Cambrian

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

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.

Please continue to use the reporting facility in the usual way. If you have a specific issue regarding moderation, or in general, that you would like to raise with the team, then please do so via here: https://www.netweather.tv/other/contact-us We greatly appreciate this feedback. Please remember that the moderators are keeping an eye on the shape of the forum across many threads. If you have reported a post and no action has been taken, it’s invariably because it has been reviewed and the decision was to leave the post as it is. For instance, at quieter times, when there is little possibility of the thread becoming derailed by a marginal post, some leeway is sometimes given in order to keep the threads moving along and as engaging as possible. 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!

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

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….

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.

Historybuff 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: https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/research/library-and-archive/library/publications/factsheets/factsheet_11-interpreting-weather-charts.pdf 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.

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

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.

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.

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

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.

As the great man himself promised, Kathleen is being taken back home again, to be reabsorbed within the PV by day 5, here on the 0z ECM operational run. As a result, for the UK and Ireland, a vastly improving picture over the coming week as heights build northeast from the Azores, temperatures picking up by the end of the week for a while too if the T850s are anything to go by. Before exiting east, Kathleen ejects some energy westward to help the next system along, this one passing east further north through Iceland, to set up over Scandinavia from day 6 through to day 10. The bulk of Kathleen has by then rejoined the PV from the Siberian side, helping it pivot to be elongated down towards the Norwegian Sea, fuelling the dropping of the trough down through Scandinavia, bringing the UK and Ireland into a cold northerly flow for several days. After this rather dramatic phase (following three inches of snow in west Wales last week and three days of gales in the west of Ireland this week!), Kathleen looking to help ultimately deliver something for everyone - a storm, briefly something a bit warmer, followed by some clear Arctic air and the possibility of a quieter, more standard meridional pattern as we head into the second half of April. So I guess it’s only fair to leave the man have the last words: “And when the fields are soft and green I will take you to your home Kathleen”

Attempting to piece together (as we are inclined to do!), emerging trends of the outputs from different models, here the 12z GEFS and UKMO at day 4: And then, taking it through to day 7: That is one very welcome surge in heights from the southwest early next week, resulting in a 1030mb+ high pressure cell making a visit on the UKMO. A tad optimistic perhaps and probably not that long-lasting in the event, but the contrast is striking and very good to start seeing all the same. Have a good one.

Hope you all had a great Easter and that the beginning of April finds you in good health. Looking at the models over the last couple of weeks it’s easy to perceive little or no change to the pattern and no respite from low pressure for the UK and Ireland. However, there are slow but important changes consistently creeping in to the Northern Hemisphere profile in the longer ranges. They’ve been in recentruns of the EPS / ECM too, but here we’re looking at the 12z GEFS. At day 5, not much change from the here and now, PV elongated in our direction, with the trough dropping down to our west, and anchored there due to an attractive bump of unseasonably warm heights along with a surface high pressure over the central Mediterranean. Another notable bump of heights up through central North America too, into Hudson Bay, maintaining the tight Bering Sea to eastern Atlantic alignment of the PV. By day 10, we’ve lost the heights heading up through the American Midwest into central Canada, replaced by an upper level trough, allowing the PV to fill out west, so we get low heights working down into Hudson Bay. As a result the Atlantic jet stream and trough begins to relax north, so though we still have low pressure anchored to our west, it’s further northwest and nowhere near as deep, central pressure about 20mb higher. At the same time, the loss of heights over the Mediterranean should allow easier eastern transfer of frontal systems through Northern Europe, so the setup not near as stuck. The same process continues through to day 16, so much indeed that the PV is now orientated Siberia to Labrador, with a fully fledged trough pointed down into eastern Canada. A good build in heights from Eastern Europe up into northern Scandinavia puts a roof over our heads so that the draught can only get in through the window. The gradual warming out of the Atlantic trough continues with the 1015mb isobar clipping the far south of the UK, high pressure relocating to the Azores, bringing the foundation for a greater chance of some more substantial ridging northeast in time, the models at least now showing signs of beginning to search out a route out of the rut towards a slow but steady improvement by, and more especially after, mid month. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5053938