john w

Have got to say its tantalising watching the developments on rain today. I always worry here that we are in a belt that only seems to do really well out of storms when they are either home grown, or you get a perfect setup and northerlies to get incoming stuff from France (mainly because there is more channel to cross if it comes due south, as well as several topographic features (south downs/north downs). Rain today shows rain cells over Ireland and South of Exeter at the moments having a distinctive North component. I look out my window and see some very high cirrus (and as I type this a red kite) going north north east. The cell over near Caen/Jersey seems to also be NNE as opposed to NE. Tomorrows CAPE etc has my patch (Reading/East Berks/West London) in an area of relatively low energy compared to the rest of the UK. I still think we will see something good, but I also wouldn't be too surprised if we miss some stuff here. But, at present I would say the cell coming off france (unless it weakens in the channel) looks good for Kent, Sussex and the south east corner, poss even south east London.

Im inclined to agree more with Steve Murr in the position reached about sustained and persistent cold developing and the significant correlators. I find this thread interesting and scientific enough to understand, but I never really feel the urge to contribute. But in the years I have followed this there seem to be certain types of posters...those who say what shows and those who like to predict what may show once the realms of 'reliable' step outside the model time frame. I.e. a good number will look at T120...T196 and suggest a way forward from that which is contrary to what the models may show whereas others will do a decent model summary and not really delve too much in to alternative evolutions. Its an interesting read, but when the two collide you often get the conundrum of...half saying the models are zonal, flat and mild for the next few days and others saying, ah but if the jet off canada had a slightly steeper angle and the AH ridged jut slightly further north its game on. I think whats important as well is context. I saw some posts getting on for a fortnight ago that suggested a prolonged and sever cold spell that contingencies should be put in place. Thats fine, but prolonged to many means more than a few days. Prolonged mild to me means 2-3 weeks, maybe more, so I can see why people would sway when its said the other way. Then you have others who post monumentally technical post that are on the periphery of my level of understanding that are related back to basic synoptics in no manner at all. I would suspect half of readers would say, 'so what if the GWO is in Phase 8. What effect does the MJO have on the UK when a Bartlett can ruin winter. As for the models, they are decidedly not showing a huge amount of potential for sustained cold and thats what they show. I can see the potential for ridging to Greenland, its been hinted at a fair few times in the last few model runs...but none to fruition in the reliable timeframe and I agree. Many who i regard as experts on here said a 2-5 day mild blip before a quick reload from the NE...apologies, but the models dont show that so come out, say why you believed what you did and what went wrong in modelling terms or otherwise (internal thought) so that we can all believe we dont just sing our praises when we are correct.

Couldn't have seen a more brilliant post this morning. Its really surprising to see the models be that off at a timescale of a week. I often wonder of they feed in norms in to the background modelling. Probably one for the technical discussion, but do they use past trends to support model progress and does this induce model bias towards a long term mean when synoptics are say..a standard deviation away from what would be average at t0. We constantly see the GFS over egging lows and gradually trying to return us to mild before backtracking and I wonder if this influences models on a macroscale basis. Incidentally, monday/tuesday looks like a forecasing nightmare Sorts of a southerly flow due to the low west of ireland and a NE or so flow from the shortwave/low to the SE. Wouldnt want to be the one calling that one, especially given the marginality. Edit: The last sentence going on the GFS of course

Three main reasons. 1. When precipitation that falls is quite light in nature (such as what we have now) it can be difficult for radar to exclusively pick it up as a shower. 2. Sometimes when precipitation is falling that is quite light (e.g. for arguments sake less than 0.5mm/hr) the organisiations providing the radar may decide not to show such low rates of precip. It can clutter the map and detract from where the main precipitation is. 3. Radar lags realtime by up to 15 mins depending on which service you use (e.g. its not realtime) so places will report precipitation before it is seen.

Well light snow in Bracknell, at least my part (north). Looking at the radar and previous NAE charts I think they have it pretty well covered. The frontal mass seems to be heading in a NNW direction in my opinion but with some westerly movement added in every now and then meaning that the Eastern edges of our patch should see 1-3cms in my opinion, unless there is a change. There are also possible event through the week for our patch but heading more marginal. As for it ending, models so undecided with the UKMET FAX being significantly different from their own raw output (implying lack of confidence or shannon entropy as they now seem to be calling it). I would say Friday still looks possible for a more mild incursion. Thoughts then turn to greenland as per GPs thoughts to see if height rises there really come about for feb.

I think he was possibly referring to sunday as models are making more of a thing of the low coming up out of france. Check main model thread and se thread for more on that. Failing that cant see mild until at least next thurs going on meto and ecm...and tbats mild relative to now

Fascinating chart watching. On the france temps i would expect anything to fall as snow in my part of the patch latest meto brings true south central more in to play. I fly back in to gatwick tomorrow so will finallt be able to posr charrs again etc...breakdown in fi in my opinion with gfs ecm and ukmet all seeming to disagree on the method Ps talking about sunday re above and sos for typos...touch screens and my thumb are not compatavble

Hmmmm away watching this as concerned about getting back...reports of rain surprising..is it not the low dragging warm temps before it bumps cold?

The atlantic has been relentless and it continues. Seems some of the aquifers are now as full as they have been in a long time and rivers like the thames loddon etc in my patch have so much baseflow that there is becoming even less capacity for any overland flow and runoff...not to mention the fact rivers are constantly being topped up from this too!

