Model Output Discussions 12z 01/06/2017

[phil nw.]

Good evening all.

A little late but here is a new thread for the start of the Summer Quarter.

The 12z models all show a similar theme during the next week or so with a move towards a rather changeable south westerly pattern.

A few snapshots of the 12z ECM for the next week shows an ongoing presence of low pressure to the north and west with occasional ridging further south from a somewhat suppressed Azores high.

http://www.meteociel.fr/modeles/ecmwf/runs/2017060112/ECM1-48.GIF?01-0http://www.meteociel.fr/modeles/ecmwf/runs/2017060112/ECM1-96.GIF?01-0http://www.meteociel.fr/modeles/ecmwf/runs/2017060112/ECM1-144.GIF?01-0

so as often the case in this pattern the warmest and brightest conditions will favour locations further south and east.Some showers or rain likely for many of us at times.

OK then please continue discussions below.

 

[ANYWEATHER]

Evening all ,looks like we are heading for an unsettled spell and feeling chilly too in any cloudy rainy spells. But on the other hand ,if the lows to our west stall ,then we will scope up some heat and plumes from the south so potential thunderstorm activity as emphasised from the ecm and gfs at T+144

[Steel City Skies]

1 hour ago, ANYWEATHER said:

Evening all ,looks like we are heading for an unsettled spell and feeling chilly too in any cloudy rainy spells. But on the other hand ,if the lows to our west stall ,then we will scope up some heat and plumes from the south so potential thunderstorm activity as emphasised from the ecm and gfs at T+144

Yep, good to see agreement from the GFS and ECM 12z on the plume potential later next week 

[Singularity]

As far as I see it, ECM and GFS are in the process one again of correcting downward a kick in the jet stream and so adjusting the mean ridge position west toward the UK and W. Europe having initially placed it almost in W. Asia.

For some reason whatever causes these errors in those two models seems to affect GEM less.

Things when get very interesting as an MJO pulse combines with an unusually 'wiggly jet' as part of a wavenumber-5 pattern that typically produces extremes of weather toward the western extent of ridges - which is where we might well be.

[38.7°C]

Now we're talking and summer wants to get down to business on the latest GFS 18z.  HP rising mid-June, if only that trough on the west could nudge out the way a little and we could be in 2006 territory.  Shame this is just an outlier

 

 

 

[TJS1998Tom]

18z looks very promising mid month (Weatheroutlook) Temps up to 26

[Chris.R]

So we're not writing June off any more then? I bet we'll be well above average again before mid month. 

[cheese]

20 minutes ago, Chris.R said:

So we're not writing June off any more then? I bet we'll be well above average again before mid month. 

Just wait, we'll be back to the wrist-slashing soon enough!

[Frosty.]

Hot and humid for the south-east today with max temp around 27c 81f with hazy sunshine but watch out because there will be some big thunderstorms breaking out during this afternoon and rumbling on into this evening with torrential downpours and hail..the weekend looks fresher but still warm with sunny spells and a few heavy showers.

[summer blizzard]

Euro does not suggest an overly cold pattern but low pressure firmly in charge..

 

[Summer Sun]

UKMO and ECM are a bit different this morning at t144

[carinthian]

3 minutes ago, Summer Sun said:

UKMO and ECM are a bit different this morning at t144

Yes Summer Sun, the difference still there out to 168t as shown on the extended N. Atlantic chart from the UKMO. A continental drift shown on that one. The same time chart from ECM shows a maritime flow for most. Take your pick, I know which one I prefer !

C

[stodge]

11 hours ago, Singularity said:

As far as I see it, ECM and GFS are in the process one again of correcting downward a kick in the jet stream and so adjusting the mean ridge position west toward the UK and W. Europe having initially placed it almost in W. Asia.

For some reason whatever causes these errors in those two models seems to affect GEM less.

Things when get very interesting as an MJO pulse combines with an unusually 'wiggly jet' as part of a wavenumber-5 pattern that typically produces extremes of weather toward the western extent of ridges - which is where we might well be.

Looking at the morning output, the westward correction takes the ridge more into the mid-Atlantic (the fabled Scenario B). Fans of heat wanted the ridge just to the east of the British Isles (Scenario A) being propped up from the mid-Atlantic trough. That has happened but the trough has now started to move eastward again dragging everything along with it and the eastward correction does us no favours leaving us under the trough.

FWIW (and that's not much), I do think the next correction will see us benefitting from the ridge but that may be late June/early July and that's often an optimum time for high temperatures if the synoptics are right and we can import some hot air from points south.

[claret047]

12 hours ago, Singularity said:

As far as I see it, ECM and GFS are in the process one again of correcting downward a kick in the jet stream and so adjusting the mean ridge position west toward the UK and W. Europe having initially placed it almost in W. Asia.

For some reason whatever causes these errors in those two models seems to affect GEM less.

Things when get very interesting as an MJO pulse combines with an unusually 'wiggly jet' as part of a wavenumber-5 pattern that typically produces extremes of weather toward the western extent of ridges - which is where we might well be.

Good Morning Singularity,

I read your posting above with interest, and not being that knowledgeable on the weather would be grateful if you could advise what you mean by extremes of weather. do you mean extreme heat, extreme thunderstorms, extreme drought or strong winds with conveyor belts of rain across the country?

Many thanks

Kind Regards

Dave

[carinthian]

2 hours ago, carinthian said:

Yes Summer Sun, the difference still there out to 168t as shown on the extended N. Atlantic chart from the UKMO. A continental drift shown on that one. The same time chart from ECM shows a maritime flow for most. Take your pick, I know which one I prefer !

