Alert archive / Illinois / Flash Flood Warnings in 2019

Flash Flood Warning 17, NWS Chicago, IL

September 12, 2019Lake County, McHenry County, Illinois

NWS Chicago, IL issued this flash flood warning at Sep 12, 2019, 2:53 AM CDT for Lake County, McHenry 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 counties it named.

The facts

Issued
Sep 12, 2019, 2:53 AM CDT (07:53 UTC)
Expired
Sep 12, 2019, 5:45 AM CDT
In force
3 hr
Issued by
NWS Chicago, IL
Area
Storm-based polygon
Flood severity
None

Counties Lake County, IL, McHenry County, IL

The radar

The Milwaukee radar (KMKX), 77 km from the middle of the area, began a volume at 07:55 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

Davenport, (KDVN), launched 00:00Z, 7.9 hours before the alert went out and 209 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, Davenport, at 00:00Z on 2019-09-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2078 joules per kilogram.LCLEL10008507005003002001001 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, Davenport, at 00:00Z on 2019-09-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 54 square meters per square second.193958Sfc1 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
2078 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
1188 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
54 m²/s²
0-3 km storm-relative helicity
156 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

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 Chicago, IL wrote its last area forecast discussion before this flash flood warning went out at Sep 12, 1:06 AM CDT, 1 hour 47 minutes earlier.

Area forecast discussion, Sep 12, 1:06 AM CDT, 1 hour 47 minutes before
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Hazardous weather outlook, Sep 11, 3:37 PM CDT, 11 hours 16 minutes before
Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
337 PM CDT Wed Sep 11 2019

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
122045-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-Cook-
La Salle-Kendall-Grundy-Will-Kankakee-Livingston-Iroquois-Ford-
Lake IN-Porter-Newton-Jasper-Benton-
337 PM CDT Wed Sep 11 2019 /437 PM EDT Wed Sep 11 2019/

This Hazardous Weather Outlook is for portions of North Central
Illinois...Northeast Illinois and Northwest Indiana.

.DAY ONE...Tonight.

Weather hazards expected...

  Elevated Thunderstorm Risk...with an associated:
     Limited hail risk...up to 1 inches in diameter.
     Limited damaging wind risk...up to 60 mph.
  Limited Flooding Risk.
  Limited Excessive heat Risk.

DISCUSSION...

  There is a chance of thunderstorms across the entire outlook
  area through tonight, but the stronger, more organized storms
  should be north of I-80. The most likely timing for stronger
  storms will be this evening into early tonight. If storms do
  indeed occur, there is a very limited chance of an isolated
  severe thunderstorm or two. In addition, any storms that
  occur could produce torrential rainfall.

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

Thursday...
  Elevated Severe Thunderstorm Risk.
  Limited Flooding Risk.
  Limited Excessive Heat Risk.
Saturday and Sunday...
  Limited Thunderstorm Risk.
Tuesday...
  Limited Thunderstorm Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotters are not expected to be needed do to the limited nature
  of any severe risk.

GENERAL STORM MOTION OF THE DAY:

  Moving toward to the east at 25 to 30 mph.

LMZ740>745-122045-
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-
337 PM CDT Wed Sep 11 2019

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...Tonight.

Weather hazards expected...

  Elevated Thunderstorm Risk...with an associated:
     Limited hail risk...up to up to 1 inch in diameter.
     Limited thunderstorm wind gust risk...up to 50 knots.

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

Thursday...
  Elevated Thunderstorm Risk.
Saturday and Sunday...
  Limited Thunderstorm Risk.

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In the hours before

Special weather statement, Sep 11, 9:23 PM CDT, 5 hours 30 minutes before
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Special weather statement, Sep 11, 10:04 PM CDT, 4 hours 49 minutes before
Special Weather Statement
National Weather Service Chicago/Romeoville
1004 PM CDT Wed Sep 11 2019

ILZ004>006-011-012-120345-
Lake IL-Kane IL-Boone IL-De Kalb IL-McHenry IL-
1004 PM CDT Wed Sep 11 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN LAKE...NORTHEASTERN
DE KALB...NORTHERN KANE...MCHENRY AND SOUTHERN BOONE COUNTIES UNTIL
1045 PM CDT...

