Alert archive / Illinois / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 127, NWS Chicago, IL

July 23, 2011Iroquois County, Illinois; Benton County, Indiana

NWS Chicago, IL issued this severe thunderstorm warning at Jul 23, 2011, 9:18 PM CDT for Iroquois County, Illinois; Benton County, Indiana. It was in force for 57 min. 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 23, 2011, 9:18 PM CDT (02:18 UTC)
Expired
Jul 23, 2011, 10:15 PM CDT
In force
57 min
Issued by
NWS Chicago, IL
Area
Storm-based polygon
Hail
0.5 in
Wind
60.0 mph

Counties Iroquois County, IL, Benton County, IN

The radar

The Chicago radar (KLOT), 112 km from the middle of the area, began a volume at 02:19 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, 2.3 hours before the alert went out and 105 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 2011-07-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2467 joules per kilogram.LCLLFCEL10008507005003002001001 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, Lincoln, IL at 00:00Z on 2011-07-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 47 square meters per square second.1939Sfc1 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
2467 J/kg
Mixed-layer CIN
-38 J/kg
Mixed-layer LCL
1436 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
47 m²/s²
0-3 km storm-relative helicity
82 m²/s²
Significant tornado parameter
0.2
Supercell composite
2.7

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Jul 23, 7:05 PM CDT, 2 hours 13 minutes earlier.

Area forecast discussion, Jul 23, 7:05 PM CDT, 2 hours 13 minutes before
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Hazardous weather outlook, Jul 23, 5:03 PM CDT, 4 hours 15 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
503 PM CDT SAT JUL 23 2011

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
242215-
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-
503 PM CDT SAT JUL 23 2011 /603 PM EDT SAT JUL 23 2011/

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

.DAY ONE...TONIGHT.

  WEATHER HAZARDS EXPECTED:

  THUNDERSTORMS...SOME MAY PRODUCE:

   HEAVY RAINFALL WITH FLASH FLOODING.
   FREQUENT LIGHTNING.
   DAMAGING WINDS IN EXCESS OF 60 MPH.

  OPPRESSIVE HEAT AND HUMIDITY.

  AREAS AFFECTED AND TIMING:

   SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS EVENING
   ACROSS PORTIONS OF NORTHWESTERN INDIANA. ADDITIONAL SCATTERED
   SHOWERS AND THUNDERSTORMS ARE EXPECTED TO MOVE ACROSS PORTIONS
   OF NORTHERN ILLINOIS FROM EASTERN IOWA THIS EVENING.

   A SECOND AREA OF THUNDERSTORMS MAY DEVELOP LATER THIS EVENING
   ACROSS NORTHERN IOWA. SHOULD THESE THUNDERSTORMS DEVELOP...THE
   COMPLEX OF THUNDERSTORMS COULD TRACK ACROSS NORTHERN ILLINOIS
   AND NORTHWESTERN INDIANA LATER TONIGHT. IT APPEARS THAT THE
   BEST AREAS THAT MAY BE IMPACTED BY THESE THUNDERSTORMS WILL BE
   SOME OF THE SAME AREAS ALREADY HIT BY HEAVY RAINFALL OVER THE
   PAST FEW DAYS.

   THE DANGEROUS HEAT AND HUMIDITY WILL CONTINUE...ESPECIALLY
   SOUTH OF INTERSTATE 80.

  DISCUSSION:

   DUE TO THE HEAVY RAINFALL PRODUCED THIS MORNING ACROSS NORTHERN
   ILLINOIS AND THE FACT THAT ADDITIONAL HEAVY RAINFALL IS
   POSSIBLE LATER TONIGHT INTO SUNDAY ACROSS THE SAME
   AREAS...THERE IS A HIGH THREAT FOR ADDITIONAL FLASH FLOODING.
   MUCH IF NOT ALL OF ANY RAINFALL THAT FALLS ACROSS NORTHERN
   ILLINOIS WILL BE CONVERTED TO RUNOFF DUE TO THE SATURATED
   GROUND. THIS RUNOFF COULD EASILY OVERWHELM SMALL STREAMS AND
   DRAINAGE BASINS.

