Cambrian
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Posts posted by Cambrian
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It looks like we’re on a 10-12 day evolution back to something strikingly similar to what we currently have.
0z EPS, days 0, 5 and 10.
0z GEFS, days 0, 5 and 10.
It’s always easy to give this model or that model a bit of flack, which I never quite get, but it does seem fair to say that in this instance the EPS first picked up on the establishment of a less challenged Atlantic trough nearby to the UK and Ireland around the middle of the month, a preferred setup that the GEFS is now gradually falling in with.
Moving on speculatively to day 10-15, it looks like the trough will bed down for a fair while in our locale. 0z EPS jet stream at day 10 and 15 - I deliberately haven’t rotated these, in order to focus on North America.
At day 10, the Pacific jet stream is bifurcated on its entry to North America, around low pressure over California. The northern and southern arms then merge to the west of the Azores and is being steered over the top of the weak Azores high, then diving southeast into Iberia to carve out the trough.
There is a pronounced lack of change in evidence by day 15 - maintenance of split Pacific jet stream, Alaskan trough, west and east coast lows, weak Azores high, Atlantic jet stream diving into Iberia, all making for very little west to east mobility to dig out the trough quickly.
It will in time move on though. After all, the steady improvement of the coming week, culminating in a very pleasant spell, will have developed from the starting point of a similarly static trough - EPS chart for 1 May (day minus 5) and today.
There may be a quite comfortable balance emerging here in the pattern going forward, bearing in mind that due to the time of the year, the “troughy” spells rarely bring constant rain but the “ridgy” spells do invariably bring a good few dry days, and the sun is strong whenever we get it.
And in the first instance, the next week or so to enjoy!
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A short but sweet one today. This is what so many of us have been looking forward to seeing, cross-model agreement coming into the close range for a good few days of dry, lovely warm afternoons and early evenings. Yeah…
Here at day 5, 0z ECM op or the 0z GEM op / 6z GFS op at various stages of day 6 - a frequent 19-21 degrees for very many, even for us in the hills, and a respectable mid to high teens at worst for many others, come the end of the working week and into next weekend.
Nothing spectacular I know but at this stage, admittedly easily pleased and why not?
A very good opportunity to recharge. Plenty of time each day to take a hard-earned cup of tea outside and enjoy it without that draughty old wind licking at our delicate bits. Ooh err.
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Day 4 and 5 on the 0z EPS are great charts for the UK and Ireland. High time (sorry!).
But subtle changes can make all the difference.
As pointed out a few weeks ago, the 5-ridge hemispheric pattern is getting reduced to a 4-ridge pattern at times, and it’s happening again here. If we look out west, the ridge running down through eastern Canada to the Gulf of Mexico at day 4 is cut off at day 5.
Looking at the jet stream on the 0z GEFS, a pulse of energy over the US at day 4 leads to an extension into the Atlantic at day 5.
This throws the models into some disarray for the following days - by day 7, the EPS forms an authentic Atlantic basin low that ultimately trundles through to the UK and Ireland by day 10 as it weakens…
…while the GEFS only flirts with this formation at day 7, producing a shallower trough approaching Western Europe by day 10 with heights keen to build once more behind it over the Atlantic, the ridges much more pronounced than on the EPS looking like squeezing out the trough quite quickly.
By then, the EPS has reverted to 5 ridges, though the two on the Atlantic side are weaker, while the GEFS sticks with 4, which allows stronger Atlantic ridges, the presence or absence of the Kazakh-Siberian ridge acting as the compensating factor.
At the moment, it doesn’t look like the 5-wave pattern can sustain 5 strong ridges to pin the pattern down, while the slowly waning PV is clearly still able to generate pulses of energy running through the jet stream that are injecting a touch more mobility into the Atlantic at times.
This is keeping the pattern just a tad flatter, restricting the building of high pressure to modest cells in the 1020’s mb ranges, meaning that they are susceptible to being pushed on after just a few days by even a modest injection of energy into the jet stream, a hemispheric pattern that will serve to keep the weather at our end of the Atlantic unremarkable for now - though nevertheless with it being May, this will at times be very pleasant indeed. Have a lovely bank holiday weekend.
