Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

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A series of thunderstorms popped up across the state today, one of these thunderstorms even caused a landspout tornado to form on Casper Mountain! The atmosphere is not primed for tornadoes today, and no rotation was evident on radar, so what happened?

Landspouts form when pre-existing horizontal circulations are stretched and tilted upward by a developing thunderstorm updraft. As with gustnadoes, landspouts do not usually form from mesocyclones or supercells. In fact, a large number of landspouts are observed in association with simple developing showers, often before precipitation is visible on radar. However, storm interceptors have noted the presence of landspouts in conjunction with supercell thunderstorms, sometimes at the same time as, but in a different part of the storm than a supercell tornado. Landspouts are usually visible, unlike gustnadoes, and most have a narrow, rope-like condensation funnel extending from cloud base to the ground. Wall clouds are not usually observed with landspouts, and these tornadoes are typically short-lived and weak. Damage associated with landspouts is usually not noted, but it can be significant with damage in the F1 category possible with wind speeds as high as 110mph possible.

Landspout tornadoes are typically not visible on radar, like their traditional supercell counterparts and usually go unwarned for that reason.

We have not recieved any reports of damage from this tornado, but we have received several pictures! Thank you to those of you that have sent them in. If you have a photo that you would like to share, please post it on our Facebook page or send it to cr.wxriw@noaa.gov

Supplemental Images - Click Thumbnails To Enlarge

Radar Velocity at the Time of the Tornado	Velocity Image of a "Real" Supercell Tornado

Image By LightAlive Photography		Image by Shawn Covert

If you have additional photos or video of this storm, please share them with us!

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