Model output discussion - hot spell beckons but then what?

[MATTWOLVES 3]

Im pretty pleased with last night's EC46, definitely signs of an improvement towards the final 10 day's of the month.. High pressure looks to exert more influence from the S/SW.. Temperatures as well look like responding to become quite warm at times with these conditions persisting into September!!! All along way off, but at least the signal is remaining constant. A very good update from the big boys as well. Would be pretty typical to see a major turn around in conditions to coincide with kids going back to school... Quite bizarre how the weather seems to pick its best moments for certain occasions!! So its poor signs for the next 10 day's, then a light at the end of the tunnel further a field!! Oh and take care with tonight and Saturdays extreme winds... Could be potentially dangerous. 

[Frosty.]

Longer term the GEFS 6z mean is looking a lot better (less unsettled) with the azores high / ridge coming more into play towards the end of August.

 

Edited August 9, 2019 by Jon Snow

[knocker]

A quick glance at the last week of August with the ecm weeklies update Looking like the usual NW/SE split with temps varying around average

Edited August 9, 2019 by knocker

[Frosty.]

Here's some GEFS 6z members for late August, very FI I know but there's better signs, it may not happen but the mean does improve as I showed above.

[knocker]

The wind to pick up this evening and overnight in the southern half of the country, particularly the south west/southern coastal areas as the low drifts north east

[knocker]

Take extra care around the south west coasts tomorrow. High tide in Cornwall is early afternoon

[Mapantz]

..and that's a wrap! Back to the norm, please?!

[Methuselah]

And that's 3 straight runs that have suggested a warm, muggy and breezy next Saturday.

   

[feb1991blizzard]

13 minutes ago, Ed Stone said:

And that's 3 straight runs that have suggested a warm, muggy and breezy next Saturday.

   

And wet as well.

[Frosty.]

The Gfs 12z operational isn't looking so bad next week, there's some weak ridging with drier and bright / sunny spells and some showery rain around but it's nothing like as bad as it's looked recently!

Edited August 9, 2019 by Jon Snow

[knocker]

The gfs  medium term mean anomaly has the TPV drifting south of Iceland which would not be particularly good news

[sunnijim]

39 minutes ago, Jon Snow said:

The Gfs 12z operational isn't looking so bad next week, there's some weak ridging with drier and bright / sunny spells and some showery rain around but it's nothing like as bad as it's looked recently!

Another week draws to a close,touted again last week 'as average or below average' and yet again temperatures between 25c and 27c somewhere everyday!

Nothing I have seen  from the models suggests anything other than above average summer values again for parts of the South next week.

[SMU]

22 hours ago, Singularity said:

Am I misinterpreting this, or are you saying that the NAO will be negative because the NAO has been negative? 

I find this a strange manner of logic. Sure, persistence has its value, but that's when major driving forces are changing very little, which isn't expected to be the case for the 2nd half of this month.

Granted, if the tropical cycle was to stall unexpectedly, then we'd be waiting for any descent of (currently strongly above normal) zonal winds from the upper stratosphere to bring about a break from the -NAO regime, which would probably take some time.

To be honest, I'd feel happier about the winter prospects if there were some +NAO phases in Sep/Oct. Having -NAO phases pre-Nov is putting a lot of surplus heat content into the N. Atlantic, which is an unstable situation to be in.

But we had the same discussion 2 months ago when you suggested a change...

In that time many variables have gone full circle or at least changed mode yet still the NAO persists-

So im not saying it will negative forever however thus far since April 26th nothing has changed apart from the level of 'negativity' of the NAO.

Ask yourself this- All current forecasting methods predicting change - including what you use are driven by the interpretation that whatever variable you are using ( IE the MJO ) creates a change of pattern going forward - You then use the MJO analogues to see what fits phase - So for example the GFS foreast says orbit PHASE 4-6 & back through 5 which will have an August Analogue...

Well what if *ALL* your analogues are out of date due to Arctic amplification, so relating to the SST anomalies ( current ) & the variables your using we have created more 'unknown unknowns'

The current times are unprecedented- For the winter forecasts

- Forget the global seasonal models 

- Forget the 'teleconnective' forecasts 

The current SSTas / Arctic Amplifications & polar feedback loops will make it impossible to forecast based on these methods thats are being used- 

Makes this winter very exciting as we can guess what the top levels of the strat will probably do - Decending EQBO + weaker strat vortex due to the sun ... BUT

What does the troposphere have instore... More disconnect & more jet stream amplification..

So back to the original point - 'Current persistence' seems more logical to follow that variable forecast change based on analogues as they could well be out of date....

Edited August 9, 2019 by Steve Murr

[shotski]

13 minutes ago, sunnijim said:

Another week draws to a close,touted again last week 'as average or below average' and yet again temperatures between 25c and 27c somewhere everyday!

Nothing I have seen  from the models suggests anything other than above average summer values again for parts of the South next week.

EPS certainly suggesting the south & south east will be at least a couple of degrees below average next week. 

[Frosty.]

There are again much better signs longer term (at least further south) from the GEFS 12z mean with pressure rising and temperatures rising through late August!

