
Castro
&&
.DISCUSSION...
Issued at 247 AM CDT Mon Apr 27 2026
Early morning radar, satellite, and ASOS/AWOS observations
depict a developing surface low in far southwestern Kansas with
an associated broad warm frontal zone extending eastward through
central Missouri and into far western Tennessee. Broad
southwesterly flow continues to advect an EML plume across the
central Plains, which with a developing low-level jet (some
50-60kt per regional VWPs) and the approach an unbalanced
upper-level short-wavelengh trough propagating into the
Southern Plains, is supporting an expansive region of elevated
gravity wave associated convection (GWAC) across central Kansas
at press time.
Owing to continued synoptic-scale ascent facilitated by the
developing surface low and upper-level trough as well as a steady
northeasterly feed of instability through the night, the expectation
is for the ongoing elevated convection across central Kansas to
coalesce into a bore-driven mesoscale convective system over the
coming hours. The orientation of the low-level jet and instability
axis would then guide the convective system through Kansas City,
Missouri by daybreak and into central Illinois (along/south of I-80)
by mid to late morning. With instability decreasing with eastward
extent, the convective system should begin to weaken as it crosses
the I-39 corridor in central Illinois. With that said, northeasterly-
oriented deep-layer shear vectors will promote a broad stratiform
precipitation region (perhaps with embedded thunder) on the northern
side of the zone of active convection across northern
Illinois/southern Wisconsin. The severe weather threat with the
first batch of activity is currently thought to be low (call it a 5
to 15% chance at any given point) owing to meager instability. With
that said, locally damaging winds cannot be ruled out particularly
south of I-80 with any decaying convective element.
Outside the convection this morning, do have growing concern
for a period of non-thunderstorm damaging winds mainly
along/north of I-80 between noon and 3 PM along the backside of
the decaying stratiform region this afternoon. CAM guidance has
remained remarkably consistent in depicting rapid
drying/subsidence along the backside of the stratiform region,
which would support the development of a very tight pressure
gradient behind the leading meso-high (a wake-low situation). The
HRRR has long had the signal for nearly 24 hours now, including
explicit wind gust output up to 75 mph in the most recent iteration.
It's always tough to go all-in on these sorts of features given
inherent dependencies on how convection evolves and a history of
false alarms of such by CAM guidance. With that said, will give a
very hearty warning to the incoming day shift to keep an eye out for
even the slightest signs of wake low development to get lead time on
what would probably be a short- fused High Wind Warning.
Attention then turns to the threat for severe weather this
afternoon and evening. There is excellent agreement among
deterministic and ensemble guidance that the upper-level
shortwave currently propagating into the Central Plains will
lift into the Great Lakes region this afternoon, allowing the
aforementioned surface low to track from roughly Kansas City, MO
this morning to near La Crosse, Wisconsin this evening. As the
upper-level wave passes overhead, an associated 75kt 500mb speed
max will arc directly across the Mississippi River as pressure
falls in the central Great Lakes induce the rapid
intensification of the 925- to 850mb wind field. The kinematic
environment will thus become very supportive of organized
convection by this evening.
Meanwhile, increasing isentropic ascent atop the (what will be
outflow-reinforced) warm front will set the stage for festering
convection from eastern Missouri into central Illinois during
the afternoon hours. Even with increasing synoptic southwesterly
flow, a steady feed of cool outflow from the festering
convection will likely impede the northeastward progression of
the warm front, and hence, instability, into area area by early
evening. Heavy cloud cover throughout the day will also hamper
the ability for low-level lapse rates to steepen and surface
temperatures to warm, with highs only poised to make it into the
upper 60s to perhaps locally 70. Nevertheless, cooling mid-
level temperatures (by virtue of synoptic-scale ascent and the
continued advection of an EML plume via southwesterly mid-level
flow) will nevertheless support the development of elevated
instability throughout the afternoon.
Even with a lack of surface-based instability, we still do
expect the rapid development and expansion of convection across
our area this afternoon as the arrival of the upper-level
shortwave interacts with the elevated instability axis.
Accordingly, we continue to see a threat for severe weather this
afternoon and evening in our local area mainly in the form of
locally damaging winds and hail. The inability for the surface-
based instability axis to make it into our area should relegate
the (what will be a higher-end) tornado threat south of our area
across central and southern Illinois, but tracking the exact
location of the warm front will be important in case it does
sneak into our area. So, today still looks active, just not
necessarily what initially looked like a very concerning
scenario in our local area. In collaboration with SPC, the Level
3/5 threat area has been adjusted southward to be closer to the
expected position of the outflow-reinforce warm front this
afternoon.
