In Depth Model Discussion, Analysis and Summaries

[davehsug]

in short Gavin - no, have a read of the post I did in the model thread?

Hi John. I do agree that in general the 500mb charts are less prone to swing & error than the models, they are however, even given some human input, only as good as the models themselves & we have seen lots of times during past winters (when they have tended to be used most), that they can be just as wrong, particularly of course, the further out you go.

[summer blizzard]

Just a side note, but it looks as though the +QBO peaked in April as lower +QBO values were recorded during May. The collapse into a -QBO from peak is generally quick (3-5 months) and as such i would caution anybody who thinks that we are in for sustained heat now, given that this will have a knock on effect on angular momentum.

Sadly, it looks as though statospheric warming has killed off May and June, and it looks as though collapsing QBO values may kill off summer, particulaly August.

[Alex]

Just a side note, but it looks as though the +QBO peaked in April as lower +QBO values were recorded during May. The collapse into a -QBO from peak is generally quick (3-5 months) and as such i would caution anybody who thinks that we are in for sustained heat now, given that this will have a knock on effect on angular momentum.

Sadly, it looks as though statospheric warming has killed off May and June, and it looks as though collapsing QBO values may kill off summer, particulaly August.

Thanks SB that post has really cheered me up lol! What would be the Predictions for qbo values for July and any analogues SB?

Also what are the mei values indicating SB and again analogues?

Thanks

[summer blizzard]

Thanks SB that post has really cheered me up lol! What would be the Predictions for qbo values for July and any analogues SB?

Also what are the mei values indicating SB and again analogues?

Thanks

Still waiting on the most recent MEI anologues, should have them in the next few days.

The QBO will still be positive but weaking in July, giving a weak signal for a mid-lattiude ridge.

The QBO will go easterly during August or September which does not bode well for late summer.

[tcc]

Still waiting on the most recent MEI anologues, should have them in the next few days.

The QBO will still be positive but weaking in July, giving a weak signal for a mid-lattiude ridge.

The QBO will go easterly during August or September which does not bode well for late summer.

But it does bode well for Winter! :ph34r:

I'll get my coat...

[Summer Sun]

Maybe winter 2011 will be worse than 2010 if we get an Easterly set-up, the country will come to a stand still again and grit will run out. :rolleyes: , lets get summer over before we get talking about winter

[Alex]

Maybe winter 2011 will be worse than 2010 if we get an Easterly set-up, the country will come to a stand still again and grit will run out. :rolleyes: , lets get summer over before we get talking about winter

I agree but you do know that the qbo going easterly has nothing to do with winds around the UK being easterly.

In a nutshell, quasi-biennial oscillation (QBO) is a quasi-periodic oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere.

[Evening thunder]

I saw a link that showed data for the QBD over past many years, but can't seem to find it. It seemed to show that the time for it to fall from values around +10 to negative values varied. I was just wondering, are we sure it will have gone negative by July/August?

Also, surely a negative QBD doesn't automatically mean a poor summer/August, especially if still +ve or recently changed and weak, like it doesn't automatically mean a cold snowy winter?

[chionomaniac]

I saw a link that showed data for the QBD over past many years, but can't seem to find it. It seemed to show that the time for it to fall from values around +10 to negative values varied. I was just wondering, are we sure it will have gone negative by July/August?

Also, surely a negative QBD doesn't automatically mean a poor summer/August, especially if still +ve or recently changed and weak, like it doesn't automatically mean a cold snowy winter?

You are right stormmad26. (It is the QBO though).

The phasing and timing of the QBO waves are far more complex than just suggesting that negative or positive values are likely to give certain types of tropospheric conditions. Remember that the QBO is a phased tropical stratosperic 'wind' that starts at the top of the stratosphere heading down towards the troposphere in a westerly or easterly direction. Each cycle takes approximately two years.

This may affect the polar stratosphere by reducing the westerly flow during winter and perhaps by increasing the easterly flow during summer increasing the likelihood of high latitude blocking. However in my opinion the exact position of the downwelling waves will be all important in the extent of the tropospheric impact. I would say timing looks good for this winter.

