Earthshine

I don't know if it's just me but I've definitely noticed far fewer climate skeptic/denial posts on Netweather. It seems back in 2008-2012 you'd often see posts playing down/denying that the climate was warming and you'd often see people talking about a "mini ice age" due to solar activity. That's almost completely disappeared now. I wonder if the frequency of cold winters and cool summers perhaps influenced people's opinions then?

A classic summer's day. The view from my office. Can't wait to summer! VID_453660106_052055_115.mp4

January: Highest UK January temperature on record. 19.9C, exceeding the Feb 1998 temperature of 19.7, before that was broken by the ludicrous 21.2C in February 2019. February: Warmest winter CET day on record at 13.7C (warmer than the average for June 2013). March: Beginning cool before high pressure builds in around the 20th. Winds turn southerly for a time with a mean of 7.8C overall (compared to 7.9C for February). A max of 21C recorded in London on the 23rd. April: Bog standard month with a remarkable heat spike on the 30th. 29.9C recorded in London. May: An exceptionally mild yet wet month. A 14C CET, boosted by overnight temperatures. Very cloudy with a long fetch SW stream. June: Begins in the same vein of May before high pressure builds to the west. Turns cooler but sunnier, a dry month overall. Turns hot in the final week as the Iberian high builds in, boosting the CET to 15.8C. A maximum temperature of 30C is recorded on the 28th. July: Wow. The Iberian high evolves into a larger Euro high. Initially very warm and dry with temperatures exceeding 30C. The high moves westwards and stretches up towards Scandinavia. An extremely unusual pattern, resembling an amplified version of September 2023, see winds drawn from the African continent for 7 days straight. Temperatures soar across Europe, with temperatures exceeding 50C in Italy. Eastern parts of the UK see two consecutive 40C days. CET is a bonkers 21.2C. August: High pressure moves northwards, dragging in a cooler SE feed. Temperatures drop to high twenties across the UK, although Northern Ireland records a new all time maximum of 34C, almost 3C above the 2021 record. Winds finally turn westerly in the final week. Overall CET 18.3C. September. SW winds prevail. Legacy warmth in the Bay of Biscay keeps temperatures elevated until winds finally turn NW. A remarkable 15C drop in temperatures over 24 hours is recorded across much of the UK. October: Very cool. A CET of 9C with frequent sunny spells. Snowfall across much of Scotland on the 29th. November: Winds turn back SW and the CET rises to 9.2C, ahead of October. December: Cold. High pressure builds to the north and strong NE winds originating deep in Siberia drag in cold air very quickly before it can be modified substantially. CET of 1.7C What a fantasy eh?

Global temperatures just keep getting higher and higher. This month has already seen the longest streak of +2°C above pre-industrial on record. There is far more energy to work with than in previous years. If we do get a favourable synoptic set up this year I would say this year would be in for a good chance of seeing more extraordinary warmth. Even last year, which was pretty lackluster for warmth, still saw two 17°C CET months. It'll be very difficult to get anything very cool with so much warmth around.

Over 10 hours of sunlight here in Exeter tomorrow with sunset at 17:31. Definitely noticing the sun getting stronger tomorrow with beautiful sunny skies and forecast temperatures up to 14°C. The sun is climbing higher now, up to 27° above the horizon. Looking forward to that first 20°C day now

Metwatch Interesting how 2021 makes it there too!

Met4Cast This is another huge nail in the coffin for those few still banging on about solar activity causing warming. If the sun was outputting more energy the entire atmosphere would be warming. The fact we can observe the stratosphere in fact cooling is a sure sign of increasing carbon dioxide in the lower atmosphere.

Metwatch Very interesting! Going by highest temperatures on record for each country is also pretty fascinating: England: July 2022 Wales: July 2022 Scotland: July 2022 Northern Ireland: July 2021 Record high minimums: England: July 2022 Wales: July 2022 Scotland: July 2019 Northern Ireland: August 2001

Derecho A lot of NWP is parameterised where the scale of events is just too small to capture in the model (e.g. really local convective events). In theory AI isn't really limited to a grid, I've seen neural fields allow variables to be mapped to arbitrary resolution (e.g. your neural network maps x, y, z coordinates f(x,y, z) --> t,p,q with no reference to an actual grid). Probably won't work in NWP, but we already can already see upscaling of precipitation using AI show encouraging results: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022MS003120

Frigid Life in the UK really is relentless a winter supposedly posed to bring cold weather ended up almost seeing 20°C being reached in Scotland.

