General Model Output Discussion:

[weather eater]

Can't say im surprised by the E,ly being shown on the models. Very pleasing from a forecasting perspective as at the moment it looks as though I even got the date right (4th Feb).

Obviously its early to start ramping but as the GFS/ECM/GEM all go for an E,ly these are promising signs. Rather simply put if some of the charts this morning come off then the 09/10 winter will be remembered for many years!

Indeed Dave and its not that often you see such broad model consensus, the UKMO looks to be heading that way too. Mind you I'm mindful of GPs posts and the fact that the models will change, even if an easterly is what we do eventually get, not every run at this range is going to show it.

[TEITS]

Interesting reading some of the comments this morning about the medium term. However let me explain why I thought the E,ly was always possible. I will use the GEFS control run as an example.

Here is the SW tracking SE that i've been harping on about for a few days.

http://91.121.94.83/modeles/gens/run/gens-0-1-162.png?0

Note the WAA!

http://91.121.94.83/modeles/gens/run/gens-0-1-180.png?0

Here comes the instinctive part. Now once I spotted the potential of a LP tracking SE the E,ly always looked possible. The door is shut to the Atlantic and the ever present block to the NE links with our existing HP.

http://91.121.94.83/modeles/gens/run/gens-0-1-192.png?0

Now I fully respect those who post very technical posts on this thread. However im still of the opinion that you also require abit of forecasting instinct in these situations because IMO the E,ly always looked possible based on the models in recent days.

The key to the E,ly is that the LP tracks SE. If this doesn't happen and it tracks E then this will result in no E,ly and HP being centred over the UK. I do not see HP centred to our W bringing NW,lys!

[Lewis]

Interesting reading some of the comments this morning about the medium term. However let me explain why I thought the E,ly was always possible. I will use the GEFS control run as an example.

Here is the SW tracking SE that i've been harping on about for a few days.

http://91.121.94.83/modeles/gens/run/gens-0-1-162.png?0

Note the WAA!

http://91.121.94.83/modeles/gens/run/gens-0-1-180.png?0

Here comes the instinctive part. Now once I spotted the potential of a LP tracking SE the E,ly always looked possible. The door is shut to the Atlantic and the ever present block to the NE links with our existing HP.

http://91.121.94.83/modeles/gens/run/gens-0-1-192.png?0

Now I fully respect those who post very technical posts on this thread. However im still of the opinion that you also require abit of forecasting instinct in these situations because IMO the E,ly always looked possible based on the models in recent days.

The key to the E,ly is that the LP tracks SE. If this doesn't happen and it tracks E then this will result in no E,ly and HP being centred over the UK. I do not see HP centred to our W bringing NW,lys!

Your prediction was spot on congratulations TEITS

Now let's hope it verifies otherwise i'll be holding you responsible

[Iceberg]

Already at 124T you can se the 06Z is going to be good trend run, the building blocks for any prolonged cold are not in FI, even though exactly what will happen obviously is.

Yep I said this morning that the METO was the wrong side of marginal for most of England for Friday/Thursday night and the GFS 06Z seems to follow this.

[cooling climate]

Personally I think an easterly type direction is the form horse to be on and has been for

some time. The composites may well be showing what GP suggests along with the GWO

phases but the models are saying otherwise.

All of these indices are fluid and with the changes already this week they will probably

come on board the Siberian express soon enough.

[Thundery wintry showers]

Very interesting outputs this morning. The cold/snow for Thursday and early Friday from that frontal slider down western areas is downgraded considerably as the colder air is shunted east initially, but the upshot is a much more potent northerly lasting through into Monday (this goes for ECM/UKMO as well as GFS). Winds are widely progged to get east of due north for a time which would bring snow showers a fair distance inland in the east, although again it is worth noting that specific wind direction is rarely pinpointed correctly until 36-48 hours out.

Reading the conflict between Glacier Point's references to the teleconnections and the models is very interesting. I remember in February 2005 the models were repeatedly going for cold easterlies but until the last third of the month these repeatedly got scuppered in favour of frequent blocking to the W and NW, so this is something to bear in mind, although I don't think it rules out the possibility of this W/NW blocking merging at times with the Siberian High bringing airmasses from a combination of north and east.

