Model Output Discussion - What does April have in store?

[SunnyDazee]

53 minutes ago, knocker said:

1800 UTC

I’m not liking the look of that!

[damianslaw]

Cracks beginning to appear from some of the models today, notably latest UKMO and ECM in terms of potential for sustained drier settled weather next week, UKMO and ECM siding together against GFS, often a common feature, and I tend to take note when this happens, and expect more of a ECM/UKMO evolution. Things may appear different tomorrow.

Alas, the ridge due to build in tomorrow followed by heights descending down from the north look fairly weak and hence a cut off trough feature may now become trapped in the flow come Wednesday, hence more showery affair and remaining fairly cool or average at best. As we approach bank holiday weekend, a colder northerly shot is being shown by ECM and UKMO - the colder air might filter further east as the trough moves further east - however, I suspect the trough will sit further west which makes the chances of the northerly or indeed north easterly higher. A probably shortlived affair before heights ridge in from the SW again, before the next low swings - we may get lucky when the window of warmer settled air settles over the UK over the bank holiday weekend.

 

[Frosty.]

An improving story from tonight's Ecm 12z ensemble mean longer term, at !east for southern uk.

[Methuselah]

4 minutes ago, damianslaw said:

Cracks beginning to appear from some of the models today, notably latest UKMO and ECM in terms of potential for sustained drier settled weather next week, UKMO and ECM siding together against GFS, often a common feature, and I tend to take note when this happens, and expect more of a ECM/UKMO evolution. Things may appear different tomorrow.

Alas, the ridge due to build in tomorrow followed by heights descending down from the north look fairly weak and hence a cut off trough feature may now become trapped in the flow come Wednesday, hence more showery affair and remaining fairly cool or average at best. As we approach bank holiday weekend, a colder northerly shot is being shown by ECM and UKMO - the colder air might filter further east as the trough moves further east - however, I suspect the trough will sit further west which makes the chances of the northerly or indeed north easterly higher. A probably shortlived affair before heights ridge in from the SW again, before the next low swings - we may get lucky when the window of warmer settled air settles over the UK over the bank holiday weekend.

 

Cracks? In the GFS? 

[ANYWEATHER]

Evening All!! The Deep low tonight will produce more wind than rain for the south overnight, Next week looks very similar to my thoughts earlier today, Frost warnings Convective weather  etc, Will be interesting , from the Ecm how far south the cold will go? at T+168 Gfs has another option?!!!! Anyway have a good night!!!

[knocker]

The three day evolution of the EPS anomalies is reaomably consistent but leaves a question mark over how much the subtropical high will amplify, if at all, in the vicinity of the UK. And the alignment and intensity of two troughs may be key to this. Whatever it will need sorting as the detail vis the UK weather will be rather dependent on this.

NOAA rather in agreement with the former pattern

 

[knocker]

The NH 500mb profile and the North Atlantic surface analysis for midnight and the UK 0400 UTC chart

storm Hannah will fill and track across the north of England into the North Sea during today and this evening. Much of the heavy showery rain is in the western quadrant associated with the wrap around occlusion and the worst of this is currently over N. Ireland and Wales. This will move very slowly north east during the day with a swathe south west Scotland to the Wash by 1800. Further to the south west/south clearer weather but frequent squally showers, particularly in the former, as the wind will continue to be very gusty with coastal gales in the southern quadrant. Quite a chilly day

The wind will ease through the evening but the rain will be slow to clear central and eastern areas whilst the west will remain dry as a transient ridge develops.

So a much better, and warmer, day on Sunday but still quite cloudy in eastern regions,with bits and bobs of rain from the old weakening occlusion, and by the afternoon more rain from a warm front, associated with a vigorous low in the Atlantic, will be effecting N. Ireland, Wales and the south west of England.

Overnight and through Monday the cloud and patchy rain will hang around in western regions as the warm front struggles to move east but sunnier in eastern regions and generally a much warmer day

On Tuesday a wave develops on the cold front and tracks north west of Ireland and thus NW and western regions will again be cloudy with patchy rain whilst central and eastern regions will be dry and quite warm

Quite a mixed bag on Wednesday as the  cold front tracks across the country and the little wave hangs around the western Isles. Best summed up as periods of rain/showers and regional temp variations

 

Edited April 27, 2019 by knocker

[knocker]

What next with the gfs? As has been indicated on previous occasions we are now entering a different regime with the migration of heights west across Greenland and the development of the vortex in the region of N. Russia and the displaced lobe, now in the western Atlantic. This facilitates the subtropical high to amplify north in the vicinity of the UK and would, if it verifies somewhere close to this, result in a dry and quite pleasant holiday weekend.

Edited April 27, 2019 by knocker

[knocker]

The ecm has the ridge starting to build next Friday but still some colder air sneaking into Scotland with showers, courtesy of the trough to the north It does build through Saturday but tends to slide a tad east by Sunday under pressure from the energy to the west with Scotland under some patchy rain. The weekend still to be resolved but the percentage play - not looking too bad for the majority

[Methuselah]

GFS T207:  FV3 T207: 

So both strongly suggest a warm weekend. And the GEFS ensemble also looks good:

                 

[johnholmes]

Looking at the 500 mb predicted pattern a week since the last time.

