Model Output Discussion - Spring Has Sprung

[WYorksWeather]

 raz.org.rain As always uncertainty does increase later on - I remember there was a point where a lot of people were thinking the January cold spell would keep getting extended. A turn before the end of the month is still very much possible but I think the next 7 days or so is pretty clearly locked in - drier than of late with temperatures averaging below average and varying from significantly below to near average.

If no change in the output by the end of the weekend, then I think warm and dry weather will have to wait until May.

[minus10]

 WYorksWeather gefs 12z showing a clear 5 wave pattern which as i understand can stay around for some time...

...this was referred to in latest met 10 day trend as potentially a self sustaining pattern...problem is the uk is not in the best position if the pattern evolves as moduled keeping the cooler north easterly theme...at least the sun is getting stronger and the nights getting shorter still...as others have said this is not untypical for spring...

 

[WYorksWeather]

 minus10 It's sometimes useful to keep an eye on the wind plumes for the ECM I find.

A bit more variation by the end, and the mean temperatures close to average (albeit accompanied by yet more rain). Of course a long way off and not to be taken seriously. I will be watching these in the coming days to see if we get any hints of a pattern change. At the moment it's just an increase in uncertainty.

[Don]

54 minutes ago, WYorksWeather said:

A clear lack of any significantly warm runs is obvious, though. It's a pretty strong signal for below average temperatures at least for this week, then a bit more uncertainty for later next week but below average the likely outcome until then.

I wish we were seeing posts like this from you 2-4 months ago! 

[WYorksWeather]

 Don Northern blocking always appears too late these days...

[Don]

 WYorksWeather Doesn't it just! 

[Metwatch]

5 hours ago, SunnyG said:

The weather doesn't seem to be very interested in our 'has to's'.

Completely agree with this part! The weather doesn't care about our preferences or if we've been suffering after many long period rainfall records broken in the last 18 months.

However it can't stay the same forever, the general pattern reshuffles every few weeks to every 2-3 months. And even in the last 12-18 months being so wet, dry spells have still occurred; i.e the very dry February 2023, Mid May to late June, early September, early October and mid January this year, but we've had much more in the way of wet periods overriding the drier spells.

Another reshuffle of the synoptic pattern is now taking place with high pressure building near the country then likely transitioning to a -NAO (Greenland - Iceland high pressure block) so we are entering a drier but coolish next 7-10 days, though still not completely dry. Given there hasn't even been a drier spell since mid January,, there should in theory be a longer one in the next few weeks, but when exactly no one really knows. Most likely it should happen in May some point or into June. It would be very weird if by the time we are heading into mid summer and there hasn't been a good 10-14 day spell of virtually no rain for most of the country.

 

Edited April 17 by Metwatch

[Kirkcaldy Weather]

On 29/01/2024 at 14:25, Kirkcaldy Weather said:

We'll continue seeing patterns which link to El Ninò throughout March and I'd favour potentially the first few weeks or so of April, following that time it's a gradual move into ENSO Neutral with some themes continuing of heading into La Ninà by late spring and particularly Summer 2024.

Want to start by revisiting the above statement from January, there can often be discrepancies between the various Meteorological Agencies particularly regarding ENSO statuses but we have BOM first to declare ENSO Neutral. 

 

Per my recent post here 

 

I discussed that the Super El Ninò Event had transitioned into more of a West Based Event, the latest ENSO discussion from NOAA agrees and gives further info 

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

We'll have to await JMA and NOAA anouncing ENSO Neutral conditions and personally I dont get involved in debates a la Twitter last year with many arguing we weren't in an El Ninò though as I have discussed prior no 2 ENSO events behave indentically though there are common characteristics of each ENSO, and there can be lag in the Oceanic > Atmospheric 'coupling'.

Newest ENSO outlooks from Met Office suggest ENSO Neutral heading into May with the oncoming La Nina conditions intensifying in the 1 & 2 Regions quite fast.

Starting to see more details to add to some of my recent posts.

On 11/04/2024 at 20:28, Kirkcaldy Weather said:

We can watch as the extremely cold airmass associated with the Tropospheric Vortex begins to move from the Russian end of the Arctic across toward the Alaskan and Canadian end. Values at -28C 850hpa ongoing possibly some nearing -30C and still maintaining at least -24C at 850hpa upon the position shift.

On 11/04/2024 at 20:28, Kirkcaldy Weather said:

Trends show the coldest conditions becoming centred across Europe.

On 11/04/2024 at 20:28, Kirkcaldy Weather said:

From now through Mid April we see the Atlantic Ridge regime which could extend across Ireland possibly the UK for a time, with this transitioning into blocking to our Northeast, North and most likely Greenland too.

Looking in more detail, the most significant developments upcoming, as the cyclonic system discussed here

 

Merges with a cut off low in Northwest America this will link to the Tropospheric Vortex which is modelled to greatly intensify with indication potentially record breaking low pressure into Canada. 

Part of the MJO Indian Ocean > Maritimes feedback in an El Ninò in April as posted prior 

As shown in my recent post we continue to see the Atlantic Ridge in an El Ninò setup with another cold plunge during the next few days.

