Model Output Discussion - Spring Has Sprung

[Addicks Fan 1981]

Nice looking GFS 6Z op run in 11 days time with a northerly tracking jet.     

WWW.METEOCIEL.FR

---

Meteociel propose des cartes de prévisions du modèle americain GFS

 

[Summer8906]

1 hour ago, Cambrian said:

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.

Mind you, the current "troughy" spell has brought a protracted period of miserable weather since around April 26th. The only decent days have been the 29th (average), 30th (very good, becoming so-so) and 4th (good all day, the only such day since the 21st) - so could do without a repeat! Hope the GFS is closer to the mark than the ECM.

Edited May 6 by Summer8906

[stodge]

Evening all

Still awaiting the end of the 12Z ECM but the path for the next week seems set at present - four to six days of increasing warm and pleasant weather from tomorrow with HP in charge but as that HP begins to transit to the north east at the end of the weekend and with the Azores HP unable to ridge in, the trough fills the gap from both the north west and south turning the weather back unsettled with rain or showers. Looking further ahead and not unusual for mid-May with pressure higher to the north and west and lower to the south and east. 

[Addicks Fan 1981]

 stodge so in other words a bit plumey, awesome stuff then with a load of winds waftng up from the south.    

[ANYWEATHER]

 Addicks Fan 1981 the winds won't be wafting in from the south ,if models are correct.....!☺

[viking_smb]

 ANYWEATHER  westerly they will be 

[WYorksWeather]

Some interesting trends to pull out of the GFS 12z temperature ensembles this evening.

Firstly, a lot of disagreement on the timing of the end of the warm influence and a return to something closer to average. The mean starts to reduce around the beginning of next week on the 13th, but there are some runs that extend the warmth well beyond that to as far as the 15th, and in fact go well above 10C at 850hPa. After that, a lot of scatter with likely options close to average but again plenty of very warm options available.

In terms of temperature forecasts, I still continue to think UKV is the best model for shorter term - it has the better resolution and is meant to be more accurate over the UK, and I usually think it does its job better than the others.

Here is today's afternoon forecast from the UKV 03z this morning, followed by ECM 00z and GFS 06z attempts next to it:

And here is verification from Meteociel:

It's pretty clear from that I think that UKV performed best - ECM was far too low with temperatures in the SW, GFS was too low with the absolute max, and UKV was probably the closest to getting it all right.

So, with that in mind, we can now reach Saturday with the UKV 15z, so here are the afternoon temperatures for every day up to and including Saturday:

So, overall consensus has Friday and Saturday as the warmest days, with a gradual build of heat through the week. 23C the highest max on those charts, but a very widespread 20C or higher towards the end of the week. The idea that we'd have 850s in the 5-10C range and temperatures limited to high teens in most places never seemed credible to me as others had also pointed out, and UKV dispenses with that idea tonight. Again UKV did under-read by 1C, so I do wonder whether somewhere will get to a sneaky 24C.

The 850hPa temperatures for the week also illustrate this quite well - just gently warming up throughout the week. Here are 850s for tomorrow afternoon, compared to Saturday afternoon.

Tomorrow warmth focused on southern and western regions, Wednesday central and eastern excluding far N England and Scotland. Thursday sees more of a N to S split with the dividing line near the Humber. Friday warm for almost all of England and Wales, and Saturday includes Scotland as well.

Of course exact details are always subject to last minute change and can even become a nowcast situation, but in terms of the overall maxes if not the exact placement, I think we can be pretty confident that most areas will be seeing low 20s towards the end of the week, and mid 20s definitely can't be ruled out in a few favoured spots.

Summary

In the short term, lots of dry and increasingly warm weather around. Uncertainty around the duration, but looks to last with some certainty to the end of the week, and possibly even beyond that. After that a bit of a cool down is likely, but warm runs are popping up again beyond that.

Everything in these charts is indicative of a warm week to come, and likely a very warm first half of May overall for many areas. 

[viking_smb]

 WYorksWeather great nice to see some nice weather now, we got a event on at cbyc this weekend (supernova dinghy traveller event) so working all weekend as beachmaster, but will be afloat as required

Edited May 6 by viking_smb

[WYorksWeather]

 viking_smb Going by these charts it should turn out nice just in time.

[viking_smb]

 WYorksWeather hope so mate, and will be nice for parade night boating (sea cadets) on thurs eve 

[Scorcher]

 WYorksWeather Wow the ECM was truly shocking for today- miles too low in this area too.

Perhaps because it overcooked the precipitation in some areas? It's stayed completely dry here today despite the Met Office and others saying rain was almost certain this afternoon.

I too have noticed how accurate the UKV has been with the surface temps recently so I will be putting my trust in it more from now on.

