Model output discussion - 20th Feb onwards

[winterof79]

1 hour ago, phil nw. said:

Quite a stiff easterly on Saturday down south.

Will feel raw in the cold wind.GFS does show some showers blowing in of a wintry mix but they don't appear widespread or heavy and with 2mtr.temps showing 4-6C nothing to get too excited about.

 

Dew points are already conducive as early as today

http://xcweather.co.uk/

 

[winterof79]

43 minutes ago, Severe Siberian icy blast said:

But why even get caught up in anything past t144 . I understand that we look for trends but how many charts at even t144 come to fruition? It's a developing situation as ever and with the mjo lag and what looks to be another strat warming I'm sure the mods will change. 

Simply because Terrier was replying to a post that said we were back to mild after this weekend which is clearly not so.

It would tie in with a lot of medium range forecasts of the Euro trough too.

Edited February 23, 2016 by winterof79

[Froze were the Days]

2 hours ago, bryan629 said:

I really hope Joes not been reading the express to come up with that statement 

Models definately not showing a winters worth of snow at the moment .... 

Oh dear...unfortunately Joe wasn't hugely correct for mid-January either, he over exaggerates greatly.

[Banbury]

Cold throughout

[Singularity]

Finally, something which resembles what phase 7 tends to bring about late Feb/early March.

Then it wraps up with the phase 8 type response while the strat. waves goodbye:

 

Strange how absent these trop. patterns have been from GFS until this evening. The strat. developments are handy too.

[mulzy]

14 minutes ago, Singularity said:

Finally, something which resembles what phase 7 tends to bring about late Feb/early March.

Then it wraps up with the phase 8 type response while the strat. waves goodbye:

 

Strange how absent these trop. patterns have been from GFS until this evening. The strat. developments are handy too.

Deep cloud-cuckoo land...

[Guest]

I am somewhat concerned that some posters are allowing themselves to be misled regarding the timing and intensity of this cold spell. There has been a continuing tendency for some to ramp up the cold and especially any possible snowfall when one or more charts hint at something quite wintry and then, on the next run, following a minor downgrade, to criticise the models. There have also been a few posters who have taken out their disappointment on others. The moderators have tried to delete some of the worst of these. Whilst I fully appreciate that the exceptionally mild winter and the occasional missed snow event has constantly frustrated many of us, we all need to remember that this is a model interpretation and discussion thread. I feel that there is plenty on offer in the coming few weeks to be excited about but we need to be patent.

When I posted early last week (page 98 on 31.1.16 model thread) I pulled together a number of reasons that indicated the ”likelihood” of a prolonged cold spell. I said that the models would take some time to factor in the main changes and we would see substantial swings before they agree. If anything, I was a little surprised at the initial very swift change to colder longer term predictive charts and then, perhaps inevitable, an  apparent downgrade. I do not feel that this week’s rather cold spell is anywhere near the main event. Let me explain why.

I started writing this post this morning but was too busy to finish it until now. I was going to draw attention to the excellent work done by AER (Atmospheric and Environmental Research) scientists. I think some of you are familiar with Judah Cohen, one of their team and the author of their “Arctic Oscillation Analysis and Forecast” reports. The latest update was published yesterday.

http://www.aer.com/science-research/climate-weather/arctic-oscillation

In the meantime, I note that bryan629 beat me to it and posted the link this morning. I often look at other areas of research to get a wider view. This report is essential reading for all those following the model threads. To summarise, you’ll see that the current colder spell is attributed to the combination of impact factors including the El Nino, the MJO in phase 7 at reasonably high amplitude and the “last” stratospheric warming event – the one which started in early February and quickly petered out.  They are expecting one final pulse of energy disrupting the polar vortex later this week but after a whole winter with a high energy polar vortex it seems that we will at last be rid of it. I would suggest that this is why this week’s cold is not particularly severe and some models have back tracked somewhat on next week’s continuing cold.

The AER are very confident that the current neutral Arctic oscillation will be moving into a negative phase imminently (probably starting as soon as this weekend) and will stay in a strongly negative state for the foreseeable future , perhaps for 4 to 6 weeks.  They expect the stratosphere and troposphere to fully couple in a negative AO state and they say that this last happened in February 2010 (perhaps one of you fellow posters would like to dig out one or two charts for that spell and show it on this thread as an analogue for current comparisons).

They are also predicting further stratospheric warming influences starting within the next week and developing from there (this has been indicated on some of the models). They feel that this will re-enforce the negative AO state.  The PV has split and the tropospheric vortex is predicted to push down into continental Europe. They expect the impact to be substantial with low heights spilling south into Europe. They favour winds veering into the north-east. Their only caveat is that this is all occurring very late in winter but they expect the pattern to follow in a similar way to a mid-winter SSW event.