Granted I know almost nothing about this, but it would be super interesting if there was a reanalysis study to see if MJO/AAM/etc. predictions do have some medium range skill and how good they are. It would probably be a huge undertaking, but say we took the MJO forecasts from previous spells that preceded high latitude blocking events. What kind of forecasting skill could we see? I'm sure the vast density of information in the ERA5 could be used to create a pseudo forecast perhaps. It would be interesting to try to quantify how useful these driver forecasts are in a historical setting, which might inform us on how to use them now.

Relativistic Thanks! It's an interesting problem. Really the model is trained to minimise the difference in variables between the ERA5 dataset and it's own output (Pangu is four surface and 5 upper air variables - MSLP, T u, v winds + mixing ratio for upper air variables on 13 pressure levels). It infers the physics on how these variables interact with zero knowledge of the known physics, something I find extraordinary that it works!

Mike Poole You're exactly right. There is no inherent knowledge of physics, only inferred from the ERA5 training data. I'm amazed it works, it seems such an ill-posed problem yet here we are. On the problem of not respecting physical laws, this is a problem because the atmosphere is chaotic and if you aren't conserving energy the intensity of storms is underestimated. We saw this with AI forecasts for Storm Ciaran which were weaker than the physics-based IFS forecast.

The PIT That's actually a problem with "AI" models. They are trained to minimise the absolute error between the output and the training reanalysis dataset. When used operationally, the output that is an optimum solution is a "blurred" forecast with no extremes at longer lead times. You can actually see the kinetic energy just randomly drop away. I've applied for a grant to work with a software engineer to hopefully incorporate physical constraints into the training of these models. Hopefully then the output will be constrained to not only fit the observational data, but to actually force it to conserve kinetic energy, mass, etc. These data-driven models are the very first generation of operational models. I would be EXTREMELY hesitant to say that they will never overtake classic physics based models. The rate of progress has just exploded - and these are basically equivalent to the very first generation of classic NWP models. Personally I think the biggest constraints to better weather forecasts at the moment is a lack of observations - satellites are great, but the vertical resolution of sounders is seriously lacking.

A very good summer that is rarely spoken about. Every month was significantly warmer than average. Here's the season and monthly maximum CET values: Summer: 22.2°C (6th hottest on record) June: 21.3°C July: 22.0°C August: 23.3°C There were unfortunately drought conditions. Every day from the 24th July to the 28th August recorded a maximum CET of at least 20°C.

lassie23 I wouldn't be so sure, the AIFS has recently been updated by the ECMWF and has skill just as good as the physics-based IFS using attention graph neural networks: https://www.ecmwf.int/en/about/media-centre/aifs-blog/2024/first-update-aifs

I would absolutely not worry about what this summer will be like - that goes for both warm weather and cool weather fans! Many were saying 2022 will have a mediocre August because of La Nina - ended up being the third warmest on record. Last summer was supposed to be a summer of heat plumes - none except in September! Personally I'll be concerned when we get to June and we see zero warm ensemble members

My ideal climate would be 32°C during the day and 20°C at night, thinking somewhere like a Carribbean climate. I love warm nights where I can just sit outside and chill. I do struggle when temperatures get close to 40°C though.

A March like 2022, an April like 2020 and a May like 2018/2020 would be fantastic. I'd like to see gin blue skies and bone dry conditions in May, a bit like 2020 (picture below).

Potential for exceptionally mild end to the month. Long way off of course but quite a few of these are very February 2019-esque

3.7°C and 60 mm please

Word of caution - in the absence of a strong driving signal, NWP models will often drift towards the climatological mean (background covariances in data assimilation will often penalise large departures from climatological mean).

I'm surprised they are predominantly done with satellite data, I would have thought they would have been created using the analysis (i.e. all assimilated observations in that time window).

5C and 80mm please

7.4°C and 70mm please