Alert archive / Illinois / Severe Thunderstorm Warnings in 2004

Severe Thunderstorm Warning 71, NWS Chicago, IL

May 22, 2004McHenry County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at May 22, 2004, 12:36 AM CDT for McHenry County, Illinois. It was in force for 54 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 22, 2004, 12:36 AM CDT (05:36 UTC)
Expired: May 22, 2004, 1:30 AM CDT
In force: 54 min
Issued by: NWS Chicago, IL
Area: Counties, with a storm outline in the text

County McHenry County, IL

The radar

The Milwaukee radar (KMKX), 72 km from the middle of the area, began a volume at 05:38 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 22, 12:05 AM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 00:00Z, 5.6 hours before the alert went out and 241 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 542 m above ground
0-6 km bulk shear: 55 kt
0-1 km storm-relative helicity: 418 m²/s²
0-3 km storm-relative helicity: 649 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 21, 6:40 PM CDT, 5 hours 56 minutes earlier.

Area forecast discussion, May 21, 6:40 PM CDT, 5 hours 56 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
640 PM CDT FRI MAY 21 2004

.DISCUSSION FOR AFTERNOON ZONES/GRIDS:

OUTFLOW BOUNDARY FROM MORNING CONVECTION HAS PROGRESSED AS FAR AS
SOUTHERN CWA WITH SURFACE BASED INSTABILITY BEING SHUT OFF. SPC
MESOANALYSIS PAGE SHOWING MUCAPE ON ORDER OF 1500 J/KG WITH 850 HPA
BASED PARCEL. SHORT WAVE CURRENTLY MOVING THROUGH SOUTHWEST IOWA
WILL LIFT NORTHEAST INTO NW IL/SW WI LATER THIS EVENING. MID LEVEL
SPEED MAX ON ORDER OF 45-50 KNOTS HAS ALSO EJECTED NORTHWARD INTO
NRN IL AHEAD OF THIS FEATURE SETTING UP A GOOD DEEP LAYER SHEAR
PROFILE. RUC/MESOETA PROGGING GOOD LOW LEVEL THETA-E ADVECTION
ACROSS NRN IA/SE MIN ABOVE SHALLOW CONVECTIVE OUTFLOW LATE THIS
AFTERNOON INTO THIS EVENING WITH THIS AXIS SHIFTING SOUTHEAST INTO
CWA AFTER 00Z. WITH MAIN LOW LEVEL BAROCLINIC ZONE FOCUSING ACROSS
SOUTHERN/CENTRAL WISCONSIN THIS EVENING...BETTER CONVECTIVE COVERAGE
SHOULD REMAIN NORTH OF CWA BUT WILL CARRY HIGH END CHANCE POPS FOR
TSRA ACROSS NORTHERN TIER OF CWA GIVEN THIS ELEVATED
FORCING/INSTABILITY. GIVEN DEEP LAYER SHEAR AND INSTABILITY COULD
STILL SEE SEVERE THREAT ACROSS MAINLY NORTHERN CWA THIS EVENING.
WILL ISSUE FLOOD WATCH GENERALLY NORTH OF INTERSTATE 88 TO COVER
POSSIBILITY OF HEAVY RAIN GIVEN SIGNIFICANT ONGOING HYDRO PROBLEMS
ALREADY OCCURRING ACROSS THIS AREA.

WILL FOCUS CHANCE POPS ACROSS NORTHERN PORTION OF CWA ON SATURDAY
MORNING WITH POSSIBLE REPEAT PERFORMANCE OF MCS CLIPPING NORTHERN
CWA DURING THE MORNING HOURS. DID BACK PEDDLE ON HIGHS A BIT FOR
SATURDAY GIVEN POSSIBILITY OF CONVECTIVE OUTFLOW WITH OVERNIGHT MCS
TO THE NORTH. REMAINDER OF WEEKEND CONTINUES TO LOOK VERY ACTIVE
WITH GOOD MID LEVEL FORCING ACROSS THE PLAINS GRADUALLY WORKING INTO
THE GREAT LAKES LATE SATURDAY INTO SUNDAY. GOOD SHEAR PROFILES AND
PLENTY OF LOW LEVEL MOISTURE WILL KEEP SEVERE THREAT GOING INTO
SUNDAY AFTERNOON BEFORE COLD FRONTAL PASSAGE SUNDAY EVENING. WILL
MAINTAIN CHANCE OF NOCTURNAL CONVECTION MONDAY NIGHT AS FAST MOVING
NORTHERN STREAM WAVE TRACKS THROUGH SOUTHERN CANADA WITH GOOD
LLJ/MOISTURE ADVECTION INTO TUESDAY. REMAINDER OF EXTENDED WILL BE
LEFT DRY WITH TRANSITION TO MORE OF A NORTHWEST UPPER FLOW AND
DIFFICULTY TIMING ANY INDIVIDUAL SMALL SCALE WAVES.

NDM/WHW

&&

.AVIATION...

