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In response to @heath question, and also to @carinthian post about Mid latitude Quasi Resonant Blocking, I did a search and came across this paper: (PDF) Quasiresonant amplification of planetary waves and recent Northern Hemisphere weather extremes WWW.RESEARCHGATE.NET PDF | In recent years, the Northern Hemisphere has suffered several devastating regional summer weather extremes, such as the European heat... A lot of it above my pay grade, but, reading between the lines I took away this: In summer, the jet can still become so meridional that it becomes more of a standing wave rather than a travelling wave, and this can lead to stuck patterns, but the wave number for this to happen is 6, 7 or 8 (number of waves around the planet). I don’t know about earlier in summer, but right now going forward we seem to have a wave 6 pattern, ECM T120, ridges highlighted: It seems this has been going on for months and because the next ridge is in situ the pattern can’t move on, it has been less obvious to us in the Uk because we weren’t stuck in a heatwave or massive trough, just mostly nondescript summer weather. But it is clear that the weather pattern has been slow moving for months. And it goes back to last winter and the SSW (I think). Just to consider winter for a moment, the wavelengths are longer, and a 3 wave pattern would have half the hemisphere blocked for at least a month, and a 4 wave pattern would gridlock the whole lot (the holy grail, I think SM once said). Also in winter, the blocks seem to form in the same places (Greenland, Scandi etc.), less so in summer. But it seems in the more fluid patterns of summer, there is still a limit to how many waves the planet can handle, it is a larger number, but once 6 or more, the pattern can grind to a halt over some portions of the northern hemisphere, and this seems to be becoming more likely with global warming. So what does this mean going forward? I think it means those thinking the Atlantic is going to come barrelling forth just because it is the equinox will find their predictions doomed. There will be realignments - winter can’t sustain a 6 wave pattern so there will be shifts, but maybe to a 5 wave, then 4 wave, then 3 wave pattern as we go into winter. But I would, given the winter blocks tend to have particular locations, expect a period of cold weather to prevail during early winter for the UK before this sorts itself out. Ironically, the best mechanism to reset this Quasi Resonant Blocking might be a major winter SSW - so my prediction is a cold early winter, followed by an SSW about January that eventually resets for mild. I’ve had to make some leaps in my own understanding in this post, so if anyone knows better, please reply and we all learn… All the best. Mike

I shall be doing a test on how on average models agree(percentage) and how close those models are to the eventual outcome on those dates. Having chosen 2 random days for part 1bto do this test beggining with the first crossover day May 1st, this is only part 1 of my test. May 1st GEM VS GFS VS ECM day 3 Model agreement: Not much difference at all between GEM and GFS except the strength of the low positioned over northern Europe and Russia, this low had been strengthened sightly towards the centre of it by the GFS, both models and the ECM are relatively similar as well. Model agreement: 95% Eventual outcome : 95% Can only get it at midnight but its close enough model agreement in line with outcome : 95% GFS: 97% ECM : 97% GEM : 91% Day 5 GFS and GEM weaken the low North of England more than the ECM, differences to the feeding through if the high towards Europe as well. Model agreenent: 90% Outcome : Model agreement to outcome : 85% ,there is a lot different to the Models in terms of that low's positioning but in model terms it's pretty accurate and so is that high. GEM: 87% GFS: 85% ECM: 83% Day 7 Model agreement: 80% Still a lot the same right now, the centre of that low is different on the Models by quite a big margin and that East Pacific low is different as well. Outcome : There is a lot different with the strength of the low here not only that but the depth of the East Pacific low across north America Model outcome : 70% Day 9 Model agreement : There is a lot different now but the principle is still the same 55% Compared to outcome : There is a big different to the Models here, including the strength of the high going up in Europe and the strength of the Arctic low's, thee incursion of the low across Greenland has definitely retreated. 50% GFS: 55% ECM: 48% GEM: 47% 2nd day run 15th May Model agreement : 90% Outcome: 85% 17th May Model agreement : 85% Outcome : 83% 19th May Model agreement : 80% Outcome : 70% 21st May Model agreement : 55% Outcome : 45% Thats it for now, part 1 done

Something odd I've noticed recently, the GFS seems to have incorrect sea temperature data around the UK. It seems to use the same data as on these charts, up to 6C below average in the channel: Whereas in reality, SST's are above average around the UK: This seems to manifest in the GFS showing air temperatures too low over the sea and windward coasts. 3pm today GFS vs ECM: tomorrow night: If this is incorporated back into the model, surely this would affect the forward accuracy of the GFS?

