Alert archive / Illinois / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 30, NWS Chicago, IL

May 14, 2018LaSalle County, Livingston County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at May 14, 2018, 9:10 PM CDT for LaSalle County, Livingston County, Illinois. It was in force for 50 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 14, 2018, 9:10 PM CDT (02:10 UTC)
Expired
May 14, 2018, 10:00 PM CDT
In force
50 min
Issued by
NWS Chicago, IL
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties LaSalle County, IL, Livingston County, IL

The radar

The Chicago radar (KLOT), 76 km from the middle of the area, began a volume at 02:10 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, 2.2 hours before the alert went out and 108 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 2018-05-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 920 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 2018-05-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 85 square meters per square second.193958Sfc1 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
920 J/kg
Mixed-layer CIN
-14 J/kg
Mixed-layer LCL
2073 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
85 m²/s²
0-3 km storm-relative helicity
60 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.2

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 14, 9:03 PM CDT, 7 minutes earlier.

Area forecast discussion, May 14, 9:03 PM CDT, 7 minutes before
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Hazardous weather outlook, May 14, 3:05 PM CDT, 6 hours 5 minutes before
Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
305 PM CDT Mon May 14 2018

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
152015-
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-
305 PM CDT Mon May 14 2018 /405 PM EDT Mon May 14 2018/

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 Hail Risk...up to golf ball size.
      Elevated Thunderstorm Wind Damage Risk...up to 60 mph.
  Elevated Flooding Risk.

DISCUSSION:

Additional scattered thunderstorms expected this afternoon
into the evening across the entire outlook area. Expect
thunderstorms to develop along and west of I-39 in northern IL,
with continued scattered thunderstorm development expected to move
east into other areas in northern IL and northwest IN soon there
after. This thunderstorm development is expected to persist
through early evening, shifting focus more into northwest IN
during that time, before exiting by mid to late evening. With any
storms that will occur today, large hail, damaging winds, and
heavy rainfall remain the primary hazards.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Tuesday...
  Limited Flooding Risk.
  Limited Thunderstorm Risk.
Wednesday through Sunday...
  Limited Thunderstorm Risk.

DISCUSSION:

Thunderstorm chances continue this week but with lower
probabilities.

.SPOTTER INFORMATION STATEMENT...

Spotters will likely be needed this afternoon and evening.

GENERAL STORM MOTION OF THE DAY:

Moving east northeast at 30 to 40 mph.

&&

LMZ740>745-152015-
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-
305 PM CDT Mon May 14 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.

  Significant Thunderstorm Risk.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Tuesday...
  Limited Thunderstorm Risk.
Saturday and Sunday...
  Limited Thunderstorm Risk.

&&

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-152015-
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-
305 PM CDT Mon May 14 2018

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

.DAY ONE...Tonight.

Significant Thunderstorm Risk for the south half of the lake.

Areas of fog are possible across the south half.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Limited Thunderstorm Risk Tuesday for the south half, and
again Saturday and Sunday for the entire lake.

&&

Rodriguez

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In the hours before

Special weather statement, May 14, 7:08 PM CDT, 2 hours 2 minutes before
Special Weather Statement
National Weather Service Chicago/Romeoville Il
708 PM CDT MON MAY 14 2018

ILZ032-150030-
Livingston IL-
708 PM CDT MON MAY 14 2018

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL LIVINGSTON COUNTY UNTIL
730 PM CDT...

At 707 PM CDT, Doppler radar was tracking a strong thunderstorm over
Chenoa, or 8 miles west of Fairbury, moving northeast at 25 mph.

Nickel size hail and wind gusts of 50 to 55 mph will be possible with
this storm.

Locations impacted include...
Pontiac, Fairbury and Forrest.

A severe thunderstorm watch remains in effect until 1000 PM CDT for
central Illinois.

LAT...LON 4076 8858 4076 8876 4096 8860 4074 8836
      4070 8858
TIME...MOT...LOC 0007Z 238DEG 22KT 4075 8868

BMD
Special weather statement, May 14, 7:21 PM CDT, 1 hour 49 minutes before
Special Weather Statement
National Weather Service Chicago/Romeoville Il
721 PM CDT MON MAY 14 2018

ILZ003-008-010-150045-
Winnebago IL-Ogle IL-Lee IL-
721 PM CDT MON MAY 14 2018

...SIGNIFICANT WEATHER ADVISORY FOR WESTERN OGLE...NORTHWESTERN LEE
AND SOUTHWESTERN WINNEBAGO COUNTIES UNTIL 745 PM CDT...

At 720 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from Forreston to near Fairhaven. Movement was east
at 25 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Dixon, Mount Morris, Polo, Forreston, Leaf River, Nelson and Adeline.

LAT...LON 4220 8969 4220 8940 4225 8940 4225 8921
      4171 8960 4172 8963 4193 8963 4193 8969
TIME...MOT...LOC 0020Z 267DEG 21KT 4215 8960 4189 8993

BMD
Special weather statement, May 14, 7:22 PM CDT, 1 hour 48 minutes before
Special Weather Statement
National Weather Service Chicago/Romeoville Il
722 PM CDT MON MAY 14 2018

ILZ005-006-150045-
Lake IL-McHenry IL-
722 PM CDT MON MAY 14 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN LAKE AND
NORTHEASTERN MCHENRY COUNTIES UNTIL 745 PM CDT...

At 721 PM CDT, Doppler radar was tracking a strong thunderstorm over
Hebron, or 7 miles south of Lake Geneva, moving northeast at 30 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Antioch, Wonder Lake, Spring Grove, Richmond, Hebron, Greenwood,
Channel Lake and Lake Catherine.

LAT...LON 4249 8799 4239 8842 4249 8853
TIME...MOT...LOC 0021Z 242DEG 28KT 4248 8841

BMD
Local storm report, May 14, 7:28 PM CDT, 1 hour 42 minutes before
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Special weather statement, May 14, 7:36 PM CDT, 1 hour 34 minutes before
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Local storm report, May 14, 7:36 PM CDT, 1 hour 34 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
May 14, 7:08 PM CDTSpecial Weather StatementLOTLivingston22 min
May 14, 7:21 PM CDTSpecial Weather StatementLOTOgle24 min
May 14, 7:22 PM CDTSpecial Weather StatementLOTMcHenry23 min
May 14, 8:49 PM CDTAreal Flood AdvisoryLOTLake, McHenry3 hr
May 14, 8:54 PM CDTSevere Thunderstorm WarningLOTDeKalb, Kane, Kendall, Lee, Ogle51 min
May 14, 9:06 PM CDTMarine Dense Fog AdvisoryLOT15 hr
May 14, 10:07 PM CDTSpecial Weather StatementLOTGrundy23 min
May 14, 10:52 PM CDTRiver Flood AdvisoryLOTLake23 hr
May 14, 11:20 PM CDTSpecial Weather StatementLOTLaSalle25 min
May 15, 1:47 PM CDTSmall Craft AdvisoryLOT5 hr
May 14, 7:36 PM CDTSpecial Weather StatementLOTPorter24 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2018Every 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.