Alert archive / Illinois / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 50, NWS Chicago, IL

August 9, 2001Cook County, DuPage County, Kane County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Aug 9, 2001, 7:55 PM CDT for Cook County, DuPage County, Kane County, Illinois. It was in force for 35 min. 4 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Aug 9, 2001, 7:55 PM CDT (00:55 UTC)
Expired: Aug 9, 2001, 8:30 PM CDT
In force: 35 min
Issued by: NWS Chicago, IL
Area: Whole counties

Counties Cook County, IL, DuPage County, IL, Kane County, IL

The radar

The Chicago radar (KLOT), 32 km from the middle of the area, began a volume at 00:57 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.

What was reported inside it

Time	Report	Where
Aug 9, 7:55 PM CDT	Thunderstorm Wind 50 E	Dundee, IL
Aug 9, 8:10 PM CDT	Thunderstorm Wind 50 E	Barrington, IL
Aug 9, 8:20 PM CDT	Thunderstorm Wind 50 E	Aurora, IL
Aug 9, 8:20 PM CDT	Hail 1.75	Villa Park, IL

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 0.9 hours before the alert went out and 205 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: 561 J/kg
Mixed-layer CIN: -179 J/kg
Mixed-layer LCL: 1554 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 5 m²/s²
0-3 km storm-relative helicity: 12 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

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 Aug 9, 2:50 PM CDT, 5 hours 5 minutes earlier.

Area forecast discussion, Aug 9, 2:50 PM CDT, 5 hours 5 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
250 PM CDT THU AUG 9 2001

MODEL COMPARISONS WITH SFC DATA INDICATE AVN HAS BETTER HANDLE ON
COLD FRONT PLACEMENT WHICH STRETCHES AT 18Z FROM JUST W OF GRB TO
JUST E OF ALO. DEVELOPMENT SO FAR IN IA AND SRN WI HAS BEEN SPARTAN
WITH A FEW SHOWERS FROM MLI ON S THRU BRL. THIS MOVING RATHER SLOWLY
EAST AND PROBABLY WONT REACH CWA TIL 5PM. LOWER DBZ ON 88D INDICATE
THE LINE ASSOCIATED WITH THESE NWRN IL SHWRS APPEARS TO CONTINUE
NEWD THRU RFD TO THE MKE AREA. SAME LIGHT DBZ HIGHLITE THE COLD
FRONT ACROSS WI AND IA.

GOES SOUNDER INDICATES THE MKE AREA HAS SOME DECENT INHIBITION BUT
NOT SO MUCH REST OF NRN IL. ON THE OTHER HAND CAPES ARE BLO 1000 IN
NWRN IL. RICK DIMAIO AT FOX NOTED THE WESTERLY 850 WINDS NOT
SUPPORTIVE OF SEVERE WX WHICH SEEMS TO BE THE CASE ON UPPER AIR PLOT
ACROSS NRN IL. THUS MAY NOT BE RISK OF SEVERE TONIGHT AND MAY EVEN
ISSUE FCST WITH CHC POPS RATHER THAN LIKELY OR CATEGORICAL.

POST FRONTAL COOLING IMMINENT THOUGH LOOKING AT TEMPS AND DWPTS WEST
OF COLD FRONT. THUS WILL KEEP HEAT WARNG GOING WITH THE 330PM
PACKAGE AND HAVE EVENING SHIFT CANCEL IT WITH FROPA. THAT SHOULD PUT
THIS EVENT TO REST WITH WELCOMED COOLER AND DRIER AIR FOR FRIDAY AND
THE WEEKEND. GUIDANCE HAS ALREADY BACKED OFF FROM MID 70S FOR HIGHS
FRIDAY AND SATURDAY ON AVN AT LEAST AND WILL LIKELY GO WITH NEAR 80
OR 75 TO 80 RANGE.

.CHI...EXCESSIVE HEAT WARNING THRU THIS EVENING CHI METRO.

BRUMER

In the hours before

Local storm report, Aug 9, 7:52 PM CDT, 3 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
Aug 9, 7:19 PM CDT	Severe Thunderstorm Warning	LOT	Lake, McHenry	41 min
Aug 9, 7:28 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb	32 min
Aug 9, 7:41 PM CDT	Severe Thunderstorm Warning	LOT	Kane	19 min
Aug 9, 7:55 PM CDT	Severe Thunderstorm Warning	LOT	Kendall	35 min
Aug 9, 8:32 PM CDT	Severe Thunderstorm Warning	LOT	Grundy, LaSalle	43 min
Aug 9, 9:29 PM CDT	Severe Thunderstorm Warning	LOT	Kankakee, Will	31 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2001 Every severe thunderstorm warning in 2001

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.