Alert archive / South Dakota / Tornado Warnings in 2020

Tornado Warning 10, NWS Rapid City, SD

August 4, 2020Tripp County, South Dakota

NWS Rapid City, SD issued this tornado warning at Aug 4, 2020, 6:39 PM CDT for Tripp County, South Dakota. It was in force for 51 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
Aug 4, 2020, 6:39 PM CDT (23:39 UTC)
Expired
Aug 4, 2020, 7:30 PM CDT
In force
51 min
Issued by
NWS Rapid City, SD
Area
Storm-based polygon
Tornado
Radar indicated
Hail
1.5 in

County Tripp County, SD

The radar

The North Platte radar (KLNX), 164 km from the middle of the area, began a volume at 23:42 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 nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 11.7 hours before the alert went out and 253 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, N. Platte/Lee Bi, NE at 12:00Z on 2020-08-04Temperature 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, N. Platte/Lee Bi, NE at 12:00Z on 2020-08-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 106 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1267 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
106 m²/s²
0-3 km storm-relative helicity
168 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

Open this sounding in Storm Lab

What forecasters said that day

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

NWS Rapid City, SD wrote its last area forecast discussion before this tornado warning went out at Aug 4, 5:55 PM CDT, 44 minutes earlier.

Area forecast discussion, Aug 4, 5:55 PM CDT, 44 minutes before
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
455 PM MDT Tue Aug 4 2020

.DISCUSSION...(This Evening Through Tuesday)
Issued at 119 PM MDT Tue Aug 4 2020

Upper level analysis shows compact shortwave pushing eastward across
southern Saskatchewan with trough axis extending southward into the
northern plains. Surface trough axis extends from developing low
pressure across NE Colorado this afternoon. Modest MUCAPE
(1000-2500 J/kg) will be in place this afternoon and evening,
although shear will be marginal. Broad upper level ascent via
shortwave trough coupled with convergent flow along the southern
Black Hills will provide impetus for thunderstorm development. The
overall environment will be conducive to a few strong to severe
storms through the evening before tapering off later tonight.
Widespread severe weather is not anticipated this evening.

Northwest flow continues Wednesday with chances for a storm or two
through the day Wednesday, mainly across SW SD, although the best
chances will remain to our northeast and south of the forecast area.
Mid-level warm air advection spreads into the northern Plains
overnight Wednesday as upper level ridge builds Thursday into
Friday. Temperatures will warm back into the upper 80s to 90s for
most locations to end the week.

Southwesterly flow aloft becomes the dominant pattern moving into
the weekend with embedded waves rippling through the flow. While the
best upper level forcing will remain well off to the north,
orographic forcing coupled with subtle waves will likely be enough
to support at least a small chance of thunderstorms each day Thursday
through the weekend. A thermal ridge will be in place across the
region Thursday into Friday, with warm air aloft and subsequent
capping concerns likely limiting more widespread storms.
Additionally, bulk shear looks rather weak through Saturday (20 to 35
knots), further limiting overall severe potential. At this point,
greatest likelihood for showers and storms looks to remain across
south-central into eastern SD each day where higher quality boundary
layer moisture will be in place.

Westerly to southwesterly flow will continue through the weekend
into next week with temperatures near normal and generally dry
conditions expected. Dry westerly flow will likely result in
elevated fire weather concerns beginning this weekend. At this point
winds look to remain below criteria, however minimum daily RH values
will likely fall into the teens, particularly across SW SD and NE WY
this weekend into early next week.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Wednesday Evening)
Issued At 453 PM MDT Tue Aug 4 2020

Isolated thunderstorms over northwest SD, as well as south central
SD, will dissipate this evening. Brief MVFR/IFR conditions in
stronger storms. Outside of storms, VFR conditions expected
through the period.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

DISCUSSION...Eagan
AVIATION...Johnson
Hazardous weather outlook, Aug 4, 12:43 PM CDT, 5 hours 56 minutes before
Hazardous Weather Outlook...UPDATED
National Weather Service Rapid City SD
1143 AM MDT Tue Aug 4 2020

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-051300-
Harding-Perkins-Butte-Northern Meade Co Plains-Ziebach-
Northern Black Hills-Northern Foot Hills-Rapid City-
Southern Foot Hills-Central Black Hills-Southern Black Hills-
Custer Co Plains-Pennington Co Plains-Haakon-Fall River-
Oglala Lakota-Jackson-Bennett-Mellette-Todd-Tripp-
Sturgis/Piedmont Foot Hills-Southern Meade Co Plains-
Hermosa Foot Hills-
1143 AM MDT Tue Aug 4 2020 /1243 PM CDT Tue Aug 4 2020/

This Hazardous Weather Outlook is for all of western and south
central South Dakota.

.DAY ONE...This Afternoon and Tonight

Isolated severe thunderstorms with large hail and strong wind
gusts are possible this afternoon and early evening.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Thunderstorms are possible through the weekend but widespread
severe weather is not expected.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

&&

Stay tuned to NOAA weather radio for further updates...or check
our web site at weather.gov/rapidcity

WYZ054>058-071-051300-
Northern Campbell-Southern Campbell-Western Crook-
Wyoming Black Hills-Weston-Northeastern Crook-
1143 AM MDT Tue Aug 4 2020

This Hazardous Weather Outlook is for northeastern Wyoming and
the Black Hills of Wyoming.

.DAY ONE...This Afternoon and Tonight

Isolated thunderstorms are possible this afternoon but are not
expect to become severe.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Thunderstorms are possible through the weekend but widespread
severe weather is not expected.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

&&

Stay tuned to NOAA weather radio for further updates...or check
our web site at weather.gov/rapidcity

In the hours before

Local storm report, Aug 4, 6:30 PM CDT, 9 minutes before
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The office that day

Everything else NWS Rapid City, SD issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 3, 8:23 PM CDTSpecial Weather StatementUNRLawrence37 min
Aug 3, 8:38 PM CDTSpecial Weather StatementUNRButte52 min
Aug 3, 9:12 PM CDTSpecial Weather StatementUNRButte48 min
Aug 4, 5:57 PM CDTSevere Thunderstorm WarningUNRTripp63 min
Aug 3, 7:34 PM CDTSpecial Weather StatementUNRCrook41 min
Aug 3, 7:35 PM CDTSpecial Weather StatementUNRWeston40 min
Aug 3, 8:18 PM CDTSpecial Weather StatementUNRCrook42 min

Nearby

Tornado Warnings in South Dakota, 2020Every tornado warning in 2020Tornadoes in 2020

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.