2021 Heat Event
While this spring has been the cool and snowy, last year between June 25-30, 2021, the Pacific Northwest experienced an extreme heat wave that broke many records. Temperatures recorded at Paradise COOP station (90°F) and Longmire COOP station (105°F) were near or matched the all-time records. All values were the highest ever recorded for the month of June. All time high temperature values were logged at two high elevation weather stations with shorter periods of record: 87°F at Sunrise (6,420 ft) and 64°F at Camp Schurman (9,500 ft).
The extreme heat led to rapid snowmelt. Snowmelt at the Paradise COOP station from April 1 through June 25th averaged about 2” every day. On June 25 (early in the heat event), snow height was 64” at Paradise. Only five days later it measured 24”, melting 8” per day, four times the previous rate of melt. The Nisqually River passing the Longmire Bridge stream gauge showed a 57% increase in maximum daily water volume (when compared to averaged daily maximum values recorded earlier in the month). Swollen rivers damaged many trail bridges in the park.
NPS Photo of the Nisqually River overwhelming the log bridge along the Wonderland Trail near Cougar Rock Campground, around noon on 6/26/21.
The North Coast and Cascades Network (NCCN) Inventory and Monitoring Program monitors climate in order to compare current and historic data to understand long-term trends, to provide data to model future impacts to park facilities and resources, and to provide park staff with information needed to make management decisions.
Read more about the 2021 heat event in the “Weather Summary: Mount Rainier National Park – Water Year 2021” monitoring brief.
Additional reports are posted at https://www.nps.gov/im/nccn/climate.htm.
~kl
