Model Output Discussion

[Buzzit]

forgive my not understanding but what is this meant to mean please

phase backwardation

Sorry - I will edit the post I basically mean reverting back to Phase 3,2,1 rather than hanging around 3,4,5. It is not a term I should of used

[johnholmes]

Sorry - I will edit the post I basically mean reverting back to Phase 3,2,1 rather than hanging around 3,4,5. It is not a term I should of used

thanks for that B

[bluearmy]

Current MJO output is currently looking positive and condusive to assisting with the % probability of summer weather for the UK. UK Met is currently wanting to reduce amplification and revert back to Phase 1 more quickly and may a general part indicator of why the UK Met output is at odds with GFS and ECM at the end of the output we see

ECM

GFS

UKM

no idea if i'm right but i would maintain that the very low amplification shown in those forecasts will have little bearing on what patterns we see this side of the planet.

[Mark Bayley]

no idea if i'm right but i would maintain that the very low amplification shown in those forecasts will have little bearing on what patterns we see this side of the planet.

That's what i was thinking, would be interested to hear from the experts!

[Thundery wintry showers]

The NOAA's 8-14 day plots have consistently placed the high pressure further and further east with each update. I'm now feeling that there's a significant chance of a spell of warm dry sunny weather affecting most parts of the country towards the end of July, with the high pressure getting far north and east enough to prevent too many issues with banks of cloud, but its duration is uncertain. I'm not envisaging a major heatwave but temperatures widely into the mid 20s is a distinct possibility.

However, I only say "significant chance" as the model consensus could quite easily U-turn at this sort of range.

[Costa Del Fal]

ECM is particularly impressive right now with the GFS quite good too. My optimism shall be reserved till when or if the UKMO comes on board which still looks rather shabby. We shall wait and see but if the ECM comes off some very warm pleasant conditions are possible and would edge towards my earlier thoughts to a spell of very good weather at the end of July.

Nothing set in stone yet, mainly due to the UKMO not properly being in the party mood yet but if it does then a settled few days at least should be ahead.

[AWD]

What's everyones perception on the duration of the probable settled spell approaching us?

Whilst a few nice warm days would be nice, it wouldn't really make me jump for joy! I'm hoping for a couple of weeks of nice warm sunny weather to enjoy!

[Weather Boy]

Is it just my local experience or did (temperature wise at least) the models massively over-do this unsettled spell?

For example I logged 21.1 C yesterday. It's similar today. That would have been totally out of the question based on the model output we saw at the end of last week. Even the forecast for yesterday was saying 20C at the very most in Central London.

If this premise is right (and I'd be pleased to hear if others agree) what does that tell us for the current output we're seeing? Maybe nothing, or does it mean that the models have been consistently over-doing the Low and the provenance of the airmass impacting on temperatures? Maybe TWS's comments about cold air mixing out have relevance.

[Buzzit]

no idea if i'm right but i would maintain that the very low amplification shown in those forecasts will have little bearing on what patterns we see this side of the planet.

Hi : I Would never profess to been an expert , but my understanding is that ultimately the MJO does affect the EPO and WPO which in turn affects the AO and the NAO and therefore affects the 500mb height pattern & anomalies. knee bone connected to the thigh bone etc... I hope someone tells me Im an idiot if Im wrong.. The amplification doe snot need to be dramatic for the upstream effects to occur

Sort of related - If you were a pattern matcher you would probably think we are due a generally postivie NAO till the end of the year

Edited July 19, 2011 by Buzzit

[johnholmes]

for those like me who have difficulty remembering these abbreviations

EPO=Eastern Pacific Oscillation

perhaps someone will enlighten me and others as to what WPO is - maybe Western ?

Use of these teleconnections is, at best, very difficult to link to effects in this part of the world , at worst near enough impossible.

Edited July 19, 2011 by johnholmes

[Polar Maritime]

for those like me who have difficulty remembering these abbreviations

EPO=Eastern Pacific Oscillation

perhaps someone will enlighten me and others as to what WPO is - maybe Western ?

Use of these teleconnections is, at best, very difficult to link to effects in this part of the world , at worst near enough impossible.

AO - The Arctic Oscillation

NAO - The North Atlantic Oscillation

PNA - The Pacific North American Oscillation

EPO - The Eastern Pacific Oscillation

WPO - The Western Pacific Oscillation

MJO - The Madden-Julian Oscillation

PDO - The Pacific Decadal Oscillation

NPO - The North Pacific Oscillation

AAO - The Antarctic Oscillation

QBO - The Quasi-biennial Oscillation

All of these teleconnections, plus MANY more that are minor or are simply NOT yet known, are pebbles and rocks dropping into the fluid atmosphere. Each one has positive, neutral, and negative phases, and each one impacts the atmosphere via waves rippling outward from their regions of origin.

Hope this helps John.

