Model Output Discussions 12z 01/06/2017

[chapmanslade]

2 hours ago, 40*C said:

Radio Key 103 said earlier that there is no more dry, sunny weather expected for at least a month!
GFS has come in with a much wetter end to the week than other solutions, the seemingly stubborn upper trough refusing to budge and allowing another low to get caught up in it.    

        
 

With the greatest respect which learned meteorologist do Radio Key 103 employ ?

Further to my post this morning, 12 hours later the ECM is showing a warmer more humid but still unsettled route for the coming week as alluded to by Frosty, just emphasising that the op runs mean very little post 5 days. Look at the ensemble spread on the GFS (the one we have easy access to). When the bunched lines turn into spaghetti around day 5 what follows is largely noise until it picks up on the next significant event. Whilst posting what these runs show after day 5 is factually correct it is usually a pretty futile exercise in predicting what the weather will do. A long time ago I thought it would make sense if the model charts got more and more blurred as they go forward so they just show general themes rather than detail. The fact that they show the same level of detail for 10 days time as today just encourages folks to give them equal credence.

[Cheshire Freeze]

19 minutes ago, chapmanslade said:

A long time ago I thought it would make sense if the model charts got more and more blurred as they go forward so they just show general themes rather than detail. The fact that they show the same level of detail for 10 days time as today just encourages folks to give them equal credence.

You've just described the SLP ensemble mean, surely?

[knocker]

29 minutes ago, chapmanslade said:

With the greatest respect which learned meteorologist do Radio Key 103 employ ?

Further to my post this morning, 12 hours later the ECM is showing a warmer more humid but still unsettled route for the coming week as alluded to by Frosty, just emphasising that the op runs mean very little post 5 days. Look at the ensemble spread on the GFS (the one we have easy access to). When the bunched lines turn into spaghetti around day 5 what follows is largely noise until it picks up on the next significant event. Whilst posting what these runs show after day 5 is factually correct it is usually a pretty futile exercise in predicting what the weather will do. A long time ago I thought it would make sense if the model charts got more and more blurred as they go forward so they just show general themes rather than detail. The fact that they show the same level of detail for 10 days time as today just encourages folks to give them equal credence.

Warmer is subjective and a pretty useless word in meteorology unless related to something specific.. So to be more precise the ecm temps for next week.

Sunday  Generally a little below average, perhaps a little above near the south coast

Monday  southern half of Britain above the rest below.

Tuesday Below average

Wednesday  Below average, significantly so in Scotland

Thursday Below average particularly in the south

Friday  Generally below but slightly above in the north of England.

Saturday Generally below average but around average in the south.

Edited June 23, 2017 by knocker

[Frosty.]

Tuesday below average? The Ecm 12z indicates mid 20's celsius for southern uk on tuesday.

[knocker]

8 minutes ago, Frosty. said:

Tuesday below average? The Ecm 12z indicates mid 20's celsius for southern uk on tuesday.

Actually it doesn't. Generally around 19-20C in the south east with 22C in Sussex with the rest of the country ranging from 12C-18C. Thus Kent and Sussex slightly above average with the rest of Britain below

Edited June 23, 2017 by knocker

[knocker]

Nothing particularly surprising about this morning's gfs output.

The fairly deep low currently around the Faeroes will fill and track SE to southern Norway over the weekend so the weather not that clever in the north and even gales in norther Scotland. So briefly on to next week.

The next upper trough tracks quickly in from the west, phases with the low in the vicinity of Portugal, and by Tuesday midday is orientated just the west and south west of the UK. This spawns a complex surface low pressure area covering western Europe from Scotland down which in turn introduces a showery regime over the UK with temps around average perhaps a little above in England.

From this point some amplification occurs with the Azores ridging north in mid Atlantic which realigns the very strong jet (for June) and slows down the pattern west-east movement and thus the low pressure area over the UK continues to be influential as it drifts only slowly east.

The result being the the UK remains in a showery regime but temps still around average, briefly below, as the SW veers N then NE. From this point he ridge is battered down by the next trough tracking north east and the associated fronts are over Ireland by 12z Saturday.

[mb018538]

Perhaps getting slightly better heading out of the first weekend in July?

Ben Rich mentioned some jet amplification last night, and while it's hardly a garden of roses, there is some scope for improvement this morning:



Either way, it's going to be a slow old process. Expect nothing in the way of summer-like weather until well into the first week of July, that's the reality of all of this!

[knocker]

Ecm temp anomaly and contour

[richep]

Hopefully an improvement as we head into July, what with the airshow season and  festival season getting underway , don't want this current weather to continue. Going to go with the metoffice who signal a change to better week 2 of July onwards 

[Captain Shortwave]

Well good agreement on a very unsettled week ahead, though perhaps improving by next weekend as heights lower further to our north and the pattern tends to flatten out to a more normal westerly pattern with temperatures returning to near normal after a cool and rather wet week.

      

GEFs in agreement with this, looking longer term, the GEFs do tend to develop a ridge to our east though at the moment we are under the influence of low pressure to our north west with a west to south west flow.

      

Temperatures do seem to recover to a little above normal which would produce warm or very warm weather at times, no signs of a settled spell on the horizon though that can change.

[Summer Sun]

Uncertainties going into Tuesday for some potentially heavy rain and where it will position its self

NMM has the bulk of it in Scotland by 2am

GFS has it extending much further south

[Singularity]

We have seen a little backing off by the models with respect to the retraction of the Azores High west - much as was to be expected given atmospheric response to attempts to force a La Nina-like state proving less than enthusiastic in recent days.

So far though, this is only enough to significantly improve prospects for the far S/SE and even here it remains changeable.

So more movement away from suppressing the Azores High's attempts to ridge into the UK is needed. With a bit of luck we might get there pretty soon into July but unfortunately up to 10 days in also remains within the range of possibilities.

