Alert archive / Illinois / Flash Flood Warnings in 2026

Flash Flood Warning 73, NWS Lincoln, IL

August 19, 2026Knox County, Illinois

NWS Lincoln, IL issued this flash flood warning at Aug 19, 2026, 5:43 PM CDT for Knox County, Illinois. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 19, 2026, 5:43 PM CDT (22:43 UTC)
Expired
Aug 19, 2026, 8:19 PM CDT
In force
3 hr
Issued by
NWS Lincoln, IL
Area
Storm-based polygon
Flood severity
None

County Knox County, IL

The radar

The Quad Cities radar (KDVN), 97 km from the middle of the area, began a volume at 22:47 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this flash flood warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 10.7 hours before the alert went out and 150 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 12:00Z on 2026-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 310 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 12:00Z on 2026-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
310 J/kg
Mixed-layer CIN
-93 J/kg
Mixed-layer LCL
917 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
63 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

891 
WGUS53 KILX 192243
FFWILX
ILC095-200145-
/O.NEW.KILX.FF.W.0073.260819T2243Z-260820T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Lincoln IL
543 PM CDT Wed Aug 19 2026

The National Weather Service in Lincoln has issued a

* Flash Flood Warning for...
  Southern Knox County in west central Illinois...

* Until 845 PM CDT.

* At 543 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 3 inches of rain 
  have fallen. The expected rainfall rate is 1.5 to 2 inches in 1 
  hour. Additional rainfall amounts of 1 to 3 inches are possible in 
  the warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Knoxville, Yates City, Maquon, Gilson and Delong.

This includes  Interstate 74 between  mile markers 54 and 67.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Move to higher ground now. Act quickly to protect your life.

&&

LAT...LON 4073 9000 4074 9039 4091 9038 4091 9000

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL RATE...1.5-2 INCHES IN 1 HOUR

$$

Auten
1 follow-up statement
948 
WGUS73 KILX 200119 RRA
FFSILX

Flash Flood Statement
National Weather Service Lincoln IL
819 PM CDT Wed Aug 19 2026

ILC095-200129-
/O.CAN.KILX.FF.W.0073.000000T0000Z-260820T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Knox IL-
819 PM CDT Wed Aug 19 2026

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHERN KNOX COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed any road closures in the area.

A Flood Watch remains in effect until 100 AM CDT for portions of 
central, east central, and west central Illinois.

&&

LAT...LON 4073 9000 4074 9039 4091 9038 4091 9000

$$

Auten

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Lincoln, IL wrote its last area forecast discussion before this flash flood warning went out at Aug 19, 2:45 PM CDT, 2 hours 58 minutes earlier. Its key messages:

  • Scattered showers and thunderstorms are expected through this evening, and into the overnight hours southeast of the IL river. Damaging winds, hail, heavy rains and localized flooding is in play today. A Flood Watch is posted until 1 am tonight from Fulton to Macon to Vermilion counties north where 1-2 inches and locally 2-4 inches of rain possible.
  • A persistent northwest flow will keep temperatures and humidity levels in check the next several days, with seasonable highs in the upper 70s to mid 80s.
Area forecast discussion, Aug 19, 2:45 PM CDT, 2 hours 58 minutes before
Area Forecast Discussion
National Weather Service Lincoln IL
245 PM CDT Wed Aug 19 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms are expected through this
  evening, and into the overnight hours southeast of the IL
  river. Damaging winds, hail, heavy rains and localized
  flooding is in play today. A Flood Watch is posted until 1 am
  tonight from Fulton to Macon to Vermilion counties north where
  1-2 inches and locally 2-4 inches of rain possible.

- A persistent northwest flow will keep temperatures and
  humidity levels in check the next several days, with
  seasonable highs in the upper 70s to mid 80s.

&&

.DISCUSSION...
Issued at 245 PM CDT Wed Aug 19 2026

We continued the Flood Watch through 1 am tonight from Fulton,
Mason, Menard, Logan, Macon, Piatt, Champaign and Vermilion
counties north. Some areas could see 1-2 inches of rain through
early overnight in central IL with pockets of 2-4 inches
possible. PWATs are in the 1.6-2 inch range over CWA (highest
over southern CWA) and supports heavy rain threat next several
hours. Parts of the flood watch area has already seen 5-10
inches of rain since last Sunday Aug 9th.

