Model Output Discussions 12z 03/05/2016

[Matthew.]

The ECM 12z looks more encouraging longer term which pressure less high over Greenland on Day 10. Hopefully it will continue in this vein and not follow the GFS trend

[northwestsnow]

20 minutes ago, Matthew Wilson said:

The ECM 12z looks more encouraging longer term which pressure less high over Greenland on Day 10. Hopefully it will continue in this vein and not follow the GFS trend

Its much better than gfs but the Atlantic looks incredibly strong - really would like to see a bit of a slow down in that regard!

[knocker]

Really not much difference to the GEFS anomalies to previous runs with the upper trough over the UK declining from around the 18th which briefly allows ridging from the Azores which soon gives way to a westerly flow with a trough to the NW. Ergo back to unsettled weather from the west which maybe more relevant to the NW with the south prone to the better weather/ As maybe suggested by the ecm ops.

Edited June 9, 2016 by knocker

[Cloud 10]

5 hours ago, Singularity said:

Found the GWO plot;

It's crunch time! The model has to be plain wrong for us to escape La-Nina territory, which seems a bit of a stretch, but whether we stay in that region or see a recovery through 3/4/5, that is the question.

The way the op runs keep bringing lows in from the northwest is based on the assumption that GLAAM will plummet, then plummet some more. Off the scale, in fact. Not even the biggest positive El Nino-driven AAM boosts of the past winter were able to get it off the scale on this plot.

Tomorrow's update is greatly anticipated - will we enter negative AAM territory and if so, by how much? The outcome will be very telling!

 

Does look almost certain that AAM will fall off the cliff (finally) over the next 2 weeks.

 

 

In the meantime a more generally unsettled weekend coming up,and if the first front doesn't get you,one of the other four will!

 

[Matthew.]

13 minutes ago, northwestsnow said:

Its much better than gfs but the Atlantic looks incredibly strong - really would like to see a bit of a slow down in that regard!

Yes a slowdown in the Jet certainly needs to happen if that Azores High is going to envelop the Uk. As Knocker said the 18th may turn out reasonable but for how long? It does'nt look sustainable at the moment as he said 'a brief ridge'

[knocker]

Matthew the jet doesn't dictate the pressure distribution, rather the other way around.

[Matthew.]

1 minute ago, knocker said:

Matthew the jet doesn't dictate the pressure distribution, rather the other way around.

Thankyou for your help. I have much to learn. I'll read up on that

[Frosty.]

The end of the Ecm 12z is more agreeable with a ridge of high pressure building in and high pressure just to the south of the UK at T+240 with warmer air...+10 T850s across the south. Backing up a little bit, most of next week we are under the influence of a showery trough but it does slowly fill more or less in situ with rather better weather to close out next week. It's not a washout by any means, there will be some sunshine to enjoy but also clusters of heavy and thundery showers...could be worse!

[knocker]

9 minutes ago, Matthew Wilson said:

Thankyou for your help. I have much to learn. I'll read up on that

There was a discussion here that might help. It is quite a complicated subject.

https://www.netweather.tv/forum/topic/84150-jet-stream-question/

 

[Frosty.]

23 minutes ago, Matthew Wilson said:

Thankyou for your help. I have much to learn. I'll read up on that

Yes knocker is an expert, like John Holmes, ex met man, old school with weather balloons, he's taught me a few things too over the years....or I like to think I've picked things up from the more senior members.

[knocker]

5 minutes ago, Frosty. said:

Yes knocker is an expert, like John Holmes, ex met man, old school with weather balloons, he's taught me a few things too over the years....or I like to think I've picked things up from the more senior members.

Whoa I'm not an expert like John and would never claim to be Frosty. John was a seniot forecaster for many years and I was just one of the jobbing gardeners who supplied the information so he could cock the forecast up.

Edited June 9, 2016 by knocker

[Frosty.]

17 minutes ago, knocker said:

Whoa I'm not an expert like John and would never claim to be Frosty. John was a seniot forecaster for many years and I was just one of the jobbing gardeners who supplied the information so he could cock the forecast up.

Whoa you are so modest knocker

I look up to you as an expert, keep up the great work!

Edited June 9, 2016 by Frosty.

[Singularity]

5 hours ago, knocker said:

As a matter of interest In what way will it be telling? As an analog for 2010 which is something Michael Ventrice seems to pondering?

Oh, I was just saying so with respect to how GEFS handles GLAAM compared to what we actually see - but a 2010 analogue is an interesting idea. If I get some time I'll give that a bit of thinking time.