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5065465-
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Day 4 and 5 on the 0z EPS are great charts for the UK and Ireland. High time (sorry!).
But subtle changes can make all the difference.
As pointed out a few weeks ago, the 5-ridge hemispheric pattern is getting reduced to a 4-ridge pattern at times, and it’s happening again here. If we look out west, the ridge running down through eastern Canada to the Gulf of Mexico at day 4 is cut off at day 5.
Looking at the jet stream on the 0z GEFS, a pulse of energy over the US at day 4 leads to an extension into the Atlantic at day 5.
This throws the models into some disarray for the following days - by day 7, the EPS forms an authentic Atlantic basin low that ultimately trundles through to the UK and Ireland by day 10 as it weakens…
…while the GEFS only flirts with this formation at day 7, producing a shallower trough approaching Western Europe by day 10 with heights keen to build once more behind it over the Atlantic, the ridges much more pronounced than on the EPS looking like squeezing out the trough quite quickly.
By then, the EPS has reverted to 5 ridges, though the two on the Atlantic side are weaker, while the GEFS sticks with 4, which allows stronger Atlantic ridges, the presence or absence of the Kazakh-Siberian ridge acting as the compensating factor.
At the moment, it doesn’t look like the 5-wave pattern can sustain 5 strong ridges to pin the pattern down, while the slowly waning PV is clearly still able to generate pulses of energy running through the jet stream that are injecting a touch more mobility into the Atlantic at times.
This is keeping the pattern just a tad flatter, restricting the building of high pressure to modest cells in the 1020’s mb ranges, meaning that they are susceptible to being pushed on after just a few days by even a modest injection of energy into the jet stream, a hemispheric pattern that will serve to keep the weather at our end of the Atlantic unremarkable for now - though nevertheless with it being May, this will at times be very pleasant indeed. Have a lovely bank holiday weekend.
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I was going to wait until the morning but there’s something very appealing about posting on the cusp of the month itself. And May is typically a lovely month of the year. Lovely long evenings, but rarely too hot, and relatively free of buggy insects nibblin’ at ya!
Another motivation was that today’s 12z EPS charts are the most compelling for a fair while in terms of setting up positive synoptics for a properly settled spell.
Here at day 9, the same slow moving 5-wave hemispheric pattern that has held us for a protracted spell under the influence of a trough now with clicking forward 45 degrees very much becomes our friend, with a firm build of heights shown in the anomaly shading and a most handsome ridge displayed in the contour lines, 569-576 gpm a convincing signal for a meaningful build in surface pressure.
This is actually evident a day earlier with a 1028+mb high pressure at day 8 on the MSLP charts, slap bang over the UK and Ireland and there through to day 10 at least, impressive for an ensemble mean product at that range.
To look beyond that stage is always a bit ambitious, but a swift return to below average pressure from there looks unlikely. May looks to be shaping up.
That the projected pick up doesn’t fall for us for the bank holiday weekend is neither here nor there for the quality of the weather itself and its impact on nature.
The fact that it coincides with the second week of May, at a time when the rate of seasonal warming is at its most rapid - bringing the potential, if it transpires as indicated, for a meaningful spell of fine weather as the days get long, the sun becomes strong and the land responds in earnest to the warmth - after the last couple of months in particular, will be very welcome indeed.
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5063283-
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I was going to wait until the morning but there’s something very appealing about posting on the cusp of the month itself. And May is typically a lovely month of the year. Lovely long evenings, but rarely too hot, and relatively free of buggy insects nibblin’ at ya!
Another motivation was that today’s 12z EPS charts are the most compelling for a fair while in terms of setting up positive synoptics for a properly settled spell.
Here at day 9, the same slow moving 5-wave hemispheric pattern that has held us for a protracted spell under the influence of a trough now with clicking forward 45 degrees very much becomes our friend, with a firm build of heights shown in the anomaly shading and a most handsome ridge displayed in the contour lines, 569-576 gpm a convincing signal for a meaningful build in surface pressure.
