Model Output Discussion - mid Autumn

[Cheshire Freeze]

1 minute ago, WYorksWeather said:

I'm not sure about the lack of extreme temperatures at the surface. Those ECM 850hPa anomalies are pretty extreme for the time of year, widespread +10C:

It's enough for temperatures like this on the last four frames from T+222 to T+240:

   

Spot maxima in the high teens, meaning that in practice accounting for model bias you are looking at temperatures probably scraping into the 20s.

 

But there's a dry, continental undercut...which at this time of year means lower dewpoints and cooler ground temperatures. If there was a TM source to the air then fair enough, but there isn't.

By mid October you can't just equate high 850s to high 2 metre temps.

[Metwatch]

4 minutes ago, WYorksWeather said:

I'm not sure about the lack of extreme temperatures at the surface. Those ECM 850hPa anomalies are pretty extreme for the time of year, widespread +10C:

Spot maxima in the high teens, meaning that in practice accounting for model bias you are looking at temperatures probably scraping into the 20s.

They are fairly warm, but mostly mid teens which is still not really close to date records, where that's all at 22C or above up to the 25th.

Edit: As Cheshire mentioned above, and was going to say myself, you also have inversions and undercuts with south easterlies this time of year.

Virtually all the date records set below, were very likely under southerlies - south westerly winds.

Edited October 11, 2023 by Metwatch

[Cheshire Freeze]

This shows it well. You can quite clearly see the undercut there despite the high 850s

[WYorksWeather]

 

5 minutes ago, Metwatch said:

They are fairly warm, but mostly mid teens which is still not really close to date records, where that's all at 22C or above up to the 25th.

Edit: As Cheshire mentioned above, and was going to say myself, you also have inversions and undercuts with south easterlies this time of year.

Virtually all the date records set below, were very likely under southerlies - south westerly winds.

One of the charts I posted though does have a spot 18C. I'd put money on the fact that given ECM usually underestimates, that's going to scrape 20-21C in practice.

Close enough I think to challenge date records, as a tiny shift could get us there. Agreed that date records are probably unlikely to fall with these charts as it stands.

I do wonder though what the latest +15C isotherm is. I remember reading that +18C earlier this month was a record breaker, so not sure what the highest is by late October. It would have to be close though.

[Metwatch]

5 minutes ago, WYorksWeather said:

I do wonder though what the latest +15C isotherm is. I remember reading that +18C earlier this month was a record breaker, so not sure what the highest is by late October. It would have to be close though.

Probably this or 2014 Halloween

Edited October 11, 2023 by Metwatch

[Cheshire Freeze]

Just now, WYorksWeather said:

 

One of the charts I posted though does have a spot 18C. I'd put money on the fact that given ECM usually underestimates, that's going to scrape 20-21C in practice.

Close enough I think to challenge date records, as a tiny shift could get us there. Agreed that date records are probably unlikely to fall with these charts as it stands.

I do wonder though what the latest +15C isotherm is. I remember reading that +18C earlier this month was a record breaker, so not sure what the highest is by late October. It would have to be close though.

You won't get record breaking temperatures later in October with a wind that is east of south. Purely because the land cools much quicker than water. Long nights now mean that ground loses heat quickly overnight, dew points are low and the airmass just won't have the characteristics to support heat when it's of a continental source.

A southerly or SSW'ly that has some TM characteristics will hold more water vapour...this means dew points are higher and the airmass will be less affected by overnight cooling. 

[WYorksWeather]

2 minutes ago, Metwatch said:

Probably this or 2014 Halloween

2014 Halloween just about gets there if you squint at it - barely grazes the far SE coast by my reckoning.

[WYorksWeather]

2 minutes ago, Cheshire Freeze said:

You won't get record breaking temperatures later in October with a wind that is east of south. Purely because the land cools much quicker than water. Long nights now mean that ground loses heat quickly overnight, dew points are low and the airmass just won't have the characteristics to support heat when it's of a continental source.

A southerly or SSW'ly that has some TM characteristics will hold more water vapour...this means dew points are higher and the airmass will be less affected by overnight cooling. 

This overnight airmass from reanalysis was enough for the date record the following day. You're right it is a bit more SSW based.

However, I think that if we're getting raw output at 18C meaning a true maxima of likely 20-21C, it's not out of the question that a slight shift could give us some date record maxes.

Record minima are perhaps more likely though I would have thought.

In any case, probably better to start talking about record-breaking potential if indeed there is any a bit closer to the time - probably getting a bit carried away! The ECM was quite a bit higher than its mean towards the end, so probably the more likely outcome is mid teens, which is still pretty mild for late October.

