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Blessed Weather

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About Blessed Weather

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  • Gender
    Male
  • Location
    Hadleigh, Suffolk
  • Interests
    Weather extremes, mountains and skiing, foreign travel, British pubs. As a 10 year old I experienced the 1962/63 winter which was the start of my life-long interest in all things weather related. The family had just moved into a new-build house on the top of a hill in Wales when the blizzard struck overnight. I woke up with my bedroom window sill covered in snow. In the bathroom the sill was covered and the bath was full of several inches of snow. The water in the toilet was frozen. Oh the joy of badly fitting, draughty wooden windows... and only a coal fire in the living room to warm the entire house!
    My first skiing trip to the Alps was in 1966. It was a school trip to Solden in Austria and we travelled by train across Europe. It was my first trip abroad and I hardly slept all way with the excitement. It led to a life-long passion for all things skiing and mountain and nowadays I try and have a few ski holidays a year if I can, spreading my visits across the Alps and try to visit less well known resorts as well as the usual suspects.
    My other passion is rugby and coming from Dinas Powys in South Wales I'm naturally enough a Wales fan. I now live in Suffolk (job move) but regularly travel back in Wales where my parents still live.
    My avatar is inspired by Brian Blessed - absolutely awesome in panto!!
  • Weather Preferences
    An Alpine climate - snowy winters and sunny summers!

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  1. Revisiting the GFS 8-10 day NH 500hPa heights anomaly (19th-21st Dec) which has now updated for the 12z run and the model has made a clear step towards the ECM solution, with higher pressure over the Arctic which is now similarly straddling the Pole and encroaching west towards Greenland. And as mentioned by Phil above, the 12z also showing a weakening of the trough to the west of the UK. Here's the two runs for comparison: GFS 0z run: GFS 12z run:
  2. Whilst some good agreement between the two major model forecasts out at 19th-21st December, particularly wrt continuation of a strong Jet Stream and Atlantic trough impacting the UK, there is indeed a disagreement regarding forecast heights over the Arctic. These features shown clearly on the 8-10 day NH 500hPa mean height anomaly chart from this morning's 0z operational output: Although the operational models disagree about the Arctic profile, both the GFS and ECM ensemble members are largely in agreement about the areas of uncertainty upstream of the UK at that time. We'll see if the 12z runs bring any noteworthy changes to this. ENS spread: GEFS spread:
  3. Fantastic! Great skiing/boarding in La Plagne and well worth taking the cross-valley cable car over to Les Arcs for epic skiing over there too. Both LP and LA have great snow conditions at the moment and look set for an amazing start to their seasons this weekend. Current depths are: LP Upper 100cms Lower 30cms LA Upper 150cms Lower 80cms. Here's the view from Roche de Mio, La Plagne, yesterday: And the forecast for the rest of this week is for another 80cms of snowfall in LP. Snow accum from today to midnight Sat 14th: It would take exceptional weather conditions to mess things up for the Christmas week. A high pressure is not necessarily bad news as the temps are likely to be sub-zero overnight and on north facing slopes no real damage will be done by day. Hope you do it and have a great week.
  4. Sorry for the late reply but I've been away on hols. You may wish to visit the Meteo France (French Met Office) website. They use their own models (such as Arpege) and not the GFS so are normally more accurate. Follow this link and enter the resort (station) you'd like the forecast for. When the daily forecasts display (they go out 2 weeks) just click on any day to get further detail including snow line and freezing level ISO. http://www.meteofrance.com/previsions-meteo-montagne
  5. Some interesting discussions going on in here, but I'm afraid they were not on-topic so I have moved them to the Winter Chat thread here. Please stick to Strat and PV discussions in this thread. Many thanks.
  6. Looks like my location has ducked the punch. I was looking forward to the squall line arriving so thought I'd check the latest radar only to find there's a great big gap heading towards my location. Never mind, I'm sure I'll be fed up with wind and rain by the time this week has done with us.