Aye, we have seen this pattern for the Atlantic trough to disrupt as you say for many months now. Mid latitude Quasi Resonant Amplification ( QRA ) as some of our European experts report could hold sway for a lot of snowfall in Western Europe/UK this coming winter, especially the Alps as they mention ( if things stay as they are ) ! This is very unusual. C

Alaska suddenly sees a large snowfall. Scattered snow continues in Siberia and is now spreading further west into central Russia. this is very early compared to the recent past. Could it be the first indication of a true Siberian winter this year - after an absence of about 8 years?. MIA

So for the first day of October the ecm0z brings a not insignificant HP to the NE stretching into Greenland with trough over us and to SE and easterly wind potential. I know its day 10 but ecm has been on this signal before. Prior to that a nice late summery spell for many. Certainly not your expected Autumn fayre and nothing is certain it seems presently. Enjoy the next few days.

There'll be no moans from me, should anything like this verify!

0z ECM and UKMO ops - Good agreement at 144h for the building of an extensive belt of high pressure from Scandinavia through northern Russia. Doesn’t look to be moving away any time soon, maintaining a strong influence for several days to come. Intensifying more over Scandinavia by day 8, and still there ridging to Iceland at day 10, as low pressure nestles in on its southern flank over the UK and Europe, bringing us into an easterly. All this descending air over Eurasia cools the T850 to below normal for an extensive area covering most of Russia and Europe, including the UK and Ireland as shown by the 850 hPa anomaly chart for 240h. 0z ECM 240h 850 hPa temps, and the anomaly chart Some relatively cold uppers over Eastern Europe (-5 in the mix) would be heading our way by then. So if the block does remain in place, some tentative signs of the potential for the set-up to lead to some colder than average temperatures over Europe heading into October, particularly as the daytime warming wanes.

Where did all these posts come from? …anyway, looking at the 0z output, the Atlantic is still floundering and the ECM looks very disrupted to say the least, these are not typical autumn charts!

https://www.meteociel.fr/modeles/archives/archives.php you tell us? Above is a link to all charts back to the 1800s. I don’ think it’s that unusual for September to be honest. The PV usually takes until end of Oct or early November to get going. I remember many year us coldies getting excited in Autumn by all the blocking and lack of PV but by November it appears and it’s business as usual lol

Interesting this feature from gfs 12z on 2nd October. Looks like a sudden appearance of a tropical storm just off coast of East Anglia. It quickly dissappears and will be gone next run. Dont often see that... After a few days of more unsettled weather (particularly for nw) gfs brings back HP again over us... ...and warmer temps....JFF....

Nice live footage with sound.

This caught my eye today. Could be nothing but I'll be keeping an eye on it as we lead upto Winter. Well below average and always a big factor for snow chances living here by the coast.

Morning fellow Kilties! Calm and cool this morning, just waiting for the light breeze to turn into a very strong breeze! Well seen it's the Equinox, although I saw hee-haw of the Harvest Moon last night. Temp round about 13/14c depending on which weather station I believe. Yep, Autumn definitely here, and very welcome it is too!

Another chart showing how the models have really struggled with September so far: Last Thursday's 500mb update had a trough dominating the UK for this week. The second chart is from last Monday. So we went from settled weather likely on Monday, to unsettled weather being favoured by Thursday. Last night's update? Back to a ridge again!

When I was delving the weather archives stumbled across a few interesting articles from the Guardian newspaper from the 1930s. I'll add to this thread if I stumble across more.

Is it just me or is this a bit unusual for late September? Any comments from the knowledgeable?

If it wasn't for Corona and the fact it costs more for a PCR test than it does to fly return to La Palma from Manchester i'd seriously consider forking out the £38 it costs for the airfare just to see this vent erupting, although there's no guarantee that the LP-3 road I was planning on driving along isn't already closed given the authorities are wanting the 10,000 residents evacuated rather than 10,000 'tourists' flocking to catch a glimpse. Windyty is showing a brief northwards-flow in the wind direction from the Canaries to the UK, so for us it might be worth catching a early sunrise/evening sunset for the typical deep-red colors resulting from volcanic particles/aerosols if the skies are clear enough.

