phil nw.

We can see the uncertainty for later next week in the 00z models. ECM at day 8 has a much sharper Canadian trough upstream compared to the GFS which throws lower heights se towards Iceland and the UK.This is reflected in the means too. The NOAA forecasters last night commented on the uncertainty over week 2's wave pattern also mentioning the large spread in yesterday's 12z ens members. http://www.cpc.ncep.noaa.gov/products/predictions/610day/fxus06.html It does look like that lower heights to our north will start to increase the zonal flow from the west around mid next week but then how far south will the real unsettled conditions get remains to be agreed on.

Our slow moving pattern continues for the next week or so by the looks with a lot of high pressure across our side of the Atlantic.Just a few showers from that Iberian low over the next few days with some added warmth especially for the southern half. Looking around the Northern hemisphere just a sign of the Polar regions starting to cool with quite a dig of colder air bringing some snow to parts of N.Siberia this week.We can see that deep trough over there modelled at T72hrs. Little changing for us yet then but as the month advances signs already of a growing pool of cold further north.

Yes good as any I reckon John.Pretty concise.

Yup my mistake Interitus cheers. Have amended my post above so that it should make more sense. I should have realised, i post enough of those things through Winter!

No problem mate. I did add that bit at the end after you posted just for further clarification on the way Winter discussions tend to go in the different threads. Both will understandably contain a lot of references to the said Vortex during Winter as i said earlier.

Hi Knocker, Wrt to the 500hPa pattern i look at the PV as the main area of low heights within the area of the Arctic-the boundary following the PFJ ,usually the 552 thickness contour. This of course is much more defined in Winter with those deep blues and purples over the high latitudes on the charts. I havent seen any accepted definition on here for it but that's my view fwiw, and of course it s a moveable feature to a certain extent when it splits or becomes displaced from it's usual position over the Polar area through warmings. I tend to use the term upper trough or simply a deep low if it's cut off when we see such low heights further south into mid-latitudes. edit to add Most of us seem to use the PV term when talking about both the Trophospheric(say 500hPa level) and Stratospheric models.I think as there are separate discussion threads for each then usually there's no misunderstanding.Not to say of course that views on either don't overlap into the other's thread from time to time. There may be more learned explanations on here but that is my current understanding.

If i could just answer FB. The orange colours are weak westerly winds in the lower Stratosphere which indicate a slow moving pattern near the surface with blocking high pressure,(We can those oranges fading to white at near ground level indicating a lack of flow) If you look at the 500hPa charts you can see a lot of high pressure around mid-latitudes in the Atlantic sector which ties in with this. The Stratospheric vortex is only just starting to cool as the Autumnal equinox approaches and the sun disappears over the pole. Any changes to the shape and development of the polar vortex will start being monitored around late October as Chiono said earlier. Until then there's not much to be gained by any discussion at this early stage really. Have a read of Chiono's first post in the thread,if you havent already,link https://forum.netweather.tv/topic/78161-stratosphere-temperature-watch-20132014/#entry2806808 which explains very nicely all the background to how the Stratosphere works and it's effects on our Winter weather patterns. I hope that helps.

Lol yeah I know you have a dislike for that term knocker,when it is misused. Be prepared for it to come into use more though as we go into the Winter half of the year.It is after all the main player as it deepens and expands and inevitably will be included in discussions.

Modelling continues with a predominantly blocked Atlantic right out into week 2 with a lot of mid-latitude high pressure. Granted we will see some showers scattered about through this week,first from the current little feature off the north sea and possibly later towards the weekend as the Iberian low edges a little closer,but overall the ensembles go with small amounts of rain until month end. Here the graphs for 3 locations north to south underline this. The main thrust of the jet,what there is, looks like remaining well north for the next 10 days at least. Many of us could end up with one of the driest Septembers for some time if this trend continues to month end.

It has certainly been very dry here so far this month. With so much mid latitude blocking in the ens this could turn out one of the driest Septembers for some time.

A very cold Stratosphere was the main driver in last Winter's storminess, coupled with the west QBO. At years end it was at an almost record low temperature at mid-levels. It created a stronger than normal thermal gradient/jet which came fast and flat across the Atlantic. At least this Winter the QBO will be negative which is thought to limit the strength of polar vortex,although this of course is only one factor.

Just a thought about those NOAA anomaly forecasts. On those anomaly charts the signal for change in week 2 is less obvious .The second image is after all only an average spread of the pattern through days 8-14. If we refer again to the daily mean charts from around day 9/10 onwards it's much clearer that the Scandinavian ridge moves away as the pattern changes further on to a westerly. Just one of the reasons to best view those anomalies in conjuction with the daily mean charts to clarify the general trend towards any changes. Sometimes there are only subtle changes to those wavelengths and positioning(green Contours) from one to the other, especially when the anomaly differences are small as they are currently.

I guess Atlantic driven wrt the outlook beyond the plume can be interpreted in different ways Captain. We are certainly not looking at raging zonality perhaps a westerly pattern would be a better term in this instance. A change to that outlook is now being modelled beyond any plume around next week end, as opposed to the current east/south east setup. Thicknesses still look reasonably high into week 2 further south and with the lowest heights to our north west it looks like our typical north/south split perhaps. Days 5 and 10 mean Atlantic flow Still some decent Autumn days would result from that i would think with the Atlantic jet still not yet fully awake.

The heat plume still showing on the 12z GFS Operational for the end of next week. Temps well into the the 20'sC and a risk of storms still being shown on this run. Not sure that it will play out like this though with mean outputs indicating something less dramatic. Signs that our semi-resident block will be pushed away eastwards as we go through next week but the uncertainty lies in the behaviour of that Iberian low. Longer term things do look like changing eventually into a more Atlantic driven pattern.

