James Peacock
@peacockreports.bsky.social
Head Meteorologist at MetSwift, working to revolutionise delivery of weather information.
LinkedIn: https://t.co/pUCAQfAfRP
LinkedIn: https://t.co/pUCAQfAfRP
One possible result of weather patterns being simultaneously pushed toward blocking highs in the Arctic & an enhanced jet stream is a succession of lows racing into Europe, bringing bouts of wet & windy weather in the 1st half of December.
Not a scenario I'm keen to experience.
Not a scenario I'm keen to experience.
November 29, 2025 at 4:33 PM
One possible result of weather patterns being simultaneously pushed toward blocking highs in the Arctic & an enhanced jet stream is a succession of lows racing into Europe, bringing bouts of wet & windy weather in the 1st half of December.
Not a scenario I'm keen to experience.
Not a scenario I'm keen to experience.
With 42.2 hours in the past 10 days, November 2025 has managed to claw its back back to the long-term average for sunshine to-date here in NE Dorset.
It's also managed to be very near the long-term average for rainfall.
Seems only the temperatures will be noteworthy this month.
It's also managed to be very near the long-term average for rainfall.
Seems only the temperatures will be noteworthy this month.
November 27, 2025 at 10:29 AM
With 42.2 hours in the past 10 days, November 2025 has managed to claw its back back to the long-term average for sunshine to-date here in NE Dorset.
It's also managed to be very near the long-term average for rainfall.
Seems only the temperatures will be noteworthy this month.
It's also managed to be very near the long-term average for rainfall.
Seems only the temperatures will be noteworthy this month.
Sometimes forecast modelling diverge as point in time draws closer, due to complicating features being picked up more.
Case in point with the middle stages of next week. The 'big Atlantic low' scenario is still there, but no longer a clear favourite.
Case in point with the middle stages of next week. The 'big Atlantic low' scenario is still there, but no longer a clear favourite.
November 27, 2025 at 9:11 AM
Sometimes forecast modelling diverge as point in time draws closer, due to complicating features being picked up more.
Case in point with the middle stages of next week. The 'big Atlantic low' scenario is still there, but no longer a clear favourite.
Case in point with the middle stages of next week. The 'big Atlantic low' scenario is still there, but no longer a clear favourite.
28th Nov looks to be when we might briefly see the zonal mean zonal wind at 60N, 10 hPa pressure level become negative.
Uncertain whether it will remain so long enough for the daily mean to be below zero, which is required for a technical major sudden stratospheric warming event.
Uncertain whether it will remain so long enough for the daily mean to be below zero, which is required for a technical major sudden stratospheric warming event.
November 26, 2025 at 1:27 PM
28th Nov looks to be when we might briefly see the zonal mean zonal wind at 60N, 10 hPa pressure level become negative.
Uncertain whether it will remain so long enough for the daily mean to be below zero, which is required for a technical major sudden stratospheric warming event.
Uncertain whether it will remain so long enough for the daily mean to be below zero, which is required for a technical major sudden stratospheric warming event.
IMO there's a good chance that the change in 7-day rolling mean temperature between mid- & late November 2025 is among the largest on record for my local area.
Dropping by 9.2°C in 8 days, it went from 5°C above the 1991-2020 average on 15th to 3.3°C below it on 23rd.
Dropping by 9.2°C in 8 days, it went from 5°C above the 1991-2020 average on 15th to 3.3°C below it on 23rd.
November 26, 2025 at 11:30 AM
IMO there's a good chance that the change in 7-day rolling mean temperature between mid- & late November 2025 is among the largest on record for my local area.
Dropping by 9.2°C in 8 days, it went from 5°C above the 1991-2020 average on 15th to 3.3°C below it on 23rd.
Dropping by 9.2°C in 8 days, it went from 5°C above the 1991-2020 average on 15th to 3.3°C below it on 23rd.
The past month's extended ECMWF ensemble sets for the (60N) zonal mean zonal wind at 10 hPa in late November through December.
The signal for a major sudden stratospheric warming event strengthens through 12th Nov, then abruptly takes on a 'reflective' appearance on 19th Nov...
The signal for a major sudden stratospheric warming event strengthens through 12th Nov, then abruptly takes on a 'reflective' appearance on 19th Nov...
November 26, 2025 at 9:13 AM
The past month's extended ECMWF ensemble sets for the (60N) zonal mean zonal wind at 10 hPa in late November through December.
The signal for a major sudden stratospheric warming event strengthens through 12th Nov, then abruptly takes on a 'reflective' appearance on 19th Nov...