Exactly my thoughts. Sunny weather is anything but boring, no matter what the season or temperature. A grey sheet of nothingness on the other hand is the epitome of boring.

Yesterday at lunchtime I thought that the clouds were clearing away. They weren’t. Quite the opposite. So, by mid-afternoon, I was standing in a field counting sheeps and wondering whether I would get back to the house without getting soaked. (I did.) Today seems, at the moment, to be going the other way; steadfastly overcast this morning but giving a hint now of becoming brighter. Still cold though. Temperature just reached 16.1⁰C up from 8.9⁰C at 05:56, humidity is 77%, wind 3 to 9mph, pressure 1027.4hPa falling slowly, there’s been no rain in the last 24 hours and cloud cover is 7/8. (The black sheep is the remaining one of the two original animals. She's having nothing to do with the newbies. My daughter says it's even more like me than before. I don't know what she means.)

I don't think they are capable of launching from a carrier. Looks like they switched the transponder on where the blue line starts. The tell tale sign of where the aircraft departed is shown by the trail line changing colour. Usually yellow to green to turquoise and various shades of blue and purple as it gains height and the reverse when coming into land.

Let's have a look at what the 00z runs are telling us then... A very marked temperature contrast showing on the 00z output. In the S/E especially, summery like weather continues for the next 5 days, with temperatures up to 23/24c at times, and staying fairly warm. At the same time, we're seeing afternoon temperatures perhaps stuck at 9c in the far NW of Scotland! Temps gradually increasing the further S and E one heads. The dry weather looks like perhaps hanging on until Monday now for the majority (far NW Scotland W Ireland excluded), with the odd spot of rain for some before a more active cold front moves through for a good soaking, before the warmer air finally leaves the SE and we see temps drop back into the 14-18c range:

Well, not a bad GFS 00Z to start the day: Anywho, there's plenty of time for all the northern blocks to dissipate before winter arrives! And, here's the GEFS 18Z ensemble for Aberdeen:

Lovely day again… blue skies warm sunshine after errands in Denton and Hyde… washed the car, made carrot ginger and lemongrass soup… was delicious and ate outside which was a bonus… chilly evening now…

A beautiful morning here too but it has clouded over a bit now with a freshening breeze. Feeling just a bit Autumnal first thing this morning for the first time this season with a heavy dew and a rare for this Summer/Autumn single figure minima. Now 17.2C .

It has been incredibly calm recently and this month is carrying on the trend too. The Atlantic has not been sending weather systems through our islands. Are there records for AVG daily wind speeds for the UK? 2021 must be one of the least windy years. It's impacting on wind power energy production too.

Right on cue an equinoxial gale tonight even managing to roll some round bales down the field. A real old fashioned harvest day with sun and wind drying everything up and a few balers about getting straw that had been rained on if the wind had not spread it. Currently 14c

Part 2 of my self research Same models in same order as before 8th June start date 10th June Model agreement : 90% Outcome : 85% 12th June Model agreement : 80% Outcome : 73% 14th June Model agreement : 65% Outcome : 52% 16th June Model agreement : 45% Outcome : 37% Run 20th June 22nd June Model agreement : 95% Outcome : 88% 24th June Model agreement : 79% Outcome : 72% 26th June Model agreement : 52% Outcome : 47% 28th June : Model agreement : 42% Outcome : 40% Total percentage average at 48 hours Model agreement : 92-94% on average Outcome : 88-90% 96 hours Model agreement : 80-87% Outcome : 72-80% 144 hours Model agreement : 58-72% Outcome : 47-57% 192 hours Model agreement : 44-55% Outcome : 40-50% As far as I can see June seems to have more differences within it compared to May, perhaps the positoning of the Arctic low's which seems to be the main difference is hard to predict further into Summer. The high's positioning is also hard to predict especially around 144 hours compared to 96 hours, after 4-7 or so days the diffence in percentage slow's down. Model agreement is definitly much more than the outcome however interestingly towards day 7 the gap closes down. GEM closer to now isn't as trustful as GFS and ECM, GEM is varying a lot more compared to the other models in terms of how close the model is at certain hours. ECM is an underrated model in terms of being up there with as close as GFS in the outcomes. GFS does prevail most of the time as the turtle style model however in June it does seem to be less of a model for high's over the UK. That's all for now

Wake me up when it snows!