[Rain All Night]

I do wish that this low pressure influence that has been favoured by the ECM would 'do one'...

The latest ECM deterministic run wouldn't even have us wait until the Scandi high is in place for some unwanted LP interference!

Partly for my own reassurance, here is the ECM deterministic alongside the three machine learning models, all showing their T+240h frames (by which point the Scandi high is in place), showing that the machine learning models don't seem to agree - for now - that I will be getting wet:

The Google model (GraphCast) even seems to agree with the GFS about an easterly!

Edited October 11, 2023 by RainAllNight

[WYorksWeather]

GFS has pretty much caved to ECM on the 18z. 12z vs 18z comparisons below.

At T+120 and T+114 there's not much change.

 

But at T+168 and T+162, the 12z as previously mentioned fires the mild air into the Atlantic, but the 18z scores a hit in similar fashion to the ECM 12z.

 

And at T+240 and T+234, the 12z is still cold, but the 18z is very mild and again, much closer to ECM than it is to the 12z GFS.

 

 

 

[Metwatch]

13 minutes ago, WYorksWeather said:

GFS has pretty much caved to ECM on the 18z. 12z vs 18z comparisons below.

At T+120 and T+114 there's not much change.

 

But at T+168 and T+162, the 12z as previously mentioned fires the mild air into the Atlantic, but the 18z scores a hit in similar fashion to the ECM 12z.

 

And at T+240 and T+234, the 12z is still cold, but the 18z is very mild and again, much closer to ECM than it is to the 12z GFS.

 

 

 

Seems like the GFS joins the pack at least for tonight, with all main runs showing milder airmass arriving next week. Might be all different tomorrow again though, who knows.

However on the surface, temperatures would remain quite average, with low teens by day into central and southern areas.

One thing's for certain is that we're back to high pressure from this weekend until at least mid next week. Might be a boring spell for October, but at least it's not impactful in terms of flooding!

Edited October 11, 2023 by Metwatch

[northwestsnow]

EC46 has some kind of scandy block

which migrates west week 2 

similar to UKMET LRF..

Edited October 11, 2023 by northwestsnow

[summer blizzard]

While it is theoretically possible to sustain a perverse outcome of mild southerlies, I don't see the model support for that to sustain as things stand. 

While subject to change, the two key things by day 9 on the GFS, GEM and Euro are..

1) They all shift the vortex away from the Atlantic as they ride our block north, eventually they'd dump into Russia. This basically reduces pressure on our block.

2) By day 9, they all have a second low by the Azores putting energy into the southern stream. So long as you don't have weird GFS style fizzle out then it's likely to either undercut or encourage the high to retrogress. Either outcome is good in our bid for surface cold and frosts. 

So long as the modelling does not change drastically then yes, it would suggest that the Euro weeklies were right for week 2.

[Kirkcaldy Weather]

"Does make logical sense as we'll see a re emerging direction of the MJO between Africa and the Pacific 

I'm eagerly awaiting the approach into Halloween  be looking particularly toward the patterns getting retrogressive in nature with scope for further blocking which looks to have the opportunities of origin towards Scandinavia, should we have the elongation of troughing also retrogressive across the UK toward the Atlantic with enough cold air come week one of November I can forsee business in this thread "

Very cool to look back at how the November into December 2010 got underway I don't think anyone has actually studied the main factors back 13 years ago with Rossby Waves not being as widely understood certainly I was still in the beginning into my passion filled meteorological journey

Starting with the MJO which was quite akin to our situation now with Oct being similar within the Pacific, and alternate Pacific / West Hemisphere and Africa during November 

 

Looking at the pattern does seem there was at least an initial significant RWB which started the developing trend for the Italian cyclonic conditions 

With 2010 being a Ninà the Atmospheric state would be somewhat different noteably in the Pacific though we definitely are watching a similar route to the aforementioned exciting outputs.

