In Depth Model Discussion, Analysis and Summaries

[johnholmes]

It will suddenly come to life in December no doubt, shame we don't get the 'expert' input year round though.

It simply goes to show that those with the expertise, either have a similar preference to the general liking of cold and snow, or, maybe, see little point in posting through the non wintry months?

just a thought.

[Aaron]

Probably because the weather outside winter is so boring and uneventful.. especially this year.

[davehsug]

Surely though John it would have helped to explain the background to, what for most of us, has been another disappointing summer? As far as I can tell, you have been the only one trying to go a bit deeper than the models. I would be very disappointed if our "experts" turned out only to be interested in cold & snow. The weather & what drives it is fascinating whatever the time of year!

[Suburban Streamer]

Surely though John it would have helped to explain the background to, what for most of us, has been another disappointing summer? As far as I can tell, you have been the only one trying to go a bit deeper than the models. I would be very disappointed if our "experts" turned out only to be interested in cold & snow. The weather & what drives it is fascinating whatever the time of year!

we do have experts on here all year round. but we have a few knowledgable members who only come here in the winter (steve murr, nick sussex etc.) but the likes of nick f, thundery wintry showers, gibby, john holmes, bluearmy, chionomaniac etc are here all year.

Maybe there's just not alot to say when you have high pressure over greenland allowing low pressure to track across the uk for months on end....but i'm no expert

[johnholmes]

this is just me giving my view, nothing to do with anyone else nor anything to do with any team member.

I spent many years as a professional forecaster and always tried hard to not show any bias at any time of the year nor to be too biased by what I could see out of the window when forecasting for the whole of northern England as a media forecaster. As an on site forecaster for the local area, the RAF/Civil airfield or oil site then its what is outside the window and how that may change ofer the next 24-72 hours that matters.

Doing an lrf, which is what this is about, means doing it without bias for the whole of the UK. Believe me that is far from easy. On top of that if you are all honest then its really the lead into and through winter that something like 90% of you are interested in.

The team ran an invite only area to enable those wanting to find out what the models were really saying rather than hopecasting but as soon as the ;'winter' left the number of views dropped to almost nothing. None of us immune are from hoping that what we post will be read by a reasonable number of folk. Its a bit like talking to oneself if time is spent preparing and posting a forecast only to discover that almost no one is reading it.

So to be fair its up to you to show you are reading the technical posts, that will encourage all those with sufficient knowledge to feel capable of posting into it to do just that, in all 4 seasons through the year.

I do my own lrf version, out to about 3 weeks or so on my own web site but on there it can be quite disheartening to see not much viewing occurring and I decided some time ago to take a back seat on Net Weather. After all I did act as a senior forecaster on here for 5-6 years. I like to drop in now and then but not to be expected to be around anything like as much as I used to be.

This is not meant as a rant just my view on how I feel about the technical page and perhaps why what a couple of you comment about has happened.

By all means anyone on the team or anyone else for that matter put your own views

many thanks SS for the kind comment including me.

Edited September 19, 2011 by johnholmes

[Swave Snow]

I was wondering where Glacier Point is as I miss his updates.

Edited September 21, 2011 by Swave Snow

[Radiating Dendrite]

I was wondering where Glacier Point is as I miss his updates.

I have been told that he is busy.

[skifreak]

I have been told that he is busy.

Hopefully pre-occupied preparing for snowmageddon

[Cleeve Hill]

its likely that an addition to the rampling household has taken a fair amount of his time up. stewart is not the type to allow a busted forecast to affect him. sh*t happens. anyway, as we head into autumn, hopefully more varied patterns will come into view and the model threads will get greater interest and input.

As one of the more respected contributors on Net Weather do you think GP was that far off the mark for the Summer forecast ? I know at one point he was talking about Summer 76, but he definately talked about a very settled & dry summer and I reckon he was there or thereabouts. In Cheltenham, for example we had a first decent rainfull yesterday for months and this summer goes down as a very good one in these parts. Well done GP I say and look forward to his next contribution.

[damianslaw]

Would like some techical input here - anyone have any forecasts for the Oct NAO/AO and predicted 500MB pattern for the first part of the month. Such info would help to try and guess where those heights next week may eventually end up.

[summer blizzard]

Would like some techical input here - anyone have any forecasts for the Oct NAO/AO and predicted 500MB pattern for the first part of the month. Such info would help to try and guess where those heights next week may eventually end up.

The forecasts are based on the GFS output and as such should be met with caution.

[johnholmes]

Would like some techical input here - anyone have any forecasts for the Oct NAO/AO and predicted 500MB pattern for the first part of the month. Such info would help to try and guess where those heights next week may eventually end up.

see my comments about the 500mb anomaly charts in the model thread

I'm no expert but if I get the time I'll do a round up of what items seem likely to affect the weather into mid October over the weekend.

