Alert archive / Iowa / Tornado Warnings in 2002

Tornado Warning 18, NWS Quad Cities, IA

August 21, 2002Scott County, Iowa

NWS Quad Cities, IA issued this tornado warning at Aug 21, 2002, 6:39 PM CDT for Scott County, Iowa. It was in force for 66 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 21, 2002, 6:39 PM CDT (23:39 UTC)
Expired
Aug 21, 2002, 7:45 PM CDT
In force
66 min
Issued by
NWS Quad Cities, IA
Area
Counties, with a storm outline in the text

County Scott County, IA

The radar

The Quad Cities radar (KDVN), 8 km from the middle of the area, began a volume at 23:41 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.

What was reported inside it

TimeReportWhereRemark
Aug 21, 7:00 PM CDTTornado F0Blue Grass, IAAn F0 tornado touched down briefly north of Blue Grass tearing down a large tree limb. Otherwise, no injuries or damage was reported.

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

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

IssuedProductOfficeLasted
Aug 21, 2:25 PM CDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 11.7 hours before the alert went out and 15 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, Davenport, at 12:00Z on 2002-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1748 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Davenport, at 12:00Z on 2002-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 173 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
1748 J/kg
Mixed-layer CIN
-90 J/kg
Mixed-layer LCL
760 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
173 m²/s²
0-3 km storm-relative helicity
150 m²/s²
Significant tornado parameter
0.0
Supercell composite
3.6

Open this sounding in Storm Lab

The text

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

314 
WFUS53 KDVN 212339
TORMLI
IAC163-220045-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
639 PM CDT WED AUG 21 2002

THE NATIONAL WEATHER SERVICE IN THE QUAD CITIES HAS ISSUED A

* TORNADO WARNING FOR...
  SOUTHERN SCOTT COUNTY IN EAST CENTRAL IOWA

* UNTIL 745 PM CDT

* AT 636 PM CDT...DOPPLER RADAR AND SPOTTERS INDICATED A TORNADO 4
  MILES WEST OF BLUE GRASS...MOVING EAST AT 20 MPH.

* THE TORNADO IS EXPECTED TO BE NEAR...
   BLUE GRASS BY 645 PM CDT.
   DAVENPORT BY 710 PM CDT.
   ELDRIDGE BY 720 PM CDT.
   BETTENDORF BY 725 PM CDT.

THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT OR ON THE
LOWEST FLOOR OF A BUILDING IN AN INTERIOR HALLWAY OR ROOM.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM CDT
WEDNESDAY EVENING FOR EASTERN IOWA AND NORTHWESTERN ILLINOIS.

LAT...LON 4160 9077 4146 9078 4154 9047 4166 9053

$$
86

The office that day

Everything else NWS Quad Cities, IA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 21, 3:35 PM CDTSevere Thunderstorm WarningDVNIowa, Johnson, Washington40 min
Aug 21, 4:53 PM CDTSevere Thunderstorm WarningDVNCedar52 min
Aug 21, 5:27 PM CDTSevere Thunderstorm WarningDVNJackson33 min
Aug 21, 6:03 PM CDTSevere Thunderstorm WarningDVNMuscatine42 min
Aug 21, 6:05 PM CDTSevere Thunderstorm WarningDVNMuscatine40 min
Aug 21, 6:13 PM CDTTornado WarningDVNMuscatine32 min

Nearby

Tornado Warnings in Iowa, 2002Every tornado warning in 2002Tornadoes in 2002

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.