Model Output Discussion - Spring Has Sprung

[Addicks Fan 1981]

 Scorcher which was highlighted by the GEFS 6Z ensemble mean which i thought was also very close to the NOAA 8-14 dayer which i have just shared above. 

i never ignore anomoly charts and always look at them for good and for bad, very similar approach to @mushymanrobactually.   

Its not going to be plain sailing though and i expect some twists and turns as the days progress.    

[WYorksWeather]

 Scorcher Quite correct - in fact latest GFS has above average temperatures persisting in both Newcastle and London (to prove it's not a location thing) right until the end of the run. Albeit more unsettled by the end but if it is westerly or south-westerly then with above average 850hPa temperatures it's still going to be a warm period overall. We're looking at a setup here that could well lead to a notably warm May.

And worth noting that there's an increasing number of very warm runs again - always worth keeping an eye on those 10-15C 850hPa runs. They may disappear again but it always seems to happen these days that at some point they build in support and verify - whether it will happen this month or not, of course, remains uncertain.

For the shorter term, UKV looks fairly promising over the next 5 days.

Increasingly widespread warmth through the next few days - tomorrow for central areas, Tuesday for more southern and western areas, and Wednesday through Friday sees increasingly widespread warmth almost everywhere away from NW England and parts of Scotland.

 

 

[Penrith Snow]

It's good and bad news from thismornings GFS.

The bad news is that the middle of next week is a washout with low pressure over southern UK and some high rainfall totals, however, beyond that a Scandy High develops bringing very warm south easterlies with temperatures in the upper twenties.

However, the high rainfall totals next week are a  concern.

Andy

[LetItSnow!]

GFS left, ECM right. Subtle differences but both looking unsettled by early next week with weakenign pressure. GFS would probably be very wet with areas of rain and thunderstorms meanwhile the ECM would be more frontal rainfall. Details of this type are not worth looking at 8 days ahead of time. The GFS has more of a well defined high up into the Barents Sea leading to more of an undercut. The ECM has more of a general area of low pressure that crashes into Scandinavia which we get pulled into.

In terms of the ensembles, the pattern differences also show up. The GFS may be hinting at some members taking that undercut and stalling it so don't be surprised if some very warm, humid and thundery runs show up around the 13th-16th time frame. The ECM ensmbles look cooler though with much less of a Scandi high signal and look a bit more blocked.

A lot to be resolved but one thing looks clear, it's probably going to turn more unsettled early next week with rain and maybe even some thunder, but whether it's due to a battleground/heat pump scenario, or cooler with low pressure around, it's yet to be solved. No extremes in temperatures either way being shown at the moment but a lack of cold nights and generally mild/warm days mean that it will likely be a period of unexceptionally above temperatures for the forseeable.

Edited May 6 by LetItSnow!

[Alderc 2.0]

 Penrith Snow Upper 20’s? 

[Alderc 2.0]

Looks like we’ll get 4-5days of reasonable weather (assuming the GFS surface charts are wrong everyday this week as it has showers and clouds persisting) before high pressure starts melting away at some point through the weekend (probably first thing Saturday as the weekend will no doubt be ruined) but it’s no compensation for what we’ve had to endure in recent times. I am concerned already about the tough that is potentially aiming for the south west as it’s always a pattern that has a habit of stalling and not lifting out for a good 7-14days due to the blocking that wedges the trough over us. 

[Scorcher]

 Alderc 2.0 The GFS has really flipped this morning in terms of its temperature predictions at the surface for Wednesday to Friday- seems quite strange to me to be honest. 

It's showing max temps 2 or 3C lower here than it was yesterday which seems odd as not a lot has changed on the pressure charts for midweek onwards.

Looking at the Fax charts for the week ahead the UK is pretty much clear of weather fronts all week (apart from northern Scotland at times). 

 

[Scorcher]

The Met Office website (notoriously Conservative with temperatures a few days out) is showing 22C for this area on Friday, meanwhile the GFS comes up with this:

Comical really in that setup. Something has to give.

[Howie]

I really hope we don't go unsettled again, I can't take anymore of it!

[LetItSnow!]

 Scorcher I checked and the precipitation charts show a big blob of rain over Scotland early in the day for some reason and into northern England so is it picking up a weather front grazing the top of the high, limiting temperature via cloud cover? Seems unusual. I would have expected decent thickness, uppers between 6-8C and strong May sun with light winds to give widespread 20-25C maxima.

[WinterOf47]

 Howie I think if it does revert to unsettled, there will be a strong market for used dinghies in Kent.

Here in coastal Sussex we had 1 good day this weekend. It feels like the weather has been mostly awful for 7 months now.

It also seems like the models just can’t seem to agree more than a few days out. 

Edited May 6 by WinterOf47

[Scorcher]

 LetItSnow! The fax charts are clear though and I find them a good indicator of whether there will be weather fronts at play.

And the Met Office definitely aren't on board with the GFS this morning. Looks great from midweek onwards on my local forecast.

[Alderc 2.0]

 LetItSnow!  ECM has that big blob of rain over Scotland too - it also has showers and mostly cloudy conditions all week like GFS. The surface charts from GFS and ECM have hardly deviated away from this pattern of a cloudy, flimsy high it’s only really been the UKV going gung-ho on the temps. 

[Addicks Fan 1981]

 Alderc 2.0 what do the ensemble means indicate this morning?   

[Howie]

 WinterOf47

It's been awful since last July

[northwestsnow]

A decent week ahead for many but by day 9/10 the EC mean backs the det

at least we have some respite this week from what has been an absolutely horrific 6 months locally.