1 hour ago, Cloud 10 said:

Does look almost certain that AAM will fall off the cliff (finally) over the next 2 weeks.

Well actually, GEFS has a large bias toward establishing a La Nina base state sooner and more dramatically than is generally considered possible. Even if the atmosphere coupled to the ocean right away, the SST anomaly configuration is not yet even close to supporting such a sudden transition. Tamara contacted me this afternoon to remind me of just that, after I forgot to re-iterate the point in my earlier post (whereas I've been saying about the GEFS bias for some time now; it shocks me how bad it is!).

As far as I know (which is not a lot due to limited data access), ECM has a better handle on such things but is still far from perfect.

Anyway, the bottom line is, there is likely an underestimation by the longer-range GFS/GEFS of the ability of the Azores High to build back into NW Europe within the final 5-10 days of June, and with any luck affect at least the south of the UK. ECM ensembles seem to be doing a better job with that, based on Knocker's much appreciated updates on this forum.

[Nouska]

1 hour ago, Cloud 10 said:

 

Does look almost certain that AAM will fall off the cliff (finally) over the next 2 weeks.

 

 

In the meantime a more generally unsettled weekend coming up,and if the first front doesn't get you,one of the other four will!

 

 

James inadvertently showed a plot from the last day of May but it does highlight how the forecast fall has been postponed over the last week - is it finally going to drop like a stone now? The full ensemble suite in good agreement but have been likewise for just over a week.

Dr Ventrice's suggestion of a 2010 analogue is an interesting one as it is a better fit than '98 where the upper atmosphere did not get the jolt of a dramatic early final warming and the Arctic ice was in a healthier position. Although 2010 saw a rapid swing to Nina conditions in mid summer, the basin profiles are quite different this year. Tropical Atlantic was like a bath tub and the current very positive PDO was not in evidence.

     

If I remember correctly, 2010 was not a record breaker for ice loss in area but it made news in that the volume of ice saw very big losses. Another year with a very distorted summer jet profile.

[Hathers]

Love the Model output discussions. Been following it for years. Thanks for everyone's input. Learnt so much from this thread.

Back to model discussion.

[knocker]

The ecm and NOAA are more or less still in agreement out to day 14. The ecm has the transition of the upper trough weakening and  the transitional Azores ridge being briefly influential around the 18th. It's not that obvious on the NOAA as they are five day means but you note the difference between the two. The 8-14 has little anomalous on it which ties in with the 10-15 EPS which indicates a westerly flow with a weak trough to the NW which has been mentioned in a previous post. In a nutshell not a great of relief in the latter stages from westerly unsettled with probably the north copping the worst of the weather.

[William of Walworth]

Thankyou for all the updates everybody. I've been avoiding NW since Tuesday for sanity reasons.

 

But then, when the medium-term synoptic output for the rest of June was looking VERY Low dominated for the UK, I was (as a summer lover) both pessimistic and sceptical.

 

Sceptical that next week's Low and Atlantic domination could really end up as extreme as some of Tuesday's outputs (and posts!) were suggesting. And pessimistic that prospects might get even less capable of High influence than Tuesday's models ....

 

More recent output looks to me somewhat more realistic for late June. Today's output (generally) does look like it might leave leave open the door for something of an HP build, or at least influence,  from the SW at or after next weekend (of Sat 18th). And closer to reliable timeframe, less of a continuous all-UK washout over the coming week, too.

 

Normal not-too-bad June returns???.

Edited June 9, 2016 by William of Walworth

[Frosty.]

9 minutes ago, William of Walworth said:

Thankyou for all the updates everybody. I've been avoiding NW since Tuesday for sanity reasons.

 

But then, when the medium-term synoptic output for the rest of June was looking VERY Low dominated for the UK, I was (as a summer lover) both pessimistic and sceptical.

 

Sceptical that next week's Low and Atlantic domination could really end up as extreme as some of Tuesday's outputs (and posts!) were suggesting. And pessimistic that prospects might get even less capable of High influence than Tuesday's models ....

 

More recent output looks to me somewhat more realistic for late June. Today's output (generally) does look like it might leave leave open the door for something of an HP build, or at least influence,  from the SW at or after next weekend (of Sat 18th). And closer to reliable timeframe, less of a continuous all-UK washout over the coming week, too.

 

Normal not-too-bad June returns???.

