Alert archive / South Dakota / Tornado Watches in 2011
Tornado Watch 465
The Storm Prediction Center issued this tornado watch at Jun 11, 2011, 3:59 PM MDT for 4 counties in Montana; 12 counties in South Dakota; Campbell County, Crook County, Weston County, Wyoming. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 11, 2011, 3:59 PM MDT (21:59 UTC)
- Expired
- Jun 11, 2011, 10:44 PM MDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 60 kt
Counties Carter County, MT, Custer County, MT, Fallon County, MT, Powder River County, MT, Bennett County, SD, Butte County, SD, Custer County, SD, Fall River County, SD, Haakon County, SD, Harding County, SD, Jackson County, SD, Lawrence County, SD, Meade County, SD, Pennington County, SD, Perkins County, SD, Ziebach County, SD, Campbell County, WY, Crook County, WY, Weston County, WY
The radar
The Rapid City radar (KUDX), 152 km from the middle of the area, began a volume at 22:02 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 60%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
12 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 11, 4:59 PM MDT | Severe Thunderstorm Warning | UNR | Fall River | 61 min |
| Jun 11, 5:14 PM MDT | Severe Thunderstorm Warning | UNR | 61 min | |
| Jun 11, 5:21 PM MDT | Flash Flood Warning | UNR | Fall River | 4 hr |
| Jun 11, 5:47 PM MDT | Flash Flood Warning | UNR | Jackson, Pennington | 3 hr |
| Jun 11, 5:51 PM MDT | Severe Thunderstorm Warning | UNR | Jackson, Pennington | 54 min |
| Jun 11, 6:03 PM MDT | Severe Thunderstorm Warning | BYZ | Powder River | 42 min |
| Jun 11, 6:43 PM MDT | Severe Thunderstorm Warning | BYZ | Carter, Powder River | 32 min |
| Jun 11, 7:12 PM MDT | Severe Thunderstorm Warning | UNR | Crook | 47 min |
| Jun 11, 7:15 PM MDT | Severe Thunderstorm Warning | BYZ | Carter | 24 min |
| Jun 11, 7:17 PM MDT | Tornado Warning | UNR | Crook | 31 min |
| Jun 11, 8:34 PM MDT | Severe Thunderstorm Warning | UNR | Butte | 56 min |
| Jun 11, 9:43 PM MDT | Severe Thunderstorm Warning | UNR | Butte, Meade | 42 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Rapid City, SD (KUNR), launched 12:00Z, 10.0 hours before the alert went out and 153 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 685 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 63 m²/s²
- 0-3 km storm-relative helicity
- 193 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
471
WWUS20 KWNS 112157
SEL5
SPC WW 112157
MTZ000-SDZ000-WYZ000-120500-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 465
NWS STORM PREDICTION CENTER NORMAN OK
400 PM MDT SAT JUN 11 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
SOUTHEAST MONTANA
WESTERN SOUTH DAKOTA
NORTHEAST WYOMING
EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 400 PM UNTIL
1100 PM MDT.
TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 100 STATUTE
MILES EAST AND WEST OF A LINE FROM 10 MILES NORTH NORTHWEST OF
BAKER MONTANA TO 80 MILES SOUTH OF RAPID CITY SOUTH DAKOTA. FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU5).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...CONTINUE...WW 462...WW 463...WW 464...
DISCUSSION...SCATTERED THUNDERSTORMS ARE EXPECTED TO INTENSIFY THIS
AFTERNOON AND EVENING ACROSS SOUTHEAST MT/NORTHEAST WY AND SPREAD
INTO THE WATCH AREA. OTHER STORMS MAY FORM OVER THE BLACK HILLS OF
WESTERN SD. STRONG EFFECTIVE SHEAR VALUES AND SUFFICIENT
INSTABILITY WILL POSE A RISK OF ISOLATED TORNADOES...ALONG WITH
LARGE HAIL AND DAMAGING WINDS.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
450. MEAN STORM MOTION VECTOR 26030.
...HARTSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 11, 1:40 PM MDT | Mesoscale Discussion | SPC | Butte, Custer, Fall River, Lawrence, Meade, Oglala Lakota and 1 more | 2 hr |
| Jun 11, 3:35 PM MDT | Severe Thunderstorm Watch | SPC | Converse, Goshen, Laramie, Niobrara, Platte | 6 hr |
Nearby
Tornado Watches in South Dakota, 2011Tornado Watches in Montana, 2011Tornado Watches in Wyoming, 2011Every tornado watch in 2011
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.