Alert archive / Illinois / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 98, NWS Chicago, IL

June 28, 2017Cook County, DuPage County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jun 28, 2017, 11:56 PM CDT for Cook County, DuPage County, Illinois. It was in force for 34 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 28, 2017, 11:56 PM CDT (04:56 UTC)
Expired: Jun 29, 2017, 12:30 AM CDT
In force: 34 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Cook County, IL, DuPage County, IL

The radar

The Chicago radar (KLOT), 35 km from the middle of the area, began a volume at 04:56 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, 4.9 hours before the alert went out and 220 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: 1521 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 1099 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 259 m²/s²
0-3 km storm-relative helicity: 334 m²/s²
Significant tornado parameter: 2.7
Supercell composite: 15.1

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 Jun 28, 9:54 PM CDT, 2 hours 2 minutes earlier.

Area forecast discussion, Jun 28, 9:54 PM CDT, 2 hours 2 minutes before

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Hazardous weather outlook, Jun 28, 3:58 PM CDT, 7 hours 58 minutes before

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
358 PM CDT Wed Jun 28 2017

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
292100-
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-
358 PM CDT Wed Jun 28 2017 /458 PM EDT Wed Jun 28 2017/

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

.DAY ONE...Tonight.

WEATHER HAZARDS EXPECTED:
  Significant Thunderstorm Risk...with an associated:
      Elevated Tornado Risk.
      Elevated Hail Risk...up to half dollar size.
      Significant Thunderstorm Wind Damage Risk...up to 70
       MPH.
  Elevated Flooding Risk.

DISCUSSION:

With low level moisture and instability increasing this
afternoon, a broken line of thunderstorms has developed. The line
should increase in coverage to a more solid line through the
remainder of the afternoon hours. While the line is currently east
of the Rockford area, it is tracking to the east and should reach
the Chicago Metro Area and western and southern suburbs by around
5:00 PM CDT. There is still some concern as to whether the line
will hold together as it moves into northwestern Indiana, but that
remains a possibility. Another line of thunderstorms has also
formed west of the outlook area over central Iowa, so there are
concerns that there will be one or more additional rounds of
thunderstorms late this evening and overnight tonight. These
storms will have the potential to produce strong, damaging winds
and large hail. Some storms will also have the potential to
produce locally heavy rainfall, and any training of storms could
produce localized flooding.

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

Thursday...
  Elevated Flooding Risk.
  Elevated Severe Thunderstorm Risk.
Friday...
  Limited Severe Thunderstorm Risk.
Saturday through Tuesday...
  Limited Thunderstorm Risk.

DISCUSSION:

There will be periodic chances for thunderstorms Thursday through
Friday evening. Some of these storms could produce severe weather
and locally heavy rainfall. There will also be periodic chances
for thunderstorms for Monday through midweek, mainly during the
afternoon and early evening hours.

.SPOTTER INFORMATION STATEMENT...

Spotters will likely be needed late this afternoon into tonight
across northern Illinois and northwest Indiana.

GENERAL STORM MOTION OF THE DAY:

Moving east at 45 MPH...

&&

LMZ740>745-292100-
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-
358 PM CDT Wed Jun 28 2017

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.
  Hazardous Conditions for Small Craft are likely.

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

Thursday...
  Elevated Thunderstorm Risk.
  Hazardous Conditions for Small Craft are likely.
Friday...
  Elevated Thunderstorm Risk.
Saturday...
  Limited Thunderstorm Risk.
Monday...
  Limited Thunderstorm Risk.

&&

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-292100-
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-
358 PM CDT Wed Jun 28 2017

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

.DAY ONE...Tonight.

Occasional south gale force gusts are possible into this evening.
Thunderstorms are likely tonight. Some storms could be strong to
severe tonight.

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

Periods of thunderstorms are expected across much of the lake
from Thursday into Saturday. Scattered storms are possible on
the south portion of the lake Sunday through Wednesday.

&&

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In the hours before

Local storm report, Jun 28, 10:38 PM CDT, 1 hour 18 minutes before

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Local storm report, Jun 28, 10:39 PM CDT, 1 hour 17 minutes before

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Local storm report, Jun 28, 10:43 PM CDT, 1 hour 13 minutes before

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Local storm report, Jun 28, 11:03 PM CDT, 53 minutes before

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Local storm report, Jun 28, 11:17 PM CDT, 39 minutes before

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Special weather statement, Jun 28, 11:36 PM CDT, 20 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 28, 7:10 PM CDT	Severe Thunderstorm Warning	LOT	Boone, Winnebago	65 min
Jun 28, 7:40 PM CDT	Tornado Warning	LOT	Winnebago	20 min
Jun 28, 7:55 PM CDT	Severe Thunderstorm Warning	LOT	Boone, DeKalb, Kane, McHenry, Ogle, Winnebago	65 min
Jun 28, 8:03 PM CDT	Flash Flood Watch	LOT	Boone, DeKalb, DuPage, Kane, Lake, Lee and 3 more	8 hr
Jun 28, 8:07 PM CDT	Special Marine Warning	LOT		3 hr
Jun 28, 8:19 PM CDT	Tornado Warning	LOT	Boone, DeKalb	26 min
Jun 28, 8:24 PM CDT	Flash Flood Warning Emergency	LOT	Boone, Winnebago	6 hr
Jun 28, 8:35 PM CDT	Severe Thunderstorm Warning	LOT	Lake	50 min
Jun 28, 8:38 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DeKalb, DuPage, Kane, McHenry	52 min
Jun 28, 9:09 PM CDT	Flash Flood Warning	LOT	Lake, McHenry	6 hr
Jun 28, 10:47 PM CDT	River Flood Advisory	LOT	Boone	3 days
Jun 28, 11:36 PM CDT	Special Weather Statement	LOT	DuPage	24 min
Jun 28, 11:58 PM CDT	Special Marine Warning	LOT		92 min
Jun 29, 2:28 AM CDT	Areal Flood Warning	LOT	Boone, Winnebago	15 hr
Jun 29, 4:39 AM CDT	River Flood Warning	LOT	Boone	30 hr
Jun 29, 4:39 AM CDT	River Flood Warning	LOT	Winnebago	41 hr
Jun 29, 6:05 AM CDT	River Flood Warning	LOT	Ogle	39 hr
Jun 29, 9:25 AM CDT	River Flood Advisory	LOT	Winnebago	59 hr
Jun 29, 9:25 AM CDT	River Flood Advisory	LOT	Winnebago	36 hr
Jun 29, 9:25 AM CDT	River Flood Advisory	LOT	Lee	71 hr
Jun 29, 9:32 AM CDT	River Flood Watch	LOT	Winnebago	4 days
Jun 29, 10:02 AM CDT	River Flood Advisory	LOT	Kane, Kendall	36 hr
Jun 29, 10:02 AM CDT	River Flood Advisory	LOT	Cook	36 hr
Jun 29, 5:58 PM CDT	Severe Thunderstorm Warning	LOT	Iroquois	29 min
Jun 29, 6:03 PM CDT	Special Weather Statement	LOT	Ford	27 min
Jun 29, 6:09 PM CDT	Severe Thunderstorm Warning	LOT	Ford	14 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2017 Every severe thunderstorm warning in 2017

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.