Alert archive / Illinois / Flash Flood Warnings in 2011

Flash Flood Warning 21, NWS Chicago, IL

July 23, 20115 counties in Illinois; Lake County, Porter County, Indiana

NWS Chicago, IL issued this flash flood warning at Jul 23, 2011, 2:37 AM CDT for 5 counties in Illinois; Lake County, Porter County, Indiana. It was in force for 5 hr. 3 reports 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 23, 2011, 2:37 AM CDT (07:37 UTC)
Expired: Jul 23, 2011, 7:30 AM CDT
In force: 5 hr
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Flood severity: None

Counties Cook County, IL, DuPage County, IL, Kane County, IL, Kendall County, IL, Will County, IL, Lake County, IN, Porter County, IN

The radar

The Chicago radar (KLOT), 35 km from the middle of the area, began a volume at 07:39 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 23, 2:45 AM CDT	HEAVY RAIN 1.6	Naperville, IL	1.00 INCHES IN PAST 10 MINUTES.
Jul 23, 7:00 AM CDT	HEAVY RAIN 1.38	Aurora, IL	24-HOUR TOTAL.
Jul 23, 7:00 AM CDT	HEAVY RAIN 2.46	St. Charles, IL	24-HOUR TOTAL. 1.77 INCHES FELL OVERNIGHT.

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, 7.6 hours before the alert went out and 176 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: 4513 J/kg
Mixed-layer CIN: -25 J/kg
Mixed-layer LCL: 1153 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 88 m²/s²
0-3 km storm-relative helicity: 102 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 5.7

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

481 
WGUS53 KLOT 230737
FFWLOT
ILC031-043-089-093-197-INC089-127-231230-
/O.NEW.KLOT.FF.W.0021.110723T0737Z-110723T1230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
237 AM CDT SAT JUL 23 2011

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL LAKE COUNTY IN NORTHWEST INDIANA...
  EASTERN KENDALL COUNTY IN NORTHEAST ILLINOIS...
  NORTHERN PORTER COUNTY IN NORTHWEST INDIANA...
  SOUTHEASTERN KANE COUNTY IN NORTHEAST ILLINOIS...
  SOUTHERN COOK COUNTY IN NORTHEAST ILLINOIS...
  WESTERN DUPAGE COUNTY IN NORTHEAST ILLINOIS...
  WILL COUNTY IN NORTHEAST ILLINOIS...

* UNTIL 730 AM CDT

* AT 237 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS WESTERN  
  DUPAGE AND NORTHERN WILL COUNTIES. THESE THUNDERSTORMS ARE         
  EXPECTED TO MOVE SOUTHEAST...AFFECTING NORTH CENTRAL WILL AND 
  SOUTHWEST COOK COUNTIES...AS WELL AS CENTRAL LAKE COUNTY IN 
  NORTHWEST INDIANA. RAINFALL RATES UP TO 3 INCHES PER HOUR ARE      
  POSSIBLE FROM THESE THUNDERSTORMS. THIS AMOUNT OF RAINFALL CAN
  QUICKLY CAUSE FLASH FLOODING...ESPECIALLY IN URBAN AREAS.

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
  OCCUR. VISIBILITIES WILL ALSO BE REDUCED TO NEAR ZERO UNDER THE    
  HEAVIEST STORMS. ADDITIONAL THUNDERSTORMS WILL BE POSSIBLE DURING  
  THE EARLY MORNING HOURS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. DO
NOT ENTER THE WATER. TURN AROUND AND MOVE UP TO HIGHER GROUND TO
ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS SUBJECT TO FLOODING WHEN
WATER BEGINS RISING.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

&&

LAT...LON 4131 8752 4130 8803 4142 8825 4146 8825
      4146 8833 4147 8836 4199 8849 4200 8823
      4169 8797 4149 8757 4152 8724 4163 8723
      4166 8715 4166 8708 4172 8694 4169 8692
      4144 8692

$$

CMS

4 follow-up statements

061 
WGUS73 KLOT 230836
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
336 AM CDT SAT JUL 23 2011

ILC031-043-089-093-197-INC089-127-231230-
/O.CON.KLOT.FF.W.0021.000000T0000Z-110723T1230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
KANE IL-KENDALL IL-WILL IL-DUPAGE IL-PORTER IN-COOK IL-LAKE IN-
336 AM CDT SAT JUL 23 2011

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR CENTRAL LAKE...SOUTHERN
COOK...NORTHERN PORTER...WESTERN DUPAGE...WILL...EASTERN KENDALL AND
SOUTHEASTERN KANE COUNTIES UNTIL 730 AM CDT...

