CW3E Post-Event Summary: Upper Colorado River Basin October Snowfall

November 5, 2019

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Analysis of the Meteorological Conditions that led to a Snowy October in the Upper Colorado River Basin

• Numerous systems over a 2 week span at the end of October resulted in heavy snowfall over the Upper Colorado River Basin
• Moisture associated with the snowfall was supplied via an inland penetrating AR over the Pacific Northwest that resulted in flooding and road closures in mid to late October in Washington and Oregon
• Tower, a SNOTEL site #825 east of Steamboat Springs in the Yampa River watershed, received ~12% of it’s annual maximum SWE in a short time-span
• Impacts were also experienced east of the Continental Divide, where Denver recorded its 12th snowiest and 4th coldest October since 1872

Link to PNW summary here.

• A loop of NCEP GFS Analysis derived IVT illustrates the numerous pulses of inland penetrating moisture transport into the intermountain west and over locations such as Steamboat Springs, CO (Red Dot on Map)
• This period of landfalling ARs over the PNW and heavy snow in the upper Colorado River Basin exemplifies the upstream connection between landfalling ARs on the U.S. West Coast and winter weather over the inland Rockies

Summary provided by C. Hecht, C. Castellano, J. Kalansky, F. M. Ralph; 1 PM PT 5 November 2019