One major difference is that while the Arctic has been anomalously warm so far this winter, it has been nothing like as warm as in the 2004/05 season and the heart of Eurasia is widely between 10 and 20 degrees colder. This means that any incursions from both north and east should be far more potent than they were in February 2005, for instance Feb '05 had a northerly between 13 and 16 February which, if the Arctic temperatures had been anywhere near normal, would have brought widespread snowfalls.

If the current modelling trends continue then my CET punt for February of 4.9 is going to start looking way too high and may have to be revised downwards by as much as two or three degrees.

[cowdog]

The LP deepens, and has a much larger core too it, with a W/NW flow (with warmer 850's inside and wrapped around it) So the result of this (if it verifies) would mean rain for everyone with some wintery precipitation over higher ground, then later in the day back edge snow for Central N england, and around the border of Scotland.

Yup, not good at all, although it might be snow for the majority of the North for most of the time, really does seem borderline.

Just checked and think this is the first none cold run for GFS since Saturday, and rather worryingly if you go back and compare each run it has been downgrading the cold for Friday near enough every run, its just finally gone over the tipping point. Hopefully GFS is not onto something.

[Guest North Sea Snow Convection]

I would agree that a north easterly looks eventual favourite this morning. As suggested might happen yesterday, after the northerly we see an evolution to a pressure rise from the arctic taking in a ridge to our north and north east.

Obviously this suggestion has to keep continuity, but all the models seem to be singing from that hymn sheet this morning

In the meantime a cold norherly finish to a very cold month

[Lewis]

Yup, not good at all, although it might be snow for the majority of the North for most of the time, really does seem borderline.

Just checked and think this is the first none cold run for GFS since Saturday, and rather worryingly if you go back and compare each run it has been downgrading the cold for Friday near enough every run, its just finally gone over the tipping point. Hopefully GFS is not onto something.

As the 06z stands, only back edge snow for N areas.

I agree with what you say about the GFS, 1 step forward 2 steps back 9 times out of 10. From having a full blown Northerly Thursday, continuing too at least Sunday in earlier runs, to a Northerly lasting 14 hours, toppling bringing in a warm sector, then with a weak effort following in behind it. If you made a trend of how the current runs have panned out, the Northerly come thursday will be gone, and the easterly in FI will be pushed further into FI or just vanish completely.

I think the GFS personally has difficulties in the long range, then all of a sudden jumps on board and gets the short range spot on. It's been like this all winter. Thats why i said the other day, i won't be jumping on the bandwagon until wednesday night/thursday as i have feeling deep down, everything is going to go tits up. I wouldn't be dissapointed if it did, we have had heavy snowfall, and fantastic cold weather, i'm happy with what i have already had. Anything extra, well it's a bonus imho.

[snowmadchrisuk]

Friday is more marginal on this run because of the track of the low , The East looked more favourable on the 00z but now even they are probably on the wrong side of marginal. The cold air still undercuts very quickly on this run though so back edge Snow is very likely in central areas. On the other hand the system on Monday looks much more favourable and would deliver some heavy Snow to much of England if it verified as shown . As for the Easterly/Northerly debate as long as the Atlantic is blocked i'm happy

[Thundery wintry showers]

As the 06z stands, only back edge snow for N areas.

I agree with what you say about the GFS, 1 step forward 2 steps back 9 times out of 10. From having a full blown Northerly Thursday, continuing too at least Sunday in earlier runs, to a Northerly lasting 14 hours, toppling bringing in a warm sector, then with a weak effort following in behind it. If you made a trend of how the current runs have panned out, the Northerly come thursday will be gone, and the easterly in FI will be pushed further into FI or just vanish completely.

I disagree with the bit in bold. The cold northerly is postponed by a day but the termination of the northerly is also postponed by another day, and when the "breakdown" attempts to make it in from the NW it results in potential for stalling against the cold polar air resulting in fairly significant snowfalls during midweek next week.

GFS 06Z is a remarkably dry run with the wishbone effect- even East Anglia is progged to stay mainly dry- but precipitation outputs always change substantially with each run at this kind of range. I think the precip outputs are one area where GFS often outperforms UKMO but it is only reliable within 2 days out.