This is actually evident a day earlier with a 1028+mb high pressure at day 8 on the MSLP charts, slap bang over the UK and Ireland and there through to day 10 at least, impressive for an ensemble mean product at that range.
To look beyond that stage is always a bit ambitious, but a swift return to below average pressure from there looks unlikely. May looks to be shaping up.
That the projected pick up doesn’t fall for us for the bank holiday weekend is neither here nor there for the quality of the weather itself and its impact on nature.
The fact that it coincides with the second week of May, at a time when the rate of seasonal warming is at its most rapid - bringing the potential, if it transpires as indicated, for a meaningful spell of fine weather as the days get long, the sun becomes strong and the land responds in earnest to the warmth - after the last couple of months in particular, will be very welcome indeed.
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A bit earlier than expected in working through, but the models sticking to the plot first hatched a fair few days ago, the ECM mean, as often, the pick of the bunch for illustration of the core evolution.
As indicated before, here on the 0z, the European plume and Atlantic heights executing a pincer movement to the north of the UK and Ireland, severing the trough, isolating then releasing the cut-off low east through Europe…
…allowing the heights to ooze southwest out of Scandinavia, meeting heights extending northeast from the Azores, taken at face value adding to the hero status of the Azores high for being the rescuer of our spring.
However, it is rarely as simple as that, and the anomalies reveal the subplot, in the form of the underpinning of the change by the oft vilified (in spring at least) northern heights.
Received a lot of bad press of late, but their persistent presence is ultimately central to the displacement of the trough and paving the way for establishment of the Azores ridge.
Distraction by the glossy pages of the GFS ops is understandable, but again at 6z, the balanced GEFS, here at day 10…
…is highly supportive of that same end storyline being developed by the ECM, in the promise of a neatly placed high pressure and some growing spring warmth as we enter the second week of May.
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Little point ducking the issue. A quacking weekend in store…
0z ECM op for day 4, as another low pressure system finds us with impressive timing!
Further ahead, some more positive signs - once we start seeing this type of “super-meridional” pattern - ambitious building of heights up through the Atlantic and more spectacularly, through all the S’s - Sahara-Sweden-Svalbard-Siberia-Seguam like here at day 6 on the 0z ECM op…
…it’s only a matter of time before we start seeing the trough becoming over-extended with the cutting off of the low at the base of the trough, it sinking south, the heights linking up through the UK and Ireland like here at day 8…
Yes, add Skegness and Sandymount to your list, spectacular super-meridional S thing!
After that, a weaker version of the trough tries to reassert itself from the northwest, which the GFS op has been keenest on, though looking at the 0z ensemble mean, the pressure never really falls away again, a steady rise to a respectable 1020mb for Birmingham by the end of week 2…
…which is consistent with the ECM charts and the pincer movement of heights weakening the polar trough at its stem - so though nothing wall to wall by any means, the chance of a somewhat more promising setup emerging into early May. I’ll post again around then. All the best.
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5060751-
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Little point ducking the issue. A quacking weekend in store…
0z ECM op for day 4, as another low pressure system finds us with impressive timing!
Further ahead, some more positive signs - once we start seeing this type of “super-meridional” pattern - ambitious building of heights up through the Atlantic and more spectacularly, through all the S’s - Sahara-Sweden-Svalbard-Siberia-Seguam like here at day 6 on the 0z ECM op…
…it’s only a matter of time before we start seeing the trough becoming over-extended with the cutting off of the low at the base of the trough, it sinking south, the heights linking up through the UK and Ireland like here at day 8…
Yes, add Skegness and Sandymount to your list, spectacular super-meridional S thing!
After that, a weaker version of the trough tries to reassert itself from the northwest, which the GFS op has been keenest on, though looking at the 0z ensemble mean, the pressure never really falls away again, a steady rise to a respectable 1020mb for Birmingham by the end of week 2…
…which is consistent with the ECM charts and the pincer movement of heights weakening the polar trough at its stem - so though nothing wall to wall by any means, the chance of a somewhat more promising setup emerging into early May. I’ll post again around then. All the best.
