Alert archive / Illinois / Flash Flood Warnings in 2014

Flash Flood Warning 20, NWS Chicago, IL

July 12, 2014Cook County, Will County, Illinois

NWS Chicago, IL issued this flash flood warning at Jul 12, 2014, 11:35 PM CDT for Cook County, Will 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 counties it named.

The facts

Issued
Jul 12, 2014, 11:35 PM CDT (04:35 UTC)
Expired
Jul 13, 2014, 5:30 AM CDT
In force
6 hr
Issued by
NWS Chicago, IL
Area
Storm-based polygon
Flood severity
None

Counties Cook County, IL, Will County, IL

The radar

The Chicago radar (KLOT), 24 km from the middle of the area, began a volume at 04:34 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, 4.6 hours before the alert went out and 223 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 2014-07-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2609 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 2014-07-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 129 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
2609 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
916 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
129 m²/s²
0-3 km storm-relative helicity
199 m²/s²
Significant tornado parameter
2.0
Supercell composite
13.9

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 Jul 12, 9:54 PM CDT, 1 hour 41 minutes earlier.

Area forecast discussion, Jul 12, 9:54 PM CDT, 1 hour 41 minutes before
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Hazardous weather outlook, Jul 12, 3:43 PM CDT, 7 hours 52 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
343 PM CDT SAT JUL 12 2014

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
132045-
WINNEBAGO-BOONE-MCHENRY-LAKE ILLINOIS-OGLE-LEE-DE KALB-KANE-
DUPAGE-COOK-LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON-
IROQUOIS-FORD-LAKE INDIANA-PORTER-NEWTON-JASPER-BENTON-
343 PM CDT SAT JUL 12 2014 /443 PM EDT SAT JUL 12 2014/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL ILLINOIS...
NORTHEAST ILLINOIS AND NORTHWEST INDIANA.

.DAY ONE...TONIGHT.

  WEATHER HAZARDS EXPECTED:

  THUNDERSTORMS...SOME COULD PRODUCE:
   TORRENTIAL DOWNPOURS LEADING TO LOCALIZED FLASH FLOODING.
   DAMAGING WIND GUSTS IN EXCESS OF 60 MPH.
   FREQUENT CLOUD TO GROUND LIGHTNING.

  AREAS AFFECTED AND TIMING:

  THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS EVENING NORTHWEST OF
  AN AMBOY TO MCHENRY LINE...THEN STEADILY SPREAD SOUTHEAST
  THROUGH ALL OF NORTHERN ILLINOIS AND NORTHWEST INDIANA TONIGHT.

  DISCUSSION:

  WARM AND VERY MOIST AIR WILL CONTINUE TO LIFT NORTH ACROSS
  NORTHERN ILLINOIS AND NORTHWEST INDIANA WITH INSTABILITY
  STEADILY INCREASING INTO THIS EVENING. A FRONTAL BOUNDARY WILL
  BE A FOCUS FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON OVER
  WISCONSIN AND IOWA AND THAT LINE OF STORMS WILL SLOWLY SINK
  SOUTHEAST THROUGH THE WARNING AREA. HEAVY RAIN WILL BE THE MAIN
  THREAT AND FLASH FLOODING AND LOCALIZED FLOODING WILL BE VERY
  POSSIBLE. SEVERE WINDS IN EXCESS OF 60 MPH ARE ALSO POSSIBLE
  ALONG THE LEADING EDGE OF THE STORMS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

THERE WILL BE A SLIGHT CHANCE TO CHANCE FOR THUNDERSTORMS SUNDAY
AFTERNOON THROUGH SUNDAY NIGHT. THEN THERE IS ANOTHER CHANCE FOR
STORMS MONDAY AFTERNOON MAINLY SOUTH OF DIXON TO CHICAGO.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS WILL LIKELY BE NEEDED THROUGH TONIGHT AND SPOTTERS ARE
ENCOURAGED TO REPORT HEAVY RAINFALL TOTALS.

&&

LMZ740>745-132045-
WINTHROP HARBOR TO WILMETTE HARBOR-
WILMETTE HARBOR TO NORTHERLY ISLAND-
NORTHERLY ISLAND TO CALUMET HARBOR-CALUMET HARBOR TO GARY-
GARY TO BURNS HARBOR-BURNS HARBOR TO MICHIGAN CITY-
343 PM CDT SAT JUL 12 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS NEARSHORE
WATERS OF LAKE MICHIGAN AND THE INDIANA NEARSHORE WATERS OF LAKE
MICHIGAN.

.DAY ONE...TONIGHT.

A LINE OF THUNDERSTORMS IS EXPECTED TO SINK SOUTH THROUGH THE
NEARSHORE WATERS THIS EVENING THROUGH TONIGHT. WIND GUSTS IN EXCESS
OF 35 KT WILL BE POSSIBLE WITH THE STRONGER STORMS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

CHANCE FOR THUNDERSTORMS SUNDAY NIGHT...AND AGAIN MONDAY
AFTERNOON.

