Model output discussion 9th April onwards

[mb018538]

2 hours ago, Alderc said:

Ugh.....little in the way of positivity here.

 

 

 

Looking like the first half of May will likely be in the rubbish bin as AAM falls away and Ely trades start dominating in the Pacific. There are hints that it won't sit around for weeks on end, and by the middle of the month the MJO should move on again and lift AAM to push the trough out of NW Europe. Until that point though, mainly unsettled and probably cool to go with it.

[Purga]

The 06z ENS are even colder than the 00z! If this were winter we'd all be jumping for joy .

 

 

 There's even some snow for early May for high ground in the north & Scotland not to mention the continuing threat of frosty nights in prone spots.

 

 

[Blessed Weather]

A few posts discussing typical summer weather and what constitutes a summer's day etc. have been moved over to the Spring 2021 Moans, Groans & Banter thread. Model Output discussion in here please. Many thanks.

 

[ChannelThunder]

Out of nowhere, GFS is producing this for Monday/Monday night! The same LP possibly affecting England and Wales more so than Scotland/NI was mentioned by the Aiden on the week-ahead forecast from the Met Office today too.

Edited April 26, 2021 by Lance M

[Timmytour]

1 minute ago, Lance M said:

Out of nowhere, GFS is producing this for Monday/Monday night! The same LP possibly affecting England and Wales more so than Scotland/NI was mentioned by the Aiden on the weed-ahead forecast from the Met Office today too.

Did the weed-ahead forecast make any mention of a high?

[ChannelThunder]

3 minutes ago, Timmytour said:

Did the weed-ahead forecast make any mention of a high?

 Oops. This is what happens when I go from having used my WFH keyboard all day to my gaming one on the other PC

Edited April 26, 2021 by Lance M

[Methuselah]

Out to T+270 and maybe, perhaps, possibly, at  the outer limits of the human imagination, the beginnings of a plume?

     

[Jordan S]

There will be many showers tomorrow developing over Wales, the Midlands, northern England and Scotland bringing an end to a dry few weeks though not everywhere getting these..one or two thunderstorms a possibility.

A line of heavy showers developing further south too they could also be thundery.

Less than the daytime but these will continue tomorrow night heavy in a few places but mostly dry for east Anglia and southeast England..

heaviest showers and longer spells of rain on wednesday for parts of Wales, southwest,southern England with a higher chance of thunderstorms, these will be slow moving too giving useful and generally needed rain but also potentially causing localized flooding as the water runs off the hard soil.

locally altogether totals for parts of England and Wales as much as 15-25mm by the end of wednesday, though some will not have much at all..

 

Quite likely more general rain develops in the southeast thursday morning which may be heavy.

 

The outlook for next week similar though to add more detail higher pressure continues to be to the northwest of us, low pressure systems likely taking a more southerly track to the south of this high and into the uk from the west/southwest, with one possibly on monday bringing heavy rain and strong winds.

 

After monday winds may be from the north at times in northern areas but generally west/southwesterly winds in central and southern areas, temperatures likely rising compared to the weekend. Longer spells of rain probably more for England and Wales most likely drier for Scotland with the continued chance of snow.

 

[Frosty.]

Wow just look at the ECM 12z @ T+240 hours..just look at those +15 T850’s (564 dam) building across Spain!!!!!!!...doesn’t it just warm the cockles of one’s heart?     

 

 

Edited April 26, 2021 by Jon Snow

[Mike Poole]

ECM T240 debt run and mean:

I think we have to keep watching on NH view until the high lat blocking has subsided, and it hasn’t yet.  Mean shows watered down version of the op run.  Still much potential for northerly winds into May unfortunately. 

UKMO CP forecasts are strongly for a hot one, May-Jul, but wetter than average (slightly), so maybe a stormy season in the pipeline for summer.  Here:

https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/business/public-sector/civil-contingency/3moutlook-mjj-v1.pdf

 

Edited April 26, 2021 by Mike Poole

[damianslaw]

Northern blocking in excelsis for the foreseeable, quite often the case at this time of year. Long drawn N/NE airflow, and welcome rain for many - if you want rain that is.. current forecast for Bank Holiday very poor, low pressure moving in on a southerly track, thereafter a possible warming up of sorts as we exchange the Northerly airflow for a westerly/SW one, but it is a split flow, still a cold feed in Scotland, and every likelihood another surge of chill air from the north behind the trough will move in. A very poor outlook it has to be said if you are after any warmth.

[stodge]

Evening all

Well, if we're going to have a hot summer, let's hope we get some rain in first because otherwise the country will be a giant tinderbox by July.

On topic, and not much sign of warmth on the evening's offering. GFS OP stays cool if not cold for several days and even those models which try to break down the high-latitude blocking only do so by dragging the jet just to the south and bringing in plenty of rain and some strong winds for southern and western parts.

[Frosty.]

We almost flirt with a plume in about 2 weeks time?.. on the Gfs 0z operational?...I did say almost!!  

 

[Purga]

Strewth!