Yes very much so I think PM.A look at the NH pattern shows the main troughing upstream over Canada setting up shop now and remaining into next week. A very quiet Atlantic still modeled with just that Iberian cut off low the only sign of anything unsettled, possibly bringing showers into the sw later. The blocking Scandinavian high the main feature for some days ahead yet. The latest ECM mean at day 10 http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=1&map=1&type=1&archive=0 Shows little change to the overall pattern with that ridge to our east still showing.

A pattern like this would be good,for cold lovers. Easterlies all the way across the Atlantic-the famous Winter of 62/3. The Atlantic attacking from the south couldn't get in and we saw plenty of low pressure around the Channel and N.France giving frequent snow for many through the following weeks. This link is a good read http://myweb.tiscali.co.uk/mtullett/1962-63/index.htm with daily charts and reports. If we recall December 2010's charts then this was similar but lasted much longer!

Yes the 00z charts continue to suggest the heights over Scandinavia will prove quite stubborn,even into next week. The Atlantic coming against the block showing no signs of breaking them down,indeed as already mentioned signs of rising heights regressing towards Iceland over the top of a cut off low to our south. It may well be tropical storm activity will shake the pattern up later, as shown in the later GFS Op run, but this is still to far away to be anything other than a possibility.

It seems we will squeeze another week or so of dry and warm weather before any real change. Models showing the Atlantic trough edging closer to western districts early next week would suggest some showery rain then moving to the south west. it may not herald a change to an active Atlantic just yet though Naefs beyond day10 http://www.meteociel.fr/modeles/naefs_cartes.php?code=0&ech=348&mode=0&map=&runpara= Still showing a relatively quiet Atlantic jet with low anomalies.

Wrt to comments above about the 500 hpa anomaly charts. We have to remember they are a mean picture of height forecasts over a period of 6 or 4 days depending on whether we look at the 8-14 day or 6-10 charts. They will never match exactly an Operational forecast for a given day but do give a good guide for the general upper pattern, taken with the mean charts and watching for how they evolve on successive runs. To see how they performed for this current pattern i selected the NOAA 8-14day forecast issued 10 days ago and put it against the latest GFS Op chart for T+48hrs about mid-way through the forecasted period. overall a good forecast i think with the ridge over NW Europe and the Atlantic trough out west(green lines).It also picks out the low heights towards the Azores. They are not perfect but read correctly and taken with other ensemble outputs they are the best we have at the moment for a couple of weeks ahead. Operational runs for the first 4-5 days comparing with each other along with the fax charts are of course better for more detail and placement of surface features for the shorter term.

Not specifically Knocker.Comments regarding upstream developments are often mentioned more so in Winter when we see a more defined jet profile. As long as it's model related i can't see any problem mate although as i am sure you appreciate the main interest for many is in our own neck of the woods. edit just seen PM's reply there you go!

It's looking pretty settled for next week with high pressure rebuilding across the UK after the current low towards ne Scotland fills. Midweek picture from all 3 operationals so after the weekend a largely dry and pleasantly warm outlook with some sun but inevitably at this time of year patchy overnight low cloud or mist may take some time to clear from some spots. Some suggestion that low pressure over the Azores will approach the south west towards the end of next week with some rain.This could just be a temporary break though as later GEFs favour a rebuild of pressure from the Azores by the end of week 2. No immediate sign of a general change to more unsettled Autumnal weather yet then with a relatively quiet Atlantic outlook continuing.

Hi John,Yes we can continue to view the mean flow but your comments wrt to assessing the weather at the surface underlines the difficulties in a pattern with weak upper air anomalies.I should perhaps have explained that was my point. A glance at the faxs underlines the presence of a number of shallow lows showing within a relatively quiet setup. One such feature will bring cloud and rain with some cooler air to the ne of Scotland over the next 2 or 3 days. Certainly a difficult period for forecasting cloud and sunshine amounts with a number of weak fronts in the Atlantic picture.

The Atlantic wave pattern continues in quite a benign state with a lot of mid-latitude high pressure and a slow jet flow. With such weak anomaly differences i am not sure we can take much guidance from the anomaly charts for next week but for what they are worth both ecm and naef show little change to the quiet early Autumn setup. Day 10 http://www.meteociel.fr/modeles/naefs_cartes.php?code=0&ech=240&mode=0&map=&runpara= http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=101&map=0&type=1&archive=0 Just a hint of a weak Atlantic trough around 10degs west and heights just to our east more or less supporting last nights NOAA chart.

Stick with it knocks see how the discussions develop as Winter arrives.Leave the off topic stuff to the team and report if we miss anything. Understandably it does get busier and a tad excitable at times but we do have this thread and others for coldies to elaborate. The team will continue to monitor the main Model Discussion thread as always to keep it relevant. Best we get back to model talk now but anymore questions can be pm,d to the team rather than clog up this thread. Cheers all.

The 3 main runs now seem agreed on high pressure lasting through to the weekend. Beyond that we seem to have less agreement with the ECM more bullish in moving the high away. Looking at both ecm and gfs means at day 10 indicate pressure declining somewhat so next week may well see the Atlantic trough move east with a gradual breakdown in the settled conditions. Tonights CPC anomaly charts indicate the movement around 10 deg.east of the long wave pattern in week 2 and is mentioned in their discussions http://www.cpc.noaa.gov/products/predictions/814day/814day.03.gif So a dry and quite warm week to come although it looks like there will be cloud around within this setup. Next week suggests something less settled gradually developing from the southwest is my current thinking.