Alert archive / Illinois / Severe Thunderstorm Warnings in 2000

Severe Thunderstorm Warning 86, NWS Chicago, IL

July 27, 2000Cook County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jul 27, 2000, 3:54 PM CDT for Cook County, Illinois. It was in force for 36 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 27, 2000, 3:54 PM CDT (20:54 UTC)
Expired
Jul 27, 2000, 4:30 PM CDT
In force
36 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 20:57 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.

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 8.9 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-pSkew-T log-p diagram, Lincoln, IL at 12:00Z on 2000-07-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 403 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 12:00Z on 2000-07-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 57 square meters per square second.1939Sfc1 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
403 J/kg
Mixed-layer CIN
-153 J/kg
Mixed-layer LCL
1317 m above ground
0-6 km bulk shear
24 kt
0-1 km storm-relative helicity
57 m²/s²
0-3 km storm-relative helicity
56 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WUUS53 KLOT 272055
SVRCHI
ILC031-272130-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE CHICAGO IL
354 PM CDT THU JUL 27 2000

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  COOK COUNTY IN NORTHEAST ILLINOIS
  THIS INCLUDES THE CITY OF CHICAGO

* UNTIL 430 PM CDT

* AT 351 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  A SEVERE THUNDERSTORM OVER DOWNTOWN CHICAGO...MOVING SOUTHEAST AT  
  5 MPH.

VERY LARGE HAIL IS POSSIBLE WITH THIS SEVERE THUNDERSTORM. IF YOU ARE
IN THE PATH OF THE STORM...PUT YOUR CAR IN A GARAGE AND MOVE TO A
SUBSTANTIAL SHELTER.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEY
WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST
OFFICE IN CHICAGO.

NNNN

BROWNING

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 27, 2:39 PM CDT, 1 hour 15 minutes earlier.

Area forecast discussion, Jul 27, 2:39 PM CDT, 1 hour 15 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
239 PM CDT THU JUL 27 2000

SYNOPTIC SCALE...NEARLY STATIONARY ANTICYCLONE CELL OVER SRN ROCKIES
SPINNING A RING OF FINE ACROSS CENTRAL AND SOUTHERN PLAINS. AREA EAST
OF MISS RIVER GENERALLY IN A TROUGH SITUATION WITH PRIMARY ROTATION
OVER NWRN GT LAKES. THIS LATTER FEATURE FORECAST TO SAG SLOWLY SOUTH
TOWARD OHIO VALLEY NEXT 2-4 DAYS AS WESTERN RIDGE HOLDS AND SHARPENS
TO NORTHWEST OF FORECAST AREA.

MESOSCALE AND FORECAST...SLUGGISH FRONTAL BOUNDARY HAS REMAINED NEARLY
STATIONARY FROM CHI CITY SWWD ACROSS NORTHERN IL TODAY.  BEST LI'S
HAVE BEEN OVER SERN WISC IN HIGH DEW PT POOL WHILE BEST MASS
CONVERGENCE HAS BEEN IN VICINITY OF THE SURFACE FRONT.  MODEL
PROFILES..NO ACARS TODAY..SHOW NEARLY ADIABATIC LAPSE RATES BELOW
800MB AND A CONVECTIVE TEMP IN THE LOW 80S.  THESE CONDS HAVE FINALLY
FORCED A BAND OF SHOWERS AND ISOLD TRW TO FORM ALONG THE CONVERGENT
ZONE AT MID AFTN.

GIVEN RATHER RIPE CONDS UNTIL SUNSET SCATTERED RW/TRW ARE LIKELY FROM
CURRENT ZONE SOUTH AND EAST. HIGHER POPS WILL BE THERE WITH LOWER POPS
TOWARD RFD.  IN TIME MODELS SHOW THIS WESTERN LAKES CIRCULATION EASING
SOUTH ACROSS CWA.  WIDESPREAD CLOUDS ACROSS CENTRAL AND NORTHERN WISC
TODAY ALONG WITH SCTD SHOWERS SUGGEST MORE CLOUDS AND AT LEAST OF
CHANCE OF SHOWERS ARE IN STORE INTO EARLY WEEKEND.  BEST THREAT MAY BE
FRI NIGHT AND EARLY SAT BUT PRECIP AMOUNTS SHOULD BE GENLY LIGHT WHERE
THEY OCCUR.  SURFACE WINDS FORECAST TO VEER AROUND TO NORTHEAST FRI
NIGHT AND SAT AND WITH CLOUDS...TEMPS MAY NOT GET THROUGH THE MID 70S
SOME SPOTS.

FAN NUMBERS 10 DEG COOLER FOR MAX'S THAN NGM MOS TODAY AND POPS
SEVERELY AT ODDS TOO...FAN MUCH HIGHER.  GIVEN CURRENT SHOWER
DEVELOPMENT WILL BOOST POPS ALONG AND SE OF SURFACE BOUNDARY THEN
BROAD BUSH CHC POPS FRIDAY AFTERNOON THROUGH SATURDAY.

EXTENDED PERIOD SHOWS ONLY SLOW CHANGES BUT IT WILL RESULT IN DRYING
AND NEAR SEASONAL TEMPS.   KML

.CHI...NONE
N

In the hours before

Special weather statement, Jul 27, 11:58 AM CDT, 3 hours 56 minutes before
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Nearby

Severe Thunderstorm Warnings in Illinois, 2000Every severe thunderstorm warning in 2000

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.