Edited July 19, 2011 by snowrob

[chionomaniac]

no idea if i'm right but i would maintain that the very low amplification shown in those forecasts will have little bearing on what patterns we see this side of the planet.

My reading on this is that a reduced amplitude MJO phase would have a reduced correlation with any linked phased anomaly chart. After all we are talking about the prevalence and position of tropical convection and if this wanes in any particular phase then one would expect the H500 anomaly chart to wane as well. However, ba as you suggest, this would occur in the absence of other extratropical influences (eg mountain torques) and any strong extratropical influences could easily overide any low amplitude MJO phase.

I think that the next strong amplitude MJO wave will be critical in determining whether that Azores Ridge will stretch our way or not, otherwise the weak Scandi trough long wave will prevent the Azores ridge from quite making it - a halfway house in affect.

[Buzzit]

for those like me who have difficulty remembering these abbreviations

EPO=Eastern Pacific Oscillation

perhaps someone will enlighten me and others as to what WPO is - maybe Western ?

Use of these teleconnections is, at best, very difficult to link to effects in this part of the world , at worst near enough impossible.

My observation is that WPO and EPO changes often are a precusor to AO and NAO moving in the same direction as the WPO and EPO change

[johnholmes]

My reading on this is that a reduced amplitude MJO phase would have a reduced correlation with any linked phased anomaly chart. After all we are talking about the prevalence and position of tropical convection and if this wanes in any particular phase then one would expect the H500 anomaly chart to wane as well. However, ba as you suggest, this would occur in the absence of other extratropical influences (eg mountain torques) and any strong extratropical influences could easily overide any low amplitude MJO phase.

I think that the next strong amplitude MJO wave will be critical in determining whether that Azores Ridge will stretch our way or not, otherwise the weak Scandi trough long wave will prevent the Azores ridge from quite making it - a halfway house in affect.

as ever ch a sensible look at what may happen-I cannot see how minor amplitude PREDICTED changes in the MJO can have any marked impact on what is going to occur in our neck of the woods. But as I've often posted the linkage is often hard to put in the correct perspective and pick which teleconnection is having the most impact at any particular time.

thanks also to snowrob for the acronym list and their meanings. Most of them I'm familiar with as I attempt to do my lrf outlooks, well lrf's in the sense of the next 3-4 weeks. Beyond that I leave it to others.

Edited July 19, 2011 by johnholmes

[Thundery wintry showers]

The MJO forecasts suggest a brief spell around phases 1 and 8 at the back end of July but the composites for July and August from those phases are very mixed. Phase 1 has low pressure for July and northerlies with an Atlantic block for August, while Phase 8 has high pressure for July and low pressure for August. Thus the MJO isn't making it any clearer to me what will happen with that ridge from the Azores High, it's all educated guesswork for now!

[Summer Sun]

The ensemble charts show the pressure rise quite nicely from next week, still time for things to change though.

http://nwstatic.co.uk/ensimages/ens.20110719/06/prmslAberdeenshire.png - http://nwstatic.co.uk/ensimages/ens.20110719/06/t2mAberdeenshire.png

http://nwstatic.co.uk/ensimages/ens.20110719/06/prmslLondon.png - http://nwstatic.co.uk/ensimages/ens.20110719/06/t2mLondon.png

[Cecil Hogmanay Melchett]

Looks like UKMO is not going to back down on this.

Absolutely no sign of anything remotely settled again this evening and for my money gfs has inched towards the metmodel on the 12z run.

Theres always 1 fly in the ointment and historically speaking when its ukmo theres only 1 outcome.(A climbdown by the others).

[Summer Sun]

As per ECM GFS show's the pressure rising from next week,

http://www.wetterzen...s/Rtavn1741.png

http://www.wetterzen...s/Rtavn1921.png

http://www.wetterzen...s/Rtavn2161.png

As August arrives the pressure is shown to drop slightly

http://www.wetterzen...s/Rtavn3361.png

http://www.wetterzen...s/Rtavn3601.png

ECM will be interesting tonight, hopefully it will continue on from last night and this morning.

Edited July 19, 2011 by Gavin D

[Guest]

It's just one run. Although i want to swear and set fire to the Met office HQ I'm still confident of a settled end to this month.

Not tempting fate, but I feel the nail in the coffin will be cross model agreement on this backtrack, and until that happens, I'm staying hopeful

[Evening thunder]

Looks like UKMO is not going to back down on this.

Absolutely no sign of anything remotely settled again this evening and for my money gfs has inched towards the metmodel on the 12z run.

Theres always 1 fly in the ointment and historically speaking when its ukmo theres only 1 outcome.(A climbdown by the others).

Does one model out of 3 showing a slightly different evolution really mean 'absolutely no sign of anything remotely settled' Most of the 12Z data still to come but the GFS/ECM ensembles and operationals showed plenty of signs this morning that there may be warm settled weather in the future. Not certain at all of course but there are definitely 'signs' of this being a possible option.