The signal for a major sudden stratospheric warming event strengthens through 12th Nov, then abruptly takes on a 'reflective' appearance on 19th Nov...
The trend in the ECMWF ensemble has me wondering how much we can trust the recent consensus for predominantly mild weather to persist across northern Europe beyond next ~Friday.
Note the trough digging down across western Europe more, with higher SLP to the north.
Note the trough digging down across western Europe more, with higher SLP to the north.
November 26, 2025 at 8:58 AM
The trend in the ECMWF ensemble has me wondering how much we can trust the recent consensus for predominantly mild weather to persist across northern Europe beyond next ~Friday.
Note the trough digging down across western Europe more, with higher SLP to the north.
Note the trough digging down across western Europe more, with higher SLP to the north.
November 2025's tremendous temperature tumble continues, with the Hadley CET to-date down to 14th warmest on record as of 24th.
With temperatures varying around the 1991-2020 average for the rest of it, the final CET will likely be around 19th warmest & about 1°C above average.
With temperatures varying around the 1991-2020 average for the rest of it, the final CET will likely be around 19th warmest & about 1°C above average.
November 25, 2025 at 2:08 PM
November 2025's tremendous temperature tumble continues, with the Hadley CET to-date down to 14th warmest on record as of 24th.
With temperatures varying around the 1991-2020 average for the rest of it, the final CET will likely be around 19th warmest & about 1°C above average.
With temperatures varying around the 1991-2020 average for the rest of it, the final CET will likely be around 19th warmest & about 1°C above average.
What are the subtypes of sudden stratospheric warming event, how can they affect surface weather patterns, & what role does absorption or reflection of energy play?
All answers are here, including why early December isn't looking cold in northern Europe:
www.metswift.com/2025/11/24/s...
All answers are here, including why early December isn't looking cold in northern Europe:
www.metswift.com/2025/11/24/s...
Sudden Stratospheric Warming Events: A Thermodynamic Wildcard - metswift
A detailed breakdown of sudden stratospheric warming event types and their differing effects on surface weather patterns.
www.metswift.com
November 24, 2025 at 5:31 PM
What are the subtypes of sudden stratospheric warming event, how can they affect surface weather patterns, & what role does absorption or reflection of energy play?
All answers are here, including why early December isn't looking cold in northern Europe:
www.metswift.com/2025/11/24/s...
All answers are here, including why early December isn't looking cold in northern Europe:
www.metswift.com/2025/11/24/s...
Are global mean temperatures in 2025 being pushed down by La Niña?
I've seen this notion doing the rounds but...
2025's mean ONI is on track to be near -0.3, while 2024's was +0.35. Historical correlation suggests this has little net effect on global mean temperature in 2025.
I've seen this notion doing the rounds but...
2025's mean ONI is on track to be near -0.3, while 2024's was +0.35. Historical correlation suggests this has little net effect on global mean temperature in 2025.
November 24, 2025 at 3:22 PM
Are global mean temperatures in 2025 being pushed down by La Niña?
I've seen this notion doing the rounds but...
2025's mean ONI is on track to be near -0.3, while 2024's was +0.35. Historical correlation suggests this has little net effect on global mean temperature in 2025.
I've seen this notion doing the rounds but...
2025's mean ONI is on track to be near -0.3, while 2024's was +0.35. Historical correlation suggests this has little net effect on global mean temperature in 2025.
There continues to be strong cross-model agreement on the opening week of December being generally mild in most of Europe, with wet & windy weather focused on the northwest.
Some uncertainty how far SE the wet & windy weather tends to reach, ECMWF's ensemble the more aggressive.
Some uncertainty how far SE the wet & windy weather tends to reach, ECMWF's ensemble the more aggressive.
November 24, 2025 at 9:56 AM
There continues to be strong cross-model agreement on the opening week of December being generally mild in most of Europe, with wet & windy weather focused on the northwest.
Some uncertainty how far SE the wet & windy weather tends to reach, ECMWF's ensemble the more aggressive.
Some uncertainty how far SE the wet & windy weather tends to reach, ECMWF's ensemble the more aggressive.
Looking back at satellite imagery from noon today, I can see the shadow cast by cirrostratus which was keeping the sunshine hazy where I was even as the sky became clear overhead.
This is with the sun at its highest point of the day. Low rider!
This is with the sun at its highest point of the day. Low rider!
November 23, 2025 at 6:42 PM
Looking back at satellite imagery from noon today, I can see the shadow cast by cirrostratus which was keeping the sunshine hazy where I was even as the sky became clear overhead.