As Singularity points out, the MJO is a little mystifying. Having reached phase 7 at quite high amplitude it seems surprising that most of the models predict it’ll only be in phase 8 very briefly before returning to 0. I hope that we stay in phase 8 at decent amplitude for longer. The MJO may well have already played its part in the current major pattern changes and perhaps the other factors are now the more major driving forces in the next few weeks.

So how do we interpret this for the UK? I would suggest that we may see a very temporary weakening of this week’s colder spell early next week (probably not mild and may continue cold throughout) and then a much stronger and longer lasting cooling later next week as indicated by several of the models like on the 00z ECM run. The cold should be sourced from much further north/north-east. Most of Europe should cool significantly and a proper cold pool should finally be established.

Although the pattern of events seems similar in timing to those of March 2013 there are probably enough differences to make a repeat of that famous cold spell unlikely.  Judah Cohen prefers the February 2010 analogy. To compensate for the lengthening days and ever greater solar energy during March, we should get much colder uppers than we have seen/will see this week. The default north-east airstream could well continue to be a predominantly dry one with showers confined to windward coasts but one would expect some disturbances and perhaps several more widespread wintry outbreaks and possibly greater convectiveness given the colder uppers. We could get up to 3 or 4 weeks of this type of weather, so surely plenty of wintry opportunities. Just how cold and how snowy is, as always, very uncertain. I believe that the models will start to take greater account of these pattern changes during the next few days.

Fergie’s update yesterday was useful (always appreciated).  I see that the monthly update he refers to was probably prepared several days before some of the latest factors could be fully assessed (perhaps I’m wrong here?). The broader picture is similar though. Do they take account of the AER updates? How do they rate them?

Nothing is guaranteed and I do not wish to lead anyone to believe that this will happen exactly as I have suggested. It is simply my view on the broader pattern changes and their possible impacts. I feel that model watching will be very interesting indeed during the next couple of weeks.

[chris pawsey]

59 minutes ago, IPredictASnowStorm said:

Still showing it lol 

Love it... That's 2 days in a row now it's been showing snow for mothers day... trends... trends... it's got to be a nailed on cert! Cancelling the visit to the in-law now although I fear she may purchase snow chains for her mobility scooter I readiness on the back of this chart. Keeping my trap shut and fingers crossed

[Hotspur62]

Latest GFS in latter stages  (3rd March onwards) shows promise but it is miles away in metrological terms and it was only Sunday that things looked promising for this weekend and now it just looks cold raw and mainly dry. Time is running out for Southern Britain now and although the outlook is generally cold for next couple weeks I don't think it will be cold enough for the south. Further North I think things will be much better and wouldn't be surprised to see some appreciable snowfalls esp for those with a bit of elevation.

On a side note I saw the comments re Big Joe B and I know he has a cold bias but felt they were a little unfair.He was talking about Europe as a whole!! I read a lot of his stuff and he talks a lot of sense and on the whole his winter & snow forecasts for winter 2015-16 for CONUS have been fairly accurate. He is also big enough to admit when he is wrong so fair play to him on that.( sorry mods feel free to delete if you see fit on this last bit.       

Edited February 23, 2016 by Hotspur61
forgot to put CONUS in

[MR EXTREMES]

To little to late for southern Britain towel thrown with pure frustration.

be nice to see a march April heatwave popping up on the models.

terrible outputs to little to late pv 3-0 

id be inclined to respectfully dismiss any future wintry runs up north winter still with u for sometime yet.

as for southern England goodbye winter with not a single flake hello spring.

Edited February 23, 2016 by emotional rollercoaster

[chris55]

The outlook IMO

Cold and frosty for a few days, with some impressive night-time lows, and crisp sunny days. I do love waking up to a proper chilly morning and having to scrape the ice off the car, I know some put covers on but I actually like the scraping lol.

Then we have Fridays frontal attempt, looks unlikely at present but Western areas should keep watch as if these lows do get their act together snowfall is a real possibility.

Then we move to some strong easterly winds into the weekend, feeling bitter, and perhaps some snow showers into the east.

Beyond this the bigger picture suggests a continuation of the colder theme, the Ops may not show this perfectly just yet, but the background signal certainly favour it.

 

 

Edited February 23, 2016 by chris55

[chris55]

11 minutes ago, Smiler1709 said:

I second this mate, terrible winter and I'm really looking forward to spring, don't know what all the fuss is about with what the models are showing. All winter it feels like we have had the carrot on a string syndrome, ramped up by the cold lovers. In turn any cold we have had, has been nothing more than cool snaps with the odd frost. 

Nothing to to get excited about now either, mainly dry and cool. Just a typical set-up with the atmosphere gearing up for spring. 

less emotional posts and more facts please lads!

