peacockreports.bsky.social
Head Meteorologist at MetSwift, working to revolutionise delivery of weather information.
LinkedIn: https://t.co/pUCAQfAfRP
900 posts
344 followers
54 following
Regular Contributor
Active Commenter
comment in response to
post
Past experience suggests the most likely outcome is somewhere between UKMET & GEM, on the basis that the GFS scenario requires the low to become 'cut off' from the jet stream, which requires the setup (jet stream position etc.) to fall within a narrow margin.
comment in response to
post
If 35°C is reached in 2025, it will make a strong case for there having been a significant shift starting in 2015.
If not, the door will be open to 2015-2022 having been a shorter-term variation, albeit one without precedent in 140 prior years.
comment in response to
post
What's more, it was very nearly 8 of 10 years. Yearly highest UK temps (°C) reveal that 2017 was only 0.5°C short, & 2024 a mere 0.2°C:
2015 36.7
2016 35.2
2017 34.5
2018 35.6
2019 38.7
2020 37.8
2021 32.2
2022 40.3
2023 33.2
2024 34.8
comment in response to
post
The slower it lifts north, the higher the potential rainfall totals Friday night, though thunderstorm activity might not be quite as intense.
If it's slow enough, Saturday could see heavy showers widely, whereas a faster lift would restrict such weather to ~N half of the UK.
comment in response to
post
A big part of the uncertainty around this event is with regard to how quickly the low that drives this swift change of airmass 'lifts' northward from the UK.
E.g. the GFS 00z det. run was a fair bit slower to do that than the subsequent 06z run.
comment in response to
post
Such a rapid drop in temperatures aloft, even when occurring overnight, is a recipe for lively thunderstorms, usually of an elevated nature - the sort that produces a lot of lightning but nearly all of it cloud-cloud rather than cloud-ground.
5-6 days away so details are subject to change.
comment in response to
post
...as we'll be seeing a hot airmass with 850 hPa temperatures perhaps as high as 20°C (which used to be rare but now happens at least one most summers) being displaced, perhaps swiftly, by one with temperatures at that height some 14-15°C cooler.
comment in response to
post
Normally, this would introduce a fresher run of weather, but this time around, very warm to hot conditions are forecast to push back westward across E&W on Friday... only for a return push eastward to occur that evening!
The results could be dramatic by UK standards...
comment in response to
post
On this basis, an outcome more like the GFS or GEM 00z deterministic runs seems a safer bet.
That being one where NW Europe experiences a dry, either warm or hot spell of weather for at least a few days next week.
comment in response to
post
In S England this is turning out to be one of the most different to anticipated days in a while. Seemingly too little surface heating for thunderstorms & now this surprising mass of more persistent rain instead 🤨
comment in response to
post
Usual caveats do apply, though, given this is looking 5-6 days ahead. We can't yet rule out the models having made presumptions that prove incorrect, causing the very hot airmass to visit at a different time &/or to a different extent.
comment in response to
post
The result being that Wednesday is relatively sunny but with the airmass conducive to mid-high 20s °C, then Thursday has the potential to climb a bit higher in E/SE England, but this might be prevented by showers & thunderstorms, or the residual clag from such.
comment in response to
post
I say 'encourage' because there's always some 'wiggle room' with these composites.
The phase 7 composite has little representation in ensemble forecasts for next weekend onward. It seems that if the MJO decays in that phase, the pattern is free to be steered by other forcing.
comment in response to
post
Composites for similar MJO behaviour during past Junes suggest that it reaching phase 8 would encourage dry, warm or hot weather in W & E Europe with the UK joining in at times.
Phase 1 would encourage settled weather focused more upon NW Europe, with E Europe more unsettled.
comment in response to
post
Away from western Scotland, temperatures will be trending upward during this time, especially in southern & eastern England where low 20s °C look to be reached in a few areas on Mon & widely on Tue.
For Wednesday onward, there's too much uncertainty to go into any details yet.
comment in response to
post
That being a deterministic model run by the Japan Meteorological Agency.
Its version of events sees low pressure making slower progress against high pressure over NW Europe.
The Canadian GEM model's 00z almost took that route, but lacked sufficient high pressure over N. Sea.
comment in response to
post
For anyone wondering, the dramatic-looking medley of much above & below normal SSTs further west in the North Atlantic are associated with varying position of the gulf stream, nothing unusual.
Basically, it's an area where the long-term average isn't a helpful benchmark.
comment in response to
post
…but I must stress this is a very small possibility built upon possible deviations outside of the recent model ensemble range.
It’s far from clear whether temps anywhere in the UK will rise past the mid-20s °C later next week, let alone into the mid-30s.
comment in response to
post
It’s worth noting that the ‘plume’ of hot air to the south is in the upper reaches of climatology for the time of year.
We need to keep an eye on what goes on around the Azores. *If* a low there is elongated south-north next Wednesday, S UK *could* see v hot temps by Thursday…
comment in response to
post
With a pretty massive shift from its prior run from 5-6 days ahead onward, GFS's deterministic model has gone from among the least to among the most enthusiastic regarding hot weather developing across the UK later next week.
There's a lot to be sorted out in the forecast.
comment in response to
post
Then for the tail end of next week & well into the week after, there's strong support for high pressure across at least the southern half of the UK.
I see this as the second of a 2-step pattern shift. Low pressure goes from over UK to near UK, & then away from the UK.
comment in response to
post
The first three model runs shown above mainly predict 5-10 mm, locally a little higher, for Saturday.
The last one, ECMWF's, predicts 10-20 mm, locally higher. IMO the overly wide convective cells issue is the main reason for this discrepancy.
comment in response to
post
The 12z ECMWF deterministic sided much more with UKMET than GFS, though it has the Atlantic trough slower-moving, such that we see a more gradual but longer duration build of heat across the UK next week.
Interesting scenario but needs more cross-model support to gain traction.
comment in response to
post
Radar estimates show a swathe of lower totals aligned SW-NE with Verwood on the fringes. It's where the squall line proved rather a weak affair, peak rain rates less than 10 mm per hour. Something that happens quite a lot in this area!
comment in response to
post
This dispute leads to GFS predicting a notably cool north-westerly flow across the UK next Tuesday, while UKMET has very warm air wafting up from the south in a classic 'destabilising plume' setup (big risk of thunderstorms).
The fog of uncertainty remains frustratingly dense.