This is with the sun at its highest point of the day. Low rider!
This is with the sun at its highest point of the day. Low rider!
There's growing confidence that ~29th Nov will see a major sudden stratospheric warming event, but one where reflection of wave activity in the stratosphere allows the polar vortex to quickly rebound.
OTOH, most runs still have it anomalously weak in the 2nd week of Dec.
OTOH, most runs still have it anomalously weak in the 2nd week of Dec.
November 22, 2025 at 8:40 PM
There's growing confidence that ~29th Nov will see a major sudden stratospheric warming event, but one where reflection of wave activity in the stratosphere allows the polar vortex to quickly rebound.
OTOH, most runs still have it anomalously weak in the 2nd week of Dec.
OTOH, most runs still have it anomalously weak in the 2nd week of Dec.
To visualise the effect of El Niño & La Niña, I decided to try applying a linear detrend to the ERA5 global mean temperature dataset, then plotting it against the annual mean Oceanic Niño Index.
The result is an astonishingly good fit to a polynomial with 3 degrees of freedom.
The result is an astonishingly good fit to a polynomial with 3 degrees of freedom.
November 22, 2025 at 6:16 PM
To visualise the effect of El Niño & La Niña, I decided to try applying a linear detrend to the ERA5 global mean temperature dataset, then plotting it against the annual mean Oceanic Niño Index.
The result is an astonishingly good fit to a polynomial with 3 degrees of freedom.
The result is an astonishingly good fit to a polynomial with 3 degrees of freedom.
There was quite the jump in temperature at Bournemouth Airport between 2 am & 3 am last night. 8.7°C in the space of an hour!
November 22, 2025 at 5:08 PM
There was quite the jump in temperature at Bournemouth Airport between 2 am & 3 am last night. 8.7°C in the space of an hour!
My current thoughts on the first ~week of December in Europe.
Events in the tropics look to drive a build of high pressure across Europe, then try to shift that northward.
Meanwhile, events in the stratosphere will probably favour low pressure in the Greenland-Iceland area...
Events in the tropics look to drive a build of high pressure across Europe, then try to shift that northward.
Meanwhile, events in the stratosphere will probably favour low pressure in the Greenland-Iceland area...
November 21, 2025 at 10:10 AM
My current thoughts on the first ~week of December in Europe.
Events in the tropics look to drive a build of high pressure across Europe, then try to shift that northward.
Meanwhile, events in the stratosphere will probably favour low pressure in the Greenland-Iceland area...
Events in the tropics look to drive a build of high pressure across Europe, then try to shift that northward.
Meanwhile, events in the stratosphere will probably favour low pressure in the Greenland-Iceland area...
Reposted by James Peacock
A polar vortex of confusion simonleewx.com/2025/11/20/a...
A polar vortex of confusion
Meteorologists have a historical penchant for giving names to atmospheric phenomena which, in today’s world, sound rather like phrases made up to fit a dramatic headline than real scientific …
simonleewx.com
November 20, 2025 at 11:52 AM
A polar vortex of confusion simonleewx.com/2025/11/20/a...
With the much colder weather of late, November's Hadley mean central England temperature to-date has begun to nosedive & is down from 1st to 5th warmest on record as of 19th.
Signs are it could drop to around 14th before a possible late recovery via an onset of milder weather.
Signs are it could drop to around 14th before a possible late recovery via an onset of milder weather.
November 20, 2025 at 2:28 PM
With the much colder weather of late, November's Hadley mean central England temperature to-date has begun to nosedive & is down from 1st to 5th warmest on record as of 19th.
Signs are it could drop to around 14th before a possible late recovery via an onset of milder weather.
Signs are it could drop to around 14th before a possible late recovery via an onset of milder weather.
With all the "will it, won't it" talk regarding a possible major sudden stratospheric warming event late this month, this seems a good time to highlight this excerpt from A. H. Butler & E. P. Gerber 's 2018 paper on the definition of such events.
journals.ametsoc.org/view/journal...
journals.ametsoc.org/view/journal...
November 20, 2025 at 10:42 AM
With all the "will it, won't it" talk regarding a possible major sudden stratospheric warming event late this month, this seems a good time to highlight this excerpt from A. H. Butler & E. P. Gerber 's 2018 paper on the definition of such events.
journals.ametsoc.org/view/journal...
journals.ametsoc.org/view/journal...
Keeping an eye on potential for strong wind events to affect NW Europe - mainly UK & Ireland - late this month.
Forcing from tropics will be trying to build high pressure over Scandinavia, but a lobe of the polar vortex in the stratosphere *might* aid dev of lows in N. Atlantic.
