Alert archive / Illinois / Severe Thunderstorm Warnings in 2003

Severe Thunderstorm Warning 147, NWS Chicago, IL

July 21, 2003DeKalb County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jul 21, 2003, 1:47 AM CDT for DeKalb County, Illinois. It was in force for 43 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, 2003, 1:47 AM CDT (06:47 UTC)
Expired: Jul 21, 2003, 2:30 AM CDT
In force: 43 min
Issued by: NWS Chicago, IL
Area: Counties, with a storm outline in the text

County DeKalb County, IL

The radar

The Chicago radar (KLOT), 65 km from the middle of the area, began a volume at 06:46 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
Jul 20, 10:15 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 6.8 hours before the alert went out and 147 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: 3041 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 1003 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 123 m²/s²
0-3 km storm-relative helicity: 251 m²/s²
Significant tornado parameter: 1.5
Supercell composite: 9.6

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 Jul 20, 3:15 PM CDT, 10 hours 32 minutes earlier.

Area forecast discussion, Jul 20, 3:15 PM CDT, 10 hours 32 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
315 PM CDT SUN JUL 20 2003

PUBLIC DISCUSSION AFTERNOON ZONES/GRIDS:

MAIN PROBLEM THIS EVENING IS WITH TSTM FCST.  SPC HAS LOWERED REGION
INTO SLIGHT RISK AS LO LEVEL FEATURES ARE AS YET POORLY DEFINED. SFC
DEW POINTS HAVE RISEN INTO LOER 70S BUT MOISTURE CONVERGENCE REMAINS
QUITE NEBULOUS ACROSS MOST OF MIDWEST.  CONVECTIVE DEBRIS HAS
CONTRIBUTED TO RELATIVE STABILIZATION COMPARED TO AREAS TO OUR W AND
S WHERE LIFTED INDEX VALUES ARE NOW RUNNING AOB -10.  BASED ON
THIS...BELIEVE DYNAMIC FORCING WILL BE REQUIRED TO GENERATE
CONVECTION.  VIGOROUS, DIGGING S/W TROF NOW ROTG SSEWD ACROSS WRN
ONTARIO WITH VORT TAIL ARCING SWWD INTO ND ATTM BASED ON AFTN SATLT
LOOPS.  EXPECT THIS TO TRIGGER MORE ORGANIZED CONVECTION NXT FEW HRS
WELL TO OUR NW WITH THESE STORMS MAINTAINING THEMSELVES OVERNIGHT
DUE TO MORE FAVORABLE DYNAMICS.  AS A RESULT WILL KEEP LIKELY POPS
GOING IN FCST BUT WILL MENTION THIS AS AN OVERNIGHT EVENT.  THIS IS
ALSO SUPPORTED BY MOS AND ALL MODELS CONCUR IN BRINGING OMEGA MAX
ACROSS FA OVERNIGHT.  SOME PRECIP WILL LIKELY LINGER INTO MONDAY
MORNING.  REMAINDER OF FCST CHANGED LTL FROM GUID WITH ETA AND GFS
IN FAIRLY GOOD AGREEMENT ON STRENGTH OF COLD AVDECTION THRU ERLY
PART OF UPCOMING WEEK.   WILL KEEP MOSTLY CLOUDY CONDS AT LEAST THRU
MONDAY DUE TO SHARP CYCLONINC TURNING IN MID/UPR LVL FLOW AND ASSD
COLD ADVECTION.  SKIES SHOULD CLEAR TUES NIGHT AS H5 TROF AXIS
SHIFTS EWD AND SFC HI PRES BUILDS SEWD INTO FA.

.CHI...NONE
MERZLOCK

Hazardous weather outlook, Jul 20, 7:35 PM CDT, 6 hours 12 minutes before

ILZ003>006-008-010>014-019-020>023-032-033-039-INZ001-002-010-011-019
-2011200-

HAZARDOUS WEATHER OUTLOOK/UPDATED
NATIONAL WEATHER SERVICE CHICAGO IL
735 PM CDT SUN JUL 20 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST
ILLINOIS...NORTHWEST INDIANA...AND THE ADJACENT WATERS OF LAKE
MICHIGAN.

.DAY ONE...TONIGHT

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE TONIGHT OVER
NORTHERN ILLINOIS AND NORTHWEST INDIANA.

A STRONG COLD FRONT AND UPPER AIR DISTURBANCE ARE STILL TO THE
NORTHWEST OF ILLINOIS. THUNDERSTORMS MAY REDEVELOPE TOWARD MIDNIGHT
OVER SOUTHWEST WISCONSIN AND THEN MOVE SOUTHEAST OVER THE AREA. ANY
STORMS WILL BE CAPABLE OF HIGH WINDS AND HAIL.

