From Cliff High Volume Weather Blog
Cliff Mass
Several rivers in and around Yellowstone Park experienced record flows this week, and my podcast today tells the story. And I also provide the forecast for the Northwest for the next week
The ice and snow on June 11, just before the floods, was extreme, with the region’s topography having a water-to-snow ratio hundreds of percent higher than normal (see below). That means a LOT of water ready to melt. This snow cover is the result of our cool, wet spring.
June 11, snow cover percentage is normal
And then there’s the rainfall. Some moisture moves in from the southwest – an atmospheric river – and is channeled directly into the Yellowstone region, where a small area of enhanced precipitation occurs (see 72-hour precipitation forecast ending Wednesday). Three at 5 a.m. PDT). By the way, the forecast is excellent.
This rain not only contributed to the river’s rise, but also helped melt the snow. Take a look at some of the area’s total precipitation below: dramatic, with values as high as 3-4 inches over the weekend.
Another way to see the combined effects of precipitation and melt is to examine observations at a USDA Snotel site where both snowfall and precipitation are measured.
Consider the nearby Monument Peak, Montana location. Accumulated precipitation is shown in black and the amount of water in the ice is shown in blue. Earlier this week, the black line went up quickly (lots of rain) and the snow and ice dropped sharply. A LOT of water was available to local rivers.
I end the podcast talking about whether global warming plays an important role in flooding, which several major media outlets and some climate activists claim.
The evidence clearly suggests a small role for global warming. Massive snow cover is the main cause and global warming in general REDUCES snow and ice. The locations of key geographic features, such as atmospheric rivers and a developing lowland on land, have no clear link to global warming.
The planet has warmed by about 1 C over the past century, and that assumes that humans are the sole cause. A 1C increase will increase atmospheric water vapor by 6-7%, which is probably enough to slightly enhance flooding, but nothing more.
Anyway, the horrible event happened.
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