Alert archive / Illinois / Flash Flood Warnings in 2021

Flash Flood Warning 16, NWS Lincoln, IL

July 11, 2021Sangamon County, Illinois

NWS Lincoln, IL issued this flash flood warning at Jul 11, 2021, 8:35 PM CDT for Sangamon County, Illinois. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 11, 2021, 8:35 PM CDT (01:35 UTC)
Expired: Jul 11, 2021, 11:24 PM CDT
In force: 3 hr
Issued by: NWS Lincoln, IL
Area: Storm-based polygon
Flood severity: None

County Sangamon County, IL

The radar

The Lincoln radar (KILX), 60 km from the middle of the area, began a volume at 01:39 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.

What was reported inside it

Time	Report	Where	Remark
Jul 11, 9:00 PM CDT	HEAVY RAIN 2.2	Chatham, IL	MOST OF THIS RAIN FELL IN AN HOUR.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 1.6 hours before the alert went out and 112 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 460 J/kg
Mixed-layer CIN: -16 J/kg
Mixed-layer LCL: 553 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 78 m²/s²
0-3 km storm-relative helicity: 89 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

450 
WGUS53 KILX 120135
FFWILX
ILC167-120530-
/O.NEW.KILX.FF.W.0016.210712T0135Z-210712T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Lincoln IL
835 PM CDT Sun Jul 11 2021

The National Weather Service in Lincoln has issued a

* Flash Flood Warning for...
  West Central Sangamon County in central Illinois...

* Until 1230 AM CDT.

* At 833 PM CDT, local law enforcement reported flooding over I-72 
  from heavy rain across the warned area. Between 3 and 5 inches of 
  rain have fallen in portions of western Sangamon County. Flash 
  flooding is already occurring.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Law enforcement.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Springfield, Chatham, New Berlin, Pleasant Plains, Loami, Jerome, 
  Leland Grove, Curran, Berlin and Farmingdale.

Additional rainfall amounts up to 1 inch are possible in the warned 
area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3963 8967 3977 8968 3990 8993 3990 8999
      3967 8993

FLASH FLOOD...OBSERVED

$$

37

1 follow-up statement

735 
WGUS73 KILX 120424
FFSILX

Flash Flood Statement
National Weather Service Lincoln IL
1124 PM CDT Sun Jul 11 2021

ILC167-120434-
/O.CAN.KILX.FF.W.0016.000000T0000Z-210712T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sangamon IL-
1124 PM CDT Sun Jul 11 2021

...FLASH FLOOD WARNING IS CANCELLED FOR WEST CENTRAL SANGAMON 
COUNTY...

The heavy rain has ended. Flash flooding is no longer expected to 
pose a threat. Please continue to heed remaining road closures.

LAT...LON 3963 8967 3977 8968 3990 8993 3990 8999
      3967 8993

$$

37

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 11, 7:00 PM CDT	Areal Flood Advisory	ILX	Vermilion	5 hr
Jul 11, 9:31 PM CDT	Flash Flood Warning	ILX	Vermilion	3 hr
Jul 12, 11:20 AM CDT	Areal Flood Advisory	ILX	Macon	6 hr
Jul 12, 2:54 PM CDT	Severe Thunderstorm Warning	ILX	Edgar	30 min

Nearby

Flash Flood Warnings in Illinois, 2021 Every flash flood warning in 2021

Sources

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