This was my comment last week based on the charts shown for 6-10 days away, see Net Wx Extra for what the flow is actually like this morning.

so best not to take too much from the latest output, although I would tend to feel that a less warm and more changeable atlantic flow is perhaps the form horse?

Today this

Looking at the models another week on=Sat 27 april

Ec-gfs have been fairly consistent with the pattern over the past 2-3 days; gfs having more of a ridge but both with a ‘double’ upper low either side of the uk (ridge for gfs as well); so quite a change for both on the charts above a week ago. You would need to look at my post of a week ago to see the charts I think!

Noaa also not that like the one above now and it has slowly got a pattern more like gfs than ec; not that often and it tends to make any certainty as to just what the 500 mb pattern will be 6-10 days down the line not as reliable to me than if it was ec and noaa. We shall see in another week! Noaa 8-14 has somewhat flattened the flow but not entirely different to its 6-10 day output.

So, possibly a pattern rather like something between the noaa and gfs 6-10 tending to flatten to a more w’ly type after this. Neither suggests any major warmth even though the flow suggests a s of w direction, starting fairly settled at 6 days perhaps, depending on where the surface ridge is would govern the temperature levels, then a bit more changeable again. So the next BH weekend may be mostly settled for many parts of the UK, and could be warmer than average if the surface high is in a favourable position, not possible to predict with accuracy off these charts 6 days out.

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

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

 

Edited April 27, 2019 by johnholmes

[MATTWOLVES 3]

Let's see if the GFS 6z brings us a similar scenario to the 0z! Bank Holiday looking very promising, high pressure to the East bringing up a Southerly plume of warm air... Could it be the 2nd warm and settled Bank Holiday period inside a couple of weeks!!  Here's hoping for another long lazy hot weekend!! 

[I remember Atlantic 252]

2 minutes ago, Mattwolves said:

Let's see if the GFS 6z brings us a similar scenario to the 0z! Bank Holiday looking very promising, high pressure to the East bringing up a Southerly plume of warm air... Could it be the 2nd warm and settled Bank Holiday period inside a couple of weeks!!  Here's hoping for another long lazy hot weekend!! 

last year was too, I remember mayday being hot, in the minority, but wanna see more days like this

[Frosty.]

I can sum up the Ecm 00z ensemble mean like this..tomorrow and early next week becomes milder and largely fine but then it turns cooler and showery for a time before later next week brings stronger ridging / high pressure and warmer, more settled weather, especially further s / e / se.

Edited April 27, 2019 by Frosty.

[Methuselah]

And here we are, at 6 a. m. next Sunday, and primed for another stonker:

 

 

 

 

 

 

 

 

[Methuselah]

And another Monday special:

[I remember Atlantic 252]

14 minutes ago, Ed Stone said:

And here we are, at 6 a. m. next Sunday, and primed for another stonker:

 

 

 

 

 

 

 

 

but for most on here a stinker

[Frosty.]

1 minute ago, I remember Atlantic 252 said:

but for most on here a stinker

I wouldn't fret about it, there won't be any!

[Methuselah]

Even right at the end, things are looking rather spiffing:

 

[Methuselah]

Though not at all bad, the FV3's take, on next weekend, is not quite so cut-and-dried:

 

Having said that, the SE could have a bit of a scorching Monday?

 

Edited April 27, 2019 by Ed Stone

[Frosty.]

The GEFS 6z mean actually makes very little of the so called cooler showery interlude next midweek before high pressure strengthens and it becomes warmer with plenty of sunshine..quite summery again!

[Methuselah]

A bit of a north-south divide, according to the FV3?

 

 

[Mike Poole]

As others have said the GFS 6z this morning looks good for the bank holiday weekend and beyond.  T180:

Later half of the run:

This is exactly the sort of evolution that I have been expecting to see into May if the signals from AAM and also from the long range models are to be reflected in the operational runs.  Seeing a northerly shift in the jet stream now should be a good indicator of the position we go into summer proper with.  

[damianslaw]

Models backing away today from a cooler northerly interlude, thanks partly to the position of low heights further to the NE and also backing west , enabling ridge development to build more strongly through the UK just in time for the bank holiday weekend. However, no obvious signal of a sustained warm settled pattern, perhaps a shortened version of easter weekend, not as warm, before a westerly breakdown into the following week. Last year brought a very good may day bank holiday, would do well to see two in a row.. is someone playing with the weather at the moment ensuring our holiday seasons coincide with good outside weather?... timings of changes seem to be coinciding just in time for these..almost to good to be true..

I'd welcome some thoughts from more seasoned forecasts - experts so to speak, why background drivers at the moment seem to consistently be favouring warmer and more settled patterns than colder and / or less settled ones since this time last year..

[chrisbell-nottheweatherman]

1 hour ago, damianslaw said:

 

I'd welcome some thoughts from more seasoned forecasts - experts so to speak, why background drivers at the moment seem to consistently be favouring warmer and more settled patterns than colder and / or less settled ones since this time last year..

I've been trying to get a similar opinion, but I think the experts are understandably reluctant to speculate!  It does seem strange that, with a weakened Jet thanks to lower polar ice expanse, the balance between blocked under a ridge vs. under a trough is as uneven as it is.