At 1004 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Woodstock to near Marengo. Movement was
southeast at 30 mph.

Half inch hail and wind gusts of 50 to 55 mph will be possible with
these storms.

Locations impacted include...
Carpentersville, Algonquin, McHenry, Belvidere, Woodstock, Loves
Park, Lake Zurich, Wauconda, Barrington, Island Lake, Marengo, Wonder
Lake, Lake In The Hills, Huntley, Gilberts, Hampshire, Poplar Grove,
Lakewood, Oakwood Hills and Prairie Grove.

This includes...  Boone County Fairgrounds, Mchenry County College,
and Mchenry County Fairgrounds.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4219 8806 4215 8820 4215 8824 4214 8824
      4205 8858 4228 8894 4233 8894 4244 8844
TIME...MOT...LOC 0304Z 299DEG 25KT 4234 8843 4223 8870

RODRIGUEZ
Local storm report, Sep 11, 10:33 PM CDT, 4 hours 20 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
1033 PM CDT WED SEP 11 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1020 PM     TSTM WND GST     2 WNW CRYSTAL LAKE      42.25N 88.35W
09/11/2019  E60 MPH          MCHENRY            IL   AMATEUR RADIO

&&
Local storm report, Sep 11, 10:46 PM CDT, 4 hours 7 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
1046 PM CDT WED SEP 11 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0931 PM     TSTM WND GST     3 E ANTIOCH             42.48N 88.04W
09/11/2019  E60 MPH          LAKE               IL   PUBLIC

&&

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 11, 7:10 PM CDTSpecial Marine WarningLOT95 min
Sep 11, 7:46 PM CDTSpecial Weather StatementLOTLake29 min
Sep 11, 9:23 PM CDTSpecial Weather StatementLOTMcHenry67 min
Sep 11, 9:30 PM CDTSevere Thunderstorm WarningLOTLake, McHenry49 min
Sep 11, 9:45 PM CDTSpecial Marine WarningLOT90 min
Sep 11, 10:04 PM CDTSpecial Weather StatementLOTBoone, McHenry41 min
Sep 11, 10:21 PM CDTSevere Thunderstorm WarningLOTCook, Kane, Lake, McHenry33 min
Sep 12, 1:00 AM CDTAreal Flood AdvisoryLOTLake, McHenry4 hr
Sep 12, 3:55 AM CDTSmall Craft AdvisoryLOT47 hr
Sep 12, 3:56 AM CDTBeach Hazards StatementLOTLake29 hr
Sep 12, 5:06 AM CDTRiver Flood WarningLOTLake11 days
Sep 12, 5:06 AM CDTRiver Flood WarningLOTLake12 days
Sep 12, 5:07 AM CDTRiver Flood WarningLOTKane, McHenry16 days
Sep 12, 5:43 AM CDTAreal Flood WarningLOTLake, McHenry5 hr
Sep 12, 7:47 AM CDTMarine Dense Fog AdvisoryLOT5 hr
Sep 12, 9:42 AM CDTRiver Flood WarningLOTLake11 days
Sep 12, 9:42 AM CDTRiver Flood WarningLOTCook9 days
Sep 12, 9:42 AM CDTRiver Flood WarningLOTKane, Kendall36 days
Sep 12, 10:09 AM CDTRiver Flood WatchLOTWinnebago22 hr
Sep 12, 10:14 AM CDTRiver Flood AdvisoryLOTWinnebago36 hr
Sep 12, 12:54 PM CDTSpecial Weather StatementLOTOgle51 min
Sep 12, 1:01 PM CDTTornado WarningLOTOgle44 min
Sep 12, 1:41 PM CDTTornado WarningLOTOgle64 min
Sep 12, 2:48 PM CDTSpecial Weather StatementLOTDeKalb27 min
Sep 12, 3:06 PM CDTSevere Thunderstorm WarningLOTDeKalb, Lee54 min
Sep 12, 3:33 PM CDTTornado WarningLOTDeKalb, Kane42 min
Sep 12, 4:14 PM CDTTornado WarningLOTDeKalb, Kane, Kendall24 min
Sep 12, 6:40 PM CDTSpecial Weather StatementLOTLake50 min

Nearby

Flash Flood Warnings in Illinois, 2019Every flash flood warning in 2019

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.