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Not very often we see a low pressure system romp so triumphantly west from Scandinavia through the UK and Ireland to the Atlantic, as here on the 12z UKMO but there are some very intricate handovers of pockets of low heights that drive the whole process and give it some considerable elegance.
The first pocket drops south to join the Scandinavian low at day 2, deepening it. The second drops out of the trough at the tip of Greenland at day 3, joining the melee at day 4 and drawing the system west over the UK and Ireland for the weekend. Thanks
A third pocket drops southeast via the same route at day 6, pulling the system west out over the Atlantic.
Looks like an “atmospheric” weekend awaits to round off this very mixed April, ripe for savoury evening treats washed down with a sumptuous glass or three of your favourite ale or wine. The late spring fitness effort can wait until some suitable conditions are laid on.
And from there, let’s grab all the potential silver linings. Though not seemingly immediately on offer, there are at least some emerging signs that this remarkable retrogression, as a part of wider adjustments occurring within the generally very static hemispheric pattern, might eventually lead to sufficiently consistent heights building over the near continent to bring us a better chance of some warmer interludes as May progresses.
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Hi Josh,
I think that we have to look at each event on its own rather than necessarily seeking a sub-classification of the classic Spanish plume.
I have looked at the archive charts for June 28th 2012. What is striking about that event is the dramatic west-east temperature gradient that developed that day and how the contrasting air masses interacted in the circulation of the developing low pressure system. I have examined the pressure charts and the T850 charts, relevant here because the 850 hPa temperature, at altitude about 1.5 km, is above the atmospheric boundary layer and so is a very good measure of the relative temperatures of the air masses.
At 0z that day, the low pressure at around 1000mb, was centred about 800 km to the southwest of Ireland. The pressure was around 1005mb over southwest Ireland. The T850 was around 11 degrees over Limerick and around 14 degrees over southeast England, though the 16 degree isotherm of the plume was over the English Channel coast. The surface circulation over Ireland was a southeasterly, drawing in warm, humid air from that region.
By 6z, the low pressure had extended northeast, and the pressure over southwest Ireland had fallen to 1000mb. The centre of the low was by then around 400 km to the west of Kerry. The T850 over Limerick was around 9 degrees, and the 16 degree isotherm had arrived in southeast England. The surface flow into southwest Ireland was still from the southeast, continuing to feed in warm, humid and unstable air.
By 12z, the deepening of the low pressure, to around 995mb had pulled in colder air from the northwest, so that the T850 over Kerry and West Cork was only 6 degrees and this knuckle of much cooler air was pushing in from the southwest behind a developing front, into the very warm humid air to the east of it. The T850 over Kent was around 17 degrees, so two things had happened.
Firstly, over 12 hours, the difference in T850 between southwest Ireland and southeast England had risen from 3 degrees to an 11 degree difference, so the temperature gradient had become extremely steep. The atmospheric instability through that zone would have become profound.
Secondly, the centre of the approaching low pressure had more or less stalled, still several hundred kilometres to the southwest of Ireland but the low was deepening in situ, so all of Ireland was by then below 1000mb as the system grew. The winds would have been slight and variable within this cyclonic circulation but with the dramatic west-east temperature contrasts within the system, and the peak convection of the afternoon, severe thunderstorms would have formed through the frontal zone, fed by the growing instability and making only very slow eastward progress. As the front approached, the wind would have backed southerly running along the front, so a local effect of air getting lifted over the Cork and Kerry mountains, enhancing the updrafts, might have been an additional factor for the Limerick area.
Limerick was in effect stuck in the trigger zone for several hours with the growing temperature contrast of the air masses and increasing convection of the day feeding a growing instability that resulted in the severe thunderstorms.
I hope this helps look at the question in another way. The precise setup for each instance of this type of event is naturally different, but I was hoping that by looking at the dynamics of this particular event, the requisites might be identified.
