Prolonged Atmospheric River in the Northwest; Snow in the North-Central US

A prolonged atmospheric river will bring heavy rainfall which may lead to widespread urban and river flooding, heavy mountain snow, along with gusty winds to the Pacific Northwest into the northern Rockies through much of the week. A clipper will bring a period of snow across the upper Midwest and the Great Lakes into Tuesday, before a stronger system bring more wintry impacts. Read More >

Overview

A tornado touched down in the central Black Hills near Silver City and Pactola Reservoir on Tuesday, May 27, 2014. It uprooted and snapped many large ponderosa pine trees and caused minor roof damage to a house.

Tornado
Damage Photos
Radar
Environment

Tornado:

Tornado - Silver City, SD
Pennington County

Date	May 27, 2014
Time (Local)	1:17 to 1:28 pm
EF Rating	EF-1
Est. Peak Winds	110 mph
Path Length	Estimated 2.5 mi
Max Width	300 yards
Injuries/Deaths	0
Summary: The tornado developed quickly in a heavily wooded area north of Silver City and eventually crossed the Deerfield Trail within one mile of Silver City.

Track Map

Track Map EF-Scale

@newscenter1 viewer Tim M. also saw the Silver City tornado from Box Elder. #SDwx pic.twitter.com/vSS7pzTMVV
— Thomas Patrick (@ThomasPatrickWx) May 27, 2014

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

Damage Photos


Trees down a few miles north of Silver City (photo by NWS Rapid City)	Trees down a few miles north of Silver City (photo by NWS Rapid City)

Radar

Radar animation from about 1 to 2 pm MDT


Radar velocity image at 1:11 pm MDT	Radar velocity image at 1:15 pm MDT	Radar velocity image at 1:20 pm MDT


Radar velocity image at 1:24 pm MDT	Radar velocity image at 1:28 pm MDT	Radar velocity image at 1:32 pm MDT	Radar velocity image at 1:37 pm MDT

Environment

NWS Rapid City balloon information showed a weakly unstable air mass with weak vertical wind shear. However, the wind shear next to the ground was moderate. Also note that the tornado occurred about 3 1/2 hours before the time of the balloon launch.


Sounding for Rapid City at 6 pm MDT 27 May 2014	Hodograph for Rapid City at 6 pm MDT 27 May 2014

The surface maps valid at noon (below left) and 1 pm (below right) show that moisture was enhanced along the eastern side of the Black Hills.


Surface map valid 12 pm MDT 27 May 2014	Surface map valid 1 pm MDT 27 May 2014

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Prolonged Atmospheric River in the Northwest; Snow in the North-Central US

May 27, 2014 Silver City Tornado