Model Output Discussion - What does April have in store?

[SizzlingHeat]

2 minutes ago, Frosty. said:

Magnificent Gfs 12z operational for later this week including the easter weekend with temps into the low 20's celsius widely!!..impressive for april!

Then crap for the remainder of April which is a shame! But subject to change given it being FI

[Frosty.]

5 minutes ago, SizzlingHeat said:

Then crap for the remainder of April

Lots to enjoy before the potential crap

Edited April 15, 2019 by Frosty.

[SizzlingHeat]

3 minutes ago, Frosty. said:

Lots to enjoy before the potential crap

Oh yes! All day BBQ and drinks Saturday are coming up!!!

[MATTWOLVES 3]

Lots to enjoy before low pressure decides to take up residence over the UK out to day 10 and beyond.... Looks like a more autumnal spell after this fine spell.... 

[MP-R]

1 minute ago, Mattwolves said:

Lots to enjoy before low pressure decides to take up residence over the UK out to day 10 and beyond.... Looks like a more autumnal spell after this fine spell.... 

That's a classic April showers setup. I'm sure there'll be plenty of convective potential even if it is on the cool side.

[Frosty.]

2 minutes ago, Mattwolves said:

Lots to enjoy before low pressure decides to take up residence over the UK out to day 10 and beyond.... Looks like a more autumnal spell after this fine spell.... 

Sunshine and heavy thundery showers would be fine by me..good growing weather following all that very warm dry and sunny weather at easter.

Edited April 15, 2019 by Frosty.

[MATTWOLVES 3]

4 minutes ago, MP-R said:

That's a classic April showers setup. I'm sure there'll be plenty of convective potential even if it is on the cool side.

Yep, rain, hail sleet, touch of snow even in the heavier stuff... Then sun gets out and it feels positively balmy again..... Got to be honest, I hate sunshine and showers! Especially when it's shower after shower! Hopefully things will turn more settled into may again. 

Edited April 15, 2019 by Mattwolves

[MP-R]

7 minutes ago, Mattwolves said:

Yep, rain, hail sleet, touch of snow even in the heavier stuff... Then sun gets out and it feels positively balmy again..... Got to be honest, I hate sunshine and showers! Especially when it's shower after shower! Hopefully things will turn more settled into may again. 

Haha fair enough. As a weather enthusiast I don't really mind it - much more interesting than leaden skies and rain, which would be the Atlantic alternative. I doubt the airmass will be cold enough for snow though without more of a northerly element, even in the heaviest of showers. Thunder and lightning however....

Beyond that, perhaps another build of pressure to bring another settled spell. All very normal practice for this time of year which does tend to chop and change quite a lot. Before that, however, a very nice looking Easter weekend - shame I'm working on Friday and Saturday but hopefully Sunday will be sunny too, if it could hold out until Monday that would be the cherry on the top.

[Frosty.]

Cracking GEFS 12z mean later this week, whether it's 18c or 22c it's going to feel lovely in all the sunshine.

[Methuselah]

So, it's fine until next Tuesday but, after that, the GFS models diverge...The FV3 looks being warmer for longer, though?

GEFS ensemble shows the Op taking a cool direction viz the ensemble as whole: 

[Frosty.]

Well the Ecm 12z looks gorgeous later this week, more like summer than mid spring but Easter Monday onwards it's back to earth with a bump..but why look for trouble?..just enjoy the upcoming warmth and sunshine.

Edited April 15, 2019 by Frosty.

[knocker]

The ecm has the fragment of the vortex in the Denmark straits at T132 and from there progresses the trough south east over the UK as the subtropical high zones (Atlantic and Europe) amplify. Thus some wet and windy weather next week as the trough dominates the eastern Atlantic, starting Sunday evening with a front effecting the north west

[Frosty.]

Although it looks like becoming unsettled and cooler next week the extended GEFS 12z mean indicates it won't last long and that high pressure will have another go towards the end of april..some very warm potential too..before we even get to May!!

[ANYWEATHER]

Evening All ! Some nice weather to enjoy in the next few days for most , next week looks  very suspicious from both ecm and gfs . Bank holiday Monday  Who Knows? 

[Frosty.]

Just freeze the Ecm 12z ensemble mean in that position..I implore you not to go any further!!

[knocker]

NOAA and the EPS in pretty good agreement in the 5-10 period with the negatively tilted trough running south east from Greenland.and high pressure to the north east of the UK. With the upper flow abating and backing sharply in the vicinity of the UK not a lot of longitudinal movement so although portending unsettled the detail may be a tad difficult to pin down  Temps returning with a bump, perhaps a tad below average, after the highs of this weekend

Looking into the ext period not a huge change with the ridge/trough axis still in place but less amplified and a suspicion the the Atlantic subtropical high pushing north so perhaps not so unsettled with temps still a tad below average.Could be a sunshine and showers routine which the det runs will sort

[Singularity]

So now the model runs are dominated by massive retraction west of the subtropical high in the mid-range with a trough of some manner (deep or shallow) dropping in and turning things cool and unsettled for at least a few days. Really bizarre to see that with the ongoing El Nino; it's more fitting of a moderate, maybe even strong La Nina event! The ECM 12z is particularly extreme, a genuine 'what the [strong word]' run for me.

As I said earlier today, falling AAM against a +ve background often leads to overblown bursts of westerly momentum across the N. Atlantic, hence 'shove-in' of troughs across the UK.

