polar vortex

Surprised at the number of amplified ens from the GFS 12z this could very well be an over reaction to a strengthening MJO signal although the signal is looking a lot more robust with a strong WWB near the date line. The lower strat vortex looks to become elongated and weaker over the coming days therefore a strong MJO signal over the coming days may well be the trigger that is needed. Certainly mid February to mid March given the right synoptics could produce a very newsworthy freeze for the UK so time is still on our side but will the weather play ball.

I think it is quite obvious the vortex is a lot more durable than we give it credit for both higher up and lower down. Also warmings that just circle the surf zone tend to tighten and strengthen the vorticies (which make sense when you think about it). That was the main problem last winter and to a certain extent has been the problem this winter.

The threat of snow over east Anglia, and southeast England Wednesday night into Thursday looks to be diminishing all the time. Also the threat of another northerly reload was never really there in the first place, just another ECM poor run to add to the growing list. Certainly not much in the way of wintry weather to look forward to in the mid range ( day 5 to 10) beyond that who knows. It certainly looks as though the vortex this winter is far more robust than we thought judging by the latest runs and despite posts throwing everything into the equation for this winter ie GWO,QBO, MJO, Enso, solar and strat and covering all angles searching for answers the weather does what it wants to do. Frosty at night and dry but rather cold perhaps by day looks the order of the day as we go through next week.

Well the worst case scenario that I spoke of yesterday seems to the more likely solution. The threat of snowfall Wednesday into Thursday looks now to have diminished as the Euro's have fallen in line with the GFS and they have also moved to the GFS way of thinking with a more eastward thrust of very cold air into Europe rather than over the UK. lose, lose from what I can see this morning.

Really hope you are right as it looks like one heck of a northerly and would certainly bring a heavy band of snow south with it. Just to comment on the temperatures. The beeb this morning showed 6c over London, I live in hertfordshire and only reached +2c so I doubt London got anywhere near 6C, +4c more like it if they were lucky. P.S looking at temps around london today on the meto site it looks like +3c was the max.

After all the talk the other day about is it or is it not a cold spell it was great to see the much colder uppers do the business today with max temps just below +2c. Slightly milder tomorrow and wednesday before the colder uppers and hopefully snow move in again.

ECM 12z looks promising for what looks like a very potent northerly but we have seen many times these modelled west and then slowly get shunted east as we get nearer to t0 and by the time you get to t0 we were never in the equation at all. Of course this could be one of the other times when it has our name on it, fingers crossed. The 12z ecm run looks a lot better for snow prospects for east anglia and the south east with a stronger flow and probably stronger trough than what the GFS is showing. I just hope we aren't left with nothing ie trough to far south and east and also northerly to far east. Not worth mentioning the second reload as it to far out in la, la land and the ECM has flip, flopped like every other model at this range. Finally nice to see with 850's around -8c today it was what you would call a proper cold day maxing out at only +2c. Slightly Milder tomorrow and Wednesday with higher 850''s before colder uppers and hopefully some snow on Thursday.

The way I see things our best bet of deep cold and significant snowfall is if the high ridges north east as per the 06z run or if our high manages to find that little bit more amplification north. If this is not to be then I fear we could be locked into a very mundane type pattern post day 7 for at least a week or so. I certainly can not see any ridging north towards Greenland that will be beneficial to us in the next 14 days.

From what I can see the energy that drops south over north western Russia post t96 makes all the difference to the developing pattern from there on. We need to see this energy distrupt more as in the 06z run allowing the link to develope between our high and the Russian high. If there is to much energy and the link is broken then our high will just sit over or slightly to the north of us instead of ridging north east.

Agreed. You could easily see small changes which would vastly improve the chances of snow and cold during the coming week. The UKMO at t96 looks a lot better than it did on the 0z I think.

Must say compared to the 06z the 12z is a bore fest. The UKMO although far from great keeps more of a stiff easterly flow through to t144 with more of a chance of hanging onto snow showers in the south east if the temps are conducive. Nothing to really get excited about though. Having said that I still do not think this is a done deal yet. UKMO looks better at t96 compared to the GFS and we know the model is not very reliable past t120 plus the 12 GFS can be overly progressive. Maybe straw clutching we shall see.

