Simon Lee
@simonleewx.com
Lecturer in Atmospheric Science, University of St Andrews. Large-scale weather & climate variability, prediction & change. simonleewx.com
The ensemble mean of today's IFS subseasonal forecast now predicts the earliest major sudden stratospheric warming in reliable records, beating 28 November 1968.
Will this verify? 👀
charts.ecmwf.int/products/ext...
Will this verify? 👀
charts.ecmwf.int/products/ext...
November 13, 2025 at 8:17 PM
The ensemble mean of today's IFS subseasonal forecast now predicts the earliest major sudden stratospheric warming in reliable records, beating 28 November 1968.
Will this verify? 👀
charts.ecmwf.int/products/ext...
Will this verify? 👀
charts.ecmwf.int/products/ext...
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
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
November 12, 2025 at 8:32 PM
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
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
Not the favoured outcome by any means, and I’m mostly posting this for fun (and my own interest in “unseen” model extremes), but the GFS 18Z has an historic major SSW on 26 November.
This would be the earliest in reliable records, beating 28 Nov 1968.
Not a forecast — just for interest!
This would be the earliest in reliable records, beating 28 Nov 1968.
Not a forecast — just for interest!
November 10, 2025 at 11:56 PM
Not the favoured outcome by any means, and I’m mostly posting this for fun (and my own interest in “unseen” model extremes), but the GFS 18Z has an historic major SSW on 26 November.
This would be the earliest in reliable records, beating 28 Nov 1968.
Not a forecast — just for interest!
This would be the earliest in reliable records, beating 28 Nov 1968.
Not a forecast — just for interest!
Reposted by Simon Lee
🌍 Postdoc research opportunity: Predictability and Climate Dynamics - University of Oxford, UK
📚 The position sits within the Predictability of Weather and Climate and Climate Dynamics research groups in Oxford’s Department of Physics.
@timwoollings.bsky.social
@oxfordphysics.bsky.social
🧵
📚 The position sits within the Predictability of Weather and Climate and Climate Dynamics research groups in Oxford’s Department of Physics.
@timwoollings.bsky.social
@oxfordphysics.bsky.social
🧵
November 8, 2025 at 9:30 PM
🌍 Postdoc research opportunity: Predictability and Climate Dynamics - University of Oxford, UK
📚 The position sits within the Predictability of Weather and Climate and Climate Dynamics research groups in Oxford’s Department of Physics.
@timwoollings.bsky.social
@oxfordphysics.bsky.social
🧵
📚 The position sits within the Predictability of Weather and Climate and Climate Dynamics research groups in Oxford’s Department of Physics.
@timwoollings.bsky.social
@oxfordphysics.bsky.social
🧵
06Z GFS has remarkably persistent Greenland blocking for the full run, and a very weak stratospheric vortex by the end of it too. Posting this just for fun, but falls within what seems to be the range of possible outcomes based on recent modelling.
November 8, 2025 at 2:45 PM
06Z GFS has remarkably persistent Greenland blocking for the full run, and a very weak stratospheric vortex by the end of it too. Posting this just for fun, but falls within what seems to be the range of possible outcomes based on recent modelling.
What is it that possesses someone to hold a phone call **on speakerphone** on an otherwise silent bus?
November 3, 2025 at 7:13 PM
What is it that possesses someone to hold a phone call **on speakerphone** on an otherwise silent bus?
Reposted by Simon Lee
A damaging hurricane in a warmer world
How would a major hurricane that hit Jamaica in 1903 be different today, in a warmer world?
It would drop more rain. (At least)
climatelabbook.substack.com/p/a-damaging...
How would a major hurricane that hit Jamaica in 1903 be different today, in a warmer world?
It would drop more rain. (At least)
climatelabbook.substack.com/p/a-damaging...
November 2, 2025 at 9:21 AM
A damaging hurricane in a warmer world
How would a major hurricane that hit Jamaica in 1903 be different today, in a warmer world?
It would drop more rain. (At least)
climatelabbook.substack.com/p/a-damaging...
How would a major hurricane that hit Jamaica in 1903 be different today, in a warmer world?