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Keeping abreast of the models, here’s a notable pair of ECM means, in near perfect hemispheric symmetry around day 9 / 10, persistent heights reinforcing the cleavage.
The sheer indecision of it all - sure to be amongst the abiding mam…oops, memories of spring 2024.
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We’ve been quite lucky this morning, it has been absolutely beautiful, steadily warming up from a -1.2 degrees frost around dawn, 1026mb and no wind. April mornings don’t come much better.
A very reasonable looking few days ahead, through the weekend and into early next week, the 0z EPS chart for next Monday morning at day 4 is a cracker. The MSLP chart shows a high pressure of 1036mb over the UK and Ireland, part of a “bar” of higher pressure extending through to the Siberian Arctic. But make the most of it!
Even with this setup, though it is nigh impossible for our high to be shifted east by anything off the Atlantic, it instead gets undermined by trough development to the east.
There were good hints of this in the models yesterday, and though still a fair way off, the subtle hints of yesterday for day 10 have grown into clear suggestions today for day 9, the trough notably deeper and further west.
This is the kind of evolution I love to see, not necessarily for the weather it will bring, but for the phenomenon itself. The 0z ECM op at days 6-10 shows the potential, the Scandinavian trough spawning a little low pressure system running down through the Norwegian Sea, joining with another more active one coming out of Greenland and sweeping down through Iceland…
…the two merging and swivelling down into the UK and Ireland, with the cold air reasserting itself in the process.
With the seasonal timing, probably not at all welcome, though I keep the faith that one of these years we’ll get this kind of thing a couple of months earlier and enjoy it a lot more. As it stands in the current modelling, it’s a spring ambush!
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This appears to be quite a telling moment in the development of this spring. The Atlantic jet stream is heading very decisively north before fragmenting, here on the 0z ECM op for the next 10 days.
The 0z ECM mean anomaly shows an impressive build in heights not only north through the Atlantic but also west into Greenland. The low pressure over the pole is lost as heights link up through the Arctic to the Siberian side. So the pattern is getting locked down.
From the meridional 5-wave hemispheric pattern we’ve been looking at recently, we might have seen the next stage involving injection of some energy to incorporate a couple more waves, reduce the amplification and introduce a more mobile setup, but instead we’re seeing the opposite happen - the Atlantic build is so substantial that it serves to carve out one of the waves altogether.
This is shown nicely by the 0z GEFS jet stream charts, the 5-wave starfish at day 5 being replaced by a 4-wave cross at day 10, the jet stream actually bending back on itself with a northeasterly component as it dives south towards the UK and Ireland.
The surface flow will be very much in the northeast for several days, following the contour lines in the mean heights charts (below) from around day 5 onwards.
So we’re moving towards a more static setup towards the end of the month, drier than it has been, but with suppressed temperatures. The stronger sunshine when on offer could make for some pleasant weather all the same, especially further west with shelter, though as discussed, the onshore breeze could be quite the dampener in eastern parts at times.
One more thing, looking through to day 10, the upper trough remains uncomfortably close by to the east, even steadily working its way further west - so small systems beginning to run down the western flank of the trough, picking up moisture through the Norwegian Sea, might well become an added complication later on next week.
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5058638 -
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This appears to be quite a telling moment in the development of this spring. The Atlantic jet stream is heading very decisively north before fragmenting, here on the 0z ECM op for the next 10 days.
The 0z ECM mean anomaly shows an impressive build in heights not only north through the Atlantic but also west into Greenland. The low pressure over the pole is lost as heights link up through the Arctic to the Siberian side. So the pattern is getting locked down.
From the meridional 5-wave hemispheric pattern we’ve been looking at recently, we might have seen the next stage involving injection of some energy to incorporate a couple more waves, reduce the amplification and introduce a more mobile setup, but instead we’re seeing the opposite happen - the Atlantic build is so substantial that it serves to carve out one of the waves altogether.
This is shown nicely by the 0z GEFS jet stream charts, the 5-wave starfish at day 5 being replaced by a 4-wave cross at day 10, the jet stream actually bending back on itself with a northeasterly component as it dives south towards the UK and Ireland.