 

[SqueakheartLW]

I bet you could just imagine the irony if the warm spell at the end of March 2021 turns out to be our warmest spell of the year if we get a dreadful cool and possible washout summer 2021

That would make a shocker of a 2021 temperature wise if it did come off. The latest outlook for late April and early May seems to be continuing the cool trend with a large blocking high pressure region near Iceland and Greenland, no doubt could be a major response to the MJO phase at present

The regimes chart also shows overall blocking will be a major feature of our weather

1 - For the next few days Mid Atlantic ridging will dominate meaning a high likelihood of northerly winds and cool weather so no real change on what we have seen really since early April

2 - In the near term it looks like the Atlantic is going to have a go at coming back in with an increased change of a +NAO setting up but this looks like it will be quite short lived

3 - The more extended range shows more of the blocking options returning again with a weakening Atlantic risk. Maybe a sign of a return to cooler and drier condition again.

Time to look at the ECM anomaly charts

+72 hours away

At 72 hours away we see a dominance of above average pressure around Iceland and Greenland with lower than average pressure over Europe

+168 hours away

At a week away we can see the Atlantic push showing up here as was shown in the regime chart with lower than average pressure taking over around the UK

+240 hours away

240 hours or 10 days away sees even more chance of wetter conditions with even lower than average pressure around the UK on all options

384 hours away

By 384 hours away we see a mix of options as you would probably expect at this range. Two of them are more blocked and the other two more +NAO. Option 1 looks like it could become quite warm and dry with high pressure and SW winds. Option 2 less settled but more average temperature likely. Option 3 looks a little unsettled with lower than average pressure both to our north and south. The final option looks to be the coolest and most unsettled option with low pressure close to the UK.

[mb018538]

@SqueakheartLW also worth remembering that as the seasons change, so do the patterns we want! All winter we dread that flat +NAO pattern....but in the summer as wavelengths change and the jet pushes to the north, a +NAO pattern can be very good for the UK with the Azores high dominating and low pressure pushed into Iceland/Greenland. June 2018 was a very good (although very extreme) example of this:



Nothing in the output this morning to suggest anything other than mainly cool and unsettled weather dominating the next couple of weeks,

[Atmogenic]

8 minutes ago, mb018538 said:

@SqueakheartLW also worth remembering that as the seasons change, so do the patterns we want! All winter we dread that flat +NAO pattern....but in the summer as wavelengths change and the jet pushes to the north, a +NAO pattern can be very good for the UK with the Azores high dominating and low pressure pushed into Iceland/Greenland. June 2018 was a very good (although very extreme) example of this:



Nothing in the output this morning to suggest anything other than mainly cool and unsettled weather dominating the next couple of weeks,

Those charts are the ones I want to be seeing now, no more of the greens and blues 

[Britneyfan]

The runs this morning look slightly better than they did this time yesterday, 

[Guest]

Another absolutely rotten GFS 12z Ops run. Pick any chart and it’s awful, the end of the run is dreadful and even, HP from Greenland stretching down into the sub tropical Atlantic and the Uk under a huge northerly

[Cheshire Freeze]

30 minutes ago, Alderc said:

Another absolutely rotten GFS 12z Ops run. Pick any chart and it’s awful, the end of the run is dreadful and even, HP from Greenland stretching down into the sub tropical Atlantic and the Uk under a huge northerly

Yes and I notice the ensembles are starting to pick up on the Russian HP I was talking about as a possible summer pattern a number of weeks back.

Back end GFS op shows it too

Edited April 27, 2021 by CreweCold

[Guest]

2 minutes ago, CreweCold said:

Yes and I notice the ensembles are starting to pick up on the Russian HP I was talking about as a possible summer pattern a number of weeks back.

Back end GFS op shows it too

Yup noticed that too, that’s usually a couple of month feature once it gets going.

[stodge]

Evening all

Those wanting early summer warmth should avoid the GFS 12Z OP at all costs - plenty of northern blocking and winds often from the north or east.

The issue of the Russian HP - well, the problem with that is if you keep heights to the west and build heights to the east, guess where the trough ends up? That's the problem with an amplified scenario - if you end up in the wrong place, you can be stuck there for a while.

It would be curious if, after an exceptionally dry April, we ended up with an exceptionally wet May.

[Britneyfan]

Everyone is so dramatic on this forum

it hasn’t felt particularly cold, strong sun this time of the year changes that, running similar to 2013 here so far, 

models seem to be chopping and changing at the moment, between some warmer members and cooler members, wouldn’t be surprised to see a big flip mid month onwards, either way, when the sun shines temps of 14 or 15 are perfect! 

[Cheshire Freeze]

28 minutes ago, stodge said:

 

It would be curious if, after an exceptionally dry April, we ended up with an exceptionally wet May.

Possible I guess. 

We seem to be lurching between extremes for extended periods. We seem to be in a period of a very meridional jet which started last summer...we were on the warm side of it for vast swathes then; with thundery outbreaks. We were quite evidently thrust into a low solar pattern last summer, which is why I was gunning for a colder than average winter (or at least a lot colder than the winters that preceded).

In low solar summers there is generally a (mean) trough located somewhere around the UK. If it sits just west then we get warm and thundery (last year) On the other hand we can see it park directly over the UK like at times between 2007-2012.

P.S this is some chart for May

Edited April 27, 2021 by CreweCold

[Frosty.]

This post is for anyone..I assume by now the majority..?  who are hoping for a change to something more summer-like next month from the GEFS 12z!  

 

 

Edited April 27, 2021 by Jon Snow