Let's see the signal for the MJO phases 7 & 8 through October via JMA

• Active West Pacific signals [super typhoon Bolaven]
• Californian >> Mexican cyclonic pattern. Major Hurricane Lidia plus Tropical Storm Max. Also the potential next Rossby Wave via Bolaven into new California Cyclonic conditions 
• Build of pressure through the UK and Scandinavia which transpires as the Rossby Wave within Atlantic continues its progression further East

'be looking particularly toward the patterns getting retrogressive in nature with scope for further blocking which looks to have the opportunities of origin towards Scandinavia"

should we have the elongation of troughing also retrogressive across the UK toward the Atlantic with enough cold air come week one of November I can forsee business in this thread "

JMA with phase 8 

• Retrogression underway via Scandi --- Greenland
• Italian Cyclone
• Troughing through southern US ie GOM
• Deep Russian Troughing

My goodness me that is literal perfection 

Evolution from 2018

 

Output upcoming 

Remember the wording I made previously 'should we have the elongation of troughing also retrogressive across the UK toward the Atlantic with enough cold air'

Just to reiterate incase anyone tries to imply that I called for a super early Beast that's not correct HOWEVER the meteorological dynamics involved are already shaping up as classic as can get for the run in to Halloween to provide lots of meteorological tricks and potential treats  

mother nature be like 

 

[Ali1977]

Hello everyone, It’s nice to be back - there’s  lots of blocking showing up in a phase that’s usually all about the ramping up of the PV - FI on the latest GFS would be a nice place to be heading into early November for us coldies!!

 

[sheikhy]

7 hours ago, WYorksWeather said:

GFS has pretty much caved to ECM on the 18z. 12z vs 18z comparisons below.

At T+120 and T+114 there's not much change.

 

But at T+168 and T+162, the 12z as previously mentioned fires the mild air into the Atlantic, but the 18z scores a hit in similar fashion to the ECM 12z.

 

And at T+240 and T+234, the 12z is still cold, but the 18z is very mild and again, much closer to ECM than it is to the 12z GFS.

 

 

 

Seems to be back to cold this morning with a mammoth scandi high!

[minus10]

Yes spoit this morning with a scandi then Greenland high...

..easterly cold pool as well !!

[Scorcher]

35 minutes ago, sheikhy said:

Seems to be back to cold this morning with a mammoth scandi high!

The ECM hasn't moved at all though. I know where my money is in a situation like this...

[sheikhy]

19 minutes ago, Scorcher said:

The ECM hasn't moved at all though. I know where my money is in a situation like this...

Yup defo ecm always but i would like the gfs to be right on this occassion!!!!no more warmth im ready for frost and cold and eventually snow!!

[Scorcher]

3 minutes ago, sheikhy said:

Yup defo ecm always but i would like the gfs to be right on this occassion!!!!no more warmth im ready for frost and cold and eventually snow!!

Your time will come for that but I don't think it's going to happen yet.

The odds are very much against the GFS scenario in FI. It keeps throwing up these op runs that are well below the mean.

 

[IDO]

According to the GEFS, the GFS ops in a smaller cluster, but low confidence in the GFS because of the apparent divergence:

 

One to watch to see where the models go...

[Rain All Night]

ECM's T+168h chart looks particularly unappealing compared to the others this morning...

It's better by T+240h, but the trough to our west/southwest still bothers me...

ECM for my south coast location...

Edited October 12, 2023 by RainAllNight

[Anthony Burden]

Good morning,ECM staying solid keeping a milder scenario in the medium term after a few colder days while GFS beginning to follow.Still GFS is continuing with the pressure rise to the north east not sure if that will occur in fantasy island but never say die.

 

[johnholmes]

Thursday 12 October and another look at NOAA and ECMWF 6-14 days from now

Noaa has a marked build of heights  over Scandinavia since Sunday’s chart; the main trough is now over and south of Greenland with a very slack S’ly flow into the UK. The pattern remains much the same on the 8-14 chart with +ve heights showing around 180 DM over the western coast of Norway. This evolution is similar to that from ECMWF with it showing a surface central pressure of  1034 MB just off southern Finland. So it would seem a spell of mostly dry weather with cloud amounts rather variable giving many sunny spells at least with clear spells

overnight=around normal temps by day and rather cold at night with frost in areas away from coasts. Obviously detail will come from the synoptic models over the period=6-14 days.

sorry missed this off about 850's

The 850’s suggest temps below average at the start but rising a bit above by the end, especially southern areas

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

Edited October 12, 2023 by johnholmes
missed a sentence off

[ANYWEATHER]

40 minutes ago, Anthony Burden said:

Good morning,ECM staying solid keeping a milder scenario in the medium term after a few colder days while GFS beginning to follow.Still GFS is continuing with the pressure rise to the north east not sure if that will occur in fantasy island but never say die.

 

I've seen gfs and ecm falter time and time again over Scandi high development over the years. As I said before its the shape of that high which will allow  the UK either get cold or mild weather......I think it's 50/50 at the moment .....!☺