[WYorksWeather]

 Scorcher Quite possibly. To be fair to it I'm comparing to the 00z so GFS and UKV both had a few hours advantage on it. But in general I find that both GFS and ECM tend to under-read outside of very rare circumstances for the UK. The only overestimations I've seen are night-time minima under snow cover (see e.g. hilly areas in January) and daytime maxima in the presence of extremely dry ground (e.g. the July 2022 record-breaker).

I'd confidently say that 90% of the time the daily maximum for the UK  will be underpredicted by GFS and ECM, whereas UKV is often within a degree or so of the overall daily maximum across the UK, and better at figuring out the regional/local trends as well.

[Daniel*]

Dreadful BH monday here in London improving from tomorrow sadly this weather will not last good agreement for Atlantic westerlies to return next week, second half of May looking iffy at this stage. Notice the -NAO is creeping in more I think the SSW is still having an influence.

Edited May 6 by Daniel*

[Derecho]

 Daniel* Do you think the Scandi high could complicate things? EC OP and the AIFS is quite bullish in bringing the cooler air after next weekend but UKMO and GFS operationals look a bit messy at this stage. 

Probably worth noting that the GFS ensemble mean is more bullish at bringing an Atlantic influence back compared to the OP but there's still quite a few members that extend the warmth past next Sunday.

Edited May 6 by Derecho

[Daniel*]

1 hour ago, Derecho said:

Do you think the Scandi high could complicate things?

Quite sure we had that feature in recent weeks and all it did was slow weather fronts over us.

Things are trending more unsettled… week for 13-20th unsettled especially further south… the pattern that just keeps recurring.

Edited May 6 by Daniel*

[WYorksWeather]

 Derecho Looking at the ECM clusters here.

For days 5-7, slight disagreement over how long any high pressure lasts for. All have it still in place at day 5 (Saturday), all except cluster 3 maintain it to day 6, but decent consensus on a breakdown by day 7.

After that, there seems to be good agreement on a largely unsettled outcome for days 8-10, though there is some variation on exactly how unsettled.

However, the day 11-15 clusters look quite different.

All 3 clusters look unsettled at day 11, but only cluster 1 remains unsettled at day 15. Clusters 2 and 3, which make up two thirds of the ensemble members, return to a settled outcome by day 15.

I think about all we can say at the moment is that on the basis of this you'd expect a cooler and more unsettled pattern relative to this week to kick in by around days 7-8. But there is a big question mark over whether it is a brief unsettled period lasting a few days or something more prolonged. 

[Derecho]

23 minutes ago, Daniel* said:

Things are trending more unsettled… week for 13-20th unsettled especially further south…

Certainly is, if we hold onto the warmth I think it could turn very wet and thundery indeed. I'm leaning towards the cooler Atlantic influence returning early next week though as you say.

[Addicks Fan 1981]

 Derecho what isn't helpful at the moment is the MJO in the COD area, we need for it to be more coherent and stronger, link below.   

Climate Prediction Center - Daily MJO Indices

WWW.CPC.NCEP.NOAA.GOV

 

[Addicks Fan 1981]

 WYorksWeather wish our friend @Tamara was online so she could shed some light on the GSDM budget and all of that and teleconnections to me ought to be noticed even when they can be faulty at the best of times.    

@MattH is also needed to give some balance and i love his detailed posts, a well respected gent who knows his stuff.    

Edited May 6 by Addicks Fan 1981

[WYorksWeather]

Showing how things can change even at relatively short range - GFS 18z fractionally stronger with the high at day 5.

Interesting to see what happens further down the line...

 

Edited May 6 by WYorksWeather

[Addicks Fan 1981]

 WYorksWeather think we need an upwelling kelvin wave to get the weather a bit more neutral, there's still to me very much a niño imprint somewhere down the line.   

The sooner we have that taking place with the east to west QBO changeover the better for our weather moving forward.   

I did see a very interesting video made by @Gavin P on YouTube which I would suggest everyone watches, it is superb, actually i think he has been on form with forecasting including giving very good model analysis and no bias at all.   

[Addicks Fan 1981]

The GFS 0Z seems to be looking OK on Monday of next week 

 

 

 

 

Would probably get some thundery activity out of that 

[northwestsnow]

EC looks warm and thundery this morning ,esp day 9/10..

[Addicks Fan 1981]

 northwestsnow I think judah Cohen hinted on X that we could have a ridge situation to the east with encroaching troughs at times from what he posted and indicated.    

[danm]

Runs this AM do seem to be dropping a trough to our SW for next. Will turn more unsettled relative to this week, but could also be warm and thundery with sunny spells at times too.