 

Edited August 9, 2019 by Jon Snow

[Frosty.]

And here's what that improved long term mean could..erm..mean!

 

[Methuselah]

Is there a mismatch in this thread?

From what I've been reading, the NAO is a winter phenomenon that oscillates over monthly, yearly and decadal timescales (for much of the 1960s it was negative; through the late 1980s and early 1990s it was mostly positive) and -ive values (during winter) tend to coincide with runs of colder-than-average winters...Its summer values correlate with nothing?

IMO, a three-day 'technically -ive (or +ive) 'index'' does not a NAO make...Rather, it's a transient weather-pattern?

And --- on to the 12Z ensembles:

   

   

Eye wateringly spiffing? No. Eye Wateringly sheet? No. Eye wateringly bland? Perhaps...

[SMU]

@Singularity

The May - July period came in as the most negative ever recorded

Whats very notable here is the distinct change in summertime NAO mode *since* 2007 ( NB 2007 > 2nd highest Record ice loss )

Highest negative peak is 2012 ( highest record ice loss )

Now topped in Negativity by 2019 ...

So when we talk persistence for August at least ..

Negative blocks MJJ years August NAO

2008     -1.16

2009     -0.19

2010     -1.22

2011     -1.35

2012     -0.98

2014     -1.68

2015     -0.76

2016     -1.65

2017     -1.10

( positive years 13/18)

So taking the post 2007 form of 12 years every single year with a Negative MJJ period had a Negative August...

Thats persistence for you.

@Ed Stone

NAO isn't reserved for Winter its an all year round 'measure' - Also its oscillation through Summer has now changed to generally 1 mode ( Negative ) 

You would be correct in assuming that historically the summer 'mode' of the NAO isnt correlated to the Winter- 

however--

* What is correlated is the depth of the phase of the NAO across the seasons IE Climate change is driving pattern change through Arctic Amplification *

The NAO ( & AO ) modes are becoming more extreme promoting extreme heat & some 'mitigating' deep cold .....  

S

 

 

 

Edited August 9, 2019 by Steve Murr

[MATTWOLVES 3]

Quite some discrepancies from the models out to day 6...the GFS 12Z is priming up low pressure to the West, also the GEM bringing in a very unsettled spell next weekend... But just look at UKMO at day 6, pressure looks to be building a little better and the low looks far less devoloped!! Ecm also showing the devoloping low as we approach the latter half of next week... Question is... Will next weekend be a similar scenario to this one... 

[knocker]

Although continuing unsettled with temps a tad below average in the later period of the run, the ecm differs from the gfs in that it is taking the TPV in the Iceland area a fair way east. Need to see what the EPS has to say.

Edited August 9, 2019 by knocker

[Methuselah]

19 minutes ago, Steve Murr said:

@Singularity

The May - July period came in as the most negative ever recorded

Whats very notable here is the distinct change in summertime NAO mode *since* 2007 ( NB 2007 > 2nd highest Record ice loss )

Highest negative peak is 2012 ( highest record ice loss )

Now topped in Negativity by 2019 ...

So when we talk persistence for August at least ..

Negative blocks MJJ years August NAO

2008     -1.16

2009     -0.19

2010     -1.22

2011     -1.35

2012     -0.98

2014     -1.68

2015     -0.76

2016     -1.65

2017     -1.10

( positive years 13/18)

So taking the post 2007 form of 12 years every single year with a Negative MJJ period had a Negative August...

Thats persistence for you.

@Ed Stone

NAO isn't reserved for Winter its an all year round 'measure' - Also its oscillation through Summer has now changed to generally 1 mode ( Negative ) 

You would be correct in assuming that historically the summer 'mode' of the NAO isnt correlated to the Winter- 

however--

* What is correlated is the depth of the phase of the NAO across the seasons IE Climate change is driving pattern change through Arctic Amplification *

The NAO ( & AO ) modes are becoming more extreme promoting extreme heat & some 'mitigating' deep cold .....  

S

 

 

 

I stand corrected, Steve...But this summer has bucked the trend; it's been warmer than usual:

https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/ens-mean/nao-description

Climate Change?

[Weather-history]

GFS 12Z op ends on an ex Charley note. (August Bank Holiday 1986). Thankfully this is at 384hrs and not 48 hrs way.

[SMU]

25 minutes ago, Ed Stone said:

I stand corrected, Steve...But this summer has bucked the trend; it's been warmer than usual:

https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/ens-mean/nao-description

Climate Change?

Depends how long their reanalysis is over -

If they did that say 2007-2019 then that cool anomaly would be replaced by a warmer one for sure!

 

Anyway August almost a write off with NAO extreme negative, only small periods of warm / dry weather when the mode wains a little ..

[knocker]

Perhaps a reminder of this paper might be of interest

Skillful long‐range prediction of European and North American winters

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014GL059637

[Don]

1 hour ago, Ed Stone said:

I stand corrected, Steve...But this summer has bucked the trend; it's been warmer than usual:

https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/ens-mean/nao-description

Climate Change?

Yes it is strange (or perhaps not now?) that after  an extended period of a negative NAO, summer has been warmer than average.  Have the goal posts been moved as a result of Global Warming?