Willow Creek Downburst-June 6 2010

Willow Creek Downburst-June 6 2010

Late spring and summertime is when downburst potential  becomes a significant severe weather concern across the Intermountain Region including Star Valley.  Thus I have reposted a blog from 5 years ago about the major downburst that struck Willow Creek in 2010

On June 6, 2010 a vicious storm crossed parts of Star Valley during the evening, producing hail and very strong winds.  While trees were reported down and large hail occurred from around Star Valley Ranch south to near  Grover, the greatest damage was up Willow Creek Canyon.  Very large pines were uprooted at some distance above the mouth of the Canyon, indicating the likelihood of an intense downburst.

A map below indicates ground zero for the downburst.

Following are several photos taken on June 6th 2013, 3 years later, of the obvious evidence of the power of the winds near the A Marker.


Google Maps Image 2009- pre-blowdown
Post-blowdown from BING maps
Additional Post-Blowdown from BING maps


Also a photo was taken looking north from Star Valley Ranch as the storm was moving by, which was not toward the most intense portion .

On examination of the Pocatello radar data of the storm it was undoubtedly a Supercell.  While tornados are associated with Supercells, in this case there is no evidence of any tornadic circulation. The storm was moving at close to 60mph and as the following radar images of the storm will attest, it was very impressive.

The first image shows a vertical radar cross-section with a very strong and high reflectivity core to above 30,000 feet and overall storm top to above 50,000 feet as it was approaching the Wyoming/Idaho  line.

Pocatello Doppler Radar  7:19 PM June 6 2010

A linear mode typical of a damaging wind squall line is shown approaching Star Valley in a horizontal display

Pocatello Doppler Radar  7:19 PM June 6 2010

The center portion of the line indicated potential for large hail heading for about the Narrows.

The following is the Vertically Integrated Liquid(VIL) which displays the area of greatest  large hail potential.

Pocatello Doppler Radar VIL 7:19 PM June 6, 2010
Pocatello Doppler Storm Relative Velocity 7:06 PM June 6, 2010

The above image is of the horizontal velocity toward/away from the radar.  It is a storm relative image and appears to be a broad counter-clockwise rotation around the center of the most intense part of the line, indicating a Supercell.

While a tornado could not be ruled out with a storm of this intensity, the character of the storm and wind fall of the trees, all up-canyon, a downburst with speeds possibly to 80 mph or more was the likely culprit of the observed damage.