[Model Output Discussion - 15th March onwards]

56 minutes ago, plymsunshine said:

Because things are shifted further west, southerly air drawn up by the low once again finds itself going straight over the UK and we're looking at a setup similar to the second week of June.

 

57 minutes ago, plymsunshine said:

00z op is very much on the warm side of the ensembles at this period, so it's wise to not consider it too much yet. What is encouraging is that quite a few members join it in being warm after around the 7th. The mean 850s and SLP improve drastically around this time:

 

Which suggests a strong signal for improvement on the cards for the second week of July? So this more unsettled spell could be short lived after all. Far from anything being confirmed but the trend is there and it's a pretty good one!!

This is good analysis based on this numerical model evolution & matches previous diagnostic summaries of late which suggested not getting too embroiled in the NW European trough scenario sticking around for the long term.

Though in the extended period, the precise timing of this is less important than the trend towards it over the coming 10 to 15 days. The latter is consistent with the re-setting of the summer default pattern, which as you say, is reminiscent of what was seen from the second week of June. I would trust in this trend getting increased support in numerical modelling as a whole in the coming days. 

From my point of view such an evolution is equally welcome as it dislodges the excess heat from the Iberian peninsula, trapped under the Atlantic/Azores ridging,  and  that surplus heat is eventually advected further north and east which in turn improves the prospects for UK/NW Europe. Less anomalously hot down here in this part of the Iberian peninsula equates to ideal outdoor summer weather as the middle daylight hours have prohibited doing much since late last week.

[Model discussion highlights]

4 hours ago, Djdazzle said:

It does show just how useless the signals can be. Wasn’t July meant to be HP dominated?

July hasn't happened yet. Numerical models that produce seasonal outlooks will provide a smoothed out representation of a dominant default pattern and will not account for periods within that season where the atmospheric circulation has a re-set/re-balance.   Such a re-balance is emphatically advertised at present.

The Spring saw an extraordinary amount of westerly inertia added to the atmospheric circulation with vigorous propagation of +AAM wind-flow eddies from the tropics into the extra tropics. This highly Nino-esque forcing resulted in a strong sub tropical jet from the Pacific downstream into the Atlantic, transferring considerable strength through the Hadley cell.

Such one way impetus is unsustainable ad infinitum. Like a vacuum operates, when such immense power is relaxed, a correction to fill that atmospheric circulation vacuum must occur & is correspondingly proportionately strong the other way to balance the global wind-flow budget. Such corrections are part of every "mini ENSO cycle" and, as stated, proportionate to the strength of inertia within such a cycle. Such strength varies according to the levels of inertia exchanged between the tropics and extra tropics.

In synoptic terms,the "relaxation" is manifested by a large upstream deceleration of inertia into the extra tropics as sudden introduction of -ve easterly inertia regressively pulls the pattern westwards. Hence the inflated Atlantic ridge and trough to fill the void and where pressure falls steeply downstream.

But it has to be remembered that the default pattern has not simply just gone away and it is intuitive to anticipate the next push back, with time, as upstream inertia returns with quite a jolt..

There are good indications of amplified MJO related activity heading through July, and especially based on periodicity (recurrence timelines) of amplified tropical convection cycles. These accord to a circa 60 to 90 day periodicity and respond especially to the relationship of a strong Hadley cell interacting with the tropical cycle.

So a repeat of the type of sequence seen through the Spring is to be watched for - and with summer wavelengths likely expanding the rossby wave-breaking response further than during Spring to produce a wider warm air advection response from a re-set Atlantic trough and downstream ridge.

Extrapolating numerical model indications further out in time, without consideration of the cyclical nature of the atmospheric circulation, leads to unnecessary and premature conclusions. Better to see numerical modelling as snapshots of time only and which will adjust as they evaluate forthcoming signals.

The signals are never useless - it these that lead the numerical modelling, not the other way around.

Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4875561

[Model Output Discussion - 15th March onwards]

4 hours ago, Djdazzle said:

It does show just how useless the signals can be. Wasn’t July meant to be HP dominated?

July hasn't happened yet. Numerical models that produce seasonal outlooks will provide a smoothed out representation of a dominant default pattern and will not account for periods within that season where the atmospheric circulation has a re-set/re-balance.   Such a re-balance is emphatically advertised at present.

The Spring saw an extraordinary amount of westerly inertia added to the atmospheric circulation with vigorous propagation of +AAM wind-flow eddies from the tropics into the extra tropics. This highly Nino-esque forcing resulted in a strong sub tropical jet from the Pacific downstream into the Atlantic, transferring considerable strength through the Hadley cell.

