When will it snow?

Tomer’s Take:

  • A large Western ridge of high pressure remains in control through 10/22.
  • A pattern change is possible on/after 10/23.
  • A large dip in the jet stream and lower atmospheric pressures might replace the large Western high pressure ridge.
  • This pattern change might run 10/23-10/27.
  • Net result: snow and colder temps for UT, CO, WY, MT, ID, Banff, and the PNW.
  • The strongest La Nina since 2010 remains in control.

Current Setup

You’re looking at the key to the potential pattern change on 10/23. Notice the trio of low pressure systems. They will set the stage for the weakening/dislodging of the big Western high. They will not act alone.

Water vapor satellite 10am 10/12/2022.

Current mid-atmosphere pressure pattern:

Current mid-atmospheric pressure pattern 10/12/2022.

Loveland Ski Area started making snow Wednesday morning 10/12/2022.

Parker the Snow Dog was there supervising:

Parker the Snow Dog, Loveland Ski Area, Photo Dustin Schaefer.

Arapahoe Basin also started making snow. See their update here.

Alta, Utah October 2021

  • October generated 67″ of total snow.
  • Average October snowfall is 28.5″.
  • Snow started falling after October 7, 2021.

The view at Alta on October 13, 2021 with 14″ storm totals:

Alta, UT, 10/13/2021.

La Nina Holding Strong

The latest (10/6/2022) Multivariate ENSO Index continues to indicate the strongest La Nina since 2010 at -1.8. This is a triple-dip La Nina.

This has created three straight Fall Seasons with abnormally warm and dry conditions across the West.

MEI valid October 6, 2022.

MEI historical values:

MEI values as of 10/6/2022.

Pattern Change

10/23 forecast mid-atmosphere pressure pattern:

10/23 forecast mid-atmosphere pressure pattern, EPS interpretation.

Some data suggest snow and colder temperatures across the West if this pattern change occurs.

The Global Forecast System is optimistic 10/23-10/27.

Total snow forecast 10/23-10/26, GFS interpretation.

The Pacific North American (PNA) pattern also shows this pattern change. It turns sharply negative on/after 10/23 through 10/27.

A negative PNA suggest lower pressures across the Western US.

Euro PNA forecast, 10/12/2022.

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