The surface flow will be very much in the northeast for several days, following the contour lines in the mean heights charts (below) from around day 5 onwards.
So we’re moving towards a more static setup towards the end of the month, drier than it has been, but with suppressed temperatures. The stronger sunshine when on offer could make for some pleasant weather all the same, especially further west with shelter, though as discussed, the onshore breeze could be quite the dampener in eastern parts at times.
One more thing, looking through to day 10, the upper trough remains uncomfortably close by to the east, even steadily working its way further west - so small systems beginning to run down the western flank of the trough, picking up moisture through the Norwegian Sea, might well become an added complication later on next week.
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A blustery and chilly morning here, showery with plenty of hail. Not great, but a 1030mb+ high building through the UK and Ireland by day 6 on the 0z ECM op, day 0-6 here, the rise in pressure and its convenient location now well inside the reliable and for once, coinciding with the weekend! Many a lawn will get mowed….
An impressive build in heights to the west and north. No doubt some fresh and chilly nights and mornings as it works its way in and settles down. Consistent signs of the high pulling back west thereafter, but for a fair few days, this is going to feel much, much better!
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Shiver me timbers!
Looks like we have a retrogressing high before our very eyes, ha ha haar (and other pirate noises) - even before it’s properly arrived.
Whether ‘twill be as shivery as 6z GFS op at day 9, where it withdraws far enough to the northwest to allow a proper cold blast down the frontage with some snow a fair way south, and settling on the hills…
or holds close enough nearby to keep the old lunger a bit further east like on the 0z GEM op at day 10 (beware that sea serpent beyond the pole, haar)…
the retrogression and European trough are definitely looking to be features of week 2 - ‘tis here too on the 0z EPS at day 11. Aar.
The CFS weeklies (weeks 1-3) show the Euro trough by week 3 being reinforced by its maritime buddy that’s come romping through the Azores in weeks 1 and 2, while to the north, the Atlantic heights hint at wobbling back east, a tad back our way again…
…the big concern for us island landlubbers looking for something to warm our jellies is that rather than a generally quiet but cool outlook, the pattern in the event all heads just that bit further north bringing us back into chilly cyclonic influences that just judder your rafters. More pirate noises….
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5057987-
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Shiver me timbers!
Looks like we have a retrogressing high before our very eyes, ha ha haar (and other pirate noises) - even before it’s properly arrived.
Whether ‘twill be as shivery as 6z GFS op at day 9, where it withdraws far enough to the northwest to allow a proper cold blast down the frontage with some snow a fair way south, and settling on the hills…
or holds close enough nearby to keep the old lunger a bit further east like on the 0z GEM op at day 10 (beware that sea serpent beyond the pole, haar)…
the retrogression and European trough are definitely looking to be features of week 2 - ‘tis here too on the 0z EPS at day 11. Aar.
The CFS weeklies (weeks 1-3) show the Euro trough by week 3 being reinforced by its maritime buddy that’s come romping through the Azores in weeks 1 and 2, while to the north, the Atlantic heights hint at wobbling back east, a tad back our way again…
…the big concern for us island landlubbers looking for something to warm our jellies is that rather than a generally quiet but cool outlook, the pattern in the event all heads just that bit further north bringing us back into chilly cyclonic influences that just judder your rafters. More pirate noises….
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The end of the coming week looking settled sooner and for longer now on the models. We’ve been watching this change develop for several days now, but it’s always good to see a signal:
a) firm up
b) come forward in time
And this one’s really beginning to look very good.
0z EPS for next Thursday (18th) from last Monday for day 10, and today at day 5, showing the two sides of the coin becoming more clearly imprinted - the bubble to the west of the UK and Ireland gaining in modelled heights and steadily being modelled further north, and the low heights earlier focused over Scandinavia, now modelled as a deeper trough extending down into southeast Europe.
Typical of how these models often work as they firm up, we can see the uncommitted, white gaps and softer shades getting gradually taken up by stronger signals, Atlantic heights growing stronger and more expansive, while a fully-fledged polar trough becomes marked out running down into Europe, the most notable synoptic difference being the development of the small low pressure to the east of Greenland that aids the link-up of low heights.