Such one way impetus is unsustainable ad infinitum. Like a vacuum operates, when such immense power is relaxed, a correction to fill that atmospheric circulation vacuum must occur & is correspondingly proportionately strong the other way to balance the global wind-flow budget. Such corrections are part of every "mini ENSO cycle" and, as stated, proportionate to the strength of inertia within such a cycle. Such strength varies according to the levels of inertia exchanged between the tropics and extra tropics.

In synoptic terms,the "relaxation" is manifested by a large upstream deceleration of inertia into the extra tropics as sudden introduction of -ve easterly inertia regressively pulls the pattern westwards. Hence the inflated Atlantic ridge and trough to fill the void and where pressure falls steeply downstream.

But it has to be remembered that the default pattern has not simply just gone away and it is intuitive to anticipate the next push back, with time, as upstream inertia returns with quite a jolt..

There are good indications of amplified MJO related activity heading through July, and especially based on periodicity (recurrence timelines) of amplified tropical convection cycles. These accord to a circa 60 to 90 day periodicity and respond especially to the relationship of a strong Hadley cell interacting with the tropical cycle.

So a repeat of the type of sequence seen through the Spring is to be watched for - and with summer wavelengths likely expanding the rossby wave-breaking response further than during Spring to produce a wider warm air advection response from a re-set Atlantic trough and downstream ridge.

Extrapolating numerical model indications further out in time, without consideration of the cyclical nature of the atmospheric circulation, leads to unnecessary and premature conclusions. Better to see numerical modelling as snapshots of time only and which will adjust as they evaluate forthcoming signals.

The signals are never useless - it these that lead the numerical modelling, not the other way around.

[Storms and Convective discussion - June 2023]

Based on the movement of this unstable very warm airmass from my part of the world where it originated from:

The convection shown in many of these pictures is carbon copy of the diurnal cycle here in Portugal over the last week and more. Cumulus fields popping up in blue skies and then blistering upwards with very solid structural profiles. Then very rapidly they develop dark bases, the first trails of ppn are seem coming out of them - and then the first booms of thunder which rapidly become a rolling overture

Some of the most powerful convection occurred after 5pm. So enjoy the process

[Model Output Discussion - 15th March onwards]

16 minutes ago, Cambrian said:

Atmospheric Angular Momentum and the Madden-Julian Oscillation and the like are undoubtedly hugely valuable tools, but extrapolating directly from there to the weather we’re likely to see over the next few weeks would I imagine be a rather fraught exercise if we didn’t have the numerical models to translate those signals into something much more easily relatable to what we’ll see on the ground. They do very different things to the numerical models and moreover, all the tools at our disposal should be considered to provide the best overall picture at any one time.

The framework of global wind-flow and the push and pull of this (in very simple terms which helps define the jet stream) is available as a helpful diagnostic to the numerical models. They are integral, harmonious and essential to each other. The diagnostic provides insight into why the numerical models might be portraying a certain outcome and suggestions can be derived as to why they may (or may not) be following a correct outcome. Such insight is very useful, albeit it can be very complex to unravel and explain. It is aimed to aid complimentary background reasoning and understanding as to why the modelling may be foreseeing a certain outcome - not to be mystical cloak and dagger clairvoyant. On that basis it is intended to be a helpful aid to suggest where the numerical models may be blindsided by more than one particular signal at a given time.

The "extrapolating" is a mutual blend of using both to try to define signal and in turn model interpretation of that signal -  not in competition or conflict in purpose and outcome of one or the other.

[Model discussion highlights]

With very good confidence that the atmospheric circulation is set to remain broadly similar through the bulk of the summer,c/o of repeated westerly wind bursts across the tropics, with a convergence standing wave in the Pacific, and as a consequence +ve AAM wind-flow anomalies propagating through the turning force exhibited by +ve torque eddy mechanisms into the extra tropics  - then we can look to natural summer wavelengths to see how the global patterns may evolve this wind-flow propagation and associated amplified wave breaking.

Under such a regime as described, as June moves closer and closer towards July, and equally closer and closer to the peak period of summer wavelength, anticyclonic wave-breaking should progressively ebb and flow further east and the split flow in the Atlantic giving ever greater influence to cut off thundery lows to pump heat from southern Europe.

The cycle presently underway with Oscar bringing very warm, humid air northwards, is the first of a likely repeated sequence, each one escalating warm air advection processes and with a subtly changed emphasis, with time, of a rather more longitudinal trough/ridge pattern than the persistent to date dominant N/S delineation. This based on a trend for the very defined & strong southward displaced sub tropical jet to evolve a more diffuse split STJ energy, under slackest peak summer wavelengths, which will also give tendency for less blocking NW of UK/ Europe. With the height anomalies tending with time more sustainably into mainland Europe & Scandinavia then (in respect of UK & NW Europe) the inference is that cool(er) air advection around the eastern perimeter of the ridging gets mixed out more and more as westward adjustments incrementally reduce.