Following on we have the high pressure moving into Ireland and the UK as mentioned prior plus as the Tropospheric Vortex developments occur in Canada this paired to the Negative PNA will see a high descending from West Canada across America with a new Arctic air outbreak, a relatively common pattern of the last few months which I've covered in the global thread. This will bring significantly below average temperatures.

On 11/04/2024 at 20:28, Kirkcaldy Weather said:

As shown in my post from October and other occasions a negative PNA can lead to a cold - potentially significantly cold temperature anomaly from the Northeast-East

During the latter stage of April week 3 through April week 4 the Atlantic and Ireland-UK high will begin to take on the MJO and PNA feedback of blocking to our Northeast > Scandinavia and Russia, this will also retrograde into Iceland and Greenland as discussed prior with a good representation of many of the major European weather regimes / teleconnective feedback.

 

Euro-Atlantic weather Regimes in the PRIMAVERA coupled climate simulations: impact of resolution and mean state biases on model performance

LINK.SPRINGER.COM

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Recently, much attention has been devoted to better understand the internal modes of variability of the climate system. This is particularly important in mid-latitude regions like...

Nothing surprising here factoring in recent MJO progression with an ongoing probable further feedback of multiple Stratospheric > Sudden Stratospheric Warming Events, *though the current zonal winds are above average.

Overall a prolonged period with below average temperatures will continue with some significant anomalies across Europe in particular, we then look during April week 4 as the High retrograde gets going for these below average conditions to extend into the UK > Ireland.

Thanks for reading. KW

[Rain All Night]

10 hours ago, Rain All Night said:

0z deterministic runs, out to Wed 24 Apr (day 7)

Harmony up to day 7 from the models this morning. There will be a cold pool sliding under the southeast during the first part of next week.

0z ensemble means, out to Thu 2 May (day 15)

The northeasterly flow looks like it will continue for quite a while. Not quite clear yet whether the Atlantic heights are going to endure into the beginning of May.

12z deterministic runs, out to Wed 24 Apr (day 7)

GFS can do one 

12z ensemble means, out to Thu 2 May (day 15)

Edited April 17 by Rain All Night

[Derecho]

4 hours ago, raz.org.rain said:

James Peacock on Twitter had commented that he was dubious of how prolonged the cooler spell is in the outputs and suggested it may only last one week as opposed to over a fortnight.

We will see, I think it will probably remain chilly most days until the 27th. After that is more uncertain, at this time of the year if you cut off the Arctic feed, suddenly easterlies can turn very warm but no sign of that yet.

Looks like the chillier air may gradually dissipate but a coldish outlook overall, especially in the east.

[Alderc 2.0]

It’s always the risk with weak high pressure initial forecast to our west that it regresses a touch more and we up under a massive euro trough and very unsettled - that’s what happened on this mornings gfs. Despite 6-7days away it’s a pattern that hard to avoid. Could be some very chilly conditions next weekend. 

[LetItSnow!]

0z sees a prominent Euro trough by Thursday the 25th which brings in a very cool north/northeasterly wind.

This forms a meandering low pressure system centred over the south of the country by Saturday the 27th.

In the extended range, pressure remains generally weak to our south with a cool E/NE flow. This is a marked change to the precocious spring so far across northern Europe. The 0z pans out quite similarly to the 18z so perhaps there is traction that unsettled weather may return to finish off the month. This pattern of low pressure overhead will usually bring sunshine and showers but a north-easterly flow, especially with warmer than average SST anomalies in the North Sea may aid with a lot of cloud development. A very dull, chilly and raw spell focused on southern and eastern England may be on the cards for the rest of the month. Combined with a very wet and dull half to the month, perhaps April 2024 is shaping up to be one of the wettest and dullest in quite a few years, particularly in the east.

Of course the final outcome is yet to be resolved but with north-easterlies likely on the cards, I’ll highlight the remarkable variety of the synoptics this month: 

 

This month is reminding me of an April version of September 2022, running ridiculously warm then turning much colder.

[LetItSnow!]

Another interesting observation on the 0z that I glossed over is the chart for the 26th. Now don’t expect this to verify but it’s a good example of how cloud and wind so heavily impact surface temperatures.  The chart is for low pressure to be in the North Sea bringing gusty NE winds. The uppers are unexceptional but the projected daytime highs are pegged into single digits for many under a mass of cold rain.

How much cloud and rain pepper the UK as we go into late April will determine how chilly it’ll be. The suns strength will easily lift temperatures into double digits even with chilly uppers. As my above post basically says though, details will be firmed up on (apologies for double post, feels like bad manners but it’s pretty quiet and I thought it was helpful). 

[ANYWEATHER]

42 minutes ago, LetItSnow! said:

0z sees a prominent Euro trough by Thursday the 25th which brings in a very cool north/northeasterly wind.

I would argue that it will feel very cold in that setup, certainly not cool!

[Sherry]

Looks like temps recover as we head into may but unsettled with it more rain

[LetItSnow!]