Completely agree mate. I've been having a look at the solar cycle last 20 years, last time we had a very similar spotless pattern over about a 5 year period was the lead up to Dec 2010. Obviously many other factors but as ever very interesting.

Its also worth noting that day and night being exactly 12 hours each happens after the Autumn equinox (and before in Spring) as the sun is visible on the horizon before sunrise and after sunset for a few extra minutes due to refraction in the atmosphere.

At this point November is looking potentially well below average. Pretty much unanimous agreement of HP being situated somewhere in the N Atlantic. CFS strengthens the November signal The issue with November is that it's a lottery as to whether we can get sufficient cold pooling to tap into.

Amazing there we go again with latest from GFS. C

fluffy wuffy puffys at Falmouth today, Quite warm this afternoon

Got this email today from United Utilities about the drought. Watch this October will be the wettest on record.

With our current very warm September with a running mean of 17.1C which isn't a big amount lower than the July CET of 17.7C as of the 20th this has got me thinking about other years that have had warm Septembers or Septembers warmer than any of the summer months before them and then looked at what happened in the following winters. I have looked through all years CET's for the summers as well as the Septembers and used 2 categories September CET's that were equal to or warmer than the August CET value the month before it September CET's that were equal to or warmer than the highest CET value from the summer just before it Now looking at this year's September CET of 17.1C this currently stands +0.3C above the all time record September CET of 16.8C from 2006 and this is seriously looking under threat of falling this year. If the predicted warmer spell comes off this weekend then a 17C CET is looking more and more likely but could July be even beaten this year on top too. That would be some achievement and would stand out as the September equivalent of a December 2015 if it did happen. Category 1 Now I will begin with the category that is much easier to achieve overall, Septembers that are equal to or warmer than the August just before it. This has happened a total of 12 times in the CET record in the years shown below in the screenshot What is notable by the winters that followed these 12 years is how many milder than average CET values are present but there are some notable cold CET's in some of the winter months and a few of the winters came out colder than average. I have included an ENSO status and QBO status but these both only cover a small number of these years. What could be good news for winter 2021/2022 for cold lovers is how 2006/2007 had an El Nino and 1956/1957 was a Neutral QBO winter as this take 2 of the milder winters out of the running potentially. However when averaging out all of the CET values and anomalies we come out almost bang on average for the Decembers, slightly milder than average for the Januaries and colder than average for the Februaries with the overall signal close to or a little below average overall which came out as a surprise to me. Maybe having an equal to or warmer September than the August before it isn't as bad a signal as you might think for the following winter if you want something colder. Category 2 Now for the tougher category overall and the one that September 2021 has the potential to achieve this year. Not only does the September have to be equal to or warmer than the August before it but it has to be equal to or warmer than any of the June, July or August CET's before it in the same year. This one took some searching and only 2 years met the criterial I specified for this one and they are below in the screenshot Only 1659 and 1890 met this criteria which shows how rarely this happens. Note 1659 fit into both groups which could be significant in terms of what could happen this year if we can get September's final CET value to be at 17.7C or higher in the end. Note that there is also another significant year here too, particularly because of the December that year, 1890. Both of the winters following these Septembers that met the criteria were significantly colder than average in both the December and January with the February less so in the case of Feb 1891 and Feb 1660 was milder than average but overall a colder signal for both winters. The other notable thing is that we had a La Nina in 1890/1891 winter too so we meet 2 criteria at least if we can get September 2021 to 17.7C CET or higher.

Don't have any wind data for UK but for Ireland, 2021 had been the calmest January to August period since 2010 and that theme has continued into September with the mean average running even closer to 2010 (which was record calm for many stations). Particularly noticed the lack of wind this summer which was reportedly one of the calmest on record:

Lovely again today - and with Wednesday to Saturday inclusive (perhaps even Sunday) looking good down here, I fully intend to enjoy what could be the last 6 days of summer 2021. September delivering the goods where August failed miserably once again!