In light of which, I'm still hopeful for a less clean and successful retraction west of the ridge, with more left across Europe and the trough grinding to a halt west of the UK rather than overhead. I've seen that manner of adjustment happen plenty of times before in the 5-10 day range.

Should that fail to occur then not only will the notion of an El Nino base state come under serious question, but the long-range modelling guidance will have landed extremely far wide of the mark yet again (for some time, they've been shouting for a notably warm 2nd half to April, which requires more than just 4 or 5 days hitting the high teens to low 20s; more like 9 or 10 - at least!).

This would further cement the idea that climate change is significantly mutating the mechanism by which the Pacific SSTs affect the global climate. So I really hope it doesn't come to that!

 

[damianslaw]

47 minutes ago, knocker said:

NOAA and the EPS in pretty good agreement in the 5-10 period with the negatively tilted trough running south east from Greenland.and high pressure to the north east of the UK. With the upper flow abating and backing sharply in the vicinity of the UK not a lot of longitudinal movement so although portending unsettled the detail may be a tad difficult to pin down  Temps returning with a bump, perhaps a tad below average, after the highs of this weekend

Looking into the ext period not a huge change with the ridge/trough axis still in place but less amplified and a suspicion the the Atlantic subtropical high pushing north so perhaps not so unsettled with temps still a tad below average.Could be a sunshine and showers routine which the det runs will sort

Good analysis, its the time of year when the azores high is more likely to amplify northwards instead of surge NE, hence negatively titled troughs can stick around for quite a while, with the UK sandwiched between heights to the west and east - slow moving patterns become the norm, as we have seen past 2 weeks.. so don't necessarily expect a swift return to a warmer drier theme once the trough anchors itself down on the UK. In the meantime a warm up by Good Friday, but now looks a 2-3 day window of dry warm weather for the north, perhaps squeeze a day possibly two more for the far SE.

 

[johnholmes]

Yes the 500 ,b charts shown by knocker along with the ECMWF-GFS output this morning all suggest the upper air in the vicinity of the UK will be trough dominated not ridge dominated in the 6-10 and using the NOAA 8-14 out to 2 weeks as well. Just what the surface weather will be is not clear and is likely to show some variations as the synoptic models, 2 or 4x daily try to work out the detail.

[Summerstorm]

18z run of the GFS going for something a little different with a plume at around 10 days away. 

It's also making less out of the LP system heading towards the UK from the Baltic with it never really reaching us before high pressure begins to extend it's influence. 

This maybe is more akin to what @Singularity is imagining with the second half of April being warm. Also the models maybe beginning to sniff out a more sensible (maybe not a plume and a more settled setup) way forward although this is only one run and may prove to be completely speculative in the long run with the ECM being right although it does look a little extreme and maybe once again we are looking for half way house solutions. 

 

[syed2878]

7 hours ago, ANYWEATHER said:

Evening All ! Some nice weather to enjoy in the next few days for most , next week looks  very suspicious from both ecm and gfs . Bank holiday Monday  Who Knows? 

   

so what has happened to all the snow you been forecasting for April I just thought I’d ask

[knocker]

The NH 500mb and the Atlantic surface analysis for midnight and the 0300UTC WV sat image

The occlusion that brought a lot of rain into western regions overnight will move only slowly ENE during the day. Thus a broad corridor of cloud and rain along the the front, the rain becoming patchy as the front weakens, with a clearance in the south west behind it  Perhaps some sunny periods in the east but still with the cooling onshore breeze here and in fact the regional temp variations with this analysis are quite striking.

During this evening and tonight the weak front remains virtually stationary so still cloudy in many areas but the very patchy rain more or less confined to western Scotland. With the surface wind now light some fog/mist patches may well form in western and southern areas.

By tomorrow the trough to the west is in the process of disrupting and forming a cut off upper low to the south west. This facilitates advection of warmer air from the continent resulting in a much warmer day generally with the usual caveat vis the north east coastal regions.

This remains the scenario overnight Wednesday and through Thursday and a very warm day generally ensues but still the onshore winds along eastern coasts and thus temps still depressed

Another very warm and sunny day on Friday but there are subtle changes as the upper trough slips south of the UK and there is a fair amount of activity to the west and frontal systems are taking closer order/

By Saturday the aforementioned fronts, although weakening against the block, will bring patchy rain to N. Ireland and Scotland but sunny again elsewhere and another very warm day generally. And even the eastern coastal regions may join in as the country is now in a very slack gradient

[knocker]

To continue briefly with the gfs. This period over the weekend was touched upon with a couple of posts yesterday evening. Renewed amplification upstream with the Bermuda high and the trough ejected from the vortex dropping south adjacent to the UK Thus Sunday and Monday will remain very warm with temps way above average but the proximity of the trough and the surface frontal system brings into play cloud, and even patchy rain. With little longitudinal movement the detail may take a little while to sort

Edited April 16, 2019 by knocker

[knocker]

The ecm has some patchy rain into N/ Ireland and Scotland by 1800 Sunday as the front approaches from the north west. And as the front tracks slowly south east overnight and trough Monday heavy and more persistent rain will effect the north west down as far as the west Midlands, This obviously will effect the temps with it still dry and sunny to the south east. As mentioned previously, the detail is still up for grabs

[MATTWOLVES 3]

Morning folks.... Still some great weather on the way this week... Low 20s possible. Next week it becomes a little cooler and more unsettled, but temps still remain not to bad to the S/SE. Beyond that, there are signs of another build in pressure and increasing temps again.... So all in all... Not to bad in my books.