Radar mosaic shows a few cells developing along a frontal trof
from southern Fulton county into central parts of McLean and
Ford county. Had a recent report and photo of a funnel clouds in
Bloomington and Galva (southern Henry county). Moderately
unstable tropical airmass over CWA with SB CAPES of 2-3k j/kg,
and highest over northern/nw CWa. The 0-6 km bulk shear values
are at moderate levels too from 35-45 kts over CWA and highest
over southern/sw CWA. A cold front over northern/nw IL will push
se thru CWA during tonight, while an associated short wave trof
over western Iowa tracks se through IL during tonight. This
will interact with the tropical air mass to likely produce
scattered showers and thunderstorms. SPC Day1 outlook has
marginal risk of severe storms over CWA for large hail and
damaging winds while tornado threat is over southern IL south of
CWA though a few more funnels may occur along weak trof over
northern CWA through 00Z/7 pm.

Quieter weather expected on Thursday and Thu night as cold
front nearing the Ohio river by sunrise Thu pushes into central
KY. Highs in the lower 80s Thu with dewpoints in the mid to
upper 60s. A northern stream system approached IL on Friday
bringing 20-40% chance of convection over northern cWA Fri
afternoon and across central IL friday night especially Fri
evening. SPC keeps severe risk west nw of IL on Fri with slight
risk of Nebraska and northeast KS. Highs in the low to mid 80s
Friday with dewpoints sneaking up into the upper 60s/lower 70s
by Fri afternoon.

Fairly quiet weather this weekend into early next week with just
slight pops at times while most areas should stay dry. Another
cold front to sweep through IL early Saturday and bringing in
less humid air during this weekend. Lows Saturday night in the
lower 60s and lows in upper 50s to around 60F Sunday night
making for more comfortable nights ahead. Highs Sat 80-85
(warmest in southeast IL) and upper 70s/lower 80s Sunday/Monday.
Still pretty not much weather expected into middle of next week
with some moderation of temperatures and dewpoints to more
summerlike readings.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 1250 PM CDT Wed Aug 19 2026

Scattered convection is forecast to develop during mid/late
afternoon and continue through this evening, and early overnight
se of the IL River with MVFR conditions possible. There is also
a chance of IFR condtions with thunderstorms with heavier rains
later this afternoon into this evening. A weak east/west trof
was just south of PIA and near BMI early this afternoon with
east to NE winds near 5 kts north of this boundary and south to
SW winds near 5 kts south of the boundary. Main cold front over
northern IL to push southward into the IL river valley/PIA late
afternoon and thru rest of central IL during this evening,
keeping convection chances going for several hours. We have MVFR
vsbys possible overnight into early Thu morning from patchy fog
after the convection chances end. Winds to stay fairly light
next 24 hours under 10 kts and veer NE during tonight into Thu
morning.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 1 AM CDT Thursday for ILZ027>031-036>038-
041>046-048-053.

&&

KEY MESSAGES...07
DISCUSSION...07
AVIATION...07
Hazardous weather outlook, Aug 19, 2:52 PM CDT, 2 hours 51 minutes before
Hazardous Weather Outlook
National Weather Service Lincoln IL
252 PM CDT Wed Aug 19 2026

ILZ027>031-036>038-040>057-061-201100-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-Logan-De Witt-Piatt-Champaign-Vermilion-Cass-Menard-Scott-
Morgan-Sangamon-Christian-Macon-Moultrie-Douglas-Coles-Edgar-Shelby-
252 PM CDT Wed Aug 19 2026

This Hazardous Weather Outlook is for central Illinois, east
central Illinois and west central Illinois.

.DAY ONE...Late This Afternoon and Tonight.

Scattered thunderstorms are expected to develop this afternoon and
persist into the evening, producing locally heavy rain which could
lead to flash flooding. A few of the storms may be strong or briefly
severe, producing damaging winds and large hail.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Additional thunderstorms are possible Friday afternoon and night.
The risk of severe weather is low.

Flooding will continue into the weekend for portions of the Illinois
and Sangamon Rivers.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be required through this evening.

