Alert archive / Illinois / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 36, NWS Chicago, IL

July 21, 2001Iroquois County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jul 21, 2001, 8:04 PM CDT for Iroquois County, Illinois. It was in force for 26 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: Jul 21, 2001, 8:04 PM CDT (01:04 UTC)
Expired: Jul 21, 2001, 8:30 PM CDT
In force: 26 min
Issued by: NWS Chicago, IL
Area: Whole counties

County Iroquois County, IL

The radar

The Chicago radar (KLOT), 98 km from the middle of the area, began a volume at 01:04 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, 1.1 hours before the alert went out and 93 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: 4745 J/kg
Mixed-layer CIN: -3 J/kg
Mixed-layer LCL: 918 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 78 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 5.1

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 Jul 21, 2:45 PM CDT, 5 hours 19 minutes earlier.

Area forecast discussion, Jul 21, 2:45 PM CDT, 5 hours 19 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
245 PM CDT SAT JUL 21 2001

THE NUMBERS ARE IN FOR TOMORROW AND MAY BE A BIT OVERDONE
CONSIDERING RH AND RANDOM CLOUD COVER. MCS DEVELPMENT IN SRN MN AND
IA NOT PICKED UP ON MODELS. CORFIDI VECTORS WOULD SUGGEST STUFF IN
SRN MN EARMARKED FOR NRN IL THIS EVENING AND ERLY TONIGHT. IF LITTLE
PCPN BY THE TIME IT ARRIVES...WILL BE MORE CLOUD COVER TO KEEP TEMPS
UP TONIGHT AND DEPARTING BY MRNG TO ALLOW GOOD AMOUNT OF SUNSHINE.
WITH THAT IN MIND...TEMPS SHOULD HAVE LITTLE PROBLEM REACHING 90+
AGAIN ON SUNDAY. THUS WILL UPGRADE EXCESSIVE HEAT WATCH TO WARNING
TO BE IN EFFECT SUNDAY.

850 THERMAL RIDGE EDGING EAST OVER NWRN IL TMRW AND JUSTIFYING
WARMER TEMPS FOR THE AREA WEST OF CHI. RFD ALREADY REACHED 92 WITH
GOOD PROSPECT OF 95 TMRW. THIS CUD MEAN HI VALUES AROUND 105.
COORDINATION WITH SURROUNDING WFO'S SUGGEST ADVISORY FOR ALL CWA
WITH WARNING CRITERIA FOR THE 8 COUNTY CHICAGO AREA.

THIS RIDGE EDGES FURTHER EAST MONDAY WITH ENHANCED 850 JET. IF NO
PCPN OR THICK CLOUD COVER...CUD CONTINUE HEAT WRNG/ADV INTO MONDAY.

NOW FOR PCPN. STILL SOME SPORADIC SHOWERS DEVELOPING IN AREA...BUT
LARGER CONCERN IS AREA IN MN AND IA...WHICH APPEARS TO BE DYING. WLL
PUT IN CHC TNGT FOR SHWERS 30%...BUT LEAVE OUT TOMORROW. BETTER
DYNAMICS APPEARING SUNDAY NIGHT WITH NEARLY ADIABATIC LAPSE BELOW
800 MB...SHEARED WIND PROFILE...AND CAPES AROUND 4K. QUESTION IS
WILL IT CONT (CLDS AND/OR PCPN) INTO MONDAY. MODELS SAY THERE IS A
CHC ON MONDAY WITH TROF MOVING THRU MONDAY EVENING. THERMAL RIDGE
NOT MOVING SOUTH OF AREA UNTIL TUESDAY NIGHT WITH ACTUAL PASSAGE OF
COLD FRONT. THUS TUESDAY COULD BE ANOTHER EXTENSION OF HOT WEATHER.

AVN BRING FNT THRU DRY ON TUESDAY WHICH SEEMS ODD AND WILL KEEP CHC
GOING. NE WINDS OVER AREA THRU FRIDAY SHUD KEEP RETURN MOISTURE
SOUTH OF AREA...PSBLY RAINING ACRS NWRN AND CNTL IL. MAY RETURN CHC
RAIN TO AREA FRIDAY NIGHT AND SATURDAY.

.CHI...EXCESSIVE HEAT WARNING FOR SUNDAY CHICAGO AREA/EXCESSIVE HEAT
ADV FOR SUNDAY REST OF CWA.

BRUMER

In the hours before

Local storm report, Jul 21, 6:39 PM CDT, 1 hour 25 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
639 PM CDT SAT JUL 21 2001

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....
w
0610 PM    MONEE                     IL   WIND DAMAGE
07/21/01   WILL                           TREES DOWN. REPORTED BY
                                          LAW ENFORCEMENT OFFICIAL.

Local storm report, Jul 21, 6:43 PM CDT, 1 hour 21 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
643 PM CDT SAT JUL 21 2001

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

0640 PM    ORLAND PARK               IL    MPH TSTM GUST
07/21/01   COOK                           60 MPH GUST. REPORTED
                                          BY STORM SPOTTER.

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 22, 3:35 PM CDT	Severe Thunderstorm Warning	LOT	Boone, DeKalb, McHenry	55 min
Jul 22, 4:03 PM CDT	Severe Thunderstorm Warning	LOT	DuPage, Will	42 min
Jul 22, 4:18 PM CDT	Severe Thunderstorm Warning	LOT	Cook, Lake	57 min
Jul 22, 4:18 PM CDT	Severe Thunderstorm Warning	LOT	DuPage	57 min
Jul 22, 5:11 PM CDT	Severe Thunderstorm Warning	LOT	Kane, Kendall	64 min
Jul 22, 5:59 PM CDT	Severe Thunderstorm Warning	LOT	Kankakee, Will	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.