Alert archive / Iowa / Tornado Warnings in 2002

Tornado Warning 10, NWS Des Moines, IA

April 18, 2002Black Hawk County, Iowa

NWS Des Moines, IA issued this tornado warning at Apr 18, 2002, 7:10 PM CDT for Black Hawk County, Iowa. It was in force for 50 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: Apr 18, 2002, 7:10 PM CDT (00:10 UTC)
Expired: Apr 18, 2002, 8:00 PM CDT
In force: 50 min
Issued by: NWS Des Moines, IA
Area: Counties, with a storm outline in the text

County Black Hawk County, IA

The radar

The Des Moines radar (KDMX), 136 km from the middle of the area, began a volume at 00:11 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

Time	Report	Where	Remark
Apr 18, 7:16 PM CDT	Hail 0.88	Hudson, IA

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.

Issued	Product	Office	Lasted
Apr 18, 4:15 PM CDT	Tornado Watch	SPC	5 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 0.2 hours before the alert went out and 177 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: 1636 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 1702 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 113 m²/s²
0-3 km storm-relative helicity: 200 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 4.3

Open this sounding in Storm Lab

The text

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

000 
WFUS53 KDMX 190010
TORDSM
IAC013-190100-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
709 PM CDT THU APR 18 2002

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* TORNADO WARNING FOR...
  SOUTHERN BLACK HAWK COUNTY IN NORTHEAST IOWA
  THIS INCLUDES THE CITY OF WATERLOO

* UNTIL 800 PM CDT

* AT 706 PM...WEATHER SPOTTERS REPORTED A TORNADO 8 MILES SOUTH OF
  HUDSON...OR ABOUT 15 MILES SOUTHWEST OF WATERLOO...MOVING NORTHEAST
  AT 30 MPH. THE TORNADO WAS LOCATED NEAR HIGHWAY 63.

* THE TORNADO WILL BE...

  7 MILES SOUTHEAST OF HUDSON AROUND 715 PM...
  9 MILES SOUTHEAST OF WATERLOO AROUND 730 PM AND
  5 MILES SOUTHEAST OF EVANSDALE AROUND 735 PM.

IF NO BASEMENT IS AVAILABLE...GO TO THE LOWEST FLOOR OF THE BUILDING
OR INTO AN INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM THURSDAY EVENING FOR
IOWA. LAT...LON 4248 9254 4231 9253 4231 9208 4251 9209

JAW

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 18, 7:02 PM CDT	Severe Thunderstorm Warning	DMX	Jasper	58 min
Apr 18, 7:04 PM CDT	Severe Thunderstorm Warning	DMX	Marshall	26 min
Apr 18, 7:04 PM CDT	Tornado Warning	DMX	Jasper	56 min
Apr 18, 7:24 PM CDT	Tornado Warning	DMX	Decatur, Ringgold	51 min
Apr 18, 7:38 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marion	52 min
Apr 18, 7:57 PM CDT	Severe Thunderstorm Warning	DMX	Warren	33 min
Apr 18, 8:11 PM CDT	Severe Thunderstorm Warning	DMX	Poweshiek	64 min
Apr 18, 9:10 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska	50 min

Nearby

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