Alert archive / Iowa / Tornado Warnings in 1999

Tornado Warning 9, NWS La Crosse, WI

July 20, 1999Chickasaw County, Iowa

NWS La Crosse, WI issued this tornado warning at Jul 20, 1999, 6:25 PM CDT for Chickasaw County, Iowa. It was in force for 50 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 20, 1999, 6:25 PM CDT (23:25 UTC)
Expired
Jul 20, 1999, 7:15 PM CDT
In force
50 min
Issued by
NWS La Crosse, WI
Area
Whole counties

County Chickasaw County, IA

The radar

The La Crosse radar (KARX), 124 km from the middle of the area, began a volume at 23:25 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.

IssuedProductOfficeLasted
Jul 20, 4:45 PM CDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 11.4 hours before the alert went out and 219 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 1999-07-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1395 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 12:00Z on 1999-07-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 31 square meters per square second.193958Sfc1 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
1395 J/kg
Mixed-layer CIN
-109 J/kg
Mixed-layer LCL
727 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
31 m²/s²
0-3 km storm-relative helicity
-18 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.8

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KLSE 202326 RRA
TORLSE
IAC037-210015-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE LA CROSSE WI
625 PM CDT TUE JUL 20 1999

THE NATIONAL WEATHER SERVICE IN LA CROSSE HAS ISSUED A

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

* UNTIL 715 PM CDT

* AT 623 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  TORNADO NEAR BASSETT...40 MILES SOUTHWEST OF DECORAH... MOVING
  EAST AT 20 MPH.

* THE TORNADO WILL BE NEAR...
  NEAR IONIA BY 630 PM
  NEAR NEW HAMPTON BY 640 PM
  NEAR BOYD BY 645 PM

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

RRS

The office that day

Everything else NWS La Crosse, WI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 20, 4:38 PM CDTFlash Flood WarningARXFloyd67 min
Jul 20, 4:38 PM CDTSevere Thunderstorm WarningARXFloyd67 min
Jul 20, 4:55 PM CDTFlash Flood WarningARXChickasaw, Floyd3 hr
Jul 20, 5:06 PM CDTTornado WarningARXChickasaw, Floyd69 min
Jul 20, 5:59 PM CDTSevere Thunderstorm WarningARXFayette61 min
Jul 20, 6:15 PM CDTFlash Flood WarningARXHoward, Mitchell3 hr
Jul 20, 6:40 PM CDTSevere Thunderstorm WarningARXMitchell60 min

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.