Alert archive / South Dakota / Severe Thunderstorm Warnings in 1986

Severe Thunderstorm Warning 109, NWS Sioux Falls, SD

July 18, 1986Aurora County, South Dakota

NWS Sioux Falls, SD issued this severe thunderstorm warning at Jul 18, 1986, 1:42 PM CDT for Aurora County, South Dakota. It was in force for 23 min.

The area

The counties it named.

The facts

Issued
Jul 18, 1986, 1:42 PM CDT (18:42 UTC)
Expired
Jul 18, 1986, 2:05 PM CDT
In force
23 min
Issued by
NWS Sioux Falls, SD
Area
Whole counties

County Aurora County, SD

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

Aberdeen, SD (KHON), launched 12:00Z, 6.7 hours before the alert went out and 132 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, Aberdeen, SD at 12:00Z on 1986-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2637 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, Aberdeen, SD at 12:00Z on 1986-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 5 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
2637 J/kg
Mixed-layer CIN
-152 J/kg
Mixed-layer LCL
959 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
5 m²/s²
0-3 km storm-relative helicity
62 m²/s²
Significant tornado parameter
0.0
Supercell composite
4.6

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, Jul 18, 11:44 AM CDT, 1 hour 58 minutes before
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Special weather statement, Jul 18, 12:46 PM CDT, 56 minutes before
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Local storm report, Jul 18, 1:24 PM CDT, 18 minutes before
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Special weather statement, Jul 18, 1:40 PM CDT, 2 minutes before
SPECIAL WEATHER STATEMENT AND RADAR SUMMARY
NATIONAL WEATHER SERVICE HURON SD
140 PM CDT FRI JUL 18 1986

AT 128 PM CDT...INTENSE THUNDERSTORMS WITH VERY HEAVY RAIN
CONTINUED OVER PARTS OF EASTERN SOUTH DAKOTA..AND SOUTHWEST
MINNEOSTA.

THESE THUNDERSTORMS WERE LOCATED FROM NEAR HAYTI..20 MILES SOUTH
OF WATERTOWN AND EASTWARD INTO SOUTHWEST MINNESOTA NEAR WILLMAR.

ALSO..INTENSE THUNDERSTORMS WERE LOCATED SOUTH OF A LOWER BRULE
/HURON LINE.

VERY HEAVY RAINS ARE POSSIBLE WITH THESE STORMS.  CONDITIONS
ARE SUCH THAT THUNDERSTORMS SHOULD CONTINUE THROUGHOUT THE
DAY IN SOUTH DAKOTA.  SMALL STREAM..LOWLAND..AND URBAN FLOODING
ARE POSSIBLE WITH THESE STORMS.  PERSONS IN THESE AREAS
SHOULD BE AWARE OF RAPIDLY CHANGING WEATHER CONDITIONS AND
BE PREPARED TO TAKE PROTECTIVE ACTION.

SMALL HAIL..STRONG GUSTY WINDS..AND FREQUENT LIGHTNING STRIKES
ARE ALSO POSSIBLE WITH THESE STORMS.

OTHERWISE..THUNDERSTORMS WERE OCCURRING IN CENTRAL SOUT?H DAKOTA.

ALL MOVEMENT WAS NORTHEAST AT 30 MILES AN HOUR.
KRAUSE/MILLER

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 18, 1:03 PM CDTSevere Thunderstorm WarningFSDBrule57 min
Jul 18, 4:54 PM CDTSevere Thunderstorm WarningFSDLincoln66 min
Jul 18, 5:55 PM CDTSevere Thunderstorm WarningFSDLincoln, Lyon65 min

Nearby

Severe Thunderstorm Warnings in South Dakota, 1986Every severe thunderstorm warning in 1986

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.