In spite of the most likely outcome outlined above, do still
feel the need to discuss the low-probability scenario in which
the surface-based instability does make it into our area.
Should convection across central Nebraska fail to coalesce into
a bore-driven MCS (as it has struggled to do so thus far and
instead remain as GWAC), or the convective footprint into
central Illinois is minimized by early afternoon (so no outflow
to counteract southwesterly flow), the safeguard of festering
convection limiting the northeastward-movement of the warm
front would fail to materialize. In such a scenario, the warm
front would be able to lift into at least northwestern Illinois,
leading to a narrow zone where surface-based instability would
overlap with an intense kinematic environment. Should this
occur, a band of supercells with a threat for all hazards
including tornadoes would materialize near the Mississippi River
with upscale growth into an intense squall line thereafter.
Would have to think that instability would still decrease with
eastward extent toward Lake Michigan... though there would still
a more pronounced threat for an all-hazard severe weather
event. Most guidance does not support this outcome at this point
in time, though it does remain completely realistic provided a
lot of dominoes fall in the wrong direction.
Tuesday onward:
The upper-level pattern will undergo a substantial pattern
shift through the rest of the week with predominant aggregate
troughing along the US/Canadian border. As a result, the
expectation is for cooler and drier conditions to prevail with
highs in the 60s and overnight lows in the upper 30s to lower
40s. We can easily envision a threat for frost by the weekend.
Thereafter, long-range ensembles advertise warming trend during
the first week of May.
Borchardt
&&
.AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 1236 PM CDT Mon Apr 27 2026
Key Aviation Messages for the current TAF period:
- Strong and gusty winds through most of the TAF period.
Strongest winds out of the southeast this afternoon in excess
of 40 knots.
- Another round of showers and storms possible this evening.
A line of showers and storms is currently moving east-northeast
over Illinois. This line is expected to be out over Lake
Michigan after 1830Z, with a period of dry VFR conditions after
the rain ends.
More notably, in the wake of the area of convection, a small
scale low pressure area will increase winds out of the
southeast this afternoon. Strongest wind gusts in the TAF were
listed at 40 kt, but obs to the west have already recorded
around 45 kt.
Winds will turn to the south as the low moves east later
tonight. Models have consistently shown another line of showers
and storms that could develop this evening. With lower
confidence in development behind the low, KRFD was converted
down to a PROB30. However, the TEMPO for the Chicago terminals
were adjusted for timing, with chances for it to linger around
KMDW and KGYY for longer.
As the threat for showers and storms diminish, drier conditions
are expected overnight, but there is a chance for lingering MVFR
cigs. Winds will turn to the southwest and eventually west with
gusts 20 to 25 knots. Breezy conditions are expected to remain
through much of Tuesday, becoming VFR in the afternoon. Models
are hinting at a weak lake breeze development tomorrow
afternoon, but not with enough confidence to introduce it into
the TAF presently.
DK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Wind Advisory until 4 PM CDT this afternoon for ILZ003-ILZ004-
ILZ008-ILZ010-ILZ019-ILZ020-ILZ021-ILZ023-ILZ105-ILZ106-
ILZ107-ILZ108.
High Wind Warning until 4 PM CDT this afternoon for ILZ005-
ILZ006-ILZ011-ILZ012-ILZ013-ILZ103-ILZ104.
IN...Wind Advisory until 4 PM CDT this afternoon for INZ001-INZ002.
LM...Gale Warning until 7 PM CDT this evening for the IL and IN
nearshore waters.
Small Craft Advisory from 7 PM this evening to 10 AM CDT
Tuesday for the IL and IN nearshore waters.
&&
Visit us at weather.gov/chicagoHazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
1248 PM CDT Mon Apr 27 2026
ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-281800-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
1248 PM CDT Mon Apr 27 2026 /148 PM EDT Mon Apr 27 2026/
This Hazardous Weather Outlook is for portions of north central
Illinois...northeast Illinois and northwest Indiana.
.DAY ONE...This Afternoon and Tonight.
Weather hazards expected...
Elevated Thunderstorm Risk...with an associated:
Level 2 of 5 Damaging Wind Risk...up to 70 mph.
Level 2 of 5 Large Hail Risk...up to quarter size.
Level 2 of 5 Tornado Risk mainly south of I-80.
Elevated Flooding Risk.
Elevated Non Thunderstorm Wind Risk this afternoon.
DISCUSSION...
Strong non-thunderstorm winds will gust up to 50 mph from the
southeast through mid afternoon, with brief localized gusts up to
60 mph.
