Will The Most Recent SOLAR MINIMUM, QBO, IOD Etc Deliver This Winter?

Written by on September 15, 2021 in Rest of Europe, United Kingdom & Ireland with 0 Comments

We have a big test coming up with regards to the solar minimum along with influences from the IOD, QBO, global SST’s, La Nina, MJO and even larger extent of Arctic sea ice compared to recent years.

Last winter’s La Nina dissipated as expected during the past summer but appears to be returning in a weak state. A weak La Nina would be quite favourable where as a strong negative ENSO state, like an El Nino would not be.

Last year’s MODERATE La Nina may have actually ‘held back’ any major winter last year.

If there’s any direct correlation between solar minimum, increased high latitude blocking and colder winters then I believe THIS upcoming winter we ‘should’ deliver and to a similar intensity to 2009-10.

Winters around and following solar maximums tend to host strong polar vortexes which drive an increase in oceanic influence across the continents while solar minimums bring weaker PV’s with greater likelihood of blocking over the high latitudes.

Over the last 10 years or so I’ve noticed what could be argued as a ‘peaking of winter warmth’ just ahead of a solar minimum where the dominant +NAO/AO’s are strong and driven by a record or near record strong PV.

As an example of this ‘pattern’, winters 98-99, 07-08 and 19-20 were very warm winters which were succeeded by much colder winters 2 years later. (00-01 and 09-10… 21-22??)

In between solar mins and max’s, our winters are often dominated by +NAO/AO’s with typically 2 or 3 very turbulent storm seasons. We saw this during the mid-90s, mid-2000s and most recently mid-2010s. One can blame warming oceans for these more hyper active ‘stormy winters’.

Solar or not, our oceans have been warming and this may or may not be increasing the trend to more +NAO/AO milder winters.

The thing to remember is that while winters seem to be warming and are along with the globe, I must stress that since the last ice age, we have always had multiple years in which we’ve experienced a string of 2 to 3 or 4 to 8 straight mild winters here in the UK. So, I wouldn’t jump too quick at the relatively mild winters of the past 10 years. It’s happened ‘many’ times.

The above being said, the trend appears to stop for 1 or 2 winters following a solar minimum. Last winter is a good example of this. After a record strong PV and +NAO/AO winter in 2019-20, we had a largely -NAO/AO winter in 2020-21 and this year ‘should’ follow suit if there is truth to the connection between solar minimum and -NAO/AO.

THIS winter in theory should push towards 2009-10 because as it stands, the current solar disk has about as much activity on it now as it did at this point in cycle 24 back in 2010 following the 2008 minimum!

As we approach the upcoming winter and the significance of the current solar state, we can almost see where nature is possibly preparing itself for another big one.

The Arctic sea ice extent at close to a 10 year high.

THIS may result in faster and stronger building of the cold reservoir…

In fact the models point to a record or near record strong PV.

The response could already to showing down at the surface…

A quickly strengthening vortex IS a good thing for this time of the year. It’s a sign of early sharp cooling within the arctic atmosphere. For maximum cold within the mid latitudes you want the north to be loaded!

Another good sign is the models ‘see’ a weakening PV as we head into winter!

An important indicator we like to look at each upcoming winter is the QBO or Quasi-biennial Oscillation. This in simple terms is a belt of zonal winds which blow either east or west over the tropics.

Recent years has seen the QBO firmly positive (westerly) which tends to correlate to a strengthened polar vortex and or polar jet stream thus coinciding with our milder winters.

During the summer it shifts easterly with the seasonal demise of the polar vortex but during the seasonal transition of autumn it either remains negative (easterly) or flips positive. Unlike last years failed attempt at remaining negative it is likely to stay negative or remain easterly for the upcoming winter ahead. THIS COULD BE CRUCIAL but isn’t be lock for winter.

IF the easterly winds blowing above the tropics from 10mb down to 50mb remain into the winter, this tends to favour a weaker jet and more blocking. Easterly winds create frictional effects on it’s northern counter part, the polar jet stream making it easier for higher pressure to develop.

 

The warmth in our oceans appears to be focusing over the northern basins closer to the pole. This also increases the likelihood of blocking highs.

Credit: Tropical Tidbits

Another major signal we tend to look at in winter forecasting is the IOD or Indian Ocean Dipole. It’s known as the ENSO or El Nino/La Nina of the Indian Ocean so it’s a big driver.

The IOD consists of a positive or negative state dependent upon ocean temperature like it’s Pacific Ocean counterpart.

 

As you can see from the below chart, the IOD soared to record positive during the late summer and autumn of 2019.

Credit: Michael Ventrice

It’s believed the ocean-atmosphere feedback helped power an unusually strong polar vortex and led to one of the warmest winter’s across the Northern Hemisphere on record in 2019-20.

A negative IOD like we have at present tends to play a favourable role when it comes to cold winters in Europe and North America. As you can see above, the IOD is almost as strongly negative now as it was positive during the same time in 2019.

The winters spanning from 2015 to 2019 had mainly +QBO’s and IOD’s, driven by El Nino and a solar maximum but in the wake of the latest solar minimum, it appears the IOD has shifted negative along with the QBO. These are TWO major players which are opposite of the recent warm winters and so here comes the test to see if these more favourable players can along with the solar minimum produce another significant cold winter.

The highly anomalous warmth within our northern ocean basins (esp Atlantic) combined with -QBO further increases the likelihood of above normal heights at 500mb over the high latitudes and particularly so North Atlantic and Greenland.

Another major global player is the madden julian oscillation or MJO. The MJO is a pulse or wave of enhanced convection which circles the tropics typically in a 30 to 60 day cycle. This can be weak or enhanced and when enhanced can have major effects on weather across the world and even the stratosphere.

I will discuss the MJO in a separate post soon!!

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