I’m pleased to report that I will once again be working with @snowwatchGB this winter providing much needed updates on snow potential & risks. Make sure you’re giving them a follow! Hopefully there will be something for us to talk about this winter ❄️

The idea that we may see an abrupt change to very unsettled weather this autumn *may* have been either delayed by the recent wobbling of the developing stratospheric vortex, this triggered by strong wave activity via Rossby wave propagation but also wave reflection from the East Asian mountains. We are now entering a negative mountain torque event (momentum is now being scrubbed from the atmosphere) and as a result, AAM tendency has fallen through the floor, we often talk about changes occurring on infliction points and this is perhaps a good example. Whilst AAM itself is likely to remain high due to the developing very strong El Nino, the direction of travel, i.e momentum now falling is more important than the sum total. All of this is essentially a fancy way of saying that towards the middle of October but particularly through the second half of the month we're more likely to see a cyclonic / low pressure driven pattern taking hold vs a continuation of the high pressure that has been anticipated through the first half of October thanks to the recent spike in AAM tendency. How the vortex develops & behaves through autumn will give hints at what type of winter we might end up having.

It was an exceptionally warm night across the UK for late September, with some stations recording 22°C during the early hours. Temp has been rising all through the night at Edinburgh, for example. Red box highlights just how much last night stands out from individual site records

Quite remarkable that we reached 28.1°C today given the time of year. Much of the UK is significantly above average.. again.

TUESDAY A dry day for most away from a few showers to the southwest early morning, variable amounts of cloud but there should be some good sunny spells around. Through tomorrow evening the next weather system pushes into the southwest.

Life can be very hard sometimes, just keep going, everything passes, if nothing else, just wait it out.

An area of instability moving out of northern France during Monday night may bring heavy rain & thunderstorms to parts of southeast England. Whilst much of the activity may stay offshore, can't rule out some cells working in across parts of Sussex/east Kent for example.

I'm getting closer to figuring out how to get these charts out to everyone. I've now got a fully working, native SwiftUI app on macOS and I think I've figured out a way to render the charts before uploading them, would bypass any potential API issues.

Certainly a wet start to the day across Ireland and western counties of England / Scotland!

Could be a very wet day for some across western counties of England, Wales and western Scotland tomorrow with an area of dynamic rain from the southwest merging with a squall line moving in from the west. Potential for some embedded thunderstorms, strong gusty winds & localised flooding.

Just a little disagreement between UKM & GFS regarding how much low pressure to the west of the UK deepens early next week...! In the past few runs GFS has really gone off the idea of a favourable interaction with the jet stream. UKM has held steady.

The UK is on track to smash the previous warmest year on record. With the exception of January, every single month this year so far has been more than 2°C above average with February, June & July coming in more than 3°C above average. Astonishing.

That’s quite the deep low pressure system to the west of the UK to end the month on the ECM. Worth noting other models aren’t anywhere near as deep.

A decaying weather front will bring a lot of cloud across the UK tomorrow with some light patchy rain across southern Scotland and northern England. Showers into western parts of Scotland.

The weather will turn more changeable through this weekend and into early next week with low pressure taking charge, spells of rain & perhaps windy weather too. Beyond that the signal becomes more mixed, small chance of high pressure returning early October.

Through tomorrow a weather front moving in against high pressure will rapidly decay, potentially quite wet for the western Isle of Scotland and western Ireland however.

When it's the middle of winter and the latest ECM is coming out.

Wow. Following a monumental positive mountain torque event we saw a huge spike in AAM tendency and as a result, total AAM is now quite literally off the charts. Essentially this means there has been a huge injection of momentum into the atmosphere, the drop off in AAM tendency as can be seen coming into view on the second chart is likely to be just as big as Earth attempts to find a balance. The MJO finally looks likely to emerge again in the western hemisphere (phase 1) which in conjunction with the recent AAM spike suggests high pressure over Northern Europe and a low pressure trough digging south to the west of the UK, this could perhaps open the door to deeper low pressure systems glancing north-western parts of the UK over the next couple of weeks and into October, albeit sample size for composites is small and there is *some* conflict between what the AAM is doing and what the MJO is doing. If we do see a substantial drop in AAM tendency as seems plausible, the likelihood of something far more unsettled by the second half of October increases markedly. It’s worth noting that an event of this magnitude in terms of AAM rise during winter would offer mouth watering prospects for colder weather. Longer range forecasting during the transitional months (spring & autumn) often proves more difficult due to changing seasonal wavelengths and often conflicting variables.

Just been to the cinema to watch Pressure. Perhaps one of the best meteorological films I’ve ever seen. The acting & casting was wonderfully done. What really struck me was how a 61 hour forecast back then was virtually impossible back then but Cpt. James Stagg was able to pull it off by looking at observations from many different look out points. Today, we can forecast out to a week with reasonable accuracy using the exact same methods Cpt. Stagg deployed, albeit with significantly more data, observation and computing power than he had. Wonderful film about how the weather shaped the D Day landings and without Cpt. Stagg and his team, it could have gone very, very differently.

I still have no idea what these bars are supposed to represent on the @metoffice app. Today is warmer than yesterday so today’s bar is longer, okay, but that doesn’t look like a 1°C difference, the gap is far too wide. The bars make zero sense!!