Wisconsin Weather

Solar Minimum Associated with Snowy Green Bay Winters

Nov 4 2018 3:00 PM CST| 0 Comments | Wisconsin | Climate

Sun Cycles

The sun goes through many cycles. A 11 year cycle called the "Sunspot Cycle". There are 200 and 400 year cycles. There's also 26,000 year cycles that coincides with ice age glaciations. We are currently at the solar minimum of our current cycle which has been one of the weakest cycles in the last 200 years. We are descending towards the Eddy Grand Solar Minimum around the year 2050. Grand solar minimums are associated with abnormally cold weather and mini-ice ages such as the Dalton and Maunder Minimums. Still half way to the next glaciation in 12,000 years or so but at the point where we start heading down.

Wisconsin Weather
Solar minimums are the low points of each cycle. Grand solar minimums (1650, 1820, 1900) or low points in both 200/400 year.

Analysis Method

I performed statistical analysis using the 100+ year weather records at Green Bay, WI compared against daily sunspot data(solar activity) from Silso. The analytic method was very simple using an Excel pivot table across the dataset. I filtered out data that was incomplete. I limited the analysis to a date range between 1890 and 1928 when sunspot counts were more comparable. And I only considered max daily sunspot value between September and December (associated with our current season) so we can compare years where we were hitting the minimum as winter began like 2018. The weather observation data is organized by winter year (July 1 start & end) where the year belongs to the ending year (i.e 2018-2019 = 2019 winter year).

Wisconsin Weather

Facts for Green Bay, WI

★ Solar Minimum is much different from simply being "below average"

When entering winter, below average solar activity (not-minimum) is surprisingly boring and probably not what you would expect. Perhaps a persistent dry northwest flow pattern like last year? I don't have an explanation for this but I wonder about timing. Were we still descending towards or coming out of solar minimum that particular year? This is in contrast to solar minimums which have distinct statistical trends vs. the average.

★ Snow accumulation increases by 25%

Total winter year snow accumulation was 62" on average for solar minimum winters. That's nearly 20" more than non-minimum below average! That is significant.

★ Temperature extremes both directions

This is the most important observation. The average lowest temperature gets lower. The average highest temperature gets higher. More extreme temperature swings but not nessissarily warmer or colder on the yearly average. Solar max shows signs of extremes but non quite like solar minimum.

I believe that in a Grand Solar Minimum you would see average yearly temperature decrease. Our Green Bay data set doesn't have one of those to compare against so this is an assumption within the context of the analysis. There might be different ways to look at it such as length of winter, days between first and last frost, etc. I recommend checking out GISP2 ice core data.

★ Days with precipitation increase by 5%

But days with snow stays at average, so that 5% increase occurs primarily with non-snow days. So snow doesn't occur more frequently, it simply becomes heavier when it does occur. Check out solar maximum days with snow! Probably not what you would expect, right?

★ Bigger snow events

It would make sense that if low pressure systems were stronger, they would be capable of producing heavier snows? This is supported by the max two day snow being 3" greater than solar max, 4" greater than the average. Once again non minimum below average is surprisingly boring.

The last solar minimum

Occurred between 2008 and 2009. 08-2009 was considered a harsh "severe" winter for the lower great lakes. Both winters were snowy for Green Bay. NOTE: These years were not considered in the analysis. When you run the analysis for all years on record, the +25% snow accumulation trend is present for both.

The winter of 2018-2019 could be like that, but simply basing the forecast on sun activity would be a mistake. Climate and weather patterns are extremely complex and not one thing drives it. That's why I tend to stay away from winter forecasts. That being said I do expect extreme weather to continue this winter with one or two major blizzards, continuing into the early 2020s similar to or worse than 2008-2011.

Additional Thoughts

We know that it's usually the flux between phases, not the steady state that drives the biggest storms (snow, tornado, or otherwise) across Wisconsin. Perhaps someone else could take this one step further and research years where solar cycles are fluxing the most?

As we approach the Eddy Grand Solar Minimum, will we continue to see more snowy winters? I tend to think yes. The oddity of non-minimum below average sunspot winters makes me wonder though.

I don't think solar minimum winters are consistently cold. The big story is extremes. Eventually though, the deeper you go I would expect cold air to start winning out more often.

There is a lot more that could be analyzed but I think this covers a lot of it.

One step further on Sun Cycles

Based on my research and observation, solar cycles are connected to weather patterns. It's not about whether the sun is getting sensibly warmer or colder, but rather the magnetic phases. Weak activity effects the magnetic connection to the jet stream, making longer and more amplified. Cold air more frequently mixes south. Strong solar activity would make the jet stream flatter (more zonal).

There is a theory that a cosmic ray increase (coming from somewhere other than the sun) due to the sun's weakened magnetosphere increases cloud cover acting to decrease global temperatures. The wild card always is volcanic activity which I believe is linked to changes in the sun's magnetic phase/activity levels. If a major eruption were to occur there would be further decrease in global temperature.

We've had a pretty well behaved sun in recent times but history shows it can get pretty wild. We seem heading for into one of those wild stretches over the next 30 years.

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