Though some colder, less settled conditions are slowly departing to the east, for the UK and Ireland, the more relevant feature is the decisive edging east of the modelled ridge, and more noticeably into southern Greenland and Iceland too, which sets up the prospect of an earlier arrival of a much quieter end to next week, and combined with the better build, dare we say it (!), hints at this being followed up by several back-to-back usable days…
….this positively illustrated by the EPS MSLP charts for day 7, with the high pressure edging in from the west at day 7, gradually establishing itself slap bang over the UK and Ireland by day 10.
Rightly being picked up on is the Atlantic becoming sealed off, but this looks a more substantial block than just that, with high pressure extending from the Azores through our stretch of Western Europe to Siberia, so by that stage it’s not only a block to weather off the Atlantic but also a block to further troughs running down through Scandinavia - with the added benefit that with the removal of the threat of the colder air to the east, in the gentle and variable circulation of the high pressure, daytime temperatures should be building to much more encouraging levels into the last week of the month - drier and warmer - good news for those yearning to give their spring freckles an airing. Have a great weekend.
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They appear to be the old Beaufort letters, used up until around that time, but replaced very swiftly thereafter.
e.g. ogm at Lerwick is o = overcast, m = mist and g = gale (mean speed 34-47 knots over a period of 10 minutes or more).
cq at Stornaway : c = cloud covering 6 to 7 oktas (eighths of the sky); q = recent squall
They are listed in this document here:
The really useful bit for these Beaufort letters gets going around page 29-30. There are some others relating to cloud cover on page 18.
It looks like you have many happy hours of meteorological detective work ahead! Best of luck.
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Blimey. Outstanding choreography from the ridge dance troupe, lining up to really sock it to the PV on the NH dance floor over the next 10 days on the 12z ECM operational run. Let’s watch the elaborate performance as successive waves of heights push north.
Starting from where we are today, PV centre stage, coordinating Atlantic, Scrussian and Bering Sea troughs in a whole hemisphere twirl.
Keep an eye on that little pocket of heights over the Canadian seaboard with the hook north, because….
…first up is the Atlantic ridge by day 3, still with the northward extension of heights, now extending well up through Baffin.
By day 5, the PV still holding centre stage, but the Atlantic ridge has been joined by the Alaska ridge, a sweet little link-up of heights pushing the lower heights east. But about to join in is a nascent ridge pushing up the east of Japan towards eastern Russia, and there are hints of a naughty little squeeze from Kazakhstan.
By day 9 / 10, the Kazakh squeeze is maintained, well and truly heating up that floor, while the Japan surge goes all-out Siberian, joining their friends from the west in a hemispheric Cha Cha that ultimately congas its way right through the heart of the Arctic.
PV exit stage left, arrivederci. A good few days respite for the UK and Ireland.
Yeah, sign up everyone (if you’re not totally exhausted), the moves are awesome.
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5057123 -
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Blimey. Outstanding choreography from the ridge dance troupe, lining up to really sock it to the PV on the NH dance floor over the next 10 days on the 12z ECM operational run. Let’s watch the elaborate performance as successive waves of heights push north.
Starting from where we are today, PV centre stage, coordinating Atlantic, Scrussian and Bering Sea troughs in a whole hemisphere twirl.
Keep an eye on that little pocket of heights over the Canadian seaboard with the hook north, because….
…first up is the Atlantic ridge by day 3, still with the northward extension of heights, now extending well up through Baffin.
By day 5, the PV still holding centre stage, but the Atlantic ridge has been joined by the Alaska ridge, a sweet little link-up of heights pushing the lower heights east. But about to join in is a nascent ridge pushing up the east of Japan towards eastern Russia, and there are hints of a naughty little squeeze from Kazakhstan.
By day 9 / 10, the Kazakh squeeze is maintained, well and truly heating up that floor, while the Japan surge goes all-out Siberian, joining their friends from the west in a hemispheric Cha Cha that ultimately congas its way right through the heart of the Arctic.