On the basis as described that takes a suggested extended perspective, better to not read too much into hints of any longer term re-set to the entrenched pattern of recent weeks or extrapolating outwards any persistent recurrence factor of the same through any greater part of the summer..

Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4863766

[Model Output Discussion - 15th March onwards]

With very good confidence that the atmospheric circulation is set to remain broadly similar through the bulk of the summer,c/o of repeated westerly wind bursts across the tropics, with a convergence standing wave in the Pacific, and as a consequence +ve AAM wind-flow anomalies propagating through the turning force exhibited by +ve torque eddy mechanisms into the extra tropics  - then we can look to natural summer wavelengths to see how the global patterns may evolve this wind-flow propagation and associated amplified wave breaking.

Under such a regime as described, as June moves closer and closer towards July, and equally closer and closer to the peak period of summer wavelength, anticyclonic wave-breaking should progressively ebb and flow further east and the split flow in the Atlantic giving ever greater influence to cut off thundery lows to pump heat from southern Europe.

The cycle presently underway with Oscar bringing very warm, humid air northwards, is the first of a likely repeated sequence, each one escalating warm air advection processes and with a subtly changed emphasis, with time, of a rather more longitudinal trough/ridge pattern than the persistent to date dominant N/S delineation. This based on a trend for the very defined & strong southward displaced sub tropical jet to evolve a more diffuse split STJ energy, under slackest peak summer wavelengths, which will also give tendency for less blocking NW of UK/ Europe. With the height anomalies tending with time more sustainably into mainland Europe & Scandinavia then (in respect of UK & NW Europe) the inference is that cool(er) air advection around the eastern perimeter of the ridging gets mixed out more and more as westward adjustments incrementally reduce.

On the basis as described that takes a suggested extended perspective, better to not read too much into hints of any longer term re-set to the entrenched pattern of recent weeks or extrapolating outwards any persistent recurrence factor of the same through any greater part of the summer..

@MattStoke  Yes exactly. Signals drive numerical models. Numerical models do not drive signals.

[Model Output Discussion - 15th March onwards]

A lot of attention from the Portuguese IPMA weather bureau on the sub tropical low heading towards the Azores and Madeira through tomorrow and Tuesday. An "atmospheric river" identified by ECM PWAT chart (precipitable water).traces right back to the Caribbean. 

 

It is this low merged within the sub tropical jet flow that starts to bump up against the high pressure across northern Europe. and with very warm/hot air becoming ensconced in the UK and much of mainland NW and central Europe.

I think this is a very good illustration of that sub tropical airstream evolving the ultimate movement by next weekend of the low pressure towards the SW approaches and hence the advection of increasingly humid and unstable conditions thereafter knocking on the door of southern and western parts of the UK especially.

Typically tropical !

[Model discussion highlights]

58 minutes ago, Mike Poole said:

As June progresses, we will need to watch the low anomaly to the SW, the extent to which it encourages southeasterly winds and warmth to the UK, and the potential for thunderstorms if it encroaches into the UK.

Yes. The sub tropical jet stream continues to be the interest as summer wavelengths take stage c/o a Nino-esque split flow driving an increasingly amplified trough in the Atlantic and corresponding tendency to inflate downstream ridges and warm air advection. Worth watching for renewed heat build moving north from southern Europe interplaying with the Atlantic trough. Which translates to larger and larger plumes and thundery potential across much of Europe/UK.

Its been some time since this type of summer pattern has been seen. The broad scale trend should greatly please many rather than getting bogged down in the detail of each and every intra day output

Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4861967

[Model Output Discussion - 15th March onwards]

58 minutes ago, Mike Poole said:

As June progresses, we will need to watch the low anomaly to the SW, the extent to which it encourages southeasterly winds and warmth to the UK, and the potential for thunderstorms if it encroaches into the UK.

Yes. The sub tropical jet stream continues to be the interest as summer wavelengths take stage c/o a Nino-esque split flow driving an increasingly amplified trough in the Atlantic and corresponding tendency to inflate downstream ridges and warm air advection. Worth watching for renewed heat build moving north from southern Europe interplaying with the Atlantic trough. Which translates to larger and larger plumes and thundery potential across much of Europe/UK.

Its been some time since this type of summer pattern has been seen. The broad scale trend should greatly please many rather than getting bogged down in the detail of each and every intra day output

[Model discussion highlights]

On 06/05/2023 at 13:29, Tamara said:

Forthcoming strong WWB's will re-set the developing and rapidly strengthening Nino influence in the Pacific and this has very interesting implications heading towards and into June and the start of summer.