It would drop more rain. (At least)
climatelabbook.substack.com/p/a-damaging...
Reposted by Simon Lee
Alrighty, ready to see something really cool? (and maybe a little nauseating)
The evolution of Hurricane Melissa's mesovortices at peak strength.
The evolution of Hurricane Melissa's mesovortices at peak strength.
October 29, 2025 at 8:10 PM
Alrighty, ready to see something really cool? (and maybe a little nauseating)
The evolution of Hurricane Melissa's mesovortices at peak strength.
The evolution of Hurricane Melissa's mesovortices at peak strength.
Reposted by Simon Lee
1-minute #GOES19/#GOESEast Visible images showed that soon after making landfall, the eye of Hurricane #Melissa became cloud-filled as the storm interacted with higher terrain on the western edge of Jamaica.
October 28, 2025 at 8:58 PM
1-minute #GOES19/#GOESEast Visible images showed that soon after making landfall, the eye of Hurricane #Melissa became cloud-filled as the storm interacted with higher terrain on the western edge of Jamaica.
Reposted by Simon Lee
One factor that supported Melissa reaching this record: an Argo float southeast of Jamaica shows a dramatic decrease in upper-level ocean temperature before (18 Oct) and after (28 Oct) the storm.
My heart goes out to the folks in Jamaica facing this powerful hurricane's numerous hazards today. 💔
My heart goes out to the folks in Jamaica facing this powerful hurricane's numerous hazards today. 💔
October 28, 2025 at 5:27 PM
One factor that supported Melissa reaching this record: an Argo float southeast of Jamaica shows a dramatic decrease in upper-level ocean temperature before (18 Oct) and after (28 Oct) the storm.
My heart goes out to the folks in Jamaica facing this powerful hurricane's numerous hazards today. 💔
My heart goes out to the folks in Jamaica facing this powerful hurricane's numerous hazards today. 💔
Reposted by Simon Lee
219-kt peak wind would be the highest wind value a dropsonde has ever recorded, ahead of 215-kt value in Super Typhoon Megi in 2010 & the 210 kt recorded just yesterday in #Hurricane #Melissa.
Still needs to be validated… so this data is preliminary.
Still needs to be validated… so this data is preliminary.
This is hands down the most extraordinary dropsonde in Atlantic recon history.
October 28, 2025 at 3:48 PM
219-kt peak wind would be the highest wind value a dropsonde has ever recorded, ahead of 215-kt value in Super Typhoon Megi in 2010 & the 210 kt recorded just yesterday in #Hurricane #Melissa.
Still needs to be validated… so this data is preliminary.
Still needs to be validated… so this data is preliminary.
Literal chills seeing the latest data for Melissa
October 28, 2025 at 2:28 PM
Literal chills seeing the latest data for Melissa
This storm is a testament to what can happen if a hurricane doesn't blow out its eyewall too quickly. Melissa didn't seem to develop the unstable pinhole eye true of many cat 5 storms.
And of course a testament to the power of weather prediction that we can forecast these things days in advance.
And of course a testament to the power of weather prediction that we can forecast these things days in advance.
#Melissa unfortunately is still intensifying. A 9am EDT Tropical Cyclone Update indicates that winds are up to 180 mph, with an estimated minimum pressure of 896 mb.
You can see how GLM lightning has 📈 in the past hour, encircling the eye, with eye WV temp still increasing!
You can see how GLM lightning has 📈 in the past hour, encircling the eye, with eye WV temp still increasing!
October 28, 2025 at 1:51 PM
This storm is a testament to what can happen if a hurricane doesn't blow out its eyewall too quickly. Melissa didn't seem to develop the unstable pinhole eye true of many cat 5 storms.
And of course a testament to the power of weather prediction that we can forecast these things days in advance.
And of course a testament to the power of weather prediction that we can forecast these things days in advance.
Reposted by Simon Lee
This meso loop of #Melissa from CIRA is absolutely stunning at it makes its closes in on landfall in southwestern Jamaica.
rammb-data.cira.colostate.edu/tc_realtime/...
#hurricanemelissa
rammb-data.cira.colostate.edu/tc_realtime/...