Forcing from tropics will be trying to build high pressure over Scandinavia, but a lobe of the polar vortex in the stratosphere *might* aid dev of lows in N. Atlantic.
November 20, 2025 at 9:40 AM
Keeping an eye on potential for strong wind events to affect NW Europe - mainly UK & Ireland - late this month.
Forcing from tropics will be trying to build high pressure over Scandinavia, but a lobe of the polar vortex in the stratosphere *might* aid dev of lows in N. Atlantic.
Forcing from tropics will be trying to build high pressure over Scandinavia, but a lobe of the polar vortex in the stratosphere *might* aid dev of lows in N. Atlantic.
At 10+ days lead time, we're probably going to see all sorts of 'wacky' model forecast scenarios in the coming weeks - & not just cold ones.
E.g. this GFS 12z with a strong blocking high over NE Europe producing well above normal airmass temperatures across much of N Europe.
E.g. this GFS 12z with a strong blocking high over NE Europe producing well above normal airmass temperatures across much of N Europe.
November 19, 2025 at 5:34 PM
At 10+ days lead time, we're probably going to see all sorts of 'wacky' model forecast scenarios in the coming weeks - & not just cold ones.
E.g. this GFS 12z with a strong blocking high over NE Europe producing well above normal airmass temperatures across much of N Europe.
E.g. this GFS 12z with a strong blocking high over NE Europe producing well above normal airmass temperatures across much of N Europe.
Even with today's properly cold wind, it looks like the max temp here in NE Dorset will be around 5.5°C.
It takes a lot to keep it much lower at this time of year. Within the middle third of November, only once since 1994 has the max been less than 5°C (4.4°C on 20th in 2004).
It takes a lot to keep it much lower at this time of year. Within the middle third of November, only once since 1994 has the max been less than 5°C (4.4°C on 20th in 2004).
November 19, 2025 at 4:38 PM
Even with today's properly cold wind, it looks like the max temp here in NE Dorset will be around 5.5°C.
It takes a lot to keep it much lower at this time of year. Within the middle third of November, only once since 1994 has the max been less than 5°C (4.4°C on 20th in 2004).
It takes a lot to keep it much lower at this time of year. Within the middle third of November, only once since 1994 has the max been less than 5°C (4.4°C on 20th in 2004).
Had a quick look at how date records have shifted over the past 5 decades in my local area.
Most striking is that the 2020s already have the largest share of date record highest max temps, & have just 4 record lowest max temps so far.
Highest rainfall on track to rival 2000s.
Most striking is that the 2020s already have the largest share of date record highest max temps, & have just 4 record lowest max temps so far.
Highest rainfall on track to rival 2000s.
November 19, 2025 at 3:44 PM
Had a quick look at how date records have shifted over the past 5 decades in my local area.
Most striking is that the 2020s already have the largest share of date record highest max temps, & have just 4 record lowest max temps so far.
Highest rainfall on track to rival 2000s.
Most striking is that the 2020s already have the largest share of date record highest max temps, & have just 4 record lowest max temps so far.
Highest rainfall on track to rival 2000s.
Last night saw a low of -3.3°C here in NE Dorset, which is 0.1°C above tomorrow's date record low (1943-2024).
That's as close to a new one as I've seen here in years. Incidentally today's date record low is -5.1°C, which is also the week-around-day record low.
That's as close to a new one as I've seen here in years. Incidentally today's date record low is -5.1°C, which is also the week-around-day record low.
November 18, 2025 at 10:14 AM
Last night saw a low of -3.3°C here in NE Dorset, which is 0.1°C above tomorrow's date record low (1943-2024).
That's as close to a new one as I've seen here in years. Incidentally today's date record low is -5.1°C, which is also the week-around-day record low.
That's as close to a new one as I've seen here in years. Incidentally today's date record low is -5.1°C, which is also the week-around-day record low.
Signs are, whether it qualifies as a major event or not, the sudden stratospheric warming to end November will be of the sort that displaces rather than splits the polar vortex (shaded blue).
Importantly, this means surface weather impacts are likely to begin 2-4 weeks later...
Importantly, this means surface weather impacts are likely to begin 2-4 weeks later...
November 17, 2025 at 2:51 PM
Signs are, whether it qualifies as a major event or not, the sudden stratospheric warming to end November will be of the sort that displaces rather than splits the polar vortex (shaded blue).
Importantly, this means surface weather impacts are likely to begin 2-4 weeks later...
Importantly, this means surface weather impacts are likely to begin 2-4 weeks later...