Heights in the Atlantic and an ebbing and flowing Azores High are not likely to be the default this summer as they have been in recent summers. Low pressure encroachment to the west and downstream ridges (with thundery potential breakdown to re-set rinse and repeat) look more probable with only temporary interruptions to this pattern when ridging in the Atlantic is evident.

Olá, boa tarde. Um sábado feliz para todos

Numerical models now seeing past the red herring of retrogression based on adjusting their expectations for the floor of angular momentum to be higher than believed in the last ten days of May.

This allows the evolution suggested in the copied post back in early May to become increasingly advertised with those implications for some proper summer warmth and ultimately quite a change for those in the UK close to the chilly North Sea cloud and breeze - as the steering vectors finally switch much more to the continental landmass of mainland Europe.

The thundery unstable pattern across Portugal and Spain for the past 10 days also tending to migrate slowly NE'wards with time. A catalyst for this will be low heights across the Azores this coming week expanding towards Biscay and the SW approaches in the further outlook.

Westerly inertia is set to keep re-booting through the tropics and propagating into the extra tropics through this summer. Therefore a subtle split jet stream accordingly allowing a sub tropical arm of the jet to sustain low pressure to the west and south west in the Atlantic - underpinning continental and Scandinavian high pressure ridges, This could be a summer with something for everyone. With that in mind and it being  exactly two years to this date since arriving permanently in Portugal  -  hopefully a summer ahead that the early season rains down here will have helped prevent the severe water shortages of last summer. 

Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4861594

[Model Output Discussion - 15th March onwards]

On 06/05/2023 at 13:29, Tamara said:

Forthcoming strong WWB's will re-set the developing and rapidly strengthening Nino influence in the Pacific and this has very interesting implications heading towards and into June and the start of summer.

Heights in the Atlantic and an ebbing and flowing Azores High are not likely to be the default this summer as they have been in recent summers. Low pressure encroachment to the west and downstream ridges (with thundery potential breakdown to re-set rinse and repeat) look more probable with only temporary interruptions to this pattern when ridging in the Atlantic is evident.

Olá, boa tarde. Um sábado feliz para todos

Numerical models now seeing past the red herring of retrogression based on adjusting their expectations for the floor of angular momentum to be higher than believed in the last ten days of May.

This allows the evolution suggested in the copied post back in early May to become increasingly advertised with those implications for some proper summer warmth and ultimately quite a change for those in the UK close to the chilly North Sea cloud and breeze - as the steering vectors finally switch much more to the continental landmass of mainland Europe.

The thundery unstable pattern across Portugal and Spain for the past 10 days also tending to migrate slowly NE'wards with time. A catalyst for this will be low heights across the Azores this coming week expanding towards Biscay and the SW approaches in the further outlook.

Westerly inertia is set to keep re-booting through the tropics and propagating into the extra tropics through this summer. Therefore a subtle split jet stream accordingly allowing a sub tropical arm of the jet to sustain low pressure to the west and south west in the Atlantic - underpinning continental and Scandinavian high pressure ridges, This could be a summer with something for everyone. With that in mind and it being  exactly two years to this date since arriving permanently in Portugal  -  hopefully a summer ahead that the early season rains down here will have helped prevent the severe water shortages of last summer. 

[Model Output Discussion - 15th March onwards]

13 hours ago, Allseasons-si said:

Music to my ears and the eps is also stunning with a trough SW of the UK

this Scandi trough is loosing momentum as we count down the NWP clock

the retrogression of the high west seems to be on the ropes but still some ironing out yet

get the high further east and we could be looking at a warm thundery setup,....one hopes

it is academic to say that taking one operational output from one model is never a sensible way of gauging the numerical output outlook but taking the GFS 06z output this morning at face value is actually, for what it is worth, a guide as the type of evolution that has been under the microscope recently. The upstream retrograde signal being something of a red herring distraction from this, and as discussed in detail over the last week/10 days would be jumped on by the models and then quite conceivably backtrack upon.

The Iberian instability continues apace down here is SW Europe. There is an element of insanity to this video. Do not attempt what these people in the Ourense region of Spain did yesterday!

Video da ponte romana de #Ourense anegada no medio dunha fortísima...

FB.WATCH

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3.7 万次观看、 146 次赞、 19 条评论、 340 次分享，Redmeteo 的 Facebook Reels: Video da ponte romana de #Ourense anegada no medio dunha fortísima treboada esta tarde. Descoñezo o autor, envíanmo por Instagram....

