bobbydog

theres no warm sector over the south east there mate- it might just briefly clip cornwall but that's it

it would actually be the first front that stalls as it comes up against the cold air to the east, with the second front following in behind and pushing into it. this is what could intensify the snowfall. the Meto seem to think this is likely-

you've pretty much summed it up yourself! thats about the thinking as it stands now but snowfall is extremely difficult to predict with any accuracy so exact amounts will be decided on the day. everyone should only take the precipitation/snowfall charts as a rough guide

by monday morning even......!!

look at the chart surrey posted. at this stage thats just an estimation but it proves that even on the coast, if that does happen it will fall as snow

snowing on the M40 near oxford

temperature here has been very slowly but steadily dropping throughout the morning. keep any snow or sleet reports coming in peeps so we can work out where the cold air boundary is and how quickly its moving

its precip rate per hour - the key is at the bottom. don't forget that 1mm of rain equates to 10mm of snow

last time it snowed, my wife spent about four hours just staring through the window. when the snow got to about a foot deep, i thought "she must be cold, i should probably let her in now"

hmm. some petty bickering going on. exactly what everyone has been asked not to do. anyway, regarding some comments about blocking and the atlantic. something i have noticed (putting aside for a moment that the models have little agreement beyond a fairly short range) is that there is a lack of blocking showing up in the output. however, all the models are showing mainly cold, snowy solutions, sometimes with brief, less cold interludes, but more often than not, predicting some very wintry weather, despite a lack of blocking, these even being delivered by the atlantic. i posted this earlier today- "ok, been trying to get my head around the wide model variation and based on available information and my (limited) understanding of it, i came up with this- normally, the stratosphere maintains a consistent 'shape' and any variations are over a relatively long period of time. when the data is input into the models, the strat data is also fed in and the models include this in the output. therefore, run to run, the strat data will have changed very little so the models concentrate on the troposheric changes, on the basis that the strat will change very little over a period of time. however, during an SSW, the strat changes very rapidly, therefore by the time of the next run, the strat data will also have changed. bearing in mind that the stratospheres effects on the troposphere are relatively unknown compared to other teleconnections, also the effects are very variable and not directly correlated, making it difficult for the models to predict any future effects whilst the strat is in a dynamic state. each model will have a slightly different 'take' on how the stratosphere might change, therefore this extra data will increase the variability between the models as they each try to work out how the rapidly changing stratosphere will affect the troposphere, alongside trying to predict the usual troposheric changes. hence the large differences between each subsequent model run and the large divergence between each of the models the further we go into the forecasting range" now, if my theory is correct (which i'm confident it is) this negates the accuracy of all of the models (during this SSW) beyond a few days. any specifics beyond a few days can be discounted completely, which also means, due to the huge tropospheric differences being modelled, we could possibly see blocking appear in the short term as much as any other scenario. one thing we are not seeing with any regularity, is a return to mild zonal weather of recent days. as the professionals have pointed out, we are in a period of unprecedented, record uncertainty. therefore anyone claiming to know how the weather will progress, is frankly, kidding themselves.

i suppose then, we are unlikely to see any consistency from the models until the strat reforms to its usual 'calmer' pattern.

hi chiono, have a look at my 'ramblings on the previous page, post #224. what do you make of my 'theory'?

ok, been trying to get my head around the wide model variation and based on available information and my (limited) understanding of it, i came up with this- normally, the stratosphere maintains a consistent 'shape' and any variations are over a relatively long period of time. when the data is input into the models, the strat data is also fed in and the models include this in the output. therefore, run to run, the strat data will have changed very little so the models concentrate on the troposheric changes, on the basis that the strat will change very little over a period of time. however, during an SSW, the strat changes very rapidly, therefore by the time of the next run, the strat data will also have changed. bearing in mind that the stratospheres effects on the troposphere are relatively unknown compared to other teleconnections, also the effects are very variable and not directly correlated, making it difficult for the models to predict any future effects whilst the strat is in a dynamic state. each model will have a slightly different 'take' on how the stratosphere might change, therefore this extra data will increase the variability between the models as they each try to work out how the rapidly changing stratosphere will affect the troposphere, alongside trying to predict the usual troposheric changes. hence the large differences between each subsequent model run and the large divergence between each of the models the further we go into the forecasting range i think that makes sense......!

lets hope the ECM is right....

there you go - http://www.meteociel.fr/modeles/gmee_cartes.php

i wouldnt worry too much about detail, at this range i would go with the professionals. as has been said, the GFS snow charts are only a rough guide and i wouldnt be surprised if we only see mostly rain on saturday. however, that could easily change for the better and confidence seems good from then on for snow. that said, the GFS did bring the snow forward a day so who knows what will happen! forecasting snow is very difficult and can often be underestimated. i remember 2010 when the forecast for me said about 3cm.we ended up under a thames streamer and a foot of snow! lamp-posts at the ready!

i might just let myself get a little bit excited!! for anyone on the south coast who might be a bit worried they'll miss out-

not the best run but we should see upgrades soon...... (i said that after yesterdays 18z......)

lets not let the facts get in the way of a good argument eh!

agreed. this run is a mild outlier........

i hope i'm only half kidding......

not the best run but we can expect to see upgrades soon.....

i'm not sure they are worth anything at this stage, if, as Ian F said earlier, the SSW effects are not properly being factored into the output as yet

model tourettes??

bearing this in mind ian, would this be a reasonable theory?- (if wishful thinking lol)