Good informative posts guys and girls thanks. As for models...nothing of major emphasis to shout about for my location pretty non descript though i wouldnt be surprised to see the odd sleey mix in the cotswolds or rumble of thunder. Nice wind blowing tonight mind! Makes a change from rain rain rain Heres hoping the ssw influences the energy channels driving our present setup

Eurgh horrble model watching at mo. Rain will be the prob. Fi is probably at about day 6 or so i would suggest not at 48 hrs...model swings from mild to cold will always be harder in our neck of the woods due to simple energy amd weather physics that drive global weather sadly. Bit worried about the model tendancy to keep throwing uncle barty in the mix. Imo we are locked in to this pattern for some.time. there may be cold incursions but at the moment we cant have a block sustain itself without then helpnof greeny and greeny aint playing ball.

Welly well. Difficult output tonight. The lows continue and while my mate Barty is not truely there, he may as well be as good as there. Interesting output. The cold/warm boundary does seem to shift about a fair bit over the run of the 18z GFS and the 12ECM but the focus is on SW and mild for our patch, sorry peeps. No optimistic opportunity of the GH building either. Id agree that FI probably sits around the 18th or so. But I cant see the models getting us out of the pattern that exists on the 18th to anything else. GH on the 18th is getting on for 1035 and barely goes to the tip. GH at present 1010. Hurgh, need WAA up the eastern seaboard of the US. At present my moneys on Ian F...hes pretty much called everything to tee so far.

Gtltw....who is the it guru for the forum...i go to type quick reply hit post but then nothing shows. I had typed Not optimistic for cold. Snow was in staines when went past on train...and some model thoughts.

Completely agree richie the greeny high we all crave has been on holiday...this thread has stayed time and time again that its needed before we embrace deep cold. Echo steves comments. I posted a long post about averages earlier but seems to have gone awry but the thrust was as we all stare at average as enthusiasts our interpretation of not average will always be skewed to exremes because of what we seek and for no other reason

Brrrrrr bitter cold. The old phone aint so good at seeing charts but i noted the real lack lf any decent height rises over greenland last night. If you remember previous cold cold spells the model forum always looked for a greeny high and a big one....its just not showing enough at present to give me much confidence. Also this weekend looks bothersome and half the reason this low takes so long to go is due to the blocks to our east. Its a monstrous feature....not sure i have seen one so big in quite some time. Ill get a decent look at the models later hopefully but from last nights views some leading edge snow on fri looked marginally possible but this will quickly be replaced by rain. Then sadly its battle royale with the atlantic...i fear...for some time.

Ha as a planner who worked at the environment agency i can only but agree with the above. However every hill is in an aonb, national park, aglv or otherwise....floodplain very rarely has any other designation unless it somehow ends up in the greenbelt. Its a problem BUT all those other desivnations are sacred cows. Id say flooding os weather related and discussions around flooding implications are on topic....i wont review the 6z at work....post later peeps but i expect it to show more of the same

Id say the models are pretty much nailed on an atlantic breakdown, ones only got to view the ensembles to see that. Whether there is any snow entrained within the leading edge or not is the only real question. IMO the models did a major u turn last week but that was at t+8 or so....we are now at t+4 and for them to about turn again i would be very surprised. The model thread has been chasing deep cold for some time but it never arrives. This morning for me is.a perfect winter morning. Not a cloud in sight, slight frost, sunny, amazing sunrise over the thames bridge on the way in to staines this morning.

Try holding down control when you click on the link for it. Failing that you could delete cookies, but I hate telling people to do that if they have spent years customising their browser.

The problem is while you have one very good model predicting one thing (UKMET) which the people in a circumstance such as this will love, you also have another very good model predicting another (ECM) and another model generally sitting somewhere in between slightly favouring (if you were a statistician) the UKMET output. So, on stats these 3 very good models are probably all going to be wrong and what will happen is that they will probably converge on something in between. The ECM isnt one to do crazy flips, people will say its not used to certain modelling situations but im sure that what a lot of people dont realise is that a lot of refinement of models goes on over the years...if a model gets something seriously wrong, they probably refine it to make sure it doesnt keep doing it. So just because the ECM/GFS/UKMET (delete as appropriate) was wrong last time, doesnt mean it will be again. Colder compared to now is likely, length of cold spell is uncertain, depth of cold spell is very uncertain. I deliberately dont post in the model thread, but id challenge them to remember the above sometimes Right, I wish for some dry weather, im sick of 'slippery' rail conditions being an excuse for my delayed trains.

Unless im mistaken...seems to be steady rain here.

Intesnsifys as it pushes east of us as well. Heathrows still up and running judging by the sound of the planes flying over urgh, roads quieter though! last check it wasnt snowing

Portsmouth is incredibly low and very densely populated, it also sits in its own valley by virtue of the hills immediatly to the north of it. Love it or loathe it, this creates its own tiny microclimate. Compared to the IOW which is generally at a higher altitude than portsmouth and also less densel populated reducing any chance of heat island effect. There is macro scale giant and then micro-scale things that can make subtle difference to macro scale expectations.

Depends how you define covering, all the pavements my way are now white, but im still seeing completely green grass lol. Ill let you know when I cant see rooftops anymore Interesting comments from Old Met Man, be interesting to see how far east the front makes it and what the intensity of this will be

Because of it getting dark. Few flakes now blowing around too

Notice how the front is slowing now as it begins to bump in to the colder air, some key moments foa nowcast. 1. does convection lead to intensification, does it completely halt progress or does mixing mean the snow is not as bad as some are predicting. Nothing here yet though is darker to the west than east. However, light levels will start to fall from 16:45 due to twilight and sundown...dont mistake that for dark clouds heralding snow. Interesting nowcast for the meto...bet they are watching intently