Thunderstorms are expected to redevelop ahead of a cold front late
this afternoon into this evening. Some of these may be severe with
damaging winds and hail, particularly south of I-80.
Heavy rainfall may lead to localized flooding and possible
renewed rises on area rivers.
.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.
Friday Night into Saturday morning...
Limited Frost Risk.
.SPOTTER INFORMATION STATEMENT...
Spotters reports will be needed into this evening.
GENERAL STORM MOTION OF THE DAY:
Moving toward the east northeast at 50 mph.
LMZ740>745-281800-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
1248 PM CDT Mon Apr 27 2026
This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.
.DAY ONE...This Afternoon and Tonight.
Weather hazards expected...
Gale force winds and hazardous waves.
Limited Thunderstorm Risk...with an associated:
Level 2 of 5 Thunderstorm Wind Gust Risk...up to 50 kts.
Level 1 of 5 Hail Risk...up to nickel size.
.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.
Tuesday Morning...
Hazardous conditions for small craft are likely.
RC
Visit us at www.weather.gov/chicagoPreliminary Local Storm Report
National Weather Service Chicago IL
100 PM CDT Mon Apr 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1245 PM Non-Tstm Wnd Gst 1 NW Cortland 41.93N 88.71W
04/27/2026 M56 MPH De Kalb IL AWOS
Dialed into KDKB AWOS. Sustained at 51 mph.
Likely not a peak gust.
&&Preliminary Local Storm Report
National Weather Service Chicago IL
106 PM CDT Mon Apr 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0103 PM Non-Tstm Wnd Gst 2 WNW Sugar Grove 41.77N 88.48W
04/27/2026 M67 MPH Kane IL ASOS
Peak wind so far at KARR ASOS.
&&Preliminary Local Storm Report
National Weather Service Chicago IL
107 PM CDT Mon Apr 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1245 PM Non-Tstm Wnd Gst 3 WSW Leland 41.59N 88.85W
04/27/2026 M56 MPH La Salle IL Public
Private weather station KILEARLV3 recorded
56 mph gust.
1244 PM Non-Tstm Wnd Gst 3 NNE Leland 41.66N 88.78W
04/27/2026 M63 MPH De Kalb IL Public
Private weather station KILLELAN7 recorded
63 mph gust.
1224 PM Non-Tstm Wnd Gst 1 SE Winnebago 42.26N 89.23W
04/27/2026 M52 MPH Winnebago IL Public
Private weather station KILWINNE5 reported
52 mph gust.
&&Preliminary Local Storm Report
National Weather Service Chicago IL
113 PM CDT Mon Apr 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1244 PM Non-Tstm Wnd Gst 3 NW Sycamore 42.02N 88.72W
04/27/2026 M63 MPH De Kalb IL Public
Private weather station KILSYCAM31 reported
63 mph gust.
&&Preliminary Local Storm Report
National Weather Service Chicago IL
134 PM CDT Mon Apr 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0103 PM Non-Tstm Wnd Dmg 2 ESE Big Rock 41.75N 88.50W
04/27/2026 Kane IL Public
Report of multiple trees with numerous
branches broken in the Big Rock area and
areas southwest of Aurora Airport. Many
branches in excess of 3 inches in diameter
broken, at least one tree with most branches
broken. Time estimated based upon nearby
weather stations.
&&
WSLPreliminary Local Storm Report
National Weather Service Chicago IL
139 PM CDT Mon Apr 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0105 PM Non-Tstm Wnd Dmg Aurora 41.76N 88.32W
04/27/2026 Kane IL Amateur Radio
Large branch broken near Wilder Street and
Park Avenue in Aurora. Time estimated by
radar. Relayed via amateur radio.
&&
WSLThe Chicago radar (KLOT), 61 km away, was scanning. The volume nearest the first event began at 23:00 UTC.
4 high wind, 1 heavy rain, 1 thunderstorm wind. Local standard time, as filed.
Multiple reports of downed power poles and trees, including some snapped at the base, came out of the vicinity of St. John, Cedar Lake, and Crown Point. Southeast of Schererville, a few trees were downed onto homes. One vehicle was struck by a falling power pole in St. John.
Multiple large branches and at least one tree were downed near Portage.
A 95-foot tall radio tower collapsed near Lincolnway and Yellowstone roads in Valparaiso. Large tree limbs were also reported down nearby.
A personal weather station recorded 2.4 inches of storm total rainfall east of Oxford through 7:15 PM EST, 2.36 of which fell between 6:00 and 7:15 PM.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Indiana in 2026Every state in 2026This day in weather historyWarnings in Indiana, April 2026
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1334324, 1334326, 1334325, 1334327, 1334329, 1334328.