Back to the here and now and as Jack Wales correctly points out the stagnant nature of the global circultion could keep the trough close to the UK for a while yet. What we would like to see develop is a strong MJO wave that will shift the GWO and MJO into a new phase. With that we may see a shift in the trough.Until then I suspect more of the same.

c

Edited June 13, 2011 by chionomaniac

[Evening thunder]

You are right stormmad26. (It is the QBO though).

The phasing and timing of the QBO waves are far more complex than just suggesting that negative or positive values are likely to give certain types of tropospheric conditions. Remember that the QBO is a phased tropical stratosperic 'wind' that starts at the top of the stratosphere heading down towards the troposphere in a westerly or easterly direction. Each cycle takes approximately two years.

This may affect the polar stratosphere by reducing the westerly flow during winter and perhaps by increasing the easterly flow during summer increasing the likelihood of high latitude blocking. However in my opinion the exact position of the downwelling waves will be all important in the extent of the tropospheric impact. I would say timing looks good for this winter.

Back to the here and now and as Jack Wales correctly points out the stagnant nature of the global circultion could keep the trough close to the UK for a while yet. What we would like to see develop is a strong MJO wave that will shift the GWO and MJO into a new phase. With that we may see a shift in the trough.Until then I suspect more of the same.

c

Thanks for that reply, interesting stuff. I'm not quite so knowledgeable on some these factors as some on here.

I for one wouldn't mind the forth cooler than normal winter, will certainly be interesting if we get one.

Not sure why I put 'QBD' in my post though as I knew in the back of my head the last word was oscillation :lol:

[feb1991blizzard]

I saw a link that showed data for the QBD over past many years, but can't seem to find it. It seemed to show that the time for it to fall from values around +10 to negative values varied. I was just wondering, are we sure it will have gone negative by July/August?

Also, surely a negative QBD doesn't automatically mean a poor summer/August, especially if still +ve or recently changed and weak, like it doesn't automatically mean a cold snowy winter?

Here is the QBO data since 1948.

http://www.esrl.noaa.gov/psd/data/correlation/qbo.data

[Uncle_Barty]

And with the MJO having moved into weak phase 4 and then smartly back to the centre ("neutral"? whats the correct terminology?), I guess we won't be seeing a change any time soon.

How often is the GWO chart updated? Last update was the 8th.

[Bale]

Recent observations have given me some potential concerns about us experiencing a hot & dry type summer (June especially). This being due to the current (La Nina) atmospheric base state, characterised by a mid Atlantic ridge and a NW to SE Jet stream over the UK. This is proving somewhat reluctant to displace despite the ever weakening La Nina in the Pacific.

Lets look at the SST profiles for 8th May and 22nd May below…

You will note that La Nina pattern has continued to weaken with positive anomalies observed migrating westwards into the key Nino 3.4 region. Although on the down side the Atlantic sst profile is far less favourable than it was at the beginning of the month. Look how the warm anomalies over Western Europe have retreated over recent weeks. This IMO could encourage the jet stream towards the UK.

Finally the Southern Oscillation Index has switched positive again, indicating an increased presence of Easterlies over the tropical Pacific which could inhibit any change to the atmospheric base state, in the short term at least. Here are the daily SOI archives back to 1999 (note how 2003 and 2006 summer period recorded strongly –ve values).

SOI

What concerns me is that I believe in the last couple of weeks of May, the summer pattern begins to emerge and summer really does start to ‘show its hand’. The weather models are clearly having difficulty with the current pattern hence why any settled synoptics keep getting pushed further back into FI.

I’d love to be corrected on my interpretations but as I set it, the overall global pattern is far less clear cut than it was maybe 2 -3 weeks ago and to me a La Nina type summer cannot be ruled out, especially for June. Having said that, I recognise that we are still in May and with the ever diminishing –ve ENSO sst pattern, there is a lot that can change over the next few months so maybe its not all doom and gloom!!

An excellent post...hats off to you,also Glacier Point's predictions/interpretations.

Around the same time as Glacier Point was predicting a pretty good june the met office from what i can recall were in tandom with Glacier Points predictions analysis of above average temps/below average rainfall in their extended outlook a few weeks back...lets just hope the jet drives well to our north soon...although on current output it dosent look like happening ( bar a couple of days ) and thats not nailed on cause its too far out tbh

[BLAST FROM THE PAST]

The Atlantic has the most cold anomalies that I have seen for some time. It reminds me of 2 or 3 years ago when ther was a mirroring of the Pacific with a 'reverse' c. The -ve NAO tendency remains in place which is not conducive to good summery weather. I can't see a break coming/change of pattern until June is through and then I ain't convinced [YET] early July will bring the goods.

