High Wind — Helena Valley, Montana

2025-12-17 · Helena Valley, Montana

Event narrative

Numerous sensors measured high winds and numerous reports of damage were received from trained spotters and the public. Sensors that reported criteria winds: ASOS station KHLN Helena Airport, mesonet station HVMT Helena Agrimet, HRWM8 Helena RAWS, and mesonet station FW7359 Helena. The peak observed gust was 91 mph at the Helena Airport ASOS. Power was lost at the Helena Airport when this gust occurred. Due to the power outage the extend of 5 minute data was lost, bur prior to this 91 mph gust, sustained winds averaged 42 mph between 1035 AM and 2 PM.

As for reports received from trained spotters and the public: 1 mile SE of Helena there was a report of a traffic sign bent over with debris blowing through the streets. Several reports were received stating large trees were down across the valley. 4 miles ENE or Helena there was a report of a horse shelter being destroyed. A more comprehensive tree damage report was received from Helena stating the top third of 50-60 ft conifers were snapped off, power poles broke, and roof tiles were coming off of buildings.

KTVH posted a video interviewing Helena Parks, which stated there were greater than 1,000 trees down across city limits, and that each tree was approximately $450 to address. Additionally, trees weakened that are still standing will still have to be addressed later in the spring, adding even most cost to the cleanup activities. The video estimated a cost between $25,000 and $30,000 for the cleanup, not including any private property damaged. Given there is additional cleanup necessary later this spring, and that there is likely no way to get a final estimate for damages combining public and private damage, the cost will be left as unknown at this time.

Additional Impacts: Helena Public Schools implemented an early release and activated emergency protocol for students traveling home. Several images were received showing a metal light post being bent all the way to the ground. Severe driving conditions were reported by 511MT along Interstate 15 through the Helena Valley due to exceedingly strong cross winds and numerous tipped semis.

Wider weather episode

Robust low to mid level flow westerly flow associated with a potent shortwave and attendant cold fronts resulted in a prolonged period of high-end winds and gusts across the entire region Dec 17 into the 18th. Multiple gusts in excess of 90 mph were observed in populated areas, with a peak observed gust of 104 mph west of Bynum. Prolonged power outages were observed across the region, mostly due to trees being damaged/falling over completely. Additional societal impacts included extremely difficult to impossible travel conditions, which prompted a Civil Emergency Message for areas along the Rocky Mountain Front the afternoon of the 17th.

Source: NOAA Storm Events Database, event_id 1306396. Narrative written by the NWS forecast office that issued the report.