Alert archive / Illinois / Severe Thunderstorm Warnings in 2011
Severe Thunderstorm Warning 131, NWS Chicago, IL
NWS Chicago, IL issued this severe thunderstorm warning at Jul 27, 2011, 8:43 PM CDT for 4 counties in Illinois. It was in force for 62 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 27, 2011, 8:43 PM CDT (01:43 UTC)
- Expired
- Jul 27, 2011, 9:45 PM CDT
- In force
- 62 min
- Issued by
- NWS Chicago, IL
- Area
- Storm-based polygon
- Hail
- 0.5 in
- Wind
- 60.0 mph
Counties Boone County, IL, DeKalb County, IL, Ogle County, IL, Winnebago County, IL
The radar
The Chicago radar (KLOT), 98 km from the middle of the area, began a volume at 01:43 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 watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Jul 27, 7:43 PM CDT | Tornado Watch | SPC | 5 hr |
The nearest sounding before it
Davenport, (KDVN), launched 00:00Z, 1.7 hours before the alert went out and 136 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.
- Mixed-layer CAPE
- 4556 J/kg
- Mixed-layer CIN
- -8 J/kg
- Mixed-layer LCL
- 962 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 141 m²/s²
- 0-3 km storm-relative helicity
- 316 m²/s²
- Significant tornado parameter
- 3.9
- Supercell composite
- 19.4
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 27, 6:50 PM CDT, 1 hour 53 minutes earlier.
Area forecast discussion, Jul 27, 6:50 PM CDT, 1 hour 53 minutes before
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</html>Hazardous weather outlook, Jul 27, 4:09 PM CDT, 4 hours 34 minutes before
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 409 PM CDT WED JUL 27 2011 ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019- 282115- 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- 409 PM CDT WED JUL 27 2011 /509 PM EDT WED JUL 27 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: WIND GUSTS UP TO 60 MPH. HEAVY RAINFALL. ISOLATED TORNADOES. FREQUENT LIGHTNING. AREAS AFFECTED AND TIMING: ISOLATED THUNDERSTORMS MAY DEVELOP ALONG A LINE FROM ROCKFORD EASTWARD ACROSS THE NORTHERN CHICAGO METRO LATE THIS AFTERNOON. MORE WIDESPREAD THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS EASTERN IOWA OR NORTHWEST ILLINOIS LATE THIS AFTERNOON AND EARLY THIS EVENING THEN MOVE EASTWARD INTO NORTH CENTRAL AND NORTHEAST ILLINOIS...PRIMARILY ALONG AND NORTH OF INTERSTATE 88 AND INTERSTATE 290. AREAS SOUTH OF THESE HIGHWAYS HAVE A CHANCE FOR THUNDERSTORMS AS WELL. THUNDERSTORMS WILL LIKELY CONTINUE THROUGH THE NIGHT ALONG AND NORTH OF INTERSTATE 80. DISCUSSION: A WARM FRONTAL BOUNDARY LIFTING NORTHWARD ACROSS NORTHERN ILLINOIS WILL BE THE FOCUS FOR THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON THROUGH TONIGHT. IT APPEARS THAT THUNDERSTORMS WILL BEGIN TO DEVELOP ACROSS EASTERN IOWA NORTHWEST ILLINOIS LATE THIS AFTERNOON WITH SOME ISOLATED DEVELOPMENT POSSIBLE ACROSS NORTH CENTRAL AND NORTHEAST ILLINOIS. THUNDERSTORM ACTIVITY IS THEN EXPECTED TO MOVE EASTWARD AND BECOME MORE WIDESPREAD THROUGH THE EVENING AND CONTINUE OVERNIGHT. WITH A VERY MOIST AIR MASS IN PLACE EXTREMELY HEAVY DOWNPOURS ARE LIKELY UNDER THE STRONGEST STORMS WITH RAINFALL RATES OF 1 TO 3 INCHES PER HOUR POSSIBLE. PLACEMENT OF THE FRONT WILL BE KEY IN IDENTIFYING THE AREA WHERE THE HEAVIEST RAIN WILL FALL. AT THIS TIME...THERE IS POTENTIAL FOR HEAVY RAIN AND FLASH FLOODING ALONG AND NORTH OF INTERSTATE 80 INTO FRIDAY MORNING. THE GREATEST THREAT FOR FLASH FLOODING WILL BE ALONG AND NORTH OF INTERSTATE 88 AND INTERSTATE 290. IN ADDITION...STREAMS AT OR NEAR BANKFULL MAY BECOME FURTHER SWOLLEN AS A RESULT OF ANY HEAVY RAINFALL. HIGH HEAT AND HUMIDITY WILL BE A CONCERN ACROSS AREAS FROM PONTIAC TO KANKAKEE TO RENSSELAER WITH HEAT INDEX VALUES BETWEEN 100 AND 110 DEGREES UNTIL EARLY EVENING. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY. THERE IS A CHANCE FOR THUNDERSTORMS THURSDAY THROUGH FRIDAY. THUNDERSTORMS MAY PRODUCE VERY HEAVY RAINFALL... ESPECIALLY FOR LOCATIONS NORTH OF THE INTERSTATE 80 CORRIDOR. HEAT AND HUMIDITY RETURNS TO NORTHERN ILLINOIS AND NORTHWEST INDIANA THURSDAY...MAINLY SOUTH OF INTERSTATE 80 WHERE HEAT INDICES WILL RANGE FROM 100 TO 110 DEGREES. .SPOTTER INFORMATION STATEMENT... SPOTTERS MAY BE NEEDED THIS EVENING AND TONIGHT. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO LMZ740>745-282115- 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- 409 PM CDT WED JUL 27 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 THUNDERSTORMS CAUSING WIND GUSTS IN EXCESS OF 35 KNOTS AND FREQUENT LIGHTNING...AS WELL AS VISIBILITY LESS THAN ONE QUARTER MILE UNDER EXTREMELY HEAVY DOWNPOURS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY. THERE WILL BE PERIODIC CHANCES FOR THUNDERSTORMS THURSDAY 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- 870-872-874-876-878-282115- 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- 409 PM CDT WED JUL 27 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE OPEN WATERS OF LAKE MICHIGAN. .DAY ONE...TONIGHT. SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE THIS AFTERNOON ACROSS CENTRAL AND SOUTHERN SECTIONS OF THE LAKE. ADDITIONAL THUNDERSTORMS ARE EXPECTED THIS EVENING AND TONIGHT ACROSS THESE SAME AREAS. THESE STORMS MAY PRODUCE WIND GUSTS IN EXCESS OF 35 KNOTS AND FREQUENT LIGHTNING....AS WELL AS VISIBILITY LESS THAN ONE QUARTER MILE UNDER EXTREMELY HEAVY DOWNPOURS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY. THERE WILL BE PERIODIC CHANCES FOR THUNDERSTORMS THURSDAY THROUGH FRIDAY. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO MDB
In the hours before
Local storm report, Jul 27, 2:58 PM CDT, 5 hours 45 minutes before
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</html>Local storm report, Jul 27, 5:00 PM CDT, 3 hours 43 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
500 PM CDT WED JUL 27 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1030 AM HEAVY RAIN 2 NE GURNEE 42.40N 87.91W
07/27/2011 M3.93 INCH LAKE IL COCORAHS
RAINFALL IN 2 HOURS. ROADWAYS FLOODED AS WELL AS YARDS
AND FIELDS. DELAYED REPORT DUE TO POWER OUTAGE.
&&
BNThe office that day
Everything else NWS Chicago, IL issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 27, 9:29 PM CDT | Severe Thunderstorm Warning | LOT | Boone, DeKalb, Kane, McHenry | 61 min |
| Jul 27, 9:51 PM CDT | Flash Flood Warning | LOT | Winnebago | 8 hr |
| Jul 27, 9:52 PM CDT | Special Marine Warning | LOT | 113 min | |
| Jul 27, 10:10 PM CDT | Severe Thunderstorm Warning | LOT | Cook, Kane, Lake, McHenry | 80 min |
| Jul 27, 10:39 PM CDT | Areal Flood Advisory | LOT | Lee, Ogle | 7 hr |
| Jul 27, 11:24 PM CDT | Special Weather Statement | LOT | Cook | 36 min |
| Jul 27, 11:43 PM CDT | Special Marine Warning | LOT | 2 hr | |
| Jul 28, 12:00 AM CDT | Special Weather Statement | LOT | Cook, DuPage | 60 min |
| Jul 28, 12:11 AM CDT | Severe Thunderstorm Warning | LOT | Cook, DuPage, Will | 64 min |
| Jul 28, 4:04 AM CDT | Heat Advisory | LOT | DeKalb, DuPage, Ford, Grundy, Iroquois, Kane and 6 more | 17 hr |
| Jul 28, 9:28 AM CDT | River Flood Advisory | LOT | Lake | 20 hr |
| Jul 28, 9:28 AM CDT | River Flood Advisory | LOT | Lake | 48 hr |
| Jul 28, 9:28 AM CDT | River Flood Advisory | LOT | Kane, Kendall | 48 hr |
| Jul 28, 9:32 AM CDT | River Flood Advisory | LOT | Will | 48 hr |
| Jul 28, 9:48 AM CDT | River Flood Watch | LOT | Winnebago | 11 hr |
| Jul 28, 1:04 AM CDT | Special Weather Statement | LOT | Lake, Porter | 56 min |
Nearby
Severe Thunderstorm Warnings in Illinois, 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.