I'm not seeing a washout William, it just looks like a showery trough next week, typical sunshine and heavy showers with thunder.

[Frosty.]

Anyone still awake?

The Gfs 18z shows a  trough drifting over the UK from the west early next week with a mixture of sunny spells and heavy showers with thunderstorms around too. As for temps, pleasant enough in the sunshine but feeling cool under the showers and longer spells of rain..as I said before, it's not a washout, it's a showery outlook next week.

[William of Walworth]

I'm still around albeit about to go.. Fervantly fkeeping fingers crossed here that beyond what you've posted above Frosty, the propects at/after next weekend become less Low-themed. We'll need a good few more days' output  for that to become clearer though.

 

Agreed though, that from those snapshots,  prospects for next week could be looking less full-on washouty than some models back on Tuesday seemed to be suggesting.

Edited June 9, 2016 by William of Walworth

[Cheshire Freeze]

1 hour ago, William of Walworth said:

I'm still around albeit about to go.. Fervantly fkeeping fingers crossed here that beyond what you've posted above Frosty, the propects at/after next weekend become less Low-themed. We'll need a good few more days' output  for that to become clearer though.

 

Agreed though, that from those snapshots,  prospects for next week could be looking less full-on washouty than some models back on Tuesday seemed to be suggesting.

Taking those GFS charts at face value, it'd be more than a washout in some places with slow moving torrential storms with hail. Spoke to W09 earlier and he agreed that the 18z GFS would put us at risk of seeing some very lively weather with the potential for tornadoes in places. Slack LP with steep lapse rates, cold air aloft and peak solar heating at this time of year.....you get the picture. Get caught in any convergence type set up in that scenario and you could be sat under a torrent of rain and hail for hours potentially....about as unstable as you can get without a plume type scenario in summer.

Edited June 10, 2016 by CreweCold

[knocker]

A look at the latest EC32 means update

I’ll look a bit earlier than usual as next week is of some interest but keep in mind this isn’t the detail which will no doubt be of more interest.

Monday finds us with upper low pressure centres NE North America, mid Atlantic and the Baltic States. In essence regarding the surface low pressure dominating from Canada east to the whole of NW Europe. Ug.

But very rapidly a ridge forms mid Atlantic so by 12z Wednesday there is a deep upper low centred over SE England with temps a little below average but some quite cold air not far away over Spain.

But if nothing else the pattern is very mobile and by the 19th the upper trough has decayed to be replaced by a short lived Azores ridge. Short lived because this rapidly becomes a westerly regime with a trough to the NW which is likely to bring a N/S split weatherwise over the UK.

After this brief period things settle down a tad and the indications are (and remember this just the means not the full suite) that the Azores HP will increasingly be more influential all the way through to the middle of July.

This morning’s GFS

The chart for mid week which looks as if it might be of interest after brief ridging over the weekend this.

[Frosty.]

5 hours ago, CreweCold said:

Taking those GFS charts at face value, it'd be more than a washout in some places with slow moving torrential storms with hail. Spoke to W09 earlier and he agreed that the 18z GFS would put us at risk of seeing some very lively weather with the potential for tornadoes in places. Slack LP with steep lapse rates, cold air aloft and peak solar heating at this time of year.....you get the picture. Get caught in any convergence type set up in that scenario and you could be sat under a torrent of rain and hail for hours potentially....about as unstable as you can get without a plume type scenario in summer.

My definition of a washout must be different to yours, I regard a washout as being fronts stalling and many hours of persistent heavy rain rather than the sunshine and showers outlook that I'm seeing.some areas could miss most of the showers and have a pleasant week, the 18z showed southern coastal counties looking rather good.

[Frosty.]

Looking at the next few days, it's no washout, there will be some pleasantly warm sunny spells with scattered heavy showers breaking out today and on saturday but parts of the south and southeast could get away with a largely fine day today and tomorrow although temps are dropping a little, low 20s c today and nearer 19 / 20c tomorrow. Sunday indicates more chance of rain with bands of showers working from southwest to northeast but still with sunshine between. Next week is trough dominated with sunny periods and heavy showers with hail and thunderstorms but the very nature of showers means some areas could miss them and wonder what all the fuss is about and even the areas which have more showers will still have spells of sunshine to dry things up so it's not a complete washout by any means.

[mb018538]

Looks like the weak ridge thrown up towards the end of next week won't amount to a great deal, and things will flatten out again after. I'd say the pressure pattern is more favourable than it is now though, so perhaps later in the month the tide will turn.