Alert archive / Illinois / Severe Thunderstorm Warnings in 2010

Severe Thunderstorm Warning 49, NWS Chicago, IL

June 18, 20104 counties in Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jun 18, 2010, 7:38 PM CDT for 4 counties in Illinois. It was in force for 52 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: Jun 18, 2010, 7:38 PM CDT (00:38 UTC)
Expired: Jun 18, 2010, 8:30 PM CDT
In force: 52 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 1.0 in
Wind: 70.0 mph

Counties DeKalb County, IL, LaSalle County, IL, Lee County, IL, Ogle County, IL

The radar

The Chicago radar (KLOT), 84 km from the middle of the area, began a volume at 00:41 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
Jun 18, 12:29 PM CDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 0.6 hours before the alert went out and 120 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: 1389 J/kg
Mixed-layer CIN: -99 J/kg
Mixed-layer LCL: 1139 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 231 m²/s²
0-3 km storm-relative helicity: 325 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.4

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 Jun 18, 6:43 PM CDT, 55 minutes earlier.

Area forecast discussion, Jun 18, 6:43 PM CDT, 55 minutes before

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Hazardous weather outlook, Jun 18, 12:35 PM CDT, 7 hours 3 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1235 PM CDT FRI JUN 18 2010

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
191745-
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-
1235 PM CDT FRI JUN 18 2010 /135 PM EDT FRI JUN 18 2010/

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

  WEATHER HAZARDS EXPECTED:

  THUNDERSTORMS...SOME LIKELY WILL BE SEVERE PRODUCING:
    DAMAGING WINDS OVER 70 MPH.
    HAIL TO THE SIZE OF HALF DOLLARS.
    TORRENTIAL DOWNPOURS WHICH COULD RESULT IN FLASH FLOODING.
    AND FREQUENT CLOUD TO GROUND LIGHTNING.

  AREAS AFFECTED AND TIMING:

  THUNDERSTORMS...SOME SEVERE...ARE LIKELY THIS AFTERNOON INTO
  EARLY THIS EVENING. THUNDERSTORMS WILL LIKELY MOVE INTO NORTH
  CENTRAL ALONG THE INTERSTATE 39 CORRIDOR AND WEST BETWEEN 2 AND
  3 PM...AFFECTING NORTHEAST ILLINOIS BETWEEN 3 PM AND 6 PM...AND
  INTO NORTHWEST INDIANA BETWEEN 5 PM AND 8 PM.

  DISCUSSION:

  MOSTLY SUNNY SKIES CONTINUE TO HEAT THE ATMOSPHERE...ALLOWING IT
  TO BECOME VERY UNSTABLE. AS INSTABILITY CONTINUES TO INCREASE
  THIS AFTERNOON THE STAGE WILL BE SET FOR STRONG TO SEVERE
  THUNDERSTORMS OVER EASTERN IOWA TO RACE RAPIDLY EAST ACROSS THE
  OUTLOOK AREA. GIVEN THE EXTREME INSTABILITY THE POTENTIAL EXISTS
  FOR FAIRLY WIDESPREAD DAMAGING WINDS...WITH POSSIBLY LOCALLY
  SIGNIFICANT WIND DAMAGE...ACROSS THE OUTLOOK AREA. WHILE THERE
  IS A LOW END POTENTIAL FOR A BRIEF TORNADO ALONG THE LEADING
  EDGE OF THE LINE...OVERWHELMINGLY THE MOST SIGNIFICANT HAZARD
  THIS AFTERNOON WILL BE DAMAGING WINDS.

  GIVEN THE VERY MOIST ATMOSPHERE...THE THUNDERSTORMS WILL BE
  CAPABLE OF PRODUCING VERY HEAVY RAINFALL IN A SHORT PERIOD OF
  TIME WHICH COULD RESULT IN LOCALIZED FLASH FLOODING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

  THERE WILL BE PERIODIC CHANCES OF THUNDERSTORMS FROM SUNDAY
  THROUGH WEDNESDAY NIGHT. THERE IS A SLIGHT CHANCE OF SEVERE
  THUNDERSTORMS IN CENTRAL ILLINOIS SATURDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS WILL LIKELY BE NEEDED BETWEEN 2 PM AND 8 PM THIS
AFTERNOON AND EVENING.

&&

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

LMZ740>745-191745-
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-
1235 PM CDT FRI JUN 18 2010

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

THUNDERSTORMS ARE LIKELY LATE THIS AFTERNOON OR EARLY THIS
EVENING. SOME OF THE STORMS MAY BE SEVERE WITH THE POTENTIAL TO
PRODUCE WIND GUSTS OVER 50 KNOTS AS WELL AS LARGE HAIL AND
FREQUENT LIGHTNING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THERE WILL BE PERIODIC CHANCES OF THUNDERSTORMS FROM SUNDAY
THROUGH WEDNESDAY NIGHT.

&&

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-
870-872-874-876-878-191745-
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 TOW 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-
1235 PM CDT FRI JUN 18 2010

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

THUNDERSTORMS ARE LIKELY EITHER LATE THIS AFTERNOON OR THIS
EVENING. SOME OF THE STORMS MAY BE SEVERE WITH THE POTENTIAL TO
PRODUCE WIND GUSTS OVER 50 KNOTS AS WELL AS LARGE HAIL AND
FREQUENT LIGHTNING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THERE WILL BE PERIODIC CHANCES OF THUNDERSTORMS FROM SUNDAY
THROUGH WEDNESDAY NIGHT.

&&

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

IZZI

In the hours before

Local storm report, Jun 18, 5:58 PM CDT, 1 hour 40 minutes before

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Local storm report, Jun 18, 6:16 PM CDT, 1 hour 22 minutes before

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Local storm report, Jun 18, 6:18 PM CDT, 1 hour 20 minutes before

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Local storm report, Jun 18, 6:19 PM CDT, 1 hour 19 minutes before

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Local storm report, Jun 18, 6:24 PM CDT, 1 hour 14 minutes before

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Local storm report, Jun 18, 6:46 PM CDT, 52 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 18, 8:13 PM CDT	Severe Thunderstorm Warning	LOT	Boone, McHenry, Winnebago	47 min
Jun 18, 8:27 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Kane, Kendall, LaSalle, Lee, Ogle	48 min
Jun 18, 8:47 PM CDT	Flash Flood Warning	LOT	Boone, Cook, DeKalb, DuPage, Kane, Lake and 4 more	3 hr
Jun 18, 8:51 PM CDT	Special Marine Warning	LOT		114 min
Jun 18, 9:01 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Grundy, Kane, Kankakee, Kendall and 5 more	59 min
Jun 18, 9:52 PM CDT	Special Weather Statement	LOT	Cook, Ford, Iroquois, Kankakee, Livingston, Will	53 min
Jun 18, 9:53 PM CDT	Areal Flood Advisory	LOT	Grundy, Kankakee, LaSalle, Livingston	3 hr
Jun 18, 10:49 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kankakee, Kendall, Lake, Will	110 min
Jun 18, 11:01 PM CDT	Areal Flood Advisory	LOT	Ford, Grundy, Iroquois, Kankakee, Livingston	2 hr
Jun 19, 1:17 AM CDT	Areal Flood Advisory	LOT	LaSalle	3 hr
Jun 19, 4:40 AM CDT	River Flood Advisory	LOT	Will	7 hr
Jun 19, 11:14 AM CDT	River Flood Warning	LOT	Bureau, LaSalle	15 days
Jun 19, 1:14 PM CDT	Small Craft Advisory	LOT		6 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 2010 Every severe thunderstorm warning in 2010

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.