IDO

I would settle for the latest GFS run. Back to average zonal tonight I expect!

Yes for anyone North of Birmingham but for the South little till January at the earliest. Even up North it is transitional and very normal Winter fare. Models are beginning to merge to zonal with no apparent change in the medium term.

"A shortwave trough can be defined in several ways. The following are characteristics that most shortwave troughs possess: (1) Shortwaves are smaller than longwave troughs (2) Shortwaves have a counterclockwise kink to the height contours (3) They are associated with an upper level front or a cold pool aloft (4) Shortwaves generate positive curvature vorticity and positive shear vorticity (5) Shortwaves often represent baroclinicity in the troposphere (WAA and CAA) (6) Shortwaves are imbedded within the longwave trough / ridge pattern (7) Shortwaves are best located on the 700 and 500 mb chart / prog (8 ) Rising motion occurs within the exit sector of a shortwave (9) Their size and influence ranges from the mesoscale to the synoptic scale (10) Shortwaves move faster than longwaves (usually more than twice as fast)." If that helps you are a better man than me!

I also said on TWO that it was trending average to mild down south (at the end of the GFS run at 2m temps.) but was told that the ensemble is cool, and cooling. Sometimes even the apparent obvious charts are not correct! Apparently the warmer charts are outliers. The trend is cooler. I bow to the greater knowledge.

Saw this and decided to look at the latest GFS as the above seemed hopeful. However the 18z has rain and average temps. on that day! It does appear GFS is on a knife edge, it has lumped on the side of a mobile picture but it cannot decide whether the zonal weather will be cool or average. Either way its nothing to get excited about. At the end of the run (7th December) the UK is trending to average with any real cold moving further north. It is hard to be hopeful for December. I cannot find any forecasting site that is optimistic for the next few weeks; but at least it is not a static set up, so there is always a chance of a change for the good.

I think you misunderstood my comment. It was in reply to a posting that suggested giving an opinion on weather 28 days down the line is not possible because our weather is so fickle. I was contradicting this by saying that over time our confidence in the future weather will lower, but depending on the variables the level of our confidence would vary. So for example in the Sahara, 28 days later we would be 99.9% confident that we could top up our sun tan. In Britain the level of confidence for 28 days later is obviously not going to be as high for whatever weather. To be specific I believe a prolonged cold spell in the next 28 days at this point in time is approx. 10% based on the variables I have looked at. So if someone's opinion, based on looking at the models and variables leads them to a conclusion that by mid December we are unlikely to see cold weather (prolonged snow, whatever you want to categorize it as) then we shouldn't dismiss this just because it doesn't feed into our wishes. That is what we are here for: to look at the models and use our own experience to come to a conclusion, be it right or wrong. To comment that I should say there is "0% chance of snow and leave it as that" is as naive as it sounds; of course this would not be the case this far out. How do you think bookmakers qualify their odds on a White Christmas and why do they vary the nearer they get to the day. They work out that there is a 12.5% chance (say in September, based on historical data) and translate that into odds of 8-1. As the day draws closer these odds will change in accordance to the forecast models. FYI, today they have only a 28% chance of snow falling in Aberdeen on Christmas day and it is a 53% chance that the highest temperature (UK) will be over 6c. They have it as a 5% chance the warmest will be 0c or less. Maybe "stewfox" should email the Bookmakers and tell them its a waste of time to calculate probability! So please lets be nice to each other no matter what the weather brings.

Yes, no one can predict the weather in 28 days time. However models suggest trends and from them we can extrapolate the probability of future weather. The current setup is HP (seems like forever) which will move to a more mobile cool (average) zonal weather pattern. These can be extremely frustrating to shake off, possibly as much as the current HP setup. Of course as the wind direction changes as the LP's move through we will get short lived cold spurts. However this is not a scenario where we will see anything significant in terms of real cold. So the probability of a prolonged spell of cold weather in the next 28 days is low (under 10%). That's not saying we will not get a cold spell as things can change and this time tomorrow that 10% may be 20% or even 5% (those odds are my opinion and others may see more hope eg. ECM is a bit more colder trending). Many of us want a cold spell, but I am a realist and at the moment, short term variables are poor (positive NAO/AO?, strong Jetstream, Jetstream too far north, no Scandi high anywhere near to help with blocking, zonality, nothing cold in the rest of Europe, lower than needed stratospheric polar temperatures, etc). But here's hoping we get changes that improve those odds!

Don't look at the GFS in FI. December has reset itself to early November with HP dominant to the SE and HP waiting in the wings in the SW for 7-10 days later. Highs of 12 for 3rd December! There is a flirtation with cold in between but it never looks like it will be anything but fleeting. Roll on January.

Yes, more of the same. Average temps with mild not far to the SW and the promise of cold that never really crosses over to us. Sounds familiar and a recurring theme this Winter I suspect.