Alert archive / Iowa / Severe Thunderstorm Warnings in 1994

Severe Thunderstorm Warning 143, NWS Sioux Falls, SD

September 20, 1994Lyon County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Sep 20, 1994, 8:00 PM CDT for Lyon County, Iowa. It was in force for 30 min.

The area

The counties it named.

The facts

Issued
Sep 20, 1994, 8:00 PM CDT (01:00 UTC)
Expired
Sep 20, 1994, 8:30 PM CDT
In force
30 min
Issued by
NWS Sioux Falls, SD
Area
Whole counties

County Lyon County, IA

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.0 hours before the alert went out and 230 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 00:00Z on 1994-09-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 190 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, Omaha, NE at 00:00Z on 1994-09-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 33 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
190 J/kg
Mixed-layer CIN
-98 J/kg
Mixed-layer LCL
2268 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
33 m²/s²
0-3 km storm-relative helicity
90 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

In the hours before

Special weather statement, Sep 20, 5:40 PM CDT, 2 hours 20 minutes before
IAZ013-210015-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX CITY IA
540 PM CDT TUE SEP 20 1994

...SCATTERED THUNDERSTORMS WILL OCCUR NORTHEAST OF SIOUX CITY...

AT 538 PM CDT A THUNDERSTORM WAS LOCATED 60 MILES NORTHEAST OF
SIOUX CITY NEAR SHELDON IOWA. MOVEMENT WAS EAST AT 30 MILES AN
HOUR. THE THUNDERSTORM WILL MOVE NEAR PRIMGHAR AND HARTLEY IOWA
BETWEEN 600 AND 615 PM.

THE THUNDERSTORM WILL PRODUCE LOCALLY HEAVY RAIN...DANGEROUS
LIGHTNING AND SMALL HAIL.

HOPPES/GREIF
Special weather statement, Sep 20, 6:01 PM CDT, 1 hour 59 minutes before
IAZ013-210015-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX CITY IA
601 PM CDT TUE SEP 20 1994

...SOME HAIL WAS OCCURING NORTHEAST OF SIOUX CITY...

AT 548 PM CDT MARBLE SIZE FELL 60 MILES NORTHEAST OF SIOUX CITY
AT RITTER IOWA. MOVEMENT WAS EAST AT 30 MILES AN HOUR. THE
THUNDERSTORMS WILL MOVE NEAR MONETA IOWA...70 MILES NORTHEAST
OF SIOUX CITY BETWEEN 630 AND 645 PM.

THE THUNDERSTORM WILL PRODUCE LOCALLY HEAVY RAIN...DANGEROUS
LIGHTNING AND HAIL.

HOPPES/GREIF

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 20, 7:29 PM CDTSevere Thunderstorm WarningFSDSioux31 min
Sep 20, 7:39 PM CDTSevere Thunderstorm WarningFSDLyon36 min
Sep 21, 2:06 PM CDTSevere Thunderstorm WarningFSDJackson54 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1994Every severe thunderstorm warning in 1994

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.