Personally, living in the south i'm looking forward to a few really cold nights, with frosty mornings and crisp sunny days

Tomorrow night looks colder than tonight.

[Polar Maritime]

Can we please leave personal preferences for the Moan/ramp thread and continue to discuss what the Models are showing, Thanks.

[ANYWEATHER]

13 minutes ago, Smiler1709 said:

I second this mate, terrible winter and I'm really looking forward to spring, don't know what all the fuss is about with what the models are showing. All winter it feels like we have had the carrot on a string syndrome, ramped up by the cold lovers. In turn any cold we have had, has been nothing more than cool snaps with the odd frost. 

Nothing to to get excited about now either, mainly dry and cool. Just a typical set-up with the atmosphere gearing up for spring. 

Evening, so are we writing anything wintry coming up in the synoptics And whats this with mainly dry and cool. It will feel damn cold in the airmass in the days ahead! Im really fed up with folks writing off any wintry potential at this time of year! Some of the biggest snowfalls historically have occurred at this time of year into March. Lesson.....Don't take every run of model output as gospel, models will really struggle with this scenario, anyway Ive only briefly scrolled through the gfs , not had time to look at the ecm in any detail.

[I Cumbria Marra I]

For SW Scotland, NW England and Yorkshire/Humberside there could be a little some snow about tomorrow even down to low levels inland, probably wintry mix on the coast, i reckon over 200M could get a couple of cm, i'd be happy seeing a few flakes.

 

 

 

 

 

 

 

 

 

[chicken soup]

I dont want to quote the whole post as it would take up to much room....but the post by new nember ...bring back 1962-63....was the best ive read all winter.....please post more.

[bryan629]

1 hour ago, Bring Back1962-63 said:

 

Excellent well balanced post... BB , i see once the European mainland has a covering of snow as predicted then the cold pool will grow.. regardless of March approaching...

Cohen , i think has been about 100% correct with his strat foresasts in the past 3 months , and his latest blog was like  liquid gold to read for us in our part of the world... 4 to 6 weeks of below average... strat --- trop coupling , and the prediction the cold air mass over eastern russia will begin to advect west... . Get that anywhere near us in march and spring is definately gonna be late. Clearly an indication of  reversal. 

Singularity has said on a few occasions the models will struggle with the -AO and MJO... i couldnt agree more with him , and as with you i`m thinking along the lines of the short /medium term ( a week to 10 days) Plus have you noticed how the EL-Nino is more in a modiki mode lately . 

It is going to be great fun watching how this pans out... and to the guys that did the winter forecast for Netweather.. your back laoded winter is a little later than planned , but its comming 

 

 

[nick sussex]

For those wanting an early spring the outlook holds out little hope, for those wanting a real taste of winter the outlooks okay but not great.

Theres cold about but still not the depth of cold we'd like to see, the issue is still the current lack of a proper block and any deep cold not in the right place.

Of course as you head into March things do often become much more marginal but equally we've seen some good snowfalls during that month.

The MJO update from NCEP has the following:

It is a complicated situation to assess clear, confident impacts to the U.S. at the current time as there are many players active. The ongoing El Nino base state, current MJO activity and strong higher latitude variability (persistent positive phases of the PNA and NAO) are all likely to play some role in evolution across the Pacific North America sector over the next 2-4 weeks. Lagged 200-hPa height composites based on RMM phase 7, support a tendency for anomalous troughing (ridging) across eastern (northwest) North America and below (above) average temperatures. The MJO may allow further enhanced convection farther east in the Pacific than has been the case to date in February and allow a more energized southern stream from the Pacific into the southwest CONUS, potentially undercutting the strong amplified ridge that has been in place on average for much of Febraury. Uncertainty for this scenario, however, remains high given the strong +PNA pattern currently in place.   
 

The models don't really depart from the west USA ridge and eastern USA trough and downstream this normally correlates with the displaced Azores high and lower pressure over Europe. The question is whether we'll see any proper blocking to the nw/n/ne developing or whether it will be a case of colder than average but not cold enough this late into the season to really deliver or whether we might squeeze out more interest if some blocking does appear.

I do feel the UK has been a bit unlucky here, every marginal set up seems to have always ended up on the wrong side. Still a chance that this might change but  theres not a load more time to keep coming up short.

 

 

Edited February 23, 2016 by nick sussex

[Tim Bland]

Now the Cold is in place disturbances will crop up at short notice. Tommorow Eve there is a weak trough heading south which will I've light snow for some 

 

 

[knocker]

So what's new with tonight's anomalies. In the 6-10 range not a lot. The upstream pattern that has been pretty static remains  namely Aleutian low, ridging western N. America into the Pole and old faithful N. Canada. With HP pushing north mid Atlantic and the trough just to the east of the UK the airflow over the uk is from the NW, sourced N. Canada, so periods of unsettled weather, wintry at time, with temps generally a little below average.

