Alert archive / Iowa / Tornado Warnings in 1990

Tornado Warning 1, NWS Sioux Falls, SD

May 18, 1990Monona County, Iowa

NWS Sioux Falls, SD issued this tornado warning at May 18, 1990, 5:55 PM CDT for Monona County, Iowa. It was in force for 20 min.

The area

The counties it named.

The facts

Issued
May 18, 1990, 5:55 PM CDT (22:55 UTC)
Expired
May 18, 1990, 6:15 PM CDT
In force
20 min
Issued by
NWS Sioux Falls, SD
Area
Whole counties

County Monona County, IA

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.9 hours before the alert went out and 88 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, Omaha, NE at 12:00Z on 1990-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Omaha, NE at 12:00Z on 1990-05-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 164 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3569 m above ground
0-6 km bulk shear
48 kt
0-1 km storm-relative helicity
164 m²/s²
0-3 km storm-relative helicity
236 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KSUX 182257
TORSUX
IAC133-182315-

BULLETIN - IMMEDIATE BROADCAST REQUESTED/EBS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SIOUX CITY IA
555 PM CDT FRI MAY 18 1990

THE NATIONAL WEATHER SERVICE HAS ISSUED A TORNADO WARNING
EFFECTIVE UNTIL 615 PM CDT FOR PEOPLE IN THE FOLLOWING COUNTY

   IN THE WEST CENTRAL PART OF IOWA
      NORTHERN MONONA

AT 5:45P PM RADAR INDICATED A POSSIBLE TORNADO 25 MILES SOUTH OF
SIOUX CITY OR 10 MILES NORTH OF DECATUR NEBRASKA. THE STORM WAS
MOVING EAST AT 30 MPH.

MAPLETON AND WHITING IOWA ARE IN THE PATH OF THIS STORM. IF YOU
LIVE IN MONONA COUNTY THEN YOU SHOULD SEEK SHELTER IMMEDIATELY.

THIS IS A DANGEROUS STORM. TAKE COVER IMMEDIATELY. IF YOU ARE IN A
STRONG BUILDING GO TO AN INTERIOR ROOM ON THE LOWEST FLOOR. AVOID
WINDOWS. ABANDON CARS AND MOBILE HOMES FOR A REINFORCED BUILDING OR
GET INTO A DITCH OR DEPRESSION...COVER YOUR HEAD WITH YOUR HANDS.

ASK THE NEAREST LAW ENFORCEMENT AGENCY TO RELAY% YOUR REPORTS OF
SEVERE WEATHER TO THE NATIONAL WEATHER SERVICE.

HOPPES

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 18, 11:12 AM CDTFlash Flood WarningFSDPlymouth4 hr

Nearby

Tornado Warnings in Iowa, 1990Every tornado warning in 1990Tornadoes in 1990

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.