MJO, NAO, AO ENSO, 500mb anomaly charts etc

[johnholmes]

Just a quick reply to what I promised

The AO link is showing a prediction at first of staying above the zero line, but not by much,later on it predicts it to rise more.

The NAO is currently above and is then predicted short and longer term to osciallate around the aero line.

Both are usually fairly accurate for the first 7-10 days, after that their accuracy falls away.

The 500mb anomaly charts, well those yesterday as I have not yet seen the ECMWF and GFS output this morning, all showed the +ve area currently east of the UK to edge slowly west, NOAA shows it, on its 8-14 day outlook last evening, for 1-7 October with the +ve anomaly just off the western Isles of Scotland (a bit nw of them), the 500mb upper ridge at that time is a few degrees east of the UK. It shows the upper trough, part off the eastern seaboard of the states, and its eastern part slanting NW-SE to be at about 20W on the 50N line.

The ECMWF and GFS yesterday had the 500mb ridge well east of the NOAA prediction with the +ve anomaly and the upper ridge also.

All 3 show a flow more SW'ly for the period in early October as opposed to the almost S'ly they had a few days ago valid for the end of September.

To me the trend is fairly sequential and looks about right.

Thus the idea of heat for much of England and Wales and even into parts of southern Scotland from mid week up to at least the start of next weekend are probably correct in my view. For the time of year.Thereafter as the upper ridge and its likely attendant surface feature beneath it as they drift west or even NW will cause a slowish decline in daytime temperatures and, possibly, if the high is centred over the UK for a day or two, a more rapid decline in overnight values.

10-14 days from now is a heck of a long time in meteorology. However I would punt for the surface high to be west or a bit north west of the UK, and far enough west for some effects of the Atlantic to move around its northern and eastern perihpery.

Hope this is what you were asking for?

Edited September 24, 2011 by johnholmes

[damianslaw]

Just a quick reply to what I promised

The AO link is showing a prediction at first of staying above the zero line, but not by much,later on it predicts it to rise more.

The NAO is currently above and is then predicted short and longer term to osciallate around the aero line.

Both are usually fairly accurate for the first 7-10 days, after that their accuracy falls away.

The 500mb anomaly charts, well those yesterday as I have not yet seen the ECMWF and GFS output this morning, all showed the +ve area currently east of the UK to edge slowly west, NOAA shows it, on its 8-14 day outlook last evening, for 1-7 October with the +ve anomaly just off the western Isles of Scotland (a bit nw of them), the 500mb upper ridge at that time is a few degrees east of the UK. It shows the upper trough, part off the eastern seaboard of the states, and its eastern part slanting NW-SE to be at about 20W on the 50N line.

The ECMWF and GFS yesterday had the 500mb ridge well east of the NOAA prediction with the +ve anomaly and the upper ridge also.

All 3 show a flow more SW'ly for the period in early October as opposed to the almost S'ly they had a few days ago valid for the end of September.

To me the trend is fairly sequential and looks about right.

Thus the idea of heat for much of England and Wales and even into parts of southern Scotland from mid week up to at least the start of next weekend are probably correct in my view. For the time of year.Thereafter as the upper ridge and its likely attendant surface feature beneath it as they drift west or even NW will cause a slowish decline in daytime temperatures and, possibly, if the high is centred over the UK for a day or two, a more rapid decline in overnight values.

10-14 days from now is a heck of a long time in meteorology. However I would punt for the surface high to be west or a bit north west of the UK, and far enough west for some effects of the Atlantic to move around its northern and eastern perihpery.

Hope this is what you were asking for?

Many thanks for this post - just what I was after. Yes the signals are for the high to slowly migrate NW setting up shop just to our NW - how far west remains to be seen and will be the difference between weak atlantic fronts drifting around the high from the NW but still with mild air, or a pronounced northerly with associated cold front as being hinted out by ECM this eve.

[The PIT]

Paul Hudson did stick the boot in somewhat within a week of saying it was well thought out forecast. I think it was a pity the media picked the forecast up and if GP knew they were going to he would have left out shades of 76 wording which were the killer.

[Glacier Point]

Ah, nice to be back.

This summer has seen angular momentum well below normal. In effect, we've seen a de-facto La Nina in place since early June. The mean trough solution is therefore very consistent with the overall pattern for a La Nina summer [video reviewing the summer coming in the next view weeks].

However, as we hit the proper part of the autumn, the pattern is shifting dramatically. The enquiring mind, would also ask why ?

Analysis of total angular momentum depicts well this below average period for the majority of the summer, but also the recent upward shift which marks it out as a significant development.

