Is the ‘October Eurasian snow cover’ a signal worth watching? This year is ‘similar’ to 2009… but?

Written by on October 21, 2018 in Rest of Europe, United Kingdom & Ireland with 0 Comments

The Eurasia snow cover is rather bleak this year.

This year is the polar opposite of 2016.

They say a big snow cover in October can enhance high latitude blocking during the winter providing southward incursions of polar air into the mid latitudes, particularly eastern North America and Europe.

I’ve shown the below chart MANY times.

However, 2009 saw little snow cover across Eurasia but record high latitude blocking followed. In October 2014 we had record Eurasia snow cover but little blocking and a not so cold winter.

Before 2016, it was 2013 which had the biggest October Eurasia snow cover since 1977.

Big winter for US but rather than record cold, it was record stormy for the UK.

So is this worth paying attention to? It ‘may’ be in a collective sense when all other factors are there but certainly in the last 10 years, it’s the lesser October snow covers which have seen the colder winters for Western Europe.

I must admit I have been doubting this long range signal for a few years now and in fact I wonder if the opposite may be more true.

The global SSTA profile, ENSO, solar cycle, autumn rainfall distribution are all likely better (not perfect) indicators. This year is very similar to 2009 with low solar (but not minimum like 2009), weak modoki El Nino, Atlantic SST profile, wet autumn (so far).

Central Pacific based El Nino’s tend to favour colder and snowier winters for the eastern US and UK.

All those factors INCLUDING low October Eurasia snow cover were in place in 2009 and that winter stands out as Britain and Ireland’s coldest since 1978-79.

So am I shooting for cold this winter if it’s similar to 2009? The key word is similar and I wish it was as clear cut. I have a couple of issues including the return of the ‘warm blob’ in the North Pacific. This fuelled the severe 2013-14 US winter but likely helped keep us mild but stormy. The weak polar vortex currently is interesting though.

January 2014

Current

I will as always post my winter forecast on the 1st of November!

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