 

[Model discussion highlights]

3 hours ago, Mike Poole said:

Well, it’s bank holiday Monday - and today’s the day, if you recall the models a week ago, that the GFS (with some support from the ensemble suites) had us in a cold northerly, due to this retrogression.  It hasn’t happened, and has kept being pushed back, in fact on this morning’s GFS 0z, the retrogression signal has been pushed back to beyond T270.  Here’s T270 and T330:

Neither the GEM nor ECM show signs of it in their 10 day range either.  Looks like a phantom retrogression to me! 

The modelling of the sub tropical jet stream continues to be of personal interest. From a southern European point if view in respect of the monsoon that has set in across the Iberian peninsula, but also how it plays its part in locking in the high pressure belt across more Northern parts of Europe (very much including UK)

Late Spring thoughts, as expressed over the last week/10 days keep consolidating on an early summer pattern evolving into low height anomalies increasingly established across the Azores (and eventually edging towards Biscay & SW approaches) & downstream ridging locating more and more to the north and east of UK/NW Europe and a tendency for higher humidity and convection trying to encroach from France into southern and western UK 

This time last year deep blue skies and scorching heat were established and set to dominate a dustbowl drought summer down here. This year is very different - seeing towering cumulus each day and strong thunderstorms especially across the interior parts and skies like this pictured yesterday (across northern municipalities of Portugal on this occasion)

 

The further outlook suggests that sub tropical jet stream is set to become more and more influential and I think for weather watchers also further north across Europe there could be some good photo captures to be taken as this instability bumps up across the entrenched downstream anticyclonic zone.

Happy UK B/H.  There are two Portuguese holidays in the coming week.

Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4859361

[Model Output Discussion - 15th March onwards]

3 hours ago, Mike Poole said:

Well, it’s bank holiday Monday - and today’s the day, if you recall the models a week ago, that the GFS (with some support from the ensemble suites) had us in a cold northerly, due to this retrogression.  It hasn’t happened, and has kept being pushed back, in fact on this morning’s GFS 0z, the retrogression signal has been pushed back to beyond T270.  Here’s T270 and T330:

Neither the GEM nor ECM show signs of it in their 10 day range either.  Looks like a phantom retrogression to me! 

The modelling of the sub tropical jet stream continues to be of personal interest. From a southern European point if view in respect of the monsoon that has set in across the Iberian peninsula, but also how it plays its part in locking in the high pressure belt across more Northern parts of Europe (very much including UK)

Late Spring thoughts, as expressed over the last week/10 days keep consolidating on an early summer pattern evolving into low height anomalies increasingly established across the Azores (and eventually edging towards Biscay & SW approaches) & downstream ridging locating more and more to the north and east of UK/NW Europe and a tendency for higher humidity and convection trying to encroach from France into southern and western UK 

This time last year deep blue skies and scorching heat were established and set to dominate a dustbowl drought summer down here. This year is very different - seeing towering cumulus each day and strong thunderstorms especially across the interior parts and skies like this pictured yesterday (across northern municipalities of Portugal on this occasion)

 

The further outlook suggests that sub tropical jet stream is set to become more and more influential and I think for weather watchers also further north across Europe there could be some good photo captures to be taken as this instability bumps up across the entrenched downstream anticyclonic zone.

Happy UK B/H.  There are two Portuguese holidays in the coming week.

[Model Output Discussion - 15th March onwards]

On 24/05/2023 at 12:14, Tamara said:

The further outlook may create some erratic modelling  as a (temporary) drop in AAM occurs as the present tropical convection concludes and re-sets across the Indian Ocean. However with the low frequency tropical convection standing wave pressing the west/central Pacific and surpluses of westerly inertia feeding from the tropics into the extra tropics, then caution is required as to the longevity of an blocking breakdown indication and cool air advection c/o high pressure relocating NW/wards On this basis better not to read too much into the significance of retrogression in the longer term (for UK and NW Europe) as such a pattern does not look sustainable (if it occurs) heading though the greater part of June. Most likely leading to a re-set of an Atlantic trough and a downstream ridge to the east. An eastward adjustment of the pattern to come over the next week which implies very warm plume like conditions.

So is proving to be the case. The retrogression signal persistently put back since the time of this post and remaining out at/beyond day 10. The inability to peruse the GSDM continues to be a handicap and make suggestions more difficult moving forward on a diagnostic level, but angular momentum remains above average and the upcoming lull in the tropical>extra tropical cycle has to be taken in context of how much westerly inertia has to be removed during any trade wind uptick (as discussed recently)

As expected, the numerical models have jumped on the signal too much and have been readjusting incrementally the pattern in the more reliable time period as they calculate greater westerly inertia still within the extra tropical circulation - and a steadfast sub tropical jet stream underpinning the blocking.