PV exit stage left, arrivederci. A good few days respite for the UK and Ireland.
Yeah, sign up everyone (if you’re not totally exhausted), the moves are awesome.
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A good indication of how far the models have come since the weekend in terms of bringing some anticyclonic promise to the UK and Ireland is provided by the MSLP charts of the 12z EPS and GEFS, and comparing today’s day 9 charts with the day 12 charts from Sunday.
EPS for the 19th, 7th + 12 days / 10th + 9 days
GEFS for the 19th, 7th + 12 days / 10th + 9 days
Both EPS and GEFS now picking up on a signal for high pressure over or near the UK and Ireland, for a few days at least. Looking a lot better.
Much more positive signs as we approach the middle of April, and high time for the models to be finally picking up on a more solid drier spell.
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Looking at the next ten days, which cover the middle third of April, t’s good to see the relevant part of the annual cycle, in the form of the springtime waning of the PV, well underway.
It is happening a bit later than the last couple of years, but is striking nonetheless, here on both the 0z ECM operational run and ensemble mean, day 1 - 10 animations, the PV very much on the wane, being nibbled away by evolving mid-latitude ridges, with the core PV diminished and returning from the Siberian Arctic to the pole.
This leaves us with a solidly meridional 5-wave hemispheric pattern by day 10, shown nicely on the op and mean anomalies, ridges by then through western North America, up through the eastern seaboard, Western Europe, Kazakhstan up into Siberia, and the far east of Russia.
The picture for the UK and Ireland alternates from seeing a shallow ridge over the next few days, to being under the influence of an active low pressure system passing through with the trough around days 5-6, before the arrival of a better amplified ridge by day 9-10 as the more meridional pattern firms up.
Day 10 provides a convenient juncture for the UK and Ireland for showing the potential for something more settled getting a bit further north to be more widely shared, op and mean again.
However, it looks very much like it’s a snapshot in a slow but steady revolution of the 5-wave ridge / trough pattern around the pole, with approximately 4 days appearing to be the current phase for the ridge to trough transition, hinting at a period of drier, brighter spells of 3-4 days alternating with more changeable spells of 3-4 days.
A much more normal and much more pleasant a pattern on view as spring more clearly shows its hand.
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5056678-
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Model discussion highlights
in Forecast Model Discussion
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It looks like we’re on a 10-12 day evolution back to something strikingly similar to what we currently have.
0z EPS, days 0, 5 and 10.
0z GEFS, days 0, 5 and 10.
It’s always easy to give this model or that model a bit of flack, which I never quite get, but it does seem fair to say that in this instance the EPS first picked up on the establishment of a less challenged Atlantic trough nearby to the UK and Ireland around the middle of the month, a preferred setup that the GEFS is now gradually falling in with.
Moving on speculatively to day 10-15, it looks like the trough will bed down for a fair while in our locale. 0z EPS jet stream at day 10 and 15 - I deliberately haven’t rotated these, in order to focus on North America.
At day 10, the Pacific jet stream is bifurcated on its entry to North America, around low pressure over California. The northern and southern arms then merge to the west of the Azores and is being steered over the top of the weak Azores high, then diving southeast into Iberia to carve out the trough.
There is a pronounced lack of change in evidence by day 15 - maintenance of split Pacific jet stream, Alaskan trough, west and east coast lows, weak Azores high, Atlantic jet stream diving into Iberia, all making for very little west to east mobility to dig out the trough quickly.
It will in time move on though. After all, the steady improvement of the coming week, culminating in a very pleasant spell, will have developed from the starting point of a similarly static trough - EPS chart for 1 May (day minus 5) and today.
There may be a quite comfortable balance emerging here in the pattern going forward, bearing in mind that due to the time of the year, the “troughy” spells rarely bring constant rain but the “ridgy” spells do invariably bring a good few dry days, and the sun is strong whenever we get it.
And in the first instance, the next week or so to enjoy!
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-spring-has-sprung/?do=findComment&comment=5066212