   ALSO DUE TO THE HEAVY RAINFALL OVER THE PAST 48 HOURS LOCATIONS
   ON THE DES PLAINES RIVER HAVE RAPIDLY REACHED FLOOD STAGE AND
   WILL CONTINUE TO RISE THROUGH THIS EVENING.

   LOCATIONS ALONG AND SOUTH OF INTERSTATE 80 SHOULD SEE VERY WARM
   TEMPERATURES TONIGHT...WITH LOWS ONLY DROPPING INTO THE MID TO
   UPPER 70S.

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

LOCATIONS SOUTH OF INTERSTATE 80 WILL SEE HEAT INDEX VALUES OF
110 TO 115 DEGREES ON SUNDAY.

LOCATIONS ALONG THE INTERSTATE 80 CORRIDOR WILL SEE HEAT INDEX
VALUES OF AROUND 105 TO 110 DEGREES ON SUNDAY.

THERE WILL BE PERIODIC CHANCES FOR THUNDERSTORMS SUNDAY AND AGAIN
WEDNESDAY THROUGH FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY THROUGH TONIGHT...ESPECIALLY
FOR FLASH FLOODING.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

LMZ740>745-242215-
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-
503 PM CDT SAT JUL 23 2011

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

.DAY ONE...TONIGHT.

THERE IS A CHANCE OF STORMS CAUSING WIND GUSTS IN EXCESS OF 35
KNOTS AND FREQUENT LIGHTNING.

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

THERE WILL BE PERIODIC CHANCES FOR THUNDERSTORMS SUNDAY AND AGAIN
WEDNESDAY THROUGH FRIDAY.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-242215-
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-
503 PM CDT SAT JUL 23 2011

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

.DAY ONE...TONIGHT.

THERE IS A CHANCE OF STORMS CAUSING WIND GUSTS IN EXCESS OF 35
KNOTS AND FREQUENT LIGHTNING. THE STRONGEST STORMS ARE LIKELY
OVER THE SOUTHERN PORTIONS OF THE LAKE.

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

THERE WILL BE PERIODIC CHANCES FOR THUNDERSTORMS SUNDAY AND AGAIN
TUESDAY NIGHT THROUGH FRIDAY.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

KJB

In the hours before

Special weather statement, Jul 23, 5:27 PM CDT, 3 hours 51 minutes before
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Local storm report, Jul 23, 5:33 PM CDT, 3 hours 45 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 23, 8:57 PM CDTAreal Flood AdvisoryLOTIroquois4 hr
Jul 23, 11:27 PM CDTSpecial Weather StatementLOTCook, DeKalb, DuPage, Kane63 min
Jul 23, 11:43 PM CDTFlash Flood WarningLOTCook, DeKalb, DuPage, Grundy, Kane, Kendall and 2 more6 hr
Jul 24, 5:51 AM CDTSpecial Weather StatementLOTLee, Ogle, Winnebago24 min
Jul 24, 6:19 AM CDTSevere Thunderstorm WarningLOTBoone, DeKalb, Kane, Kendall, Lee, McHenry and 2 more56 min
Jul 24, 6:44 AM CDTSevere Thunderstorm WarningLOTDeKalb, Grundy, Kendall, LaSalle, Lee, Livingston47 min
Jul 24, 8:16 AM CDTSevere Thunderstorm WarningLOTFord, Iroquois, Kankakee, Livingston, Will59 min
Jul 24, 8:26 AM CDTFlash Flood WarningLOTCook, Kane, Kendall, Will106 min
Jul 24, 8:31 AM CDTSpecial Weather StatementLOTDuPage29 min
Jul 24, 8:54 AM CDTRiver Flood AdvisoryLOTKane, Kendall11 hr
Jul 24, 10:07 AM CDTAreal Flood WarningLOTCook, Kane, Kendall, Will6 hr
Jul 24, 9:19 AM CDTSpecial Weather StatementLOTBenton, Jasper, Newton41 min
Jul 24, 9:47 AM CDTSpecial Weather StatementLOTBenton, Jasper13 min
Jul 24, 5:43 PM CDTRip Current StatementLOTLake, Porter13 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 2011Severe Thunderstorm Warnings in Indiana, 2011Every severe thunderstorm 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.