AT 336 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS EAST 
CENTRAL WILL AND SOUTHWEST COOK COUNTIES...MOVING SOUTHEAST. 
RAINFALL RATES UP TO 3 INCHES PER HOUR ARE POSSIBLE FROM THESE 
THUNDERSTORMS. THIS AMOUNT OF RAINFALL CAN QUICKLY CAUSE FLASH 
FLOODING...ESPECIALLY IN URBAN AREAS.

RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
OCCUR. VISIBILITIES WILL ALSO BE REDUCED TO NEAR ZERO UNDER THE    
HEAVIEST STORMS. ADDITIONAL THUNDERSTORMS WILL BE POSSIBLE DURING 
THE EARLY MORNING HOURS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLOODING IS OBSERVED...ACT QUICKLY. DO NOT
ENTER THE WATER. TURN AROUND AND MOVE UP TO HIGHER GROUND. DO NOT
STAY IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

&&

LAT...LON 4131 8752 4130 8803 4142 8825 4146 8825
      4146 8833 4147 8836 4199 8849 4200 8823
      4169 8797 4149 8757 4152 8724 4163 8723
      4166 8715 4166 8708 4172 8694 4169 8692
      4144 8692

$$

CMS

864 
WGUS73 KLOT 231014
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
514 AM CDT SAT JUL 23 2011

ILC031-043-089-093-197-INC089-127-231230-
/O.CON.KLOT.FF.W.0021.000000T0000Z-110723T1230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
KANE IL-KENDALL IL-WILL IL-DUPAGE IL-PORTER IN-COOK IL-LAKE IN-
514 AM CDT SAT JUL 23 2011

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR CENTRAL LAKE...SOUTHERN
COOK...NORTHERN PORTER...WESTERN DUPAGE...WILL...EASTERN KENDALL AND
SOUTHEASTERN KANE COUNTIES UNTIL 730 AM CDT...

AT 507 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS WITH VERY HEAVY RAINFALL CONTINUING TO EXIT THE WARNED 
AREA. ALTHOUGH THESE STORMS ARE EXITING...THEY HAVE PRODUCED UP TO 
ONE TO TWO INCHES OF RAINFALL IN A VERY SHORT AMOUNT OF TIME IN MANY 
LOCATIONS. THESE RAINFALL TOTALS AS WELL AS CONTINUED DEVELOPMENT OF 
THUNDERSTORMS TO THE WEST WILL CONTINUE TO PROVIDE FLASH FLOODING 
EARLY THIS MORNING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE ELEVATED LEVELS ON SMALL
CREEKS AND STREAMS...PONDING OF WATER ON ROADS...URBAN AREAS...
HIGHWAYS... UNDERPASSES AND LOW LYING AREAS.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLOODING IS OBSERVED...ACT QUICKLY. DO NOT
ENTER THE WATER. TURN AROUND AND MOVE UP TO HIGHER GROUND. DO NOT
STAY IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

&&

LAT...LON 4131 8752 4130 8803 4142 8825 4146 8825
      4146 8833 4147 8836 4199 8849 4200 8823
      4169 8797 4149 8757 4152 8724 4163 8723
      4166 8715 4166 8708 4172 8694 4169 8692
      4144 8692

$$

RODRIGUEZ

749 
WGUS73 KLOT 231152
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
652 AM CDT SAT JUL 23 2011

ILC031-043-089-093-197-INC089-127-231230-
/O.CON.KLOT.FF.W.0021.000000T0000Z-110723T1230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
KANE IL-KENDALL IL-WILL IL-DUPAGE IL-PORTER IN-COOK IL-LAKE IN-
652 AM CDT SAT JUL 23 2011

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR CENTRAL LAKE...SOUTHERN
COOK...NORTHERN PORTER...WESTERN DUPAGE...WILL...EASTERN KENDALL AND
SOUTHEASTERN KANE COUNTIES UNTIL 730 AM CDT...