[cooling climate]

The track of the low down across the country on Friday is meaningless at the momement

as it is only Tuesday and there will be further changes.

[TEITS]

Astonishing blocking in the 06Z so far.

http://www.wetterzentrale.de/pics/Rtavn2521.png

Dare I say the 0Z/06Z is showing Feb 1947 synoptics.

[Strider]

GFS 06z op showing the Atlantic winning by Tuesday...

[snowmadchrisuk]

The 6z is Inline with what GP has been saying , No real Easterly , but plenty of blocking to the North and West bringing in Northerly's at times North-Easterly's .

[Southender]

Errrrr, FI is looking a bit tasty...

Edited January 26, 2010 by LeighShrimper

[Lewis]

I disagree with the bit in bold. The cold northerly is postponed by a day but the termination of the northerly is also postponed by another day, and when the "breakdown" attempts to make it in from the NW it results in potential for stalling against the cold polar air resulting in fairly significant snowfalls during midweek next week.

GFS 06Z is a remarkably dry run with the wishbone effect- even East Anglia is progged to stay mainly dry- but precipitation outputs always change substantially with each run at this kind of range. I think the precip outputs are one area where GFS often outperforms UKMO but it is only reliable within 2 days out.

I agree TWS,

When i meant "weak effort" i was basing it on the strength of the flow. As runs have gone on, it's become much slacker with the HP ridging East.

I suppose the 06z is another evolution/possible scenario. Instead of an Easterly in FI, we are looking at another Northerly with a possible easterly. Nice model watching, with a lot of ibuprofen at the ready.

I'm certainly looking forward to the 12Z ECM.

Regarding precipitation, i can do nothing but agree with regards to the GFS plots. The other month when it was a Northerly switching NE then slight easterly, we had a HP close by. They was still a lot of precipitation around and lots out into the N sea, we won't know until real time.

Edited January 26, 2010 by Storm Force Lewis

[snowmadchrisuk]

GFS 06z op showing the Atlantic winning by Tuesday...

The Atlantic doesn't really win , High pressure starts to build , the cold air doesn't really go anywhere and shortly after we see retrogression towards Greenland

[TEITS]

The 6z is Inline with what GP has been saying , No real Easterly , but plenty of blocking to the North and West bringing in Northerly's at times North-Easterly's .

I disagree as GP was suggesting the HP to our W bringing NW,lys.

What the 06Z shows is actually very rare and hardly ever experienced. What we have in F.I is a monster block consisting of a Greenland HP/Siberian HP. This is what happened during Feb 1947 which is why I referred to it earlier.

Ignore the detail and note the GFS yet again goes for significant blocking. The detail doesn't matter at this stage.

http://www.wetterzentrale.de/archive/slp/1947/Rslp19470204.gif

http://www.wetterzentrale.de/pics/Rtavn3001.png

Edited January 26, 2010 by THE EYE IN THE SKY

[snowmadchrisuk]

I disagree as GP was suggesting the HP to our W bringing NW,lys.

What the 06Z shows is actually very rare and hardly ever experienced. What we have in F.I is a monster block consisting of a Greenland HP/Siberian HP. This is what happened during Feb 1947 which is why I referred to it earlier.

Ignore the detail and note the GFS yet again goes for significant blocking. The detail doesn't matter at this stage.

I hope your right , a decent Easterly would be much more beneficial for my part of the UK . The link up would likely be crucial for a decent shot of an Easterly though.

[Lewis]

I disagree as GP was suggesting the HP to our W bringing NW,lys.

What the 06Z shows is actually very rare and hardly ever experienced. What we have in F.I is a monster block consisting of a Greenland HP/Siberian HP. This is what happened during Feb 1947 which is why I referred to it earlier.

Ignore the detail and note the GFS yet again goes for significant blocking. The detail doesn't matter at this stage.

I agree with snowmadchrisuk,

The fact that it's all in F.I pretty much sums it up. Where as personally i'm the sort of guy that looks at short term and will sometimes ponder deep into F.I trying to look into trends/patterns. The GFS would be bottom of my list when looking for patterns/trends deep in FI.

