Alert archive / Illinois / Flash Flood Warnings in 2023

Flash Flood Warning 4, NWS St. Louis, MO

May 7, 2023Montgomery County, Illinois

NWS St. Louis, MO issued this flash flood warning at May 7, 2023, 10:13 PM CDT for Montgomery County, Illinois. It was in force for 6 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
May 7, 2023, 10:13 PM CDT (03:13 UTC)
Expired
May 8, 2023, 4:15 AM CDT
In force
6 hr
Issued by
NWS St. Louis, MO
Area
Storm-based polygon
Flood severity
None

County Montgomery County, IL

The radar

The Lincoln radar (KILX), 84 km from the middle of the area, began a volume at 03:12 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.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 3.2 hours before the alert went out and 119 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 00:00Z on 2023-05-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2003 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 00:00Z on 2023-05-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -67 square meters per square second.19395878Sfc1 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
2003 J/kg
Mixed-layer CIN
-80 J/kg
Mixed-layer LCL
822 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
-67 m²/s²
0-3 km storm-relative helicity
-65 m²/s²
Significant tornado parameter
-0.6
Supercell composite
-3.3

Open this sounding in Storm Lab

The text

As transmitted.

833 
WGUS53 KLSX 080313
FFWLSX
ILC135-080915-
/O.NEW.KLSX.FF.W.0004.230508T0313Z-230508T0915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
1013 PM CDT Sun May 7 2023

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Northwestern Montgomery County in south central Illinois...

* Until 415 AM CDT Monday.

* At 1013 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 3 and 4 inches of rain 
  have fallen since late Sunday afternoon. 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...
  White Oak, Farmersville, Waggoner and Harvel.

This includes the following streams and drainages...
  Shop Creek, Macoupin Creek, West Branch Horse Creek, Horse Creek, 
  West Fork Shoal Creek and Deer Branch.

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 3935 8953 3934 8970 3935 8970 3937 8970
      3938 8970 3942 8970 3949 8970 3951 8970
      3952 8970 3952 8964 3952 8953 3947 8953
      3944 8953 3942 8953

FLASH FLOOD...RADAR INDICATED

$$

Carney
2 follow-up statements
848 
WGUS73 KLSX 080546
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
1246 AM CDT Mon May 8 2023

ILC135-080915-
/O.CON.KLSX.FF.W.0004.000000T0000Z-230508T0915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery IL-
1246 AM CDT Mon May 8 2023

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 415 AM CDT EARLY THIS 
MORNING FOR NORTHWESTERN MONTGOMERY COUNTY IN SOUTH CENTRAL 
ILLINOIS...

At 1246 AM CDT, Doppler radar indicate showers and a few 
thunderstorms continue to move across the area where earlier 
thunderstorms produced between 3 and 5 inches of rain. Additional 
rainfall amounts up to 1 inch 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...
  White Oak, Farmersville, Waggoner and Harvel.

This includes the following streams and drainages...
  Horse Creek, Macoupin Creek, Shop Creek, Deer Branch, West Fork 
  Shoal Creek and West Branch Horse Creek.

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 3935 8953 3934 8970 3935 8970 3937 8970
      3938 8970 3942 8970 3949 8970 3951 8970
      3952 8970 3952 8964 3952 8953 3947 8953
      3944 8953 3942 8953

FLASH FLOOD...RADAR INDICATED

$$

Britt
910 
WGUS73 KLSX 080911
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
411 AM CDT Mon May 8 2023

ILC135-080921-
/O.EXP.KLSX.FF.W.0004.000000T0000Z-230508T0915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery IL-
411 AM CDT Mon May 8 2023

...FLASH FLOOD WARNING WILL EXPIRE AT 415 AM CDT EARLY THIS MORNING 
FOR NORTHWESTERN MONTGOMERY COUNTY IN SOUTH CENTRAL ILLINOIS...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

LAT...LON 3935 8953 3934 8970 3935 8970 3937 8970
      3938 8970 3942 8970 3949 8970 3951 8970
      3952 8970 3952 8964 3952 8953 3947 8953
      3944 8953 3942 8953

$$

Fuchs

The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 7, 7:19 PM CDTAreal Flood AdvisoryLSXBond, Fayette, Montgomery3 hr
May 7, 7:21 PM CDTSevere Thunderstorm WarningLSXBrown9 min
May 8, 12:15 AM CDTAreal Flood AdvisoryLSXFayette, Montgomery6 hr
May 8, 11:00 AM CDTRiver Flood WarningLSXCalhoun, Greene, Jersey21 days

Nearby

Flash Flood Warnings in Illinois, 2023Every flash flood warning in 2023

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.