Models all over the place at the moment, supposed to be unsettled by Thursday, but high pressure not pulling away now, looks like the 10 day trend forecast from last Wednesday was actually correct in the end!

Heard this fly over just now. Pretty loud considering it was a good few miles to the west. Looks like it took off from a carrier in the North Sea.

A quiet day weatherwise. Nothing to comment on. Once again 'wake me up when September ends'...

A northern hemisphere more akin to a PV smashed by a SSW.. rather than one entering Autumn proper. What has happened to the energy in the Atlantic? I wonder if the uniform warm SSTs over the Atlantic as a whole are having an effect?

Evening everyone, here's the latest average outlook from the weather models from this evening, Tuesday to Thursday Tuesday will see high pressure in control, making for a fairly pleasant day with warm temperatures for many. Because of a deep area of low pressure passing Iceland, it will be cloudier and windier farther north, with gusts of 40 to 55 mph predicted for exposed parts of Scotland. By Wednesday, the deep low pressure system will start to affect our weather, with a band of rain and gale force winds moving through Scotland and Northern Ireland, but it will be another lovely day in England and Wales, with sunshine and warm temperatures. Thursday is unsettled in the north with wind and rain, but warmer, drier, and sunnier in the south. Friday and the Weekend On Friday and Saturday, the ridge of high pressure will remain in the south, keeping things dry and settled, while rain will fall in the north, but temperatures will recover and warm up there. Low pressure remains in the Atlantic and is slowly moving towards the UK. The models were keen on having low pressure to the far North of Scotland at the end of the week, but it's been pushed further West today with some high pressure building to the South East. Next week Monday to Thursday The extended outlook shows high pressure attempting to build to our east, while low pressure in the Atlantic travels over or near to the west of the UK, keeping things unsettled, as has been the trend on the extended outlook for the past few days. However, this low pressure still appears to be weak, so expect changeable weather. Latest amination, 21st Sept to 30th (average model outlook)

Long may this pattern continue. This is nature's payback for the awful cold May. Plenty of time for cold from November onwards.

As Turnedoutniceagain posted above more general increases in snow in both Americas and Europe yesterday. Ice continues to grow steadily on JAXA (between 20 and 40K Km2) each day, but Masie is going through another mini 'crisis' with losses of over 100K and 30K Km2 in the last 2 days to give us a low of 5,048KKm2 currently. but still not lower than the still current low of 5,022K Km2. AND still above the politically sensitive number of 5.000K KM2. Low pressure is now taking over in the Arctic and the temperature above 80degrees (as given by DMI) looks to be fairly stable, but losing its contact with the 1970 -2000 medium line that it started the season by faithfully following.. Temperature are forecast to fall in both N America and Russia/Siberia over the next 10days so hopefully snow cover will become more extensive there. Minimums - and in 10days MIA

We had a lovely morning here and a fairly nice day. Feeling colder though.

At times yes, but overall the warm theme continued. I remember quite a few engagements in relatively warm weather that month. That was the October that half term was warm and sunny, and Halloween reached 23 degrees. The autumn was a weird one, like each month felt like the month before. September felt like August, October like September, November like October etc... At least for quite an Atlantic influenced winter, 14/15 was a sunny one with a lot of Pm conditions.@

Nice to have such a lovely sunny afternoon to greet me on my return to the N Yorkshire coast after an absence of two weeks. Seems there will be more of the same tomorrow.

Unusual Snowfall in Greenland EARTHOBSERVATORY.NASA.GOV The remnants of Hurricane Larry dropped abundant snowfall on Greenland just as the summer melt season was coming to an end. Hurricane Larry. On September 12, 2021,Greenland snow

After a coolish start yet another great late summers day. Hopefully it’s rinse and repeat again tomorrow and even Wednesday might offer mainly dry conditions but it’s likely going downhill after that. even if this week turns out to be the end of Summer 2021 it’s not been a bad one, certainly in this part of the country and, given that I’ve still got a two week UK holiday in the first half of October, I’d hope that there’s still a bit more sun and warmth before we head into late autumn.