 

Edited May 6 by northwestsnow

[Addicks Fan 1981]

 LetItSnow! if I am being truthful here at this stage i would trust the GFS 6Z and the GEFS 6Z ensemble mean.   Think ECMWF are not consistent currently and toying with us with signals.  

Edited May 6 by Addicks Fan 1981

[Alderc 2.0]

 Addicks Fan 1981 I generally don't like using the mean charts especially if there are outliers as skews the means badly however this mornings GFS 00Z has a reasonably tightly packed ensemble grouping depicting as a trough centred between the Brest peninsular and Cornwall and Devon for at least a week - as I maintain always a tough pattern to lift out.  

[Uncle_Barty]

 Alderc 2.0  I agree, which is why I never look at means.... it's like mixing several different colours of paint and ending up with a grey mush.

I much prefer to look at the clusters which tell us a lot more.

[Uncle_Barty]

 WYorksWeather  I think too quick and strong a final warming increases the likelihood of high latitude blocking... the occurance of which rarely produces a decent outcome in our part of the world for early summer patterns.

[Rain All Night]

23 hours ago, Rain All Night said:

0z ensemble means, out to Mon 20 May (day 15)

ECM has dropped its aggressive Atlantic troughing solutions of yesterday morning and has moved towards to the GEFS, which shows a shallow trough transferring from the Atlantic to the south of the UK for the week beginning Mon 13th May. This will presumably bring some unsettled conditions to my vicinity.

Beyond mid-May, though the means are heavily blurred, a couple of themes consistent between the models are the jet stream preferring a southerly track, and Atlantic high expansion remaining on the table.

0z deterministic runs, on Sun 12 May (day 7)

The settled regime looks as though it should survive through to the end of next weekend, with the chances of this appearing greater towards the southeast.

0z ensemble means, out to Tue 21 May (day 15)

The ECM ensemble has by now established itself as the designated pessimist for the middle third of May.

This GEFS ensemble mean suggests to me that some member runs are offering some rather warm (if not entirely dry) conditions.

0z deterministic runs, on Mon 13 May (day 7)

An interesting selection. ECM really is keen to blow up an Atlantic trough. But UKMO offers an extension of settled and warm conditions for many as the next working week begins.

[*Stormforce~beka*]

 Alderc 2.0 Not happening ..

[damianslaw]

In the short term, the ridge set to build tomorrow does appear to be a rather flimsy weak affair, and a light atlantic pull on its west and north west flank will result in the classic NW- SE divide, NW cloudy and damp, SE clearer settled conditions. Scotland fairs worse with dull drizzly skies at times.

By the weekend the atlantic trough inching in from the west against the ridge, SE parts could turn very warm briefly as a southerly drift moves in, by early next week, rain from the west.

Temps will stay above average into next week away from the NW, May 24 likely to be a notably warm first half but not on the scale of first half of April in terms of deviation from the norm.

Overall England about to see a fine spell of almost early summer warmth, the sun now is as strong as late July. 

Edited May 6 by damianslaw

[Cambrian]

It looks like we’re on a 10-12 day evolution back to something strikingly similar to what we currently have. 

0z EPS, days 0, 5 and 10.

  

0z GEFS, days 0, 5 and 10.

  

It’s always easy to give this model or that model a bit of flack, which I never quite get, but it does seem fair to say that in this instance the EPS first picked up on the establishment of a less challenged Atlantic trough nearby to the UK and Ireland around the middle of the month, a preferred setup that the GEFS is now gradually falling in with.

Moving on speculatively to day 10-15, it looks like the trough will bed down for a fair while in our locale. 0z EPS jet stream at day 10 and 15 - I deliberately haven’t rotated these, in order to focus on North America. 

At day 10, the Pacific jet stream is bifurcated on its entry to North America, around low pressure over California. The northern and southern arms then merge to the west of the Azores and is being steered over the top of the weak Azores high, then diving southeast into Iberia to carve out the trough. 

 

There is a pronounced lack of change in evidence by day 15 - maintenance of split Pacific jet stream, Alaskan trough, west and east coast lows, weak Azores high, Atlantic jet stream diving into Iberia, all making for very little west to east mobility to dig out the trough quickly. 

It will in time move on though. After all, the steady improvement of the coming week, culminating in a very pleasant spell, will have developed from the starting point of a similarly static trough - EPS chart for 1 May (day minus 5) and today.

 

There may be a quite comfortable balance emerging here in the pattern going forward, bearing in mind that due to the time of the year, the “troughy” spells rarely bring constant rain but the “ridgy” spells do invariably bring a good few dry days, and the sun is strong whenever we get it.

And in the first instance, the next week or so to enjoy! 

[Summer8906]

2 hours ago, damianslaw said:

May 24 likely to be a notably warm first half but not on the scale of first half of April in terms of deviation from the norm.

Not sure that it's been warm here though, yet. True, the nights have been mild but the days have mostly failed to reach average so far, some by quite a few degrees (13-15 seems to have been typical), except for the 1st which was mild and humid and the 4th probably about average for the time of year, would have estimated around 17.

It does sadly look though that May could be yet another notably dull and wet month from the discussion on here, though the GFS 06z, and 00z to a lesser extent, seem more optimistic about bringing the ridging back. Mild nights though, so likely above average overall: so yet another month with that awful mild, dull and wet combination. Conditions good for ticks and mosquitoes and not a lot else...

Hoping the timings are such that next Sunday isn't a washout. Looks like it's a knife-edge at the moment and could be anything from sunny to very wet.

 

Edited May 6 by Summer8906