To anyone who hasn't looked at the charts your post may sound more like there are deep lows stuck over us constantly on all 3 models..

Anyway there doesn't even have to be a warm high overhead for it to be 'settled'

The UKMO isn't the be all and end all, but if this possible spell doesn't materialise I can understand it being very frustrating for some (me included)

Edited July 19, 2011 by Stormmad26

[Cecil Hogmanay Melchett]

Does one model out of 3 showing a slightly different evolution really mean 'absolutely no sign of anything remotely settled' Most of the 12Z data still to come but the GFS/ECM ensembles and operationals showed plenty of signs this morning that there may be warm settled weather in the future. Not certain at all of course but there are definitely 'signs' of this being a possible option.

To anyone who hasn't looked at the charts your post may sound more like there are deep lows stuck over us constantly on all 3 models..

Anyway there doesn't even have to be a warm high overhead for it to be 'settled'

The UKMO isn't the be all and end all, but if this possible spell doesn't materialise I can understand it being very frustrating for some (me included)

Couple of points..

UKMO *IS* an unsettled run,and is backed up by the meto 15dayer today.

There doesn't have to be deep lows to be stuck over us as you put it for it to be unsettled.

GFS/ECM are very warm settled runs but as someone who has watched models for years and years my experience is that the other 2 will fall into line when the 3 disagree majority of the time.

I'll bet my bottom dollar ecm looks much mroe like ukmo this evening.

[Guest]

Couple of points..

UKMO *IS* an unsettled run,and is backed up by the meto 15dayer today.

There doesn't have to be deep lows to be stuck over us as you put it for it to be unsettled.

GFS/ECM are very warm settled runs but as someone who has watched models for years and years my experience is that the other 2 will fall into line when the 3 disagree majority of the time.

I'll bet my bottom dollar ecm looks much mroe like ukmo this evening.

I'd be very surprised if it did. You may say that the other two will fall in line, and that can, and might still happen. However the fact is two models are in agreement, one is not.

Also, and I'm not splitting hairs here, but the MetO 15 dayer looks alright to me, suggesting settled conditions building from the southwest, with a return to average or above average temperatures and settled weather for much of England and Wales.

Now to me that seems more in line with GFS and ECM...

[January Snowstorm]

Slight backtrack again tonight

The gfs has the high pressure cell barely ridging over us and never quite properly for early next week.

ECM will be key but so far you would have to back the form horse all Summer, being the azores high unable to move in properly.

Very frustrating that we cant get a decent bit of weather. Let's hope the ECM agrees with this mornings run!

Edited July 19, 2011 by January Snowstorm

[Backtrack]

Couple of points..

UKMO *IS* an unsettled run,and is backed up by the meto 15dayer today.

There doesn't have to be deep lows to be stuck over us as you put it for it to be unsettled.

GFS/ECM are very warm settled runs but as someone who has watched models for years and years my experience is that the other 2 will fall into line when the 3 disagree majority of the time.

I'll bet my bottom dollar ecm looks much mroe like ukmo this evening.

Well of course the Met Office 15 day forecast is going to look like their model, because they base the forecasts on that model!

[mushymanrob]

I must be looking at something else this morning to Mushy, the settled spell begins this weekend and is now looking reliable. The progression north east of the azores high settles nicely across the country by 216 with 15 850's suggesting hot weather. Fi yes but its a plausible run and the gfs has counted down to this weekend from 240 very consistently in my opinion.

as anyweather replied, chances of high pressure developing are slim whilst predicted high pressure often gets degraded closer to the event... plus ....

Mushy,are you looking at the same 0z ECM run?

As far as nothing hot is concerned i'll have you a wager ecm 0z would produce high 70's low 80's if it came off.

The only problem this morning is UKMO which is having absolutely none of it.

Well i guess he's siding wit the ukmo 0z run which is poor,to be fair.

.... i expect IF the ecm came off, there would be the problem of cloud, only the other august (04?05?06? memory lets me down) there was alot of high pressure sited just to our west, this produced (here at least) a cloudy sun-less lengthy spell. atlantic high = moisture in its circulation = possible problem with cloud.

The NOAA's 8-14 day plots have consistently placed the high pressure further and further east with each update. I'm now feeling that there's a significant chance of a spell of warm dry sunny weather affecting most parts of the country towards the end of July, with the high pressure getting far north and east enough to prevent too many issues with banks of cloud, but its duration is uncertain. I'm not envisaging a major heatwave but temperatures widely into the mid 20s is a distinct possibility.

However, I only say "significant chance" as the model consensus could quite easily U-turn at this sort of range.

ive just seen those too ... but as john said only yesterday, he views several runs before making a judgement upon them. atm the anomoly charts are only good for 1 run, if they are similar in a few days time then the current gfs (12z) which shows alot of high pressure dominance close by might have some weight to it..

cautious optimism... something might just evolve....