&&

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-132045-
LAKE MICHIGAN FROM MICHIGAN CITY IN TO ST. JOSEPH MI 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM SEUL CHOIX POINT TO ROCK ISLAND PASSAGE 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN SOUTH OF A LINE FROM SEUL CHOIX POINT TO THE
MACKINAC BRIDGE AND NORTH OF A LINE FROM CHARLEVOIX MI TO SOUTH
FOX ISLAND 5 NM OFFSHORE-
LAKE MICHIGAN FROM CHARLEVOIX TO POINT BETSIE MI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM POINT BETSIE TO MANISTEE MI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM ROCK ISLAND PASSAGE TO STURGEON BAY WI-
LAKE MICHIGAN FROM STURGEON BAY TO TWO RIVERS WI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM TWO RIVERS TO SHEBOYGAN WI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM SHEBOYGAN TO PORT WASHINGTON WI 5 NM OFFSHORE
TO MID LAKE-
LAKE MICHIGAN FROM PORT WASHINGTON TO NORTH POINT LIGHT WI 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM NORTH POINT LIGHT TO WIND POINT WI 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM WIND POINT WI TO WINTHROP HARBOR IL 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM WINTHROP HARBOR TO WILMETTE HARBOR IL 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM WILMETTE HARBOR IL TO MICHIGAN CITY IN 5 NM
OFFSHORE TO MID LAKE-
LAKE MICHIGAN FROM PENTWATER TO MANISTEE MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM WHITEHALL TO PENTWATER MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM GRAND HAVEN TO WHITEHALL MI 5 NM OFFSHORE TO
MID LAKE-
LAKE MICHIGAN FROM HOLLAND TO GRAND HAVEN MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM SOUTH HAVEN TO HOLLAND MI 5 NM OFFSHORE TO MID
LAKE-
LAKE MICHIGAN FROM ST. JOSEPH TO SOUTH HAVEN MI 5 NM OFFSHORE TO
MID LAKE-
343 PM CDT SAT JUL 12 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE OPEN WATERS OF LAKE
MICHIGAN.

.DAY ONE...TONIGHT.

A LINE OF THUNDERSTORMS IS EXPECTED TO SINK SOUTH OVER THE
SOUTHERN TWO THIRDS OF THE LAKE THIS EVENING THROUGH TONIGHT.
WIND GUSTS IN EXCESS OF 35 KT WILL BE POSSIBLE WITH THE STRONGER
STORMS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

SLIGHT CHANCE FOR THUNDERSTORMS LATE SUNDAY MORNING AND THEN AGAIN
SUNDAY AFTERNOON AND NIGHT OVER THE SOUTHERN HALF OF THE LAKE.
THEN THERE IS AN ADDITIONAL CHANCE FOR THUNDERSTORMS MONDAY
AFTERNOON OVER THE FAR SOUTHERN PORTION OF THE LAKE.

JEE

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
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In the hours before

Local storm report, Jul 12, 9:46 PM CDT, 1 hour 49 minutes before
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Local storm report, Jul 12, 9:47 PM CDT, 1 hour 48 minutes before
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Local storm report, Jul 12, 10:10 PM CDT, 1 hour 25 minutes before
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Local storm report, Jul 12, 10:25 PM CDT, 1 hour 10 minutes before
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Special weather statement, Jul 12, 10:41 PM CDT, 54 minutes before
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Local storm report, Jul 12, 10:50 PM CDT, 45 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 12, 8:35 PM CDTSpecial Weather StatementLOTOgle, Winnebago40 min
Jul 12, 8:58 PM CDTRiver Flood WarningLOTCook16 hr
Jul 12, 9:01 PM CDTSpecial Weather StatementLOTOgle, Winnebago29 min
Jul 12, 9:11 PM CDTRiver Flood WarningLOTWill28 hr
Jul 12, 9:11 PM CDTRiver Flood WarningLOTLaSalle63 hr
Jul 12, 9:19 PM CDTSevere Thunderstorm WarningLOTLee, Ogle, Winnebago56 min
Jul 12, 9:32 PM CDTRiver Flood AdvisoryLOTKane, McHenry4 days
Jul 12, 9:32 PM CDTRiver Flood AdvisoryLOTKane, Kendall6 days
Jul 12, 9:53 PM CDTRiver Flood WarningLOTBureau, LaSalle4 days
Jul 12, 9:53 PM CDTSevere Thunderstorm WarningLOTDeKalb, Kane, Kendall, LaSalle, Lee, Ogle52 min
Jul 12, 10:03 PM CDTRiver Flood AdvisoryLOTLaSalle4 days
Jul 12, 10:18 PM CDTSpecial Marine WarningLOT117 min
Jul 12, 10:26 PM CDTSpecial Marine WarningLOT2 hr
Jul 12, 10:38 PM CDTAreal Flood AdvisoryLOTBoone, DeKalb, Lee, McHenry, Ogle, Winnebago4 hr
Jul 12, 10:41 PM CDTSpecial Weather StatementLOTCook, DuPage, Kane, Lake, McHenry49 min
Jul 12, 10:59 PM CDTAreal Flood AdvisoryLOTCook, DuPage, Kane, Kendall, Lake, McHenry and 1 more6 hr
Jul 13, 1:37 AM CDTAreal Flood AdvisoryLOTFord, Livingston4 hr
Jul 13, 2:15 AM CDTSpecial Weather StatementLOTIroquois45 min
Jul 13, 9:22 AM CDTRiver Flood AdvisoryLOTWill22 hr
Jul 13, 9:22 AM CDTRiver Flood AdvisoryLOTCook16 hr
Jul 13, 9:22 AM CDTRiver Flood AdvisoryLOTLaSalle36 hr
Jul 13, 10:53 AM CDTRiver Flood AdvisoryLOTGrundy29 hr
Jul 13, 2:54 AM CDTSpecial Weather StatementLOTBenton36 min

Nearby

Flash Flood Warnings in Illinois, 2014Every flash flood warning in 2014

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.