A good time to remain especially cautious from trying to draw too many conclusions from extended ensemble products. It continues to be the case that any retrogressive signal is not inextricably either robust or at all sustained , even if ultimately there is something of a drift west of the pattern through week 2.

[Model discussion highlights]

3 hours ago, MattStoke said:

I’m remembering Tamara’s advice to be cautious of any NWP showing retrogression.

There is sometimes a problem when a change is hinted at in numerical models towards the end of a 10 day period and it then tends to then get extrapolated out in time as some kind of sustained switch in pattern. Taking these evolutions as snapshots in time and set against the general direction of travel of the atmospheric circulation presents some context and perspective.

As mentioned yesterday, computer modelling will jump on the signal from the conclusion of the present ENSO "mini cycle" which acts to provide a (temporary) buffer to the highly anomalous westerly inertia within the tropics and extra tropics as both negative trending frictional and mountain torques serve to bump up the trade winds and the vacuum needs to be filled c/o decelerating the downstream pattern accordingly (retrogression)

But this is just a natural lull period in the overall trend away from La Nina type influences and renewed westerly winds added back into the system should re-set the pattern heading through June. This next re-set is especially interesting in respect of the fact that summer wavelengths will assist the placement of the anticyclonic wave breaking further east and that implies greater influences from southerly and south easterly vectors. At the same time, shallow low pressure anomalies from Iberia and Biscay become more influential and provide some thundery incursion interest accordingly.

So attempting context of the suggested cooler incursion is always a good thing.

Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4858031

[Model Output Discussion - 15th March onwards]

11 minutes ago, mushymanrob said:

Im not liking this, ok i take Tamaras point and its likely to not be a complete pattern change, lets hope that right because this could go the way of 2012....

Further to recent post and the switch to -ve inertia across the tropics and to the dateline (blue shading), the culprit can be identified here:

But as per the detail, there has to be suspicion as to the longevity of this signal based,( in very truncated terms) on the strength of the evolution to El Nino, the quite different QBO profile (to the likes of 2012) and a diminishing effect of -ve PDO forcing in the Pacific.

I am not by any means an appointed forecaster, or pretend to be - but see no reason at all to worry about the coming season (if you like a mix of seasonal warmth, periodic humidity and convection) and things could well get very interesting after a possible spell of cool air advection.

 

[Model Output Discussion - 15th March onwards]

3 hours ago, MattStoke said:

I’m remembering Tamara’s advice to be cautious of any NWP showing retrogression.

There is sometimes a problem when a change is hinted at in numerical models towards the end of a 10 day period and it then tends to then get extrapolated out in time as some kind of sustained switch in pattern. Taking these evolutions as snapshots in time and set against the general direction of travel of the atmospheric circulation presents some context and perspective.

As mentioned yesterday, computer modelling will jump on the signal from the conclusion of the present ENSO "mini cycle" which acts to provide a (temporary) buffer to the highly anomalous westerly inertia within the tropics and extra tropics as both negative trending frictional and mountain torques serve to bump up the trade winds and the vacuum needs to be filled c/o decelerating the downstream pattern accordingly (retrogression)

But this is just a natural lull period in the overall trend away from La Nina type influences and renewed westerly winds added back into the system should re-set the pattern heading through June. This next re-set is especially interesting in respect of the fact that summer wavelengths will assist the placement of the anticyclonic wave breaking further east and that implies greater influences from southerly and south easterly vectors. At the same time, shallow low pressure anomalies from Iberia and Biscay become more influential and provide some thundery incursion interest accordingly.

So attempting context of the suggested cooler incursion is always a good thing.

[Model discussion highlights]

The broad scale pattern of anomalous high pressure locating close to the UK with lower pressure across southern Europe is well advertised by the numerical models and as previously discussed in respect of the non numerical diagnostic model.

The further outlook may create some erratic modelling  as a (temporary) drop in AAM occurs as the present tropical convection concludes and re-sets across the Indian Ocean. However with the low frequency tropical convection standing wave pressing the west/central Pacific and surpluses of westerly inertia feeding from the tropics into the extra tropics, then caution is required as to the longevity of an blocking breakdown indicaton and cool air advection c/o high pressure relocating NW/wards On this basis better not to read too much into the significance of retrogression in the longer term (for UK and NW Europe) as such a pattern does not look sustainable (if it occurs) heading though the greater part of June. Most likely leading to a re-set of an Atlantic trough and a downstream ridge to the east. An eastward adjustment of the pattern to come over the next week which implies very warm plume like conditions.

