Tornado Watch 171

Issued

Jun 10, 2018, 2:52 PM MDT (20:52 UTC)

Expired

Jun 10, 2018, 10:00 PM MDT

In force

7 hr

Issued by

the Storm Prediction Center

Largest hail expected

3 in

Strongest gust expected

70 kt

Counties Butte County, SD, Corson County, SD, Dewey County, SD, Haakon County, SD, Harding County, SD, Lawrence County, SD, Meade County, SD, Pennington County, SD, Perkins County, SD, Stanley County, SD, Ziebach County, SD, Campbell County, WY, Crook County, WY, Weston County, WY

The Rapid City radar (KUDX), 113 km from the middle of the area, began a volume at 20:54 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.

Two or more tornadoes

50%

One or more EF2 to EF5 tornadoes

30%

Ten or more severe wind reports

70%

One or more gusts of 65 knots or more

60%

Ten or more severe hail reports

60%

One or more hailstones of 2 inches or more

60%

Six or more combined severe hail and wind reports

95%

• Mesoscale Discussion 695Jun 10, 1:15 PM MDT
• Mesoscale Discussion 701Jun 10, 5:36 PM MDT
• Mesoscale Discussion 703Jun 10, 7:52 PM MDT
• Mesoscale Discussion 705Jun 10, 9:21 PM MDT

804 
WWUS20 KWNS 102049
SEL1  
SPC WW 102049
SDZ000-WYZ000-110400-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 171
NWS Storm Prediction Center Norman OK
250 PM MDT Sun Jun 10 2018

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Western South Dakota
  Northeast Wyoming

* Effective this Sunday afternoon and evening from 250 PM until
  1000 PM MDT.

* Primary threats include...
  A few tornadoes and a couple intense tornadoes possible
  Scattered damaging winds and isolated significant gusts to 80
    mph likely
  Scattered large hail and isolated very large hail events to 3
    inches in diameter likely

SUMMARY...Storms will develop along and behind a cold front from the
Big Horns and Black Hills within a favorable environment for
supercells capable of producing all hazards. With time this evening,
these cells should merge into a line which develop bowing structures
as it spreads east towards the Missouri River, enhancing the risk
for severe wind gusts.

The tornado watch area is approximately along and 95 statute miles
east and west of a line from 70 miles east northeast of Buffalo SD
to 35 miles west southwest of Rapid City SD. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 168...WW 169...WW 170...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 3 inches. Extreme turbulence and surface wind
gusts to 70 knots. A few cumulonimbi with maximum tops to 550. Mean
storm motion vector 22030.

...Grams

Tornado Watches in South Dakota, 2018Tornado Watches in Wyoming, 2018Every tornado watch in 2018

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.