C

The latest UKMO update seems reasonably confident that the end of next week to turn warm for most and even very warm for the Southeast with the Northwest getting the more unsettled /rainy conditions, but even here temps well up to average.

 C

[Singularity]

1 hour ago, claret047 said:

Good Morning Singularity,

I read your posting above with interest, and not being that knowledgeable on the weather would be grateful if you could advise what you mean by extremes of weather. do you mean extreme heat, extreme thunderstorms, extreme drought or strong winds with conveyor belts of rain across the country?

Many thanks

Kind Regards

Dave

Hello 

I was deliberately unspecific there; extreme heat, thunderstorms/excessive rainfall and strong winds are all possible outcomes with such a setup. Drought would however require the pattern to adjust further west than looks likely at this time and even then it would take many weeks of persistently dry, often hot weather to produce one.

This morning I am shocked at the sheer strength of the low being modelled to cross the Atlantic days 8-10. 

 

This currently looks to be an over 2-sigma event i.e. more than two standard deviations outside of the 'norm' i.e. very unusual indeed.

Such large and powerful storms have the ability to shift the longwave pattern against the backgroud signals which is worrying as that typically means eastward of what would otherwise occur. The remnants of the B-name Atlantic tropical cyclone in Aug 2014 had this effect and led to a cool showery month instead of a warm, sometimes thundery one as was looking likely to be the case otherwise.

I sincerely hope the packet of energy that fuels this major storm does not manage to journey across so smoothly and instead gets involved with some developments along the way that lower the remaining potential energy for LP development.

Ireland's tree population would not fare too well if this came to pass  - good thing it's still over a week away with plenty of time for changes!

[Singularity]

5 minutes ago, carinthian said:

The latest UKMO update seems reasonably confident that the end of next week to turn warm for most and even very warm for the Southeast with the Northwest getting the more unsettled /rainy conditions, but even here temps well up to average.

 C

Following my post just how - this is encouraging from UKMO as the big trough off the U.S. is clearly slower with a more amplified jet stream ahead of it.

UKMO was second only to GEM in spotting the more settled outcome for last week.

GEM is now rather explosive-looking for Thu though, and barely gets the next Euro ridge set up before breaking it down:

   

...but again, this is all far enough out in time for much adjustment to potentially occur  

[Frosty.]

As far as temperatures are concerned, no complaints from me as the seasonal ( longer range ) models, GloSea5 etc must be indicating above average to very warm and even hot at times, especially further south so I'm happy with the latest update.

[carinthian]

It now looks like the formation of heat low over Paris Basin. This will move into the North Sea ahead of the cold front pushing into Central Eastern England now. As I mentioned on Tuesday a delay of this clearance to fresher air mass will now be delayed until later tomorrow in the SE . The cyclostomous  development ( flabby low ) will open the isobars across Eastern and Central areas of the England with some thundery rain down East Coastal Regions for a while longer before clearance to maritime airmass takes over. Looking to Monday a storm brewing heralding a windy start to next week before pressure rises again in the south bring warmth to end the week. Good weather viewing to be had . A bit for everyone.

 C

[carinthian]

2 hours ago, carinthian said:

It now looks like the formation of heat low over Paris Basin. This will move into the North Sea ahead of the cold front pushing into Central Eastern England now. As I mentioned on Tuesday a delay of this clearance to fresher air mass will now be delayed until later tomorrow in the SE . The cyclostomous  development ( flabby low ) will open the isobars across Eastern and Central areas of the England with some thundery rain down East Coastal Regions for a while longer before clearance to maritime airmass takes over. Looking to Monday a storm brewing heralding a windy start to next week before pressure rises again in the south bring warmth to end the week. Good weather viewing to be had . A bit for everyone.

 C

Its just great now watching how the synopitcs are evolving from hour to hour. Our so called flabby low ( cyclostomous formation ) seems to be centred now over the Thames Estuary. Note how this has the effect of creating a slacking of the pressure gradient over the British Isles and retaining some potential energy in the atmosphere, especially SE parts. Wish I could have access to the mid-day East Sussex sounding  to view any potential convectional energy. Still think the SE will stay in the warmth for much of tomorrow  with added rain threat for Eastern coastal regions. Cooler maritime air mass now being deflected into NW France with warmth advecting into SE Britain as I type.

C

[wimblettben]

3 hours ago, Frosty. said:

As far as temperatures are concerned, no complaints from me as the seasonal ( longer range ) models, GloSea5 etc must be indicating above average to very warm and even hot at times, especially further south so I'm happy with the latest update.

I think above average temperatures alone are not enough for most heat summer lovers though.

They want it to be dry too otherwise not much chance of staying dry doing outdoor activities!

[Summer Sun]

Later next week UKMO shows the chance of some warm air drifting up from mainland Europe

[Steel City Skies]

19 minutes ago, Summer Sun said:

Later next week UKMO shows the chance of some warm air drifting up from mainland Europe

GFS 12z once again toying with the idea of stalling low pressure to the SW temporarily drawing up some hot and humid air for southern and eastern areas. Could be a recurring theme for the first part of this summer?

[mb018538]

Looks like into next weekend things may get a bit wild! Finer details to come, but the recurring theme of a very deep low spinning up is one worth watching for sure.

[weatherguru14]

3 hours ago, Frosty. said:

The Gfs 6z shows the uk weather changing gear next week, becoming more atlantic driven, especially for the n / w with the s / se having occasional fine and warmer spells but really it looks like an increasingly changeable / unsettled few weeks ahead.

 

shame these charts  are for the first month of the summer aint it?? seems always the case.