Expected storm motion is to the east around 25 mph.

ILZ062-063-066>068-071>073-201100-
Cumberland-Clark-Effingham-Jasper-Crawford-Clay-Richland-Lawrence-
252 PM CDT Wed Aug 19 2026

This Hazardous Weather Outlook is for east central Illinois and
southeast Illinois.

.DAY ONE...Late This Afternoon and Tonight.

Scattered thunderstorms are expected this evening, lingering past
midnight. Isolated damaging wind gusts and locally heavy rain which
could lead to flash flooding are the primary hazards.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Flooding will linger on the Wabash River for several days.
Otherwise, no hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be required this evening.

Expected storm motion is to the east around 25 mph.

Geelhart

In the hours before

Special weather statement, Aug 19, 2:40 PM CDT, 3 hours 3 minutes before
Special Weather Statement
National Weather Service Lincoln IL
240 PM CDT Wed Aug 19 2026

ILZ027>031-036>038-040-041-192300-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-
Including the cities of Galesburg, Toulon, Peoria, Lacon, Eureka,
Canton, Pekin, Bloomington, Normal, Rushville, and Havana
240 PM CDT Wed Aug 19 2026

...FUNNEL CLOUDS SIGHTED OVER CENTRAL ILLINOIS...

At 145 PM, broadcast media reported a funnel cloud near Bloomington,
and at 235 PM, a storm spotter reported one near the Knox and Henry
county line.

Atmospheric conditions exist that favor the possible formation
of weak circulations along a pre-existing boundary. Some of these
circulations are occurring underneath developing showers and
thunderstorms, where a funnel cloud may develop. Once the rain
begins, the funnel cloud usually dissipates.

Low hanging clouds can also appear to dip up and down at times,
but they will not show signs of any rapid rotation. An actual
funnel cloud will exhibit spinning in a counter-clockwise direction.

In rare instances these funnels may briefly touch down. Stay alert
and be prepared to move to a safe shelter if a funnel cloud
approaches the ground.

Geelhart
Special weather statement, Aug 19, 3:43 PM CDT, 2 hours before
Special Weather Statement
National Weather Service Lincoln IL
343 PM CDT Wed Aug 19 2026

ILZ027>031-036>038-040>051-053-200000-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-Logan-De Witt-Piatt-Champaign-Vermilion-Cass-Menard-Scott-
Morgan-Sangamon-Macon-
Including the cities of Galesburg, Toulon, Peoria, Lacon, Eureka,
Canton, Pekin, Bloomington, Normal, Rushville, Havana, Lincoln,
Clinton, Monticello, Champaign, Urbana, Danville, Beardstown,
Petersburg, Winchester, Jacksonville, Springfield, and Decatur
343 PM CDT Wed Aug 19 2026

...FUNNEL CLOUDS SIGHTED OVER CENTRAL ILLINOIS...

At 315 PM, broadcast media and Emergency Management personnel reported
additional funnel clouds over parts of central Illinois.

Atmospheric conditions exist that favor the possible formation
of weak circulations along pre-existing boundaries. Some of these
circulations are occurring underneath developing showers and
thunderstorms, where a funnel cloud may develop. Once the rain
begins, the funnel cloud usually dissipates.

Low hanging clouds can also appear to dip up and down at times,
but they will not show signs of any rapid rotation. An actual
funnel cloud will exhibit spinning in a counter-clockwise direction.

In rare instances these funnels may briefly touch down. Stay alert
and be prepared to move to a safe shelter if a funnel cloud
approaches the ground.

Auten

The office that day

Everything else NWS Lincoln, IL issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 19, 2:35 AM CDTFlood WatchILXChampaign, DeWitt, Fulton, Knox, Logan, McLean and 10 more22 hr
Aug 19, 6:13 PM CDTFlash Flood WarningILXVermilion3 hr
Aug 19, 6:34 PM CDTSevere Thunderstorm WarningILXFulton56 min
Aug 19, 6:52 PM CDTFlash Flood WarningILXTazewell, Woodford6 hr
Aug 19, 6:58 PM CDTFlash Flood WarningILXChampaign2 hr

Nearby

Flash Flood Warnings in Illinois, 2026Every flash flood warning in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.