Marginal Risks of Severe Storms on the Central Plains; Flash flooding on the Northern Plains; Frost & Freeze Warnings in portions of the West & Northeast

A storm system developing across the Plains may cause locally severe weather in western Kansas and southwestern Nebraska today, with isolated flash flooding possible in portions of eastern Montana and western North Dakota. Frost and Freeze Warnings are in effect for portions of the central Rockies and central Appalachians tonight into Friday morning. Read More >

Overview

During the afternoon of June 29, 2018, two supercells moved across northeastern Wyoming and western South Dakota. In addition to producing very large hail, the southern supercell spawned a tornado with a continuous path from southeast of Sundance eastward to Spearfish Canyon. The majority of damage occurred in wooded areas, with widespread snapped trees observed throughout the tornado path. Some structural damage was also observed southeast of Sundance, just east of Highway 585, near the beginning of the tornado's path. Based on the damage, maximum winds were estimated to be 105 mph, giving the tornado an EF-1 rating.

Tornado
Photos & Video
Radar
Storm Reports
Environment

Tornado - Northern Black Hills
Crook Co., WY and Lawrence Co., SD

Date	June 29, 2018
Time (Local)	405 PM - 430 PM
EF Rating	1
Est. Peak Winds	105 mph
Path Length	19 miles
Max Width	200 yards
Injuries/Deaths	0
Summary: Snapped trees and minor structural damage resulted from this tornado, which traveled from southeast of Sundance to Spearfish Canyon.

Track Map

The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:

EF0 Weak 65-85 mph	EF1 Moderate 86-110 mph	EF2 Significant 111-135 mph	EF3 Severe 136-165 mph	EF4 Extreme 166-200 mph	EF5 Catastrophic 200+ mph

Photos & Video:


Spring Canyon Road (NWS Survey)	Spring Canyon Road (NWS Survey)	Moskee Road (NWS Survey)	Moskee Road (NWS Survey)


Sand Creek Road (NWS Survey)	Cement Ridge Road (NWS Survey)	Spearfish Canyon (NWS Survey)	Spearfish Canyon (NWS Survey)

Radar:


	Reflectivity at 4:17 PM MDT	Storm-Relative Motion at 4:17 PM MDT

Accumulation of the maximum radar reflectivity values from about 1:15 pm to 7:30 pm MDT on June 29, 2018. Note the two long swaths of intense (red, purple, and white) colors from west of Gillette across the northern Black Hills and into central South Dakota. The southern swath is associated with the storm that produced the northern Black Hills tornado, while the northern swath is associated with a storm that produced considerable hail and wind damage (and also two brief tornadoes).

Storm Reports

The satellite image above shows a "damage scar" caused by the combination of high winds and large hail (white oval). This extends from west of Belle Fourche to south of Faith and to the north of Pierre.

Environment


	Temperature, dew point, and wind data from the sounding launched from the Rapid City, SD forecast office at 12 PM on June 29, 2018.

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Marginal Risks of Severe Storms on the Central Plains; Flash flooding on the Northern Plains; Frost & Freeze Warnings in portions of the West & Northeast

June 29, 2018 Northern Black Hills Tornado from Sundance, WY to Spearfish Canyon, SD