The lower heights now established across the Iberian peninsula leading to some very unsettled conditions with floods in SE Spain and some quite large thunderstorms elsewhere and across the border into Portugal. A couple of thundery showers here in my own locality yesterday.   A supercell (c/o Portuguese social media) pictured across the Capanca coast (due south of Lisbon) was pictured yesterday which produced some sizeable hail. Some flooding in Lisbon itself.

 

 

Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4857730

[Model Output Discussion - 15th March onwards]

The broad scale pattern of anomalous high pressure locating close to the UK with lower pressure across southern Europe is well advertised by the numerical models and as previously discussed in respect of the non numerical diagnostic model.

The further outlook may create some erratic modelling  as a (temporary) drop in AAM occurs as the present tropical convection concludes and re-sets across the Indian Ocean. However with the low frequency tropical convection standing wave pressing the west/central Pacific and surpluses of westerly inertia feeding from the tropics into the extra tropics, then caution is required as to the longevity of an blocking breakdown indicaton and cool air advection c/o high pressure relocating NW/wards On this basis better not to read too much into the significance of retrogression in the longer term (for UK and NW Europe) as such a pattern does not look sustainable (if it occurs) heading though the greater part of June. Most likely leading to a re-set of an Atlantic trough and a downstream ridge to the east. An eastward adjustment of the pattern to come over the next week which implies very warm plume like conditions.

The lower heights now established across the Iberian peninsula leading to some very unsettled conditions with floods in SE Spain and some quite large thunderstorms elsewhere and across the border into Portugal. A couple of thundery showers here in my own locality yesterday.   A supercell (c/o Portuguese social media) pictured across the Capanca coast (due south of Lisbon) was pictured yesterday which produced some sizeable hail. Some flooding in Lisbon itself.

 

 

[Model discussion highlights]

22 hours ago, mushymanrob said:

Ok, its verification time... what the MJO should be giving us now, as per the phase 5 composite, compared with the EPS prediction for today both made on the 5th ...

Heres todays EPS chart..... id suggest the result of this is pretty clear ..... MJO? MJ NO more like!

 

You have provided a very good example of something I have repeatedly made on the few occasions I visit this thread. The MJO is just one part (an important part) of the whole atmospheric circulation wind-flow budget. The relationship and interaction of forcing in the tropics has to include the extra tropical circulation as determined by the Global Wind Oscillation (GWO) which is a plot depiction of aggregate wind-flow in both tropics and extra tropics.

Providing an accurate diagnostic analysis using these particular weather tools continues to be hampered by the diagnostic maproom of the Global Synoptic Dynamical Model (GSDM) being out of operation since the middle of March. Despite indications that this would be fixed, nothing as yet has materialised in respect of resolving the problem.

In the absence of this highly useful and insightful information & data, comparison of VP200 tropical convection anomalies, convergence zones within these anomalies, trade wind strength and fluxing of wind-flows between tropics and extra tropics can't be be compared as usefully against the ongoing strength of atmospheric angular momentum (AAM)

Westerly Wind Bursts (WWB) continue  across a wide swathe west of the dateline

 

However, in respect of the tropics it is complex presently with this extensive area of attempted eastward push of westerly inertia across both the  Maritimes and the Western Pacific and with some (relative) weakness of inertia from the dateline and into the eastern Pacific. Such "west based" forcing is influencing the extra tropics in a way that is a-typical of many El Nino transitions, especially with -ve PDO forcing persisting.

Angular momentum is above average in accordance with the direction of travel of increased propagation between the tropics and extra tropics, though is is not possible to see both frictional and mountain torque budgets which would confirm the precise locations and strengths of wind-flow propagation into the extra tropics.

C/o the -ve PDO and extensive forcing across a wide swathe west of the dateline then the total angular momentum anomaly does not have a breakdown analysis of the aggregate forcing and therefore not tell the whole story as much of this extra tropical propagation from the tropics is blindsided by this -ve PDO and residual 3 year La Nina lag. Hence the present stronger pressure anomaly of the Azores High (which in previous posts was predicted to play less of a role this coming summer).

I think this continues to be the case. The forcing west of the dateline is very strong with a lot of warm water upwelling trying to push eastwards across the dateline. Summer wavelengths heading into June, a waning of the a-typical ENSO forcing in the coming weeks, and the tropical standing wave becoming greater focussed across the Pacific itself (and less around 120E to 150E) are likely to evolve the advertised pattern towards less Azores ridging across the Atlantic and  troughs cut-off west and south west of mainland Europe bumping up against downstream high pressure zones across much of northern Europe.

This could be a summer of thundery/thermal low being advected northwards and north eastwards and repeated plume type heat - rather than stationary prolonged dry heat conditions.