  7. MJO Update 9th December Forecasts from a couple of weeks ago that the MJO might progress into Phases 8 and 1 - supportive of a negative NAO – seem to have been wide of the mark. Current signals from the tropics over the next couple of weeks suggest little MJO influence on the UK weather pattern. The Indian Ocean Dipole – which set a new November record - continues to interfere with the development of the MJO in the IO, in particular causing uncertainty about its eastward progression going forward. IOD record Nov peak: The Phase diagram from the GFS Ensemble (bias corrected) shows the MJO in Phase 2 over the next week, then briefly Phase 3 in week two, before slipping into the COD (denoting insignificant impact on the mid-latitudes). Source: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml#discussion Beyond that the CFS forecast 850hPa wind anomalies out to 6th Jan (also showing MJO, Kelvin and Rossby Wave activity) has good and bad news. The good news is the strong easterly anomalies over the IO fade as the IOD also enters its natural period of winter decay. This allows westerly wind anomalies and an active MJO to start building again, this time – with fading IOD interference - hopefully looking good to move east into the Kelvin Wave generation area (approx. 135E to 170W) around the end of the year/early January. Source: https://ncics.org/portfolio/monitor/mjo/
  8. For the record, November in the East: Coldest November since 2016 (-0.6°C) Wettest November since 2015 (114%) Dullest November since 2015 (84%) The rainfall deficit for the past 12 months is 19mm. The deficit for the past 3 years is 142mm. Stats and chart courtesy of Dan Holley, Weatherquest. Twitter @danholley_
  9. An interesting Tweet from Simon Lee referring to new research into the impact of warming in the Indo-Pacific tropical oceans causing a slowing of the progression of the MJO in Phases 5 - 7. I've also copied the abstract from the paper he refers to but unfortunately the full paper is behind a paywall. It would be good to see the full paper as Phases 6 and 7 are supportive of -NAO and SSW developments. Twofold expansion of the Indo-Pacific warm pool warps the MJO life cycle The Madden–Julian Oscillation (MJO) is the most dominant mode of subseasonal variability in the tropics, characterized by an eastward-moving band of rain clouds. The MJO modulates the El Niño Southern Oscillation1, tropical cyclones2,3 and the monsoons4,5,6,7,8,9,10, and contributes to severe weather events over Asia, Australia, Africa, Europe and the Americas. MJO events travel a distance of 12,000–20,000 km across the tropical oceans, covering a region that has been warming during the twentieth and early twenty-first centuries in response to increased anthropogenic emissions of greenhouse gases11, and is projected to warm further. However, the impact of this warming on the MJO life cycle is largely unknown. Here we show that rapid warming over the tropical oceans during 1981–2018 has warped the MJO life cycle, with its residence time decreasing over the Indian Ocean by 3–4 days, and increasing over the Indo-Pacific Maritime Continent by 5–6 days. We find that these changes in the MJO life cycle are associated with a twofold expansion of the Indo-Pacific warm pool, the largest expanse of the warmest ocean temperatures on Earth. The warm pool has been expanding on average by 2.3 × 105 km2 (the size of Washington State) per year during 1900–2018 and at an accelerated average rate of 4 × 105 km2 (the size of California) per year during 1981–2018. The changes in the Indo-Pacific warm pool and the MJO are related to increased rainfall over southeast Asia, northern Australia, Southwest Africa and the Amazon, and drying over the west coast of the United States and Ecuador. Link: https://www.nature.com/articles/s41586-019-1764-4
  10. ENSO Modulation of the MJO That’s a great paper you’ve spotted @Kirkcaldy Weather and worthy of a more detailed look. It articulates with great clarity the way in which multiple teleconnections interact to impact weather around the world and specifically the way in which the combined impact of ENSO and MJO interworking impacts the NAO and thus UK weather. At the end of this post I draw my conclusions about the implications for the current outlook for the UK. So first of all the title (with embedded link to full paper) and ‘plain English’ abstract: ENSO Modulation of MJO Teleconnections to the North Atlantic and Europe "The Madden‐Julian Oscillation (MJO) is the dominant source of differing weather conditions in the tropics on timescales within a season. The remote linkage (teleconnection) from the MJO to the North Atlantic‐European (NAE) region provides a source to modify or persist weather conditions and add predictive power to weather forecasts on 10‐ to 30‐day timescales. The El Niño‐Southern Oscillation (ENSO) has