AT 648 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS WITH VERY HEAVY RAINFALL HAVE SINCE EXITED THE WARNED 
AREA. ALTHOUGH THESE STORMS HAVE EXITED...THEY PRODUCED UP TO 
ONE TO TWO INCHES OF RAINFALL IN A VERY SHORT AMOUNT OF TIME IN MANY 
LOCATIONS. THESE RAINFALL TOTALS AS WELL AS CONTINUED THUNDERSTORM 
DEVELOPMENT OFF TO THE WEST WILL CONTINUE TO PROVIDE FLASH FLOODING 
EARLY THIS MORNING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE ELEVATED LEVELS ON SMALL
CREEKS AND STREAMS...PONDING OF WATER ON ROADS...URBAN AREAS...
HIGHWAYS... UNDERPASSES AND LOW LYING AREAS.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

&&

LAT...LON 4131 8752 4130 8803 4142 8825 4146 8825
      4146 8833 4147 8836 4199 8849 4200 8823
      4169 8797 4149 8757 4152 8724 4163 8723
      4166 8715 4166 8708 4172 8694 4169 8692
      4144 8692

$$

RODRIGUEZ

798 
WGUS73 KLOT 231232
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
732 AM CDT SAT JUL 23 2011

ILC031-043-089-093-197-INC089-127-231247-
/O.EXP.KLOT.FF.W.0021.000000T0000Z-110723T1230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
KANE IL-KENDALL IL-WILL IL-DUPAGE IL-PORTER IN-COOK IL-LAKE IN-
732 AM CDT SAT JUL 23 2011

...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR CENTRAL LAKE...
SOUTHERN COOK...NORTHERN PORTER...WESTERN DUPAGE...WILL...EASTERN
KENDALL AND SOUTHEASTERN KANE COUNTIES HAS BEEN REPLACED WITH A NEW 
FLASH FLOOD WARNING THIS MORNING WITH FLOODING CONTINUING ACROSS 
MANY AREAS.

LAT...LON 4131 8752 4130 8803 4142 8825 4146 8825
      4146 8833 4147 8836 4199 8849 4200 8823
      4169 8797 4149 8757 4152 8724 4163 8723
      4166 8715 4166 8708 4172 8694 4169 8692
      4144 8692

$$

RODRIGUEZ

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 23, 12:11 AM CDT	Special Weather Statement	LOT	Ogle, Winnebago	64 min
Jul 23, 12:36 AM CDT	Flash Flood Warning	LOT	Boone, Cook, DeKalb, Kane, Lake, McHenry and 2 more	6 hr
Jul 23, 12:41 AM CDT	Severe Thunderstorm Warning	LOT	Boone, DeKalb, Lee, McHenry, Ogle, Winnebago	64 min
Jul 23, 12:53 AM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	54 min
Jul 23, 12:58 AM CDT	Special Marine Warning	LOT		2 hr
Jul 23, 1:19 AM CDT	Flash Flood Warning	LOT	Cook, DuPage	6 hr
Jul 23, 1:50 AM CDT	Special Weather Statement	LOT	DuPage	55 min
Jul 23, 3:00 AM CDT	Special Marine Warning	LOT		48 min
Jul 23, 3:40 AM CDT	Heat Advisory	LOT	DeKalb, Grundy, Kane, Kendall, LaSalle, Lee and 2 more	32 hr
Jul 23, 5:21 AM CDT	River Flood Warning	LOT	Cook	38 hr
Jul 23, 5:21 AM CDT	River Flood Warning	LOT	Cook	3 days
Jul 23, 6:14 AM CDT	River Flood Advisory	LOT	Will	9 hr
Jul 23, 6:30 AM CDT	Flash Flood Warning	LOT	Boone, Cook, DeKalb, Kane, Lake, Lee and 3 more	5 hr
Jul 23, 7:30 AM CDT	Flash Flood Warning	LOT	Cook, DuPage, Kane, Will	4 hr
Jul 23, 9:37 AM CDT	River Flood Warning	LOT	Kane, McHenry	11 hr
Jul 23, 9:37 AM CDT	River Flood Warning	LOT	Kane, Kendall	23 hr
Jul 23, 11:13 AM CDT	Areal Flood Warning	LOT	Cook, DuPage, Lake	19 hr
Jul 23, 2:46 PM CDT	River Flood Warning	LOT	Will	43 hr
Jul 23, 4:15 PM CDT	Flash Flood Watch	LOT	Boone, DeKalb, DuPage, Kane, Kendall, Lake and 4 more	18 hr
Jul 22, 10:20 PM CDT	Flash Flood Warning	LOT	Jasper, Lake, Newton, Porter	6 hr
Jul 23, 8:09 AM CDT	Rip Current Statement	LOT	Lake, Porter	6 hr
Jul 23, 5:27 PM CDT	Special Weather Statement	LOT	Jasper	33 min
Jul 23, 6:41 PM CDT	Areal Flood Advisory	LOT	Jasper, Newton	3 hr

Nearby

Flash Flood Warnings in Illinois, 2011 Flash Flood Warnings in Indiana, 2011 Every flash flood warning in 2011

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.