Alert archive / Iowa / Tornado Warnings in 1999

Tornado Warning 13, NWS La Crosse, WI

August 23, 1999Clayton County, Iowa

NWS La Crosse, WI issued this tornado warning at Aug 23, 1999, 7:58 PM CDT for Clayton County, Iowa. It was in force for 42 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
Aug 23, 1999, 7:58 PM CDT (00:58 UTC)
Expired
Aug 23, 1999, 8:40 PM CDT
In force
42 min
Issued by
NWS La Crosse, WI
Area
Whole counties

County Clayton County, IA

The radar

The La Crosse radar (KARX), 109 km from the middle of the area, began a volume at 01:01 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

Davenport, (KDVN), launched 00:00Z, 1.0 hours before the alert went out and 153 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 00:00Z on 1999-08-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 196 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, Davenport, at 00:00Z on 1999-08-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -182 square meters per square second.19395878Sfc1 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
196 J/kg
Mixed-layer CIN
-42 J/kg
Mixed-layer LCL
1185 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
-182 m²/s²
0-3 km storm-relative helicity
-94 m²/s²
Significant tornado parameter
-0.2
Supercell composite
-3.8

Open this sounding in Storm Lab

The text

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

049 
WFUS1 KLSE 240059 RRA
TORLSE
IAC043-240140-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE LA CROSSE WI
758 PM CDT MON AUG 23 1999

THE NATIONAL WEATHER SERVICE IN LA CROSSE HAS ISSUED A

* TORNADO WARNING FOR...
  CLAYTON COUNTY IN NORTHEASTERN IOWA

* UNTIL 840 PM CDT

* AT 755 PM CDT...AREA LAW ENFORCEMENT INDICATED A TORNADO 10 MILES
  WEST OF FARMERSBURG...MOVING SOUTHEAST AT 15 MPH.

* THE TORNADO WILL BE NEAR...
  GARNAVILLO AT 805 PM

GO TO THE BASEMENT OR A SMALL INTERIOR ROOM ON THE LOWEST FLOOR

SJT/KING


&

Nearby

Tornado Warnings in Iowa, 1999Every tornado warning in 1999Tornadoes in 1999

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.