an influence on the seasonal climate state, through which the waves and linkages from the MJO to the NAE region travel. Here we find a robust dependence of these teleconnections from the MJO to NAE weather regime patterns on the ENSO state, such that under certain states of the MJO, certain regimes occur more than twice as often. The different sources and pathways also become clearer, with the teleconnections travelling via the troposphere and the stratosphere. This dependence on ENSO state has significant implications for predictions on 10‐ to 30‐day timescales." In my previous post above I’ve described how the MJO, via Rossby-Kelvin Waves, impacts weather around the world, so I’ll not cover that aspect again. Rather, I’ll focus on the new aspects revealed in this paper. Significant aspects shown in bold. First up, this paper states that the MJO impact on the North Atlantic-European (NAE) region is typically around 10 Days, but this can vary depending on the strength of the MJO and also Phase (where it is in its circumnavigation of the globe) as each Phase lengthens or shortens the teleconnection pathway. MJO Phase 3 – approximately 10 days after this Phase (active convection over the eastern Indian Ocean), the occurrence of +NAO regime is increased by ~60% relative to climatology. MJO Phase 4 - This +NAO impact can extend for up to 12 days after phase 4. Following the above Phases 3 and 4 there is a small (~30%) increase in the chance of a Scandi Block (SB) and Atlantic Ridge (AR) developing at lags of around 0–6 and 10 days, respectively, likely as a result of in situ development and dynamics in the NAE. MJO Phase 6 – at lags of 10+ days after (active convection over the western Pacific Ocean) there is an increased occurrence of a -NAO by up to ~70%. Phase 7 and 8 – the increased occurrences of a -NAO lasts through MJO Phase 8. The above impacts are nicely summarised in the next diagram, also posted by @sebastiaan1973 above: ENSO Impact – this teleconnection with its El Nino (EN - warm Pacific) and La Nina (LN - cold Pacific) provides the key backdrop within which the MJO propagates. The paper finds that during the extended winter months of Nov – March there is a robust dependence of the MJO > NAE teleconnection on the differing status of ENSO (EN, LN and Neutral). El Nino Impact During EN years the +NAO teleconnection is of a much larger amplitude, significant following MJO Phase 1, with increased occurrence up to ~100% (twice climatology), restoring to climatology around 6 days (one MJO Phase) later. When there is no active MJO teleconnection (Phase 0; around one third of winter days), there is an increased frequency of -NAO and AR, and decreased frequency of +NAO. The -NAO regime has significant increases in occurrence only after MJO Phase 7 (also up to ~100%). The paper concludes that the MJO‐NAE teleconnection during El Niño years results in a much more frequent +NAO regime state, occurring after MJO phases 1–5 and dominating the seasonal mean teleconnection. Neutral ENSO Impact The paper concludes that the MJO‐NAE teleconnection results in a slightly more frequent +NAO state after MJO Phases 1 - 4 and a much more frequent -NAO regime state after MJO Phases 6 - 7. La Nina Impact The paper concludes that the only complete MJO‐NAE teleconnection during LN years is a strong -NAO teleconnection but this only occurs late in the MJO Phase 8 and rapidly fades. This illustration is a good visualisation of the processes involved: Implications for current UK Outlook The MJO is currently flirting with Phase 0 (Circle of Death - COD) but expected to move into Phase 1 and progress through Phases 2 and 3. Here’s the latest ECM forecast for 27th to 11th December: Based on the MJO Phase and current ENSO Neutral status, what 500hPa pattern should we expect in our neck of the woods? A look at the following diagrams from the paper shows the expected 500hPa heights anomalies for the various combinations of MJO Phase and ENSO status. I’ve marked the relevant patterns which are in line with the findings of the paper for a "slightly more frequent" +NAO state in Phases 1 - 4. The +NAO signal lasts until the MJO once again cycles through to Phase 6 where this switches to supporting a "much more frequent -NAO regime". Current MJO forecasts suggests the progression to Ph 6 will not be until late December: With MJO Phases 0 and 1: With MJO Phases 2 and 3: Edit: There are other teleconnections that also impact the NAO (and indeed the MJO) such as low solar activity, Strat Polar Vortex strength and whether there is an easterly or westerly QBO. In this post I have focussed on the findings of this new paper and have made no attempt to introduce any potential impact from other teleconnections. There are many complex interactions and feedback loops between various teleconnections and these will be subject to further posts.
