Most extreme snowfall rates on record in Alaska: 10 inches of snow per hour reported at Thompson Pass near Valdez

Dec 8, 2017

Alaska is collecting extreme weather events in the last weeks. After a bombogenesis brought hurricane-like winds to the Bering Sea, now a completely crazy 10 inches of snow per hour was reported at Thompson Pass near Valdez, Alaska on Wednesday, December 6, 2017. This is extraordinary even for Valdez, the snowiest town in the United States. The phenomenon behind this unprecedented snowfall is a “snow AR” or an atmospheric river that is producing snow instead of rain. Meanwhile the mainland western USA stays high and dry.

What is hitting the North Gulf Coast is what we like to call a “snow AR” or an atmospheric river that is producing snow instead of rain. Over the last 3 days, nearly 6 feet of snow has been recorded at Thompson Pass near Valdez, Alaska. pic.twitter.com/Hoa8XUAMGQ

— NWS APRFC (@NWSAPRFC) December 6, 2017

On Wednesday, December 6, this storm dropped 5 inches of snow in 30 minutes, 10 inches in 60 minutes and 15 inches in 90 minutes at Thompson Pass. Between December 3 – 6, 13:00 local time, the National Resources Conservation Service (NRCS) SNOTEL site at Nicks Valley at 4 280 feet picked up 83 inches of snow, making a total of 126 inches. And now this:

This Thompson Pass storm ranks among the most intense snowfalls we know of. Other violent snowstorms are Copenhagen, N.Y. on December 2, 1966, where 12 inches fell in 60 minutes and Oswego, NY on January 26, 1972, where 17.5 inches fell in a two hour period. Both storms were the result of a lake effect snow, which is actually going on right now on the eat coast of the US (see pictures below).

Unprecedented snow storm hits Alaska on Dec 6 2017. Twitter

Enormous snow accumulation in Alaska on December 6 2107. Facebook

This week’s atmospheric river over Alaska was aided by the North American Winter Dipole, a fancy term to describe abnormally warm conditions in the West and cold conditions in the East. Under such a pattern, the jet stream, the super highway for storms that divides cold and warm air, surges north in the western half of the nation, and crashes south in the eastern half.