#hurricanemelissa
October 28, 2025 at 12:52 PM
This meso loop of #Melissa from CIRA is absolutely stunning at it makes its closes in on landfall in southwestern Jamaica.
rammb-data.cira.colostate.edu/tc_realtime/...
#hurricanemelissa
rammb-data.cira.colostate.edu/tc_realtime/...
#hurricanemelissa
Those radially propagating gravity waves 😍
The monster eye at the center of a still strengthening Hurricane Melissa.
October 27, 2025 at 7:08 PM
Those radially propagating gravity waves 😍
Reposted by Simon Lee
The NHC forecast for Melissa at 15 UTC today was the first time they have ever projected a hurricane to reach 130kt at 96 hours, starting from a 40kt storm.
Projecting 130kt at 96 hours is rare, just in general.
Projecting 130kt at 96 hours is rare, just in general.
October 24, 2025 at 9:58 PM
The NHC forecast for Melissa at 15 UTC today was the first time they have ever projected a hurricane to reach 130kt at 96 hours, starting from a 40kt storm.
Projecting 130kt at 96 hours is rare, just in general.
Projecting 130kt at 96 hours is rare, just in general.
“…there is a distinct possibility that Melissa could become a Category 5 hurricane during this time period. In fact, the latest 12z Google DeepMind ensemble distribution shows the majority of its members reaching this lofty intensity.”
Atlantic Tropical Storm Melissa Advisory Number 14
...MELISSA EXPECTED TO RAPIDLY INTENSIFY INTO A MAJOR HURRICANE THIS WEEKEND... ...LIFE-THREATENING AND CATASTROPHIC FLASH FLOODING AND LANDSLIDES EXPECTED IN PORTIONS OF SOUTHERN HISPANIOLA AND JAMAICA THROUGH THE...
Additional Details Here.
...MELISSA EXPECTED TO RAPIDLY INTENSIFY INTO A MAJOR HURRICANE THIS WEEKEND... ...LIFE-THREATENING AND CATASTROPHIC FLASH FLOODING AND LANDSLIDES EXPECTED IN PORTIONS OF SOUTHERN HISPANIOLA AND JAMAICA THROUGH THE...
Additional Details Here.
October 24, 2025 at 9:27 PM
“…there is a distinct possibility that Melissa could become a Category 5 hurricane during this time period. In fact, the latest 12z Google DeepMind ensemble distribution shows the majority of its members reaching this lofty intensity.”
QBOi-SNAP-QUOCA workshop: improved simulations of the stratosphere for better predictions of weather, climate and extreme events
Meeting report from the @wcrpclimate.bsky.social APARC workshop in Cambridge earlier this year
Free to view in @rmets.org Weather: doi.org/10.1002/wea....
Meeting report from the @wcrpclimate.bsky.social APARC workshop in Cambridge earlier this year
Free to view in @rmets.org Weather: doi.org/10.1002/wea....
QBOi‐SNAP‐QUOCA workshop: improved simulations of the stratosphere for better predictions of weather, climate and extreme events
Click on the article title to read more.
doi.org
October 23, 2025 at 9:09 AM
QBOi-SNAP-QUOCA workshop: improved simulations of the stratosphere for better predictions of weather, climate and extreme events
Meeting report from the @wcrpclimate.bsky.social APARC workshop in Cambridge earlier this year
Free to view in @rmets.org Weather: doi.org/10.1002/wea....
Meeting report from the @wcrpclimate.bsky.social APARC workshop in Cambridge earlier this year
Free to view in @rmets.org Weather: doi.org/10.1002/wea....
I often find myself confused by some app forecasts where the icon is rain, but the stated probability of precipitation is small (e.g., 30%). So it's more likely to be dry but... the expectation is (somehow) rain? Or is the icon just flagging a risk? Do non-meteorologists actually think about this?
October 22, 2025 at 2:21 PM
I often find myself confused by some app forecasts where the icon is rain, but the stated probability of precipitation is small (e.g., 30%). So it's more likely to be dry but... the expectation is (somehow) rain? Or is the icon just flagging a risk? Do non-meteorologists actually think about this?