  11. Thanks Mike. I was scratching my head here, trying to think through why a heights anomaly correlation would give a different seasonal result to an RMS error rate. Then I looked at your charts again and twigged it's showing a 3-month mean correlation for Day 5. Maybe that's got something to do with it but to get to the bottom of it I wonder if you could pm me the methodology (or link) used to produce those charts. Ta.
  12. There's a lot of opinion being expressed in here about the performance of various models. I think if you are to criticise a model it is only fair your opinion is backed by facts to justify your remarks. So let's look at the latest Root Mean Square Error (RMSE) rates for the NH published by ECMWF (note: data published for testing purposes but presumed factually correct). The RMSE is a measure of the differences between values predicted by a model and the values observed. I've plotted data for ECM, Met Office, NCEP (Old GFS), and DWD (ICON) for June 2019 and it can be seen that: ECM is clearly the model with the lowest error rates from Day 1 out to Day 10. There is minimal difference between Met Office, GFS (old), and ICON (based on June 2019 results) Met Office is second best up to Day 4 but by Day 5 has been overtaken by the GFS. By Day 6 it has been overtaken by ICON. Source: https://apps.ecmwf.int/wmolcdnv/scores/mean/500_z Next a look at the verification stats for model performance in America and Canada published by the Canadian Met Office. Their graph compares the error rates at Day 5 and runs from 2017 up to Sept 2019. The latest results have the top models in the following order: ECM Europe (best) Met Office UK GFS (old) America ICON Germany JMA Japan CMC Canada (worst) Source: https://weather.gc.ca/verification/monthly_ts_e.html Some interesting observations on the graph. First is that the models all show fewer errors in the summer months than in the winter. Secondly it appears that every year it is the months of Nov and Dec that give the biggest headache for the models and the highest error rates each year, no doubt caused by the dynamics of the weather waking up from its summer slumbers, for example as the increasing temperature gradient between the rapidly cooling northern areas interacts with the warmers temps lingering further south and fires up the Jet Stream. Final thought, forecasting for our small island, on the edge of the Atlantic and continental Europe, inevitably gives its own challenges to the models.
  13. Hot and sultry here in Suffolk today with the temp up to 32.9C and 100% humidity. Well at least that was according to a malfunctioning weather station! The reality was a miserable, drizzly day with a high of 10.3C and zero sunshine according to my local Met Office station. In terms of weather, November is my least favourite month and I think the stats out next week will show this one to have been wetter and colder than average.
  14. @ghoneym has kindly posted the link through to the workshop presentations in the Teleconnections thread. Thanks Gary. "A lot of presentations to get through but worth a watch, lots of learnings. Amy Butler's presentation is superb in session 1."
  15. The Zonal Mean Zonal Wind charts from Berlin are interesting this morning. I've animated them and at the start of the sequence (24th to 28th Nov) we can see the westerly zonal winds (red) descending into the troposphere. Then from 29th Nov the descent stops as easterly zonal winds (blue) kick in and dominate at 80N, all the way from the troposphere up into the stratosphere. As bluearmy says above, it's showing a reversal at 70N and with the SPV wind speed measure at 60N 10hPa considerably reduced to around 6m/s. Sustained Wave 1 activity looking to be the cause as illustrated by the GEFS graph. Source GIF charts: https://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html Source Wave graph: http://weatheriscool.com/index.php/stratospheric-forecast-wave-series/
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