Alert archive / Illinois / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 72, NWS Chicago, IL

October 24, 2001Cook County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Oct 24, 2001, 9:10 AM CDT for Cook County, Illinois. It was in force for 35 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: Oct 24, 2001, 9:10 AM CDT (14:10 UTC)
Expired: Oct 24, 2001, 9:45 AM CDT
In force: 35 min
Issued by: NWS Chicago, IL
Area: Whole counties

County Cook County, IL

The radar

The Chicago radar (KLOT), 49 km from the middle of the area, began a volume at 14:10 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 12:00Z, 2.2 hours before the alert went out and 210 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: 1102 J/kg
Mixed-layer CIN: -54 J/kg
Mixed-layer LCL: 597 m above ground
0-6 km bulk shear: 65 kt
0-1 km storm-relative helicity: 180 m²/s²
0-3 km storm-relative helicity: 226 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.0

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 Oct 24, 2:45 AM CDT, 6 hours 25 minutes earlier.

Area forecast discussion, Oct 24, 2:45 AM CDT, 6 hours 25 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
245 AM CDT WED OCT 24 2001

TIME TO BATTEN DOWN THE HATCHES.

SEVERE BOW ECHO THAT RAN THROUGH FAR NRN IL NOW WELL ACROSS THE
LAKE. FRONTAL DISCONTINUITY EVIDENT...AS TEMPS SHIFT FROM LOWER 60S
HERE TO LOWER 50S OVER SRN WISCONSIN.

EXTREMELY DYNAMIC SYSTEM TO AFFECT THE REGION THROUGH THE NEAR TERM
OF THE FORECAST. MODEL FORECAST WIND FIELDS STRONGER THAN PROJECTED
LAST NIGHT. NRN ILLINOIS IN THE LEFT FRONT QUAD OF APPROACHING 130+
KNOT 2H JET...PROVIDING ADDITIONAL SUPPORT FOR POWERFUL MIDLEVEL
JET PUNCHING INTO THE AREA. EXPECT SQUALL LINE TO FORM TO OUR WEST
THIS AM AND ROLL THROUGH THE AREA BY EARLY AFTERNOON. DAMAGING
WINDS ARE LIKELY WITH THIS SQUALL LINE...ESPECIALLY XTRM SE
SXNS...WHICH SPC HAS IN A HIGH RISK AREA.

MODELS ARE CONSISTENT TO A DEGREE IN VERY RAPIDLY DEEPENING SFC
LOW...TO THE EXTENT OF A 970MB SURFACE LOW BY EARLY AFTERNOON
THURSDAY. STORM WARNINGS ARE ALREADY POSTED FOR LAKE MICHIGAN...AND
SOME SORT OF WIND ADVISORY/HIGH WIND WARNING WILL LIKELY BE NEEDED
FOR THE DAYLIGHT HOURS TOMORROW.

COLD AIR COMING IN BEHIND THE FRONT WILL SHARPLY DROP TEMPERATURES
THIS AFTERNOON...WITH COLD AIR BECOMING ENTRENCHED FROM TONIGHT
THROUGH AT LEAST FRIDAY. CONDITIONS TO REMAIN BLUSTERY RIGHT ON
INTO THE WEEKEND BEFORE SOME MODERATION AS UPPER LOW MOVES EAST OF
THE AREA.

.CHI...STORM WARNING LKMICH.

JHV

In the hours before

Local storm report, Oct 24, 3:50 AM CDT, 5 hours 20 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
350 AM CDT WED OCT 24 2001

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1110 PM    LAKE SUMMERSET                 IL   QUARTER SIZE HAIL
10/23/01   WINNEBAGO

1115 PM    3 N OF PECATONICA              IL   QUARTER TO HALF DOLLAR
10/23/01   WINNEBAGO                           SIZE HAIL

1143 PM    ROCKFORD                       IL   DIME SIZE HAIL
10/23/01   WINNEBAGO

1208 AM    1 N BELVIDERE                  IL   QUARTER SIZED HAIL
10/24/01   BOONE

1258 AM    INGLESIDE                      IL   3/4 INCH HAIL
10/24/01   LAKE

104  AM    GRAYS LAKE                     IL   3/4 INCH HAIL
10/24/01   LAKE                                COVERING THE GROUND

PAUL MERZLOCK
WFO CHICAGO

Special weather statement, Oct 24, 6:05 AM CDT, 3 hours 5 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
Oct 23, 11:01 PM CDT	Severe Thunderstorm Warning	LOT	Boone, Winnebago	44 min
Oct 23, 11:45 PM CDT	Severe Thunderstorm Warning	LOT	Boone, McHenry	45 min
Oct 24, 12:23 AM CDT	Special Marine Warning	LOT		2 hr
Oct 24, 12:23 AM CDT	Special Marine Warning	LOT		2 hr
Oct 24, 12:30 AM CDT	Severe Thunderstorm Warning	LOT	Lake, McHenry	45 min
Oct 24, 9:08 AM CDT	Special Marine Warning	LOT		52 min
Oct 24, 9:08 AM CDT	Special Marine Warning	LOT		52 min
Oct 24, 11:16 AM CDT	Severe Thunderstorm Warning	LOT	Kane	29 min
Oct 24, 11:37 AM CDT	Severe Thunderstorm Warning	LOT	Cook, Lake	38 min
Oct 24, 11:59 AM CDT	Special Marine Warning	LOT		61 min
Oct 24, 1:33 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Livingston	27 min
Oct 24, 2:12 PM CDT	Special Marine Warning	LOT		93 min
Oct 24, 2:12 PM CDT	Special Marine Warning	LOT		93 min
Oct 24, 2:12 PM CDT	Special Marine Warning	LOT		93 min
Oct 24, 2:31 PM CDT	Tornado Warning	LOT	Kankakee	14 min
Oct 24, 2:44 PM CDT	Severe Thunderstorm Warning	LOT	Jasper, Lake, Porter	61 min
Oct 24, 2:44 PM CDT	Severe Thunderstorm Warning	LOT	Benton, Newton	61 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.