A named storm. But maybe not. But maybe it will be, but maybe not because of impacts in the UK. And maybe it will have a name from our list, or someone else’s list. Bram or Benjamin. And if it isn’t named it might still be bad locally.
www.bbc.com/weather/arti...
www.bbc.com/weather/arti...
UK weather: Met Office issues rain and wind warnings as named storm possible
With weather warnings issued and the potential for a named storm, Simon King takes a look at the forecast.
www.bbc.com
October 21, 2025 at 2:41 PM
A named storm. But maybe not. But maybe it will be, but maybe not because of impacts in the UK. And maybe it will have a name from our list, or someone else’s list. Bram or Benjamin. And if it isn’t named it might still be bad locally.
www.bbc.com/weather/arti...
www.bbc.com/weather/arti...
Can we all agree that subseasonal is one word, without a hyphen
October 20, 2025 at 12:49 PM
Can we all agree that subseasonal is one word, without a hyphen
8 AM EDT WED OCT 19 2005
"BASED ON DROPSONDE AND FLIGHT-LEVEL DATA FROM AN AIR FORCE PLANE JUST RETURNING FROM ITS MISSION IN WILMA...THE MINIMUM CENTRAL PRESSURE IS ESTIMATED TO BE 882 MB...26.05 INCHES. THIS IS THE LOWEST PRESSURE ON RECORD FOR A HURRICANE IN THE ATLANTIC BASIN"
"BASED ON DROPSONDE AND FLIGHT-LEVEL DATA FROM AN AIR FORCE PLANE JUST RETURNING FROM ITS MISSION IN WILMA...THE MINIMUM CENTRAL PRESSURE IS ESTIMATED TO BE 882 MB...26.05 INCHES. THIS IS THE LOWEST PRESSURE ON RECORD FOR A HURRICANE IN THE ATLANTIC BASIN"
October 19, 2025 at 2:33 PM
8 AM EDT WED OCT 19 2005
"BASED ON DROPSONDE AND FLIGHT-LEVEL DATA FROM AN AIR FORCE PLANE JUST RETURNING FROM ITS MISSION IN WILMA...THE MINIMUM CENTRAL PRESSURE IS ESTIMATED TO BE 882 MB...26.05 INCHES. THIS IS THE LOWEST PRESSURE ON RECORD FOR A HURRICANE IN THE ATLANTIC BASIN"
"BASED ON DROPSONDE AND FLIGHT-LEVEL DATA FROM AN AIR FORCE PLANE JUST RETURNING FROM ITS MISSION IN WILMA...THE MINIMUM CENTRAL PRESSURE IS ESTIMATED TO BE 882 MB...26.05 INCHES. THIS IS THE LOWEST PRESSURE ON RECORD FOR A HURRICANE IN THE ATLANTIC BASIN"
Storm Amy really sticks out in an otherwise dominantly slowly-varying & anticyclonic month (until today, that is!). Pressure data from northeast Fife (~10m above sea level)
October 19, 2025 at 12:06 PM
Storm Amy really sticks out in an otherwise dominantly slowly-varying & anticyclonic month (until today, that is!). Pressure data from northeast Fife (~10m above sea level)
Reposted by Simon Lee
Tackling challenges of subseasonal-to-seasonal forecasting—which could transform our ability to anticipate heatwaves, flooding, wildfires, and more—requires siloed scientific communities to work together, write Jadigwa Richter and Everette Joseph of @ncar-ucar.bsky.social. eos.org/opinions/sci...
Scientists Must Join Forces to Solve Forecasting’s Predictability Desert - Eos
To strengthen societal resilience to worsening natural hazards, siloed Earth system science communities must collaborate to understand conditions that favor skillful subseasonal-to-seasonal forecasts.
eos.org
October 17, 2025 at 1:59 PM
Tackling challenges of subseasonal-to-seasonal forecasting—which could transform our ability to anticipate heatwaves, flooding, wildfires, and more—requires siloed scientific communities to work together, write Jadigwa Richter and Everette Joseph of @ncar-ucar.bsky.social. eos.org/opinions/sci...