Historically Does US Warmth In Fall Connect to Higher Eurasian Snow Cover?

Eurasian Snow Cover - November 12 (2015 vs 2016)

The snow cover across northern Asia is now 3rd highest since record keeping began in the mid 1960s for early November.

The northern Pacific jet has been very strong and stable with little "waviness" until the last few days. The low over the Aleutian Islands is locked in place as the strong northern Pacific jet undercuts the low pumping up the ridge across North America locking in abnormally warm temperatures.

November temperatures vs normal

Is the high snow cover across Asia influencing the strong jet stream?  Is there a history of this in early November in very high/very low Eurasian snow cover years?

I examined the 500 mb vector wind, sea surface temperature anomaly and US surface temperature anomalies (Oct 15 through Nov 15) for the years (top 10) with greatest Eurasian snow cover in week 44 (early November): These are: 1976, 72, 2016, 1969, 2015, 2012, 1973, 2009, 2014 and 1966.

While this year's cool pool in the northern Pacific has expanded recently, three of the top four years had significantly larger and colder cool pools (reanalysis is in Kelvin). Interestingly, widespread US warmth from mid October to mid November only occurred in 2016, 2015, 2014, 2012 and 2009.

1976

1972

2016

1969

2015

2012

1973

2009

2014

1966

What about the years with very low Eurasian snow cover (bottom 10) since 1966? 10th lowest to all-time lowest? The 500 mB jet seems consistently stronger in years with lower Eurasian snow cover. The northern Pacific water temperatures seem cooler overall. Only 1975, 83 and 2007 has widespread above normal temperatures in late October and early November.

1997

2007

1974

1983

1980

1979

1981

1975

1982

1988

Comparing high and low Eurasian snow cover to the ENSO state shows a blend to either side--cool and warm. 8 of the 20 years occurred during a strong ENSO state. Overall, there doesn't seem to be an overall trend which suggests that other factors are at play aside from ENSO.

Thoughts?

 

Developing La Nina Is Old News!

Many meteorologists including myself have written about the state of the winter El Nino and the strong probability that ENSO would transition to an infant La Nina in spring/summer of 2017 for a while now.  Main news sources give the impression at this transition out of El Nino as something new.  I tweeted a preliminary La Nina outlook based on CPC analogs BACK IN NOVEMBER!

Recently, NOAA stated in their newest bulletin, very accurately, that El Nino was finished as of June 9th. These transitions don't occur instantly. The transition away from El Nino toward La Nina has been ongoing for months.

The region used in determining the state of the equatorial Pacific is the ENSO 3.4 region.

All Nino regions (especially the key Nino 3.4 region) temperatures have been falling since the start of the year.

This animation showing the ocean temperatures vs normal values show this perfectly. See the cooler water on the right side (east).

A larger spherical look at the ocean temperatures show the transition even better starting in January. The last image is what the mature La Nina looked like in January of 1999.

According Bob Hensen at Weather Underground, a recent study found that about a 1/3 of first year La Nina events returned of persisted for a second year. This behavior seems to be more frequent over the last 150 years.  It is possible that La Nina could linger into 2018.

It takes months for the effects of any ENSO state (El Nino, neutral or La Nina) to be reflected in the atmosphere. So its very difficult to predict at this time what the winter will be like for specific locations. But we can perform some basic albeit general statistical comparisons between snowfall and La Nina.

Using the ERSSTv4 ocean temperature dataset, a list of La Nina strengths can be determined. Hat tip to Eric Webb.

Based on these years and rankings, I matched up our Cleveland snowfall for these La Nina years. Here is what I found.  The majority of these years had ABOVE NORMAL SNOWFALL in Cleveland!

This is no guarantee of above normal snowfall during the winter of 2016-17 as there are other factors yet to be determined. 

Last year, I posted my thoughts on the upcoming winter (2015-16) around Labor Day. Expect some more detailed thoughts on the effects of La Nina on the upcoming winter of 2016-17 around the same time this year.  Until then, let's enjoy summer!

El Nino Update: 1997 vs 2015

I plotted the weekly sea surface temperature anomalies starting in early June for the ENSO 1.2 region (closest to the South American coastline).

 Notice how 2015 is running cooler versus the 1997 event. Another component into our winter weather outlook which airs this Thursday at 6PM on FOX8!