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Michael Sigmond

@michaelsigmond

Climate scientist, CCCma, Environment and Climate Change Canada, IPCC AR7 Lead Author

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29.11.2024
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Latest posts by Michael Sigmond @michaelsigmond

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Jet stream response to future Arctic sea ice loss not underestimated by climate models npj Climate and Atmospheric Science - Jet stream response to future Arctic sea ice loss not underestimated by climate models

Proud to share our new paper in npj Clim. Atmos. Sci. (@SpringerNature)!

Our findings:
1️⃣ reduce uncertainty in mid-latitude climate projections
2️⃣ increase confidence that #ClimateModels correctly predict a future poleward shift of the #JetStream

Read the paper here 👉 rdcu.be/eS73b

#ClimateScience

09.12.2025 20:07 👍 15 🔁 4 💬 0 📌 1
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Honoured to open @ipcc.bsky.social's first Lead Author Meeting for AR7 in Paris today. Congratulations to 600+ authors on their appointments—this marks the beginning of our scientific assessment. Thank you to France for generously hosting this historic meeting.

🔗 bit.ly/4ir09cC

01.12.2025 12:34 👍 26 🔁 7 💬 2 📌 1
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Uh oh. The dreaded polar vortex may be making an appearance very soon | CBC News In 2014, the term “polar vortex” burst on the scene across Canada and the U.S. as temperatures plunged. In some places, it was colder than it was on Mars. Well, get ready to hear more about it.

www.cbc.ca/news/science...

25.11.2025 00:14 👍 3 🔁 0 💬 0 📌 0
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The polar vortex is about to bring a wild weather pattern change | CNN Over the next 10 days, scientists say, changes in the stratosphere will upend weather patterns and set the stage for a cold, snowy December across parts of the Northern Hemisphere.

An unusually early sudden stratospheric warming event is likely to send the polar vortex on the move. Questions exist re: how this will affect US weather, but odds for colder, snowier weather are ticking up esp. in Central/Eastern US www.cnn.com/2025/11/19/w...

19.11.2025 14:12 👍 27 🔁 13 💬 2 📌 1
ECMWF 10 hPa 60°N zonal-mean zonal wind ensemble plume from 12 Nov 2025

ECMWF 10 hPa 60°N zonal-mean zonal wind ensemble plume from 12 Nov 2025

The ensemble mean from today's IFS subseasonal run almost predicts the earliest major sudden stratospheric warming on record 😮

Will be interesting to see if this signal progresses as it is just on the cusp of typical SSW prediction lead-times – daily runs of 101 members can still vary a fair bit

12.11.2025 20:32 👍 35 🔁 8 💬 3 📌 0
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005 | The Hidden Cost of Cleaner Air? Earth System Warming 📘 Summary of: "Reduced Aerosol Pollution Diminished Cloud Reflectivity Over the North Atlantic and Northeast Pacific" by Knut von Salzen, Ayodeji Akingunola, Jason N. S.

www.linkedin.com/pulse/005-hi...

06.11.2025 21:05 👍 3 🔁 0 💬 0 📌 0
The forecasted structure of the tropospheric jet stream (yellow) and several levels of the stratospheric polar vortex from the lower stratosphere to the upper stratosphere in the NOAA GFS model for 17 January 2025 (initialized on 16 January 2025).

The forecasted structure of the tropospheric jet stream (yellow) and several levels of the stratospheric polar vortex from the lower stratosphere to the upper stratosphere in the NOAA GFS model for 17 January 2025 (initialized on 16 January 2025).

Is the polar vortex responsible for the current cold snap over much of the U.S.?

Our experts discuss this in our most recent Polar Vortex Blog: www.climate.gov/news-feature...

21.01.2025 21:34 👍 354 🔁 88 💬 20 📌 12
Image of mean sea-level pressure and 1000 hPa winds centred on the UK, from earth.nullschool.net

Image of mean sea-level pressure and 1000 hPa winds centred on the UK, from earth.nullschool.net

A reminder that earth.nullschool.net is a great resource for visualising the weather now.

#StormDarragh visible in the surface image below; going to different pressure levels will help you see the jet stream.

(Thanks @cambecc.bsky.social!)

06.12.2024 11:43 👍 54 🔁 28 💬 4 📌 2
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Here is why 2024 is virtually certain be the warmest year on record and first one above 1.5°C 👇

08.11.2024 07:58 👍 111 🔁 72 💬 1 📌 12

I've made a starter pack of people who work on the stratosphere/middle atmosphere and/or often post about the stratosphere, including forecasts of the polar vortex.

Please do suggest anyone I've missed – quite hard to keep up with everyone on here now!

go.bsky.app/MxwzdEi

04.12.2024 19:00 👍 75 🔁 26 💬 10 📌 2