One other point to mention although I think most are aware of this and that is that as we move further into February towards March lapse rates increase, so where in December or January -10 uppers would usually translate to surface temps of around 0c to +1c by the time you get to say the third week of February you would probably be looking at temps of around +3c and increasing further as you move into March. These are of course a rough guide to temps on a sunny day and where as in December or January it does not really matter that much but makes a big difference in later on during February and into March. Of course there are exceptions to the rule especially with a deep cold sourced easterly but as I said this is just a rough guide.

You are of course quite correct in what you say. After all it is only 1st of February and it is only midday therefore you might even max out at 6c which you would be hard pressed to call even rather cold even if the wind is a tad nippy. Talk such as not living in Siberia etc is a tad unfair as we all know given the right synoptics from the north, or east etc it can be very much colder than this. The Met have been using terms such as deep cold etc which does not even gell with their definitions of what is rather cold, cold, very cold etc and is typical of the way they over hype these type of events when we are having a generally mild winter. Of course this is much better than anything we saw last winter but it still does not make it a decent cold spell or even close to being one.

This is the strat profile at t 216 70mb from the ECM and you can see a week sausage shaped vortex which would be conducive I think for height rises to the north, north east rather than over the Greenland plateau. If this is a new trend from the 06z then perhaps we will see more amplified heights to the north, north east from t96 onwards.

I think the 06z is much more believable than the chances of pressure rising north towards Greenland as S. Murr has suggested. The reason being that we know that the strat profile shows the vortex moving back towards the Greenland area in the mid term and if this is so then it would leave the door open for higher heights to our north, northeast perhaps. Of course I could be talking a load of cobblers agreed but it would make sense to me. I would take the 06z run with both hands as I am sure most on here would but we have been here before where a cold spell looks lost only for a run from one of the models to resurrect it only to find it was a complete outlier and red herring. Still because of the reasons mentioned above and the stage of winter we are now in I am in the GFS 06z camp and rooting for another 100 or so miles of amplification then we really would be in a deep,deep freeze.

Ah I can see where the precipitation is coming from now. The radar had not refreshed and all it was showing was the precip exiting the east coast. At least I know what peeps are talking about now. Thanks.

Could someone please point me in the direction of where this potential snowfall or precipitation is coming from.

I must admit if I lived in the southeast corner, Kent especially I would be very excited about the prospects for next week. I remember seeing and reading about it during seventies and eighties where it would be dry inland etc but the far south east and kent would have up to 12"of snow. I am not saying that there will be 12" of snow but the potential is definitely there for some moderate to heavy snowfall.

I have mentioned this two or three times already this evening and I.F. has alluded to threat of significant snowfall for the more western areas perhaps. As you say though the track at +t72 is far from resolved. If it did take a more east southeast track along the channel then apart from the risk of widespread heavy snowfall it would also force the high to ridge further north and draw in an even colder stronger easterly. The Euro models have it much further west and south where as to my eyes the GFS has it much further north as it turns and further east/ south east.

Could you please enlighten us thanks.

Apart from coastal counties that would be dry as a bone inland as the model shows. Plenty of time for that to change though. Sunday morning there are opportunities over eastern england and into east Anglia and the southeast perhaps.

Agreed. We really want to see a strong easterly flow with instability mixed in leading to plenty of snow showers feeding in off the north sea. Alas this is not been shown at the moment. Why we nearly always have this problem with the high to far south sending the coldest and snowiest weather into southern Europe. Still plenty of time for the output to change to our way of thinking perhaps. I think the track of the low moving south at t72 is still far from settled yet and this could have a big bearing on what follows depending on track and depth. Still not buying into the the dominance of the low heights to the north in the mid to long range just yet either.

That is a lovely looking chart I must say. Much better ridging than the GFS and surely a much better chance of a more potent easterly. I noticed on the GFS run the low started to track east much earlier at t72 if this is a new trend then could we be looking at a channel low. Also the low is much deeper on this run which would help sustain better heights to the north.

I must say with temps today maxing out at +5°c this is not a cold spell at all and with uppers of around -4°C it is no different to what I would expect. Rather cold is probably the right term for the weather both today and tomorrow and then hopefully we will see it get progressively colder thereafter. Despite my brief but rather downbeat post this morning ( I was just commenting on what the models were showing) I would love nothing more than to see a bitter easterly setting up shop and with the 12z just starting to role who knows, fingers crossed.

Models seem to be singing from the same hyme sheet this morning of a break down in the cold theme towards the end of next week. Its all right rolling out the JMA models etc but when do they ever verify, hardly ever.