 ANYWEATHER Certainly will feel cold if we get cold, wet and blustery north-easterly winds! I imagine the feels like temperatures would be quite the picture on the 0z around the 26th with 40-50mph NE winds around north-east coastal areas with heavy rain to boot. But it may not be that bad, little movements in where the low eventually ends up could make such a large difference as to whether it’s just showery and chilly or cold and miserable. Shades of 1998/2007 yet again…

[Northwest NI]

The thread title “Spring has sprung” is becoming less and less appropriate with each passing day. There is hope in my locale at least, for a decent spell beginning this weekend.

The Metoffice is notoriously pessimistic with temps in my area so hoping for mid teens to maybe 16 - 17 degrees during mid afternoons.

 

Edited April 18 by Northwest NI
Add metoffice jpeg

[Cambrian]

We’ve been quite lucky this morning, it has been absolutely beautiful, steadily warming up from a -1.2 degrees frost around dawn, 1026mb and no wind. April mornings don’t come much better. 

A very reasonable looking few days ahead, through the weekend and into early next week, the  0z EPS chart for next Monday morning at day 4 is a cracker. The MSLP chart shows a high pressure of 1036mb over the UK and Ireland, part of a “bar” of higher pressure extending through to the Siberian Arctic. But make the most of it!

  

Even with this setup, though it is nigh impossible for our high to be shifted east by anything off the Atlantic, it instead gets undermined by trough development to the east. 

There were good hints of this in the models yesterday, and though still a fair way off, the subtle hints of yesterday for day 10 have grown into clear suggestions today for day 9, the trough notably deeper and further west. 

 

This is the kind of evolution I love to see, not necessarily for the weather it will bring, but for the phenomenon itself. The 0z ECM op at days 6-10 shows the potential, the Scandinavian trough spawning a little low pressure system running down through the Norwegian Sea, joining with another more active one coming out of Greenland and sweeping down through Iceland…

 

…the two merging and swivelling down into the UK and Ireland, with the cold air reasserting itself in the process. 

With the seasonal timing, probably not at all welcome, though I keep the faith that one of these years we’ll get this kind of thing a couple of months earlier and enjoy it a lot more. As it stands in the current modelling, it’s a spring ambush!

[Rain All Night]

9 hours ago, Rain All Night said:

12z deterministic runs, out to Wed 24 Apr (day 7)

GFS can do one 

12z ensemble means, out to Thu 2 May (day 15)

0z deterministic runs, out to Thu 25 Apr (day 7)

GFS persists with its mini-beast.

0z ensemble means, out to Fri 3 May (day 15)

GEFS shows something mildly threatening in the Atlantic right out at the end of week 2, but ECM does not.

GEFS also seems to want the eastern trough in the nearer timeframe to cause us more misery than ECM does.

[Pauski]

It looks like there will be snow on Saturday, in my area and in part of the rest of Finland. Next week more snow or sleet is perhaps coming, this time of the year, it is not necessary anymore. 

Hoping that Summer months June/July is something like showing reanalysis, not like lastest summers.

Sorry My bad english. 

 

[minus10]

The 12z gefs 2m temp anom switch is certainly quite stark over the continent from the 20th in particular..

..we go from this..

..(uk already below average)..

...to these..

..notable that nw Scotland and Ireland modelled to recover to above average temps  for a while with more Atlantic influence perhaps...

..these tranlate into mid to high single digit temps over the continent and the uk according to gefs ..i should imagine there will be quite a lot of cloud around but where the sun does get through it could push temps into double digits depending on topography / wind direction etc..some frost also being modelled mainly over the continent again...particularly Germany , Switzerland , Eastern France and the Alps...uk according to the model mainly escapes frost...well i hope so anyway from a gardening point of view...i understand that French vineyards are already using fires to keep the worst effects of the frost away....

...more to come i should imagine..

..by 29th April the colder anom is reducing and becoming less potent...

...uk still hanging onto little below average temps...lets hope May will warm up although i get the feeling this weather pattern will be quite stubborn for a while..todays sun here in wgc felt lovely...enjoy any sun you get in next week or two if you can...

 

Edited April 18 by minus10

[raz.org.rain]

2 hours ago, Pauski said:

Hoping that Summer months June/July is something like showing reanalysis, not like lastest summers.

There seems to be pretty good agreement in the long range outputs that pretty much all of Europe will see significantly above average surface temperatures in summer. However, I believe they were saying the same thing this time last year, so who knows.

[SunnyG]

21 hours ago, Metwatch said:

Most likely it should happen in May some point or into June. It would be very weird if by the time we are heading into mid summer and there hasn't been a good 10-14 day spell of virtually no rain for most of the country.

It's always some time in the future though, and when we get closer to that fated period, it turns into another unsettled spell. Weird or not, it's what we got.

[Cheshire Freeze]

These charts are starting to look wet once again

[Scorcher]

Yes the ECM is looking less cool now for next week but incredibly it looks likely low pressure will be influencing us yet again after midweek.

The nightmare continues it seems.