The polar vortex has been a hot topic lately... How does the polar vortex from last winter compare to this winter?

Last winter: This winter:
Last winter had a strong and stable polar vortex like a robust doughnut, holding cold air in the Arctic regions.

This year was weak and wavy, allowing cold arctic air to spread to lower latitudes.
The jet stream last year was also particularly strong and stable. Aiding the warm, wet and often windy conditions.

Last winter was the warmest winter on record for the Northern Hemisphere .

Stats are being gathered for this winter, certainly not like the warmth last winter. The role of the polar vortex and jet stream is obviously crucial in the type of winter we get in the Northern Hemisphere.
It is worth noting that there is variability and wobbles even in a strong and stable vortex.

In the strong and stable winter last year, the jet stream still buckled and folded. This is not unusual.
This is really bugging me 🙄
This winter, we saw more of things like this. A very perturbed and weak jet.

This allowed Arctic cold to escape south into places like Europe, Asia and North America. While other places saw warmth push up north.

Essentially, the jet became weak and wavy.
I discuss more about some of the cold spells and the role of climate change in a piece I wrote for @euronews

Some explainer graphics in there and research articles looking at both sides of the argument.

euronews.com/2021/02/23/cli…
The disruption to polar vortex and jet stream winter also helped explain why it was possible to go from extreme cold to extreme warmth in a short space of time. The weather pattern can flip a lot easier when the jet is weak.
And if you want this animation to 'Lord of the dance' sound track.

No problem.
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More from @ScottDuncanWX

2 Mar
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Via @Jvl52

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🎥 @andrewmiskelly

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The cold beast plagued Russia to give a cold winter here.

This is a summary from December 2020 through February 2021.

THREAD
Meteorologists like to split the year up into 3-month seasonal chunks for statistical purposes. Winter in the Northern Hemisphere is considered Dec, Jan & Feb.

This was December on its own.
This was January on its own. Cold building in Russia, remarkable warmth in Canada and Arctic. North Africa and Tibet notably warm/hot.

Cool Antarctica and Australia.
Read 7 tweets
2 Mar
February 2021... a month of extremes.

🔴 Very warm month especially from China through Central Asia into the Middle East and also parts of Arctic

🔵 Very cold month for much of North America (Alaska to Gulf of Mexico). Also very cold in Russia and NE Europe.
A global perspective.

We often observe extreme patterns when there is polar vortex disruption.
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The winter heat is starting to gather momentum. This is just the beginning with countless records about to fall later this week.

Hamburg, Germany 🇩🇪 just shattered the record for its hottest winter day ever. Average for this time of year is closer to +4°C.
Hamburg was not alone...

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Some records getting broken dating back to 1896.

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Holy smokes! Beijing, China 🇨🇳 just hit +25.6°C today.

This is a full +5.8° hotter than the record from 1996 and about +20°C warmer than normal for this time of year!

North and South Korea also recorded their hottest February day ever.

This winter heatwave is truly immense.
This is how the temperature compares to normal.

🔴 = warmer than normal
🔵 = colder than normal

Absolutely insane and unheard of to achieve this warmth in February.
A fantastic breakdown of the stats today by @EKMeteo

Read 8 tweets
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From Sahara to Scandinavia. We are in for another round of #dust and warmth widely across Europe.

The jet stream will buckle in an ideal fashion, optimising dust transport from the Sahara Desert to Scandinavia this weekend.

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The #CopernicusAtmosphere Monitoring Service forecast for aerosol optical depth ⬇️⬇️⬇️

@CopernicusEU @CopernicusECMWF
A lot of dust has already pushed out of the Sahara into the western Atlantic. More to come though.
Read 4 tweets

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