There is so much uncertainity this week, so shall we get this week nailed first, before we look into 2/3 weeks time? That's why there is so much dissapointment in this thread from the less experienced members, they see more experienced members always looking ahead.

I wouldn't know what it's like, but i suppose model watching is like a drug, once you have some you want more. And you'll do whatever it takes to try and find some again, works the same with cold trend spotting with the models.

I think we should talk about this Northerly, and then see what shows on the models come Sunday/Monday.

Please don't be offended by my post, i respect your input and courage.

[Tim Bland]

I disagree as GP was suggesting the HP to our W bringing NW,lys.

What the 06Z shows is actually very rare and hardly ever experienced. What we have in F.I is a monster block consisting of a Greenland HP/Siberian HP. This is what happened during Feb 1947 which is why I referred to it earlier.

Ignore the detail and note the GFS yet again goes for significant blocking. The detail doesn't matter at this stage.

http://www.wetterzentrale.de/archive/slp/1947/Rslp19470204.gif

http://www.wetterzentrale.de/pics/Rtavn3001.png

I love how you go into Ramp mode TEITS when the charts strt looking good. Feb 1947 was a one off IMO but I would love to be proven wrong. This is from the Met office report of Feb 1947;

Coldest February on record

Easterly winds persisted throughout February, with only brief breaks in the cold snowy weather. On no day did the temperature at Kew Observatory top 5 °C, and only twice in the month was the night minimum temperature above freezing. It was the coldest February on record in many places and, for its combination of low temperatures with heavy snow, bore comparison with January 1814.

In some parts of the country, snow fell on 26 days. It was often light and powdery so it was easily whipped up into deep drifts that affected roads and the railway network. New ways were tried in order to clear them. One method was to mount jet-turbine engines on towed trailers and angle the hot-air outflow of the engines towards the ground; these were hugely effective in clearing the snow from roads but the underlying surface melted too, so the experiment was rather short-lived!

[cooling climate]

Well if that run comes off then I think even the most ardent snow fan would be sick of the stuff by the end of winter(only joking as I would never get sick of snow).

Seriously though what a run and by the way hats off to you GP if the evolution shown by this 06z GFS run does come off, although I will stick with the easterly scenario.

What a choice though spoilt between a stonking northerly or a beasterly easterly or better still both.

Blowing my own trumpet a little here but after banging on about a prolonged cold from the

start of the northerly at the end of the week and then progressing into a east of north a

airflow for about a week now if not more. It is nice to see it coming to fruition and read

correctly the signs that I was seeing from the northern hemisphere charts.

[TEITS]

I think we should talk about this Northerly, and then see what shows on the models come Sunday/Monday.

Please don't be offended by my post, i respect your input and courage.

No offence taken Lewis.

You are right in what you say about the N,ly however I do enjoy trying to spot the trend in the medium term. Whilst the detail is uncertain in the medium term the trend does suggest blocking to become established. Whats most pleasing is the ECM beyond +240 would see the block back W bringing very similiar synoptics as shown on the GFS. Although the E,ly/NE,ly is in F.I the building blocks are certainly within the reliable timeframe and its these im concentrating on.

[Lewis]

No offence taken Lewis.

You are right in what you say about the N,ly however I do enjoy trying to spot the trend in the medium term. Whilst the detail is uncertain in the medium term the trend does suggest blocking to become established. Whats most pleasing is the ECM beyond +240 would see the block back W bringing very similiar synoptics as shown on the GFS. Although the E,ly/NE,ly is in F.I the building blocks are certainly within the reliable timeframe and its these im concentrating on.

I must admit the blocking does look fairly significent, and mouth watering. What the models are showing in the medium turn would probably suggest the same evolution in the longer term. As we have seen this winter upto now "compared to past winters" when we do get a block, it's fairly hard for the Atlantic to break through, and we do end up with some potential significent cold periods.

If we can get too Sunday/Monday with the same model outputs outlining the block. I will certainly be singing my way through this thread. Mouth watering prospects again from the models, long may it continue.

I'm going to concentrate on this weeks patterns as i think it's crucial to the blocking pattern mid range and long range.