chionomaniac

New thread here. Hopefully this will be the best cold spell for years. But what will the models forecast? Discuss.

my memory definitely isn’t what it was. That’s for sure. but, but, I see an opportunity for a historic cold spell despite the climate changing massively since 2010. Reminded of that Carpenters track Its only just begun

That ECM. Mark 2.

Passion. It takes a bit of self control to step back and look at the bigger picture. Just stick to day5-6 and past that just for fun. In 2010, the models constantly showed the end of the cold spell, but this was put back time and time again. With this being a strong split into the lower Strat, rather than a transient Greenland High, I suspect the same will happen again.

I would just like to point out that the jet stream profile on that icon run does not support an Azores high. It’s messy, granted, but it’s past day 5 so not worthy of other than just a fleeting mention

Before the afternoon fun starts I will just put out a link to the upper Strat forecast animations GSFC Arctic Met Animation: Temperature @ 0010 mb ACD-EXT.GSFC.NASA.GOV first at 10hPa. Note how the distorted vortex that is being overwhelmed by the lower split then starts getting attacked by a strong upper wave 1 event. This was the timeframe that I suspected to see this occur - so all good. now just to confirm that this is Strat through check out the upper Strat at 1hPa. Yep. Strong wave 1 here too so what does this mean? Well, it very much suggests that the upper vortex is under attack too and we are making steps towards an SSW too in the second half of the month…..

I have seen something similar to a wave three pattern in the past, so yes it can happen. Especially if wave 1 hits first and wave 2 second. Glad I had a night off model watching yesterday. Sometimes it does benefit to do this. And I only have gone back 10 pages today to catch up. I think I may have spared myself a painful read. I am still only concentrating on the long wave pattern that is very close now. Once the cold becomes entrenched next week then I will look at snow possibilities. With a cold slack low heights air mass trying to predict precipitation type or amount is futile. My daughter commented earlier that he weather app kept changing from rain to sleet to snow and back again. Exactly, I thought - no point in looking at the specifics other than for fun. The risk and reward of this game.

That should tell you something….. is it past day 5? is day 5 looking good? are other models and background signals suggesting that the block will hold and pretty steady on day 5? are we more likely to see cold from a day 5 scenario than any other? If you answer yes to any of these questions then disregard your own statement and wait to see what happens. In a compendium of poor runs over the last 10 years this doesn’t even make it into the top1000

Great post, and explains exactly why in plain English that this may well be a more than a transient cold outbreak.

The angulation of that channel low is perfect.

Lol. I like the idea of a rouge feature. Sounds kinda like a red warning feature. A typo with meaning.

I can remember the opposite with significant Strat splits. Day 10 in 2009 feb showed a split vortex from the Strat downwards, but no matter what scenario evolved in between, the end result drew closer and was always the same. With this Greenland block I have a similar feeling

I have been on here too many years to mention. I loved the thrill of comparing each model run, and will do so again when modelling comes down to within 24 hours with potential snow events. However, I now look at day five and see that as a base mark for what is likely going forward. If the long wave patterns are in agreement between models, then I will look at 850’s etc for fun only. Because these are likely to change considerably, with only slight broad scale changes. And changes in the 850’s and lower flow will have major impacts on surface conditions. So be patient with surface pressure and 850 temp differences on runs, but look firstly and foremost on the upper level Synoptics up to day five and don’t be concerned with surface activity. Also, take a break, and don’t feel the need to look at every model and every run. You will be better off for it, it’s not as if you can have any control either. The outlook is good, enjoy it.

It’s difficult to be sure, Foz. But it definitely one for another thread.

We have favourable Mjo type activity - possibly high amplitude, with trop precursors leading to these repeated dampenings obstructing Strat strengthening. And add a possible late month SSW into the mix. Even if wave 1 displacement the lower Strat will already be damaged goods unable to resist

So so so….. another day has passed, and another day closer to achieving a superb looking Greenland high. Everything looks good at day 5 and post this we are somewhat unsure of the specifics other than deep cold will be getting entrenched. The background signals to keep the cold have remained and if anything have improved. If anyone has access to the 10hPa EPS anomaly chart at T +360 then the longer term signal is also fantastic. These suggest a wave 1 warming with a hint of wave 2 thrown in for good measure. And with the lower Strat set to be under pressure for some time, then the upper Strat will likely cut through this and continue the lower weak Strat vortex outlook. I can’t remember ever seeing this combination before, so this could be special, especially against the background of climate change warming. Time will tell…

I love the shape of this block at T+114 - Id say its almost perfect 12Z GFS

Now I know I shouldn’t but I am liking this run so far. The weak low pressure is to the south and not the west around day 6. Should assist the northerly

I’ve not been concentrating on slight inter run differences today, but it still looks like the best block is building for over 10 years, and that this won’t be some transitory event. Obviously there is no guarantee of snow falling over a particular place at a particular time, but there is a strong likelihood that the vast majority of us will see snow at some point. I have seen some suggestion on here that pacific tropical activity will wain, and that the Greenland block will retrograde west opening the door for milder SWesterlies to materialise soon after the initial polar surge. Yes this is always a possibility but unlikely probability. In fact the tropical forecasts are somewhat suggesting the opposite of this, and the latest 12z Gefs and Eps mjo ensembles show a lot of members heading into phase 7 with some strong high amplitude members amongst them. What does this mean, well any blocking is likely to repeat, meaning a longer lasting cold spell. The tropospheric weakening of the lower Strat will continue and maybe long enough lasting that when the inevitable upper Strat attack comes it will have a lower Strat ripe for submission There are signs both tropospherically ( look up tripathi paper precursors) and hints at the 10hPa long range too that wave 1 is increasing and could be fully fledged towards the end of December I know this may differ from other thoughts, but I see strong signs to be optimistic if a prolonged cold spell floats your boat

This site gives 00Z daily, but not every run and cant see where you can look at previous days that easily Climate Prediction Center - Stratospheric Analyses and Forecasts WWW.CPC.NCEP.NOAA.GOV ,

Spot on Matt. The early winter upward trop split is the true holy grail. And to think that with the way the MJO is set up to hopefully reinforce the blocking pattern. Could we get a rinse and repeat, then followed by a riskier SSW when the lower strat vortex has already taken a bashing, and hopefully still on the ropes....

Leeds and Manchester look good odds

Out of interest, anyone taken the plunge and put a bet on a white Christmas? Percentages wise this may be the year to do it. Risk reward and all of that. If I was going to then I would go for eastern coasts. Depends on the odds though. If anywhere gives odds greater than 4-1 then I would be inclined….

Happy with the trend. The block is there. 850temps are always petty semantics at this far out. Though….. I know when they are good it’s great to look at

Yep. It’s me. Always been keeping an eye on things but not necessarily chatting publicly. At this point we are looking at 2010 lite, 2010 repeat, or a new 2022. I suspect the pattern is a new 2022 with a SSW sting in the tail towards Jan. Early days, but first Block block block, otherwise we won’t even get started to reach 2010 lite