BFTP

[Alex]

I would so far put this June similar to 2008, I don't think June 08 was a washout but the rest of the summer was pretty awful. I did worry with the analogues tracking 76, 08 and a few others, they are all at different ends of the spectrum and nothing in the models are suggesting any sudden changes.

[johnholmes]

.

welcome Paul I'm sure you will enjoy all that Net Weather has to offer, lots on the site away from the forum, actual data, model output etc as well as forecasts

thanks for the kind comment by the way.

I'm sure the kind mods will help you if you have any problems posting, just ask if you would like them to help you out.

[Uncle_Barty]

Solar activity now is a little higher than it was in 1975/6........ I've never placed much store on solar activity versus weather patterns. July 1988 for example came at a time of high solar activity, as did the winters of 78/9 and 1981/2.

[johnholmes]

yes, as observer and forecaster for the last 23 years, thanks for the kind comment and welcome to Net Wx, lots of good things and have a look around the site, ask questions, someone is bound to be able to answer you-well usually.

[Summer Sun]

GP hasn't been around for a while, but i'm sure a lot of us would like to here is views for the coming week, Also welcome to the Netweather forums.

[Kentish Kiwi]

Any word on that westerly wind burst GP was discussing at the start of the month? I believe it was meant to be making an appearance around this time...

[jonboy]

Solar activity now is a little higher than it was in 1975/6........ I've never placed much store on solar activity versus weather patterns. July 1988 for example came at a time of high solar activity, as did the winters of 78/9 and 1981/2.

Those periods where at the bottom of cycle 20 not as at present when we are supposed to be at the Max of cycle 24. If this is the max of this cycle what will the bottom bring us I wonder?

[Uncle_Barty]

MJO now generally forecast to move into Phase 2 by early July....

Composite anomaly chart looks more encouraging for something more summery perhaps? Chiono?

[Bale]

I wouldn't too concerned, indeed, the pattern at present is a very good precursor and I would be more worried if we were getting blistering heat. Think of May as the same as November, Ice in November and ducks and all that !

The SOI has shifted positive in line with a weakening MJO wave and general scrubbing of westerlies from the atmospheric circulation as a result of the strong increase in westerlies on the back of the MJO which reached high amplitude in the last few weeks. We should see a general falling back in angular momentum over the next 2-3 weeks before the next westerly wind burst is due to start somewhere around the 10th June tied into the MJO booting up again.

The falling back in angular momentum should help shift the upstream ridge to the eastern US and displace the mean trough into the Atlantic allowing for the ridge to develop over Europe. The evolution to Scandinavian ridge needs the rise in pressure over Europe to happen first. Keep any eye also on pressure just west of Greenland as this should begin to fall over the coming week to 10 days which also teleconnects to pressure rise over Europe.

The presence of a ridge in the Atlantic is a good fit for phase 8 GWO / MJO type pattern but crucially this changes with the seasonal wavelength to more of a trough regime the longer time passes - a really nice example of how seasonal wavelengths can change a pattern.

The Atlantic SSTs still look to have a troughing profile particularly those within the sub-tropical area which is the key one.

looking at the latest sypnotics,maybe a little later than expected but i am noticing what you have described starting to unfold,regarding pressure to drop west of greenland/ and high pressure out to our east introducing a southerly/south easterly flow

[chionomaniac]

MJO now generally forecast to move into Phase 2 by early July....

Composite anomaly chart looks more encouraging for something more summery perhaps? Chiono?

My feeling has always been that unless we see a major shift or change in direction in the MJO then things will slowly start to improve as we enter July due to the seasonal longwave change - as seen in the phase 2 anomaly chart. I don't think that there will be a dramatic pattern change - more likely a slow transitional type change with ridging slowly giving up residence over Greenland and the jet stream slowly tracking further north and weakening. No major ridging over the UK though just yet, but warmer and drier the further south and east one is.

[lorenzo]

Okay what happened here on or around June 18th,

Pretty much a discernible pattern from March aside from April wobble.

Then mid June the pattern breaks and shoots off on a tangent.. anyone... >>>?