Alert archive / North Dakota / Tornado Warnings in 1991

Tornado Warning 12, NWS Grand Forks, ND

July 11, 1991Cass County, North Dakota

NWS Grand Forks, ND issued this tornado warning at Jul 11, 1991, 9:34 PM CDT for Cass County, North Dakota. It was in force for 56 min.

The area

The counties it named.

The facts

Issued
Jul 11, 1991, 9:34 PM CDT (02:34 UTC)
Expired
Jul 11, 1991, 10:30 PM CDT
In force
56 min
Issued by
NWS Grand Forks, ND
Area
Whole counties

County Cass County, ND

The nearest sounding before it

Aberdeen, SD (KHON), launched 00:00Z, 2.6 hours before the alert went out and 243 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 00:00Z on 1991-07-12Temperature 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, Aberdeen, SD at 00:00Z on 1991-07-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -39 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
196 J/kg
Mixed-layer CIN
-35 J/kg
Mixed-layer LCL
1711 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
-39 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

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

The office that day

Everything else NWS Grand Forks, ND issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 11, 7:15 PM CDTTornado WarningFGFNelson60 min
Jul 11, 8:05 PM CDTSevere Thunderstorm WarningFGFCass55 min
Jul 11, 9:06 PM CDTSevere Thunderstorm WarningFGFCass24 min
Jul 11, 9:22 PM CDTTornado WarningFGFRichland38 min
Jul 11, 10:02 PM CDTTornado WarningFGFRichland43 min

Nearby

Tornado Warnings in North Dakota, 1991Every tornado warning in 1991Tornadoes in 1991

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.