In the 10-15 range there are some differences. The GEFS is not that much different but the ecm strengthens the Atlantic HP into Greenland, and intensifies the trough over the UK resulting in the flow veering a little but still nw  possibly increasing the chances of dragging some colder air south. NOAA would not appear to be adverse to this idea but really takes up a position between the two.

Conclusion. No compelling reason to deviate from the scenario of periods of unsettled weather, wintry at times with possible some brief transient snow events, but interspersed with drier spells and actually quite pleasant. Temps varying a bit but generally a little below average.

 

Edited February 23, 2016 by knocker

[phil nw.]

The Warks.GEFs 850 temp and precipitation graphs

underline the rather cold but pretty dry outlook going into the first week of March.

Looking at the overall pattern as Knocker showed above essentially a repeating scenario of north westerly winds interspersed with brief ridging as low pressure drops into Europe.

As Nick S mentioned on the face of it a decent setup for cold but given the lateness in the season not cold enough for widespread snow,Indeed the lack of precipitation on many days will be another hurdle. Plenty of sharp frosts at night and some crisp sunshine though seems the more likely outcome for many of us with just some scattered wintry showers.

The pv fragment over Canada continues to be the main factor preventing lasting Atlantic ridging.At this time of year we really need a more direct Arctic northerly type of flow with Greenland heights to get the coldest possible uppers here and currently this isn't modeled.

There remains the hope as we go further into the new month that we evolve into a more -ve AO and we get one last shot at an Arctic spell but for lowland lying snow this really needs to show up soon and only the very best pattern would deliver. 

 

[damianslaw]

Reiterating what others have said, the models continue to show a protracted rather chilly spell for the time of year, nothing desperately cold, but below average all the same with some sharp frosts especially in the north and some wintry precipitation at times for some places.

PV fragment over NE Canada is scuppering the chance of blocking to the north taking a proper foothold, at least for now... there are signs from both GFS and ECM that a more significant remnant could drop into the N atlantic sinking across the UK aided by the NW-SE tracking jet by next weekend with a more pronounced build of heights to the NW thereafter heralding the development of more significant robust heights to our north, this is a long way off, but certainly has a lot of credence to it - one to watch.

In the meantime we have a trough feature moving down across the country tomorrow, a shallow disturbance which could deliver a surprise snowfall to some in the NW and Yorkshire in particular.

Weekend looking a rather cold raw affair under easterly winds, that early spring cold easterly feel...

Early next week a slight moderation of the cold, as the atlantic pushes in some rain.

 

[Dunstable Snow]

Lots of very measured and sensible posts tonight. My Cricket Club planned outdoor nets from the beginning of March at the last meeting in January. I did say at the time that I felt they were being a tad ambitious and not to be fooled by the very mild winter thus far. I will be surprised if that is a warm and pleasant experience much before the middle of April at the very earliest...

[nick sussex]

Tonights fax charts leave me with that if only the 850's to the e/ne were a bit colder feeling. Or why didn't this set up appear a few weeks ago?

 

I hope no ones got a trip planned to Iberia as it looks decidedly cold. In terms of the UK a trough shown at T120hrs, that weak occlusion could give something wintry and also the trough but we're back in marginal territory again, earlier some showers possible across the south and se. I'm beginning to detest the term "marginal"! Very hard to know whether anything white will fall from the sky. Going by the GFS dew points you'd think yes but I'm not very trusting of those. Its a wait and see. Hopefully the models can find another couple of degrees colder 850's in the coming days.

 

Edited February 23, 2016 by nick sussex

[Timmytour]

Sorry if this is slightly off the wall....

It turns out on the 6th Feb a meteorite hit the earths' atmosphere 600 miles off the coast of Brazil and exploded  unleashing an energy equivalent of 13,000 tons of TNT. This is the largest atmospheric impact recorded since the famous Chelyabinsk meteor that exploded over Russia in 2013 - which happened around the same time of year.

Can't help wondering if this had an impact upon the atmosphere and that it was soon after that the models began to show their colder outcomes with the PV distressed.  The 2013 impact was bigger....and of course therafter followed our coldest March for over 50 years.  This year it appears as if March could again be a cold one, albeit as well as the meteor explosion being smaller, we began from a much colder starting point.

I'm not saying there is a connection.... but it's an interesting consideration.  If such atmospheric explosions can send waves of impact around the world that upset existing balances and impact upon our weather, it would mean the models have got a long long way to go before they contain all the data they need to provide us with the accurate runs some demand of them  

Edited February 24, 2016 by Timmytour