.DAYS TWO THROUGH SEVEN... MONDAY THROUGH SUNDAY

THERE IS A CHANCE OF LINGERING SHOWERS AND THUNDERSTORMS EARLY
MONDAY. THESE THUNDERSTORMS ARE NOT EXPECTED TO BE SEVERE.  THE NEXT
CHANCE OF THUNDERSTORMS WILL BE ABOUT SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED AGAIN LATE TONIGHT.
.

&&

           NWS CHICAGO WEBPAGE

    HTTP://WWW.CRH.NOAA.GOV/LOT (LOWER CASE)
OR  HTTP://WEATHER.NOAA.GOV/CHICAGO (LOWER CASE)

AF

In the hours before

Local storm report, Jul 20, 11:04 PM CDT, 2 hours 43 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
1104 PM CDT SUN JUL 20 2003

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

1050 PM    PALATINE                  IL   1 INCH HAIL
07/20/03   COOK                           REPORTED BY EMERGENCY
                                          MANAGEMENT.

Local storm report, Jul 20, 11:27 PM CDT, 2 hours 20 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
1127 PM CDT SUN JUL 20 2003

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

1052 PM    ARLINGTON HGTS            IL   .75 INCH HAIL
07/20/03   COOK                           REPORTED BY OFF-DUTY
                                          NWS EMPLOYEE.

1052 PM    DES PLAINES               IL   .75 INCH HAIL
07/20/03   COOK                           REPORTED BY PUBLIC.

Local storm report, Jul 20, 11:44 PM CDT, 2 hours 3 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
1144 PM CDT SUN JUL 20 2003

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

1113 PM    LINCOLNWOOD               IL   .75 INCH HAIL
07/20/03   COOK                           LINCOLN AVE. COVERED
                                          LIGHTLY WITH PENNY SIZE
                                          HAIL FOR 10 MIN.
                                          REPORTED BY STORM
                                          SPOTTER.

Local storm report, Jul 21, 1:11 AM CDT, 36 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
111 AM CDT MON JUL 21 2003

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

1250 AM    LANSING                   IL   1 INCH HAIL
07/21/03   COOK                           REPORTED BY PUBLIC.

0104 AM    RENSSELAER                IN   .88 INCH HAIL
07/21/03   JASPER                         REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.

Local storm report, Jul 21, 1:34 AM CDT, 13 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
134 AM CDT MON JUL 21 2003

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

0131 AM    WHEATFIELD                IN   1.75 INCH HAIL
07/21/03   JASPER                         REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.

Local storm report, Jul 21, 1:37 AM CDT, 10 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
137 AM CDT MON JUL 21 2003

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

0122 AM    UNKN                      IL   WIND DAMAGE
07/21/03   LEE                            TRANSFORMERS, TREE
                                          LIMBS, POWER LINES
                                          DOWN. REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 10:12 PM CDT	Special Marine Warning	LOT		93 min
Jul 20, 10:12 PM CDT	Special Marine Warning	LOT		93 min
Jul 20, 10:12 PM CDT	Special Marine Warning	LOT		93 min
Jul 20, 10:17 PM CDT	Severe Thunderstorm Warning	LOT	Kankakee	58 min
Jul 20, 10:50 PM CDT	Severe Thunderstorm Warning	LOT	Cook	25 min
Jul 20, 11:49 PM CDT	Special Marine Warning	LOT		86 min
Jul 20, 11:49 PM CDT	Special Marine Warning	LOT		86 min
Jul 21, 1:21 AM CDT	Severe Thunderstorm Warning	LOT	Lee	54 min
Jul 21, 2:08 AM CDT	Severe Thunderstorm Warning	LOT	Kendall, LaSalle	32 min
Jul 21, 2:16 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Livingston	44 min
Jul 21, 2:26 AM CDT	Severe Thunderstorm Warning	LOT	Will	64 min
Jul 21, 2:45 AM CDT	Flash Flood Warning	LOT	Cook, Will	3 hr
Jul 21, 2:53 AM CDT	Severe Thunderstorm Warning	LOT	Iroquois	37 min
Jul 20, 11:03 PM CDT	Severe Thunderstorm Warning	LOT	Jasper	42 min
Jul 20, 11:37 PM CDT	Severe Thunderstorm Warning	LOT	Newton	38 min
Jul 21, 12:50 AM CDT	Severe Thunderstorm Warning	LOT	Jasper	25 min
Jul 21, 5:37 AM CDT	Flash Flood Warning	LOT	Jasper, Lake, Newton, Porter	113 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2003 Every severe thunderstorm warning in 2003

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.