Much of this is related to an eastward propagating tropical (MJO) wave drawing cooperation from the extratropics. Contextually, the sun is also much more active (August solar flux was highest since November 2004) and the tropics have been notably more active since August (Accumulated Cyclone Energy is globally not far off average). There have been two significant mountain torgues in the last ten days which have added significant westerly wind totals globally.

All of this has driven the global wind oscilation out its summer slumber and we are experiencing a textbook Branstrator Circum Global Anomalous Mid Latitude Ridges in the NWP for the next 6-10 day period as the GWO moves towards phase 4. It's also interesting to note that a similar but weaker evolution in the GWO took place in late July and early August which was directly responsible for the settled period then (again tied into the MJO which emphasises the need for rigorous monitoring of this teleconnector).

If this were the only variable at play, we would expect angular momentum to decrease and the ridge to shift back to our west. However, the sun continues to be active and the QBO has begun to show a slow evolution towards an easterly phase similar to other east QBO years under increasing solar activity. We may well be looking at the start of a 3 month period of low heights to our north.

Of particular interest here is the development of a westerly wind in the upper atmosphere between 80N and 40N. This type of wind development will aid lowering of pressure at the mid and lower layers and is likely to continue to at least the end of October, probably November (QBO analogues are interesting here in suggesting the coldest part of the winter not to be like last year, more towards February and strongish polar vortex to develop early and be centred in the Canadian Arctic).

Putting this together, the trend in angular momentum is extremely interesting to monitor. I would punt at it remaining close to neutral if not rising for the rest of the autumn. I suspect also that the solar - QBO interface is helping to weaken the heights over the Arctic, a trend that is likely to continue into the early part of the winter.

The most likely outcome for this is an extremely anticyclonic picture (dry, settled weather) with high pressure centred over NW Europe, possibly a second high pressure cell in the central parts of the North Atlantic which might achieve some dominance in November setting a bit more of a trough to our east.

[chionomaniac]

Welcome back, Stewart. So the warnings of a snowy Autumn could be premature in your opinion.

[Glacier Point]

Thanks Ed.

The periodicity of the MJO has been two active waves spaced 60 days apart. During November, the MJO should be weak which might result in a fairly typical La Nina type pattern for November which would loosely translate to the mid Atlantic ridge scenario and potential for a trough digging into NW Europe. The thing that bothers me here is that we would need to see a strong blocking signal to take advantage of the ridge. Are we going to see this if the QBO / solar signal is for strong enough inertia in the jet to topple the ridge ? Notable that the CFS is on board with this type of pattern.

On the plus side, the fact that angular momentum has risen during the autumn should result in less destructive interferance with the Brewer Dobson Ciculation which would mean a less strong polar vortex during the final third of the winter opening the door for a warming event.

[Isolated Frost]

I didn't understand a word you posted - but it's brilliant to see you back GP!

Actually, low heights to the north doesn't sound too good, but I'm liking the idea of anticyclonic weather, and as you say, hopefully a cooler January into February.

[johnholmes]

Branstrator Circum Global Anomalous Mid Latitude Ridges

Come on Stewart what the heck is this please?

or at least the first two words?

[davehsug]

Welcome back Stuart! You've been missed by us geeks so badly. Go for him JH!

[damianslaw]

Interesting thoughts from GP even though I must confess I don't understand a word of it neither. Seems to go against many of the forecasts being banded about for the rest of the autumn and the winter. Its only one forecast, and didn't GP get the summer forecast very wrong indeed...

[summer blizzard]

Thanks Ed.

The periodicity of the MJO has been two active waves spaced 60 days apart. During November, the MJO should be weak which might result in a fairly typical La Nina type pattern for November which would loosely translate to the mid Atlantic ridge scenario and potential for a trough digging into NW Europe. The thing that bothers me here is that we would need to see a strong blocking signal to take advantage of the ridge. Are we going to see this if the QBO / solar signal is for strong enough inertia in the jet to topple the ridge ? Notable that the CFS is on board with this type of pattern.

On the plus side, the fact that angular momentum has risen during the autumn should result in less destructive interferance with the Brewer Dobson Ciculation which would mean a less strong polar vortex during the final third of the winter opening the door for a warming event.

Interesting thoughts and i agree in regards to the coming October/early November featuring a mainly +AO pattern with a mean ridge in the local of the UK however in regards to late November/early winter i actually expect the mean ridge being west of the UK in the Atlantic as the AO tanks.

[ZONE 51]

Welcome back GP.

I find i understand the more in-depth stuff more now than i did last year ,and i really look foward to your posts.

[UV-RAY]

Interesting post as usual GP, so at this moment in time you envisage a rather average early winter temp wise, with the prospects of a cold spell late on. Doesn't fill me with much optimism if you are right, in fact a rather boring early winter if it's extremes of weather your looking for.