The coming week down here across Portugal and Spain sees the first hints of that change which should become more influential with time as they embed across continental Europe as downstream high pressure ridges establish themselves fairly close to the N and NE of the UK

 

Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4855546

[Model Output Discussion - 15th March onwards]

22 hours ago, mushymanrob said:

Ok, its verification time... what the MJO should be giving us now, as per the phase 5 composite, compared with the EPS prediction for today both made on the 5th ...

Heres todays EPS chart..... id suggest the result of this is pretty clear ..... MJO? MJ NO more like!

 

You have provided a very good example of something I have repeatedly made on the few occasions I visit this thread. The MJO is just one part (an important part) of the whole atmospheric circulation wind-flow budget. The relationship and interaction of forcing in the tropics has to include the extra tropical circulation as determined by the Global Wind Oscillation (GWO) which is a plot depiction of aggregate wind-flow in both tropics and extra tropics.

Providing an accurate diagnostic analysis using these particular weather tools continues to be hampered by the diagnostic maproom of the Global Synoptic Dynamical Model (GSDM) being out of operation since the middle of March. Despite indications that this would be fixed, nothing as yet has materialised in respect of resolving the problem.

In the absence of this highly useful and insightful information & data, comparison of VP200 tropical convection anomalies, convergence zones within these anomalies, trade wind strength and fluxing of wind-flows between tropics and extra tropics can't be be compared as usefully against the ongoing strength of atmospheric angular momentum (AAM)

Westerly Wind Bursts (WWB) continue  across a wide swathe west of the dateline

 

However, in respect of the tropics it is complex presently with this extensive area of attempted eastward push of westerly inertia across both the  Maritimes and the Western Pacific and with some (relative) weakness of inertia from the dateline and into the eastern Pacific. Such "west based" forcing is influencing the extra tropics in a way that is a-typical of many El Nino transitions, especially with -ve PDO forcing persisting.

Angular momentum is above average in accordance with the direction of travel of increased propagation between the tropics and extra tropics, though is is not possible to see both frictional and mountain torque budgets which would confirm the precise locations and strengths of wind-flow propagation into the extra tropics.

C/o the -ve PDO and extensive forcing across a wide swathe west of the dateline then the total angular momentum anomaly does not have a breakdown analysis of the aggregate forcing and therefore not tell the whole story as much of this extra tropical propagation from the tropics is blindsided by this -ve PDO and residual 3 year La Nina lag. Hence the present stronger pressure anomaly of the Azores High (which in previous posts was predicted to play less of a role this coming summer).

I think this continues to be the case. The forcing west of the dateline is very strong with a lot of warm water upwelling trying to push eastwards across the dateline. Summer wavelengths heading into June, a waning of the a-typical ENSO forcing in the coming weeks, and the tropical standing wave becoming greater focussed across the Pacific itself (and less around 120E to 150E) are likely to evolve the advertised pattern towards less Azores ridging across the Atlantic and  troughs cut-off west and south west of mainland Europe bumping up against downstream high pressure zones across much of northern Europe.

This could be a summer of thundery/thermal low being advected northwards and north eastwards and repeated plume type heat - rather than stationary prolonged dry heat conditions.

The coming week down here across Portugal and Spain sees the first hints of that change which should become more influential with time as they embed across continental Europe as downstream high pressure ridges establish themselves fairly close to the N and NE of the UK

 

[Model discussion highlights]

4 hours ago, MattH said:

Definitely need to keep a watchful eye on NWP moving forward to hopefully see this broader signal gain consistency with an Atlantic trough and downstream ridge pattern.

Yes agreed.

Forthcoming strong WWB's will re-set the developing and rapidly strengthening Nino influence in the Pacific and this has very interesting implications heading towards and into June and the start of summer.

Heights in the Atlantic and an ebbing and flowing Azores High are not likely to be the default this summer as they have been in recent summers. Low pressure encroachment to the west and downstream ridges (with thundery potential breakdown to re-set rinse and repeat) look more probable with only temporary interruptions to this pattern when ridging in the Atlantic is evident.

Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4850394

[Model Output Discussion - 15th March onwards]

4 hours ago, MattH said:

Definitely need to keep a watchful eye on NWP moving forward to hopefully see this broader signal gain consistency with an Atlantic trough and downstream ridge pattern.

Yes agreed.

Forthcoming strong WWB's will re-set the developing and rapidly strengthening Nino influence in the Pacific and this has very interesting implications heading towards and into June and the start of summer.

Heights in the Atlantic and an ebbing and flowing Azores High are not likely to be the default this summer as they have been in recent summers. Low pressure encroachment to the west and downstream ridges (with thundery potential breakdown to re-set rinse and repeat) look more probable with only temporary interruptions to this pattern when ridging in the Atlantic is evident.