Alert archive / Illinois / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 18, NWS Chicago, IL

May 2, 2018Lake County, McHenry County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at May 2, 2018, 9:08 PM CDT for Lake County, McHenry County, 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: May 2, 2018, 9:08 PM CDT (02:08 UTC)
Expired: May 2, 2018, 10:00 PM CDT
In force: 52 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 1.75 in
Wind: 60.0 mph

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 02:08 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
May 2, 3:56 PM CDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 2.1 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-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: 1023 J/kg
Mixed-layer CIN: -37 J/kg
Mixed-layer LCL: 1402 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 69 m²/s²
0-3 km storm-relative helicity: 184 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 5.1

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 May 2, 6:44 PM CDT, 2 hours 24 minutes earlier.

Area forecast discussion, May 2, 6:44 PM CDT, 2 hours 24 minutes before

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Hazardous weather outlook, May 2, 4:06 PM CDT, 5 hours 2 minutes before

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
406 PM CDT Wed May 2 2018

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
032115-
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-
406 PM CDT Wed May 2 2018 /506 PM EDT Wed May 2 2018/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR North Central Illinois...
Northeast Illinois AND Northwest Indiana.

.DAY ONE...Tonight.

WEATHER HAZARDS EXPECTED:
  Elevated Thunderstorm Risk...with an associated:
      Limited Tornado Risk.
      Elevated Hail Risk...up to quarter size.
      Elevated Thunderstorm Wind Damage Risk...up to 65 MPH.
  Elevated Flooding Risk.

DISCUSSION:

Multiple rounds of thunderstorms are expected through tonight as
as a slow moving cold front approaches from the northwest. Some
storms could be severe with the capability of producing damaging
winds and large hail through this evening. The severe threat
should gradually diminish with time and eastward extent overnight.
Locally heavy rainfall amounts, in excess of an inch, are
possible.

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

Thursday...
  Elevated Flooding Risk.
  Elevated Severe Thunderstorm Risk.
Friday through Sunday...
  Limited Thunderstorm Risk.

DISCUSSION:

Isolated to scattered thunderstorms may occur at times during the
day Thursday, though the best focus for potentially strong to
severe thunderstorms will be from late Thursday afternoon into the
overnight hours of Thursday night. Damaging winds, large hail and
locally heavy rainfall will be possible with these storms.
Thunderstorms will end from northwest to southeast Friday.

.SPOTTER INFORMATION STATEMENT...

Spotters will likely be needed through mid evening.

GENERAL STORM MOTION OF THE DAY:

Moving to the northeast at 45 MPH.

&&

LMZ740>745-032115-
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-
406 PM CDT Wed May 2 2018

THIS HAZARDOUS WEATHER OUTLOOK IS FOR the Illinois nearshore
waters of Lake Michigan AND the Indiana nearshore waters of Lake
Michigan.

.DAY ONE...Tonight.

  Elevated Thunderstorm Risk.

 Some thunderstorms through this evening will be capable of
 producing wind gusts of 34 knots or greater and small hail.

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

Thursday...
  Limited Thunderstorm Risk.
  Hazardous Conditions for Small Craft are possible.
Friday through Sunday...
  Limited Thunderstorm Risk.

&&

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-032115-
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-
406 PM CDT Wed May 2 2018

THIS HAZARDOUS WEATHER OUTLOOK IS FOR the open waters of Lake
Michigan.

.DAY ONE...Tonight.

  Elevated Thunderstorm Risk.

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

Thursday through Sunday...
  Limited Thunderstorm Risk.

&&

JEE

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In the hours before

Local storm report, May 2, 6:29 PM CDT, 2 hours 39 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
629 PM CDT WED MAY 2 2018

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

0620 PM     TSTM WND GST     3 S DUNNS BRIDGE        41.19N 86.97W
05/02/2018  M61 MPH          JASPER             IN   TRAINED SPOTTER

            MEASURED VIA MOBILE WEATHER STATION AT SR 10 AND CR 400E
            IN JASPER COUNTY.

&&

KLUBER

Local storm report, May 2, 6:33 PM CDT, 2 hours 35 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
633 PM CDT WED MAY 2 2018

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

0623 PM     HAIL             BELVIDERE               42.25N 88.85W
05/02/2018  M1.25 INCH       BOONE              IL   AMATEUR RADIO

            RELAYED VIA RFD HAM NET

0607 PM     HAIL             ROCKFORD AIRPORT        42.20N 89.10W
05/02/2018  M2.00 INCH       WINNEBAGO          IL   AMATEUR RADIO

            REPORT RELAYED BY ROCKFORD HAM NET

&&

JEE

Local storm report, May 2, 6:42 PM CDT, 2 hours 26 minutes before

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Local storm report, May 2, 6:50 PM CDT, 2 hours 18 minutes before

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Local storm report, May 2, 6:53 PM CDT, 2 hours 15 minutes before

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Local storm report, May 2, 6:56 PM CDT, 2 hours 12 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
May 2, 7:02 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Kane, Lake, McHenry	43 min
May 2, 7:21 PM CDT	Special Marine Warning	LOT		84 min
May 2, 7:24 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Lake	36 min
May 2, 8:31 PM CDT	Severe Thunderstorm Warning	LOT	Boone, McHenry, Winnebago	59 min
May 2, 8:41 PM CDT	Special Marine Warning	LOT		3 hr
May 2, 8:51 PM CDT	Flash Flood Watch	LOT	Boone, DeKalb, DuPage, Ford, Grundy, Iroquois and 10 more	11 hr
May 2, 11:31 PM CDT	Special Weather Statement	LOT	Kendall	14 min
May 2, 11:41 PM CDT	Special Marine Warning	LOT		2 hr
May 2, 11:48 PM CDT	Special Weather Statement	LOT	DuPage	27 min
May 2, 11:57 PM CDT	Areal Flood Advisory	LOT	Cook, DeKalb, DuPage, Kane, Kendall, LaSalle and 2 more	3 hr
May 3, 8:48 AM CDT	River Flood Warning	LOT	Kane, Kendall	6 days
May 3, 10:16 AM CDT	River Flood Watch	LOT		24 hr
May 3, 11:08 AM CDT	River Flood Advisory	LOT	Will	23 hr
May 2, 8:09 PM CDT	Severe Thunderstorm Warning	LOT	Lake, Porter	51 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2018 Every severe thunderstorm warning in 2018

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.