[johnholmes]

I think an objective acceptance of a fairly unsettled 7-14 days is the most likely outcome. Beyond that I have not enough depth of knowledge to give any guidance.

Yes, the anomaly charts are what I use for the above comment. They can be wrong just as any model output can but not very often and even less so if all 3 are showing a similar outcome and all 3 are doing so consistently over a number of days.

I spend time with each output and make a summary each day and this was my note in the file this morning.

Saturday 24 June and there is no sign of any major change on any of the 3 models=westerly unsettled type in general out day 14 at least!

The links are below

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Some 'slight' signal for rising heights west of Iberia

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

again re the above, NOAA is similar, but shows little sign of this on the 8-14 day chart.

Just a very slight idea to watch perhaps?

[Singularity]

It's all about that slight signal as this is an emerged feature and it becomes a question as to whether this will continue to develop as more ensembles come around and/or ridges are made stronger/more expansive, or go no further than what we've been presented with this morning.

Also worth bearing in mind that 'average' 500 mb heights are typically associated with conditions being more settled than not at this time of  year (as in, 2 days fine, 1 day not - that sort of thing).

[chapmanslade]

19 hours ago, CreweCold said:

You've just described the SLP ensemble mean, surely?

Ahh but the op runs show the same detail start to finish which is what a lot of people quote. Perhaps if the op runs increasingly merged into the ensemble mean with time from T0 then that would work ?

19 hours ago, knocker said:

Warmer is subjective and a pretty useless word in meteorology unless related to something specific..

 

Warmer in the context of my post was warmer than the run earlier in the day so therefore entirely appropriate

[CK1981]

Looking quite warm for the next few days in the south. According to the latest GFS run, mid twenties possible up to Wednesday. Not too shabby really!

[Summer Sun]

58 minutes ago, CK1981 said:

Looking quite warm for the next few days in the south. According to the latest GFS run, mid twenties possible up to Wednesday. Not too shabby really!

Aye maybe some thundery rain on Tuesday with the burst of warmth in the SE?

[CK1981]

10 minutes ago, Summer Sun said:

Aye maybe some thundery rain on Tuesday with the burst of warmth in the SE?

Sounds good! Here in Berkshire, we've not had any rain for almost 3 weeks.

[knocker]

No significant change with the ecm this evening

[Frosty.]

Definitely some warmth and humidity around next week on the Ecm 12z, especially further south and in any sunshine which would really boost the temperatures. It looks generally unsettled with spells of heavy rain and a risk of thunder but in any dry sunny periods it would feel very nice.

Edited June 24, 2017 by Frosty.

[CK1981]

41 minutes ago, Frosty. said:

Definitely some warmth and humidity around next week on the Ecm 12z, especially further south and in any sunshine which would really boost the temperatures. It looks generally unsettled with spells of heavy rain and a risk of thunder but in any dry sunny periods it would feel very nice.

Might only be a short cooler and unsettled spell for the south, Frosty 

[knocker]

Nothing significantly different regarding the GEFs and EPS anomalies this evening.

Still with ridging over NW Canada and low pressure northern Greenland with associated trough dominating the NW Atlantic and south down through the UK.With little northern movement of the Azores high the upper flow, and slightly weaker jet, has backed a tad more westerly, Thus a continuation of changeable weather over the UK with temps generally a little below average Nothing hugely different in the ext period.

[Frosty.]

Longer term the GEFS 12z mean indicates an improvement across southern uk as the azores high ridges towards the south with more in the way of fine pleasantly warm spells, staying generally unsettled further north..so, following an unsettled spell for all areas next week there are hints of better times not too far into July and hopefully we will then see a marked change to summery weather from the south as the met office continue to describe in their daily updates.

[knocker]

The long wave pattern continue to be consistently somewhat uninviting  so we are left to find some rays of sunshine with the evolution of the det. runs so on to this morning's gfs.

By now I would imagine everyone is familiar with the sequence of events this week. By 12z Tuesday the upper trough is orientated W/SW of the UK and a complex area of unstable  low pressure is in situ over the latter producing a showery regime with the possibility of some heavy downpours, Temps around average but a fair bit of geographic variability ranging from 10C in northern Scotland to 21C in the south of England.

Over the next 48 hours the amplification that has been signaled for some time occurs with the Azores ridging in mid Atlantic and the upper low becoming more organized, ditto the surface low pressure, and situated over the western approaches. Resulting in the strong west-east jet being displaced and the pattern movement east slowed. Thus by 12z Thursday we have the centre of one low over Cleethorpes, still a showery regime and temps a little below average but still geographically variable with 13-15C in the north and 18-20C in the south east.

From this point it is a familiar story of the Azores ridging against the energy/troughs tracking in from upstream resulting pretty much the perennial N/S split although temps for the weekend slightly below average, All in all pretty changeable fayre with nothing sinister lurking in the woodshed

 

Edited June 25, 2017 by knocker

[knocker]

The ecm not dissimilar to the gfs with low pressure in situ Tuesday through to 12z Friday thus sunshine and showers, perhaps heavy in places, before transient ridging NE before the next low tracks east north of the UK suppressing the ridge over the weekend and introducing a north westerly flow.

Temps no great shakes but not too bad

Monday 13-16C in the north 18-22C in the south perhaps 23C in the London area

Tuesday 12C-18C in the North 18-22c in the south.

Wednesday generally a cool day, particularly in the north and midlands where temps are in the 12-14C range

Thursday another generally cool day with temps ranging from 11-17C but 18-19C in the SE.

Friday generally around average, perhaps a little above in places, ranging from 18-21C in England and 14-16C in Scotland.

 

Edited June 25, 2017 by knocker