FOR 00Z TAFS...LINE OF TS EXTENDS FROM KENW ACROSS IL/WI BORDER
BACK INTO EASTERN IA. THIS LINE TO PASS THRU TERMINALS BY 03Z-04Z.
WIND GUSTS TO 40KTS AND VERY HEAVY RAIN EXPECTED WITH THESE STORMS.
FRONTAL BOUNDARY ALONG I-80 CORRIDOR TO LIFT NORTH ACROSS NORTHERN
IL TONIGHT SHIFTING WINDS FROM SE AT 10KTS TO SW AT 15KTS OR SO
LATER THIS EVENING. SW WINDS CONTINUE THRU THE PERIOD WITH GUSTS TO
20-25KTS LATE SAT MORNING INTO THE AFTERNOON. CHANCE OF ANOTHER
ROUND OF STORMS AFTER SUNRISE SAT MORNING ACROSS NORTHERN IL AND
HAVE INCLUDED AT PROB30 FOR TS FOR THAT TIME PERIOD.

&&

.LOT...WATCHES/WARNINGS/ADVISORIES...
IL...FLOOD WATCH THRU 12Z SAT FOR WINNEBAGO...BOONE...MCHENRY...
     LAKE...OGLE...LEE...DEKALB...KANE...DUPAGE AND COOK.
IN...NONE.
LK MI...NONE.

Hazardous weather outlook, May 21, 11:00 PM CDT, 1 hour 36 minutes before

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In the hours before

Local storm report, May 21, 7:51 PM CDT, 4 hours 45 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
751 PM CDT FRI MAY 21 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0747 PM     HAIL             DIXON                   41.85N 89.48W
05/21/2004  1.00 INCH        LEE                IL   EMERGENCY MNGR

0741 PM     HAIL             DIXON                   41.85N 89.48W
05/21/2004  0.88 INCH        LEE                IL   PUBLIC

&&

Local storm report, May 21, 8:08 PM CDT, 4 hours 28 minutes before

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Local storm report, May 21, 9:06 PM CDT, 3 hours 30 minutes before

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Local storm report, May 21, 9:27 PM CDT, 3 hours 9 minutes before

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Local storm report, May 21, 9:44 PM CDT, 2 hours 52 minutes before

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Special weather statement, May 21, 10:49 PM CDT, 1 hour 47 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
May 21, 7:00 PM CDT	Severe Thunderstorm Warning	LOT	Lee, Ogle, Winnebago	60 min
May 21, 7:09 PM CDT	Flash Flood Warning	LOT	Lake, McHenry	3 hr
May 21, 7:12 PM CDT	Special Marine Warning	LOT		108 min
May 21, 7:12 PM CDT	Special Marine Warning	LOT		108 min
May 21, 7:12 PM CDT	Special Marine Warning	LOT		108 min
May 21, 7:12 PM CDT	Special Marine Warning	LOT		108 min
May 21, 7:13 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Kane	47 min
May 21, 7:23 PM CDT	Flash Flood Warning	LOT	Cook, DeKalb, DuPage, Kane, Lee, Ogle	3 hr
May 21, 7:59 PM CDT	Severe Thunderstorm Warning	LOT	Lee, Ogle, Winnebago	61 min
May 21, 8:01 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Kane	59 min
May 21, 8:03 PM CDT	Tornado Warning	LOT	DeKalb	27 min
May 21, 8:22 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	53 min
May 21, 8:35 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	40 min
May 21, 8:58 PM CDT	Special Marine Warning	LOT		2 hr
May 21, 8:58 PM CDT	Special Marine Warning	LOT		2 hr
May 21, 8:58 PM CDT	Special Marine Warning	LOT		2 hr
May 21, 9:10 PM CDT	Severe Thunderstorm Warning	LOT	Kane, Kendall	50 min
May 21, 11:47 PM CDT	Special Marine Warning	LOT		118 min
May 21, 11:47 PM CDT	Special Marine Warning	LOT		118 min
May 22, 12:22 AM CDT	Severe Thunderstorm Warning	LOT	Lake	23 min
May 22, 1:33 AM CDT	Special Marine Warning	LOT		117 min
May 22, 1:33 AM CDT	Special Marine Warning	LOT		117 min
May 22, 1:33 AM CDT	Special Marine Warning	LOT		117 min
May 22, 1:40 AM CDT	Severe Thunderstorm Warning	LOT	Cook	50 min
May 22, 2:16 AM CDT	Severe Thunderstorm Warning	LOT	DeKalb	44 min
May 22, 4:22 AM CDT	Severe Thunderstorm Warning	LOT	Lee, Ogle, Winnebago	83 min
May 22, 12:36 PM CDT	Severe Thunderstorm Warning	LOT	Grundy, Will	39 min
May 22, 12:42 PM CDT	Special Marine Warning	LOT		93 min
May 22, 12:42 PM CDT	Special Marine Warning	LOT		93 min
May 22, 12:42 PM CDT	Special Marine Warning	LOT		93 min
May 22, 1:48 PM CDT	Severe Thunderstorm Warning	LOT	Iroquois	42 min
May 22, 6:23 PM CDT	Severe Thunderstorm Warning	LOT	Grundy, Will	37 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2004 Every severe thunderstorm warning in 2004

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.