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knocker

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Everything posted by knocker

  1. Toasty from the gfs........always the model of choice
  2. In my experience, which I admit is very limited, whenever they are indicating severe cold and snow. Otherwise discard without further thought.
  3. The rapid cyclogenesis on this evening's gfs worth a mention as the low tracks NE south of Iceland down to 924mb by 00 Saturday
  4. The gfs temp panels through the 10-15 period show an increasing number of members along the same limes as the ecm. Oh suffering succotash
  5. Fascinating discussion over in the mod thread, it will be repeated again and again if you have missed it this time around, on the length and severity of the upcoming cold spell. Mind its not due to start for another ten days
  6. The good news from the gfs this evening is that the Arctic air is slowly being shunted east. I understand defibrillators are on standby
  7. Looking at the latest updates there is every chance the Dafs will be early down here this year,
  8. Maybe two hours if the ecm doesn't follow and drop the lobe of the vortex down the eastern US
  9. Need to give the barby a quick dust before the weekend
  10. I don't think that is what he is saying. But in any case it is not that easy to evaluate the probable influence of the the forecast background signals on the Atlantic and European weather as some on here make out. But having said that they should always be taken into account along with a keen scrutiny of the model outputs. Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4974204
  11. I don't think that is what he is saying. But in any case it is not that easy to evaluate the probable influence of the the forecast background signals on the Atlantic and European weather as some on here make out. But having said that they should always be taken into account along with a keen scrutiny of the model outputs.
  12. Could you post a link to the research that will corroborate that comment Ta
  13. Right, and the key to the gfs is the arctic plunge down eastern NA that amplifies the ridge into Greenland with the resultant CAA into Europe. Place your bets on the ecm doing the same but I know where my money is going
  14. Quote of the day in the mod thread. "We can't cherry pick what we want to see , this is the model thread" I actually came over quite faint reading it.
  15. Ocean surface temperatures set records during the Northern Hemisphere summer of 2023. This comparison shows how much warmer the ocean was in 2023 compared to the previous summer Introduction In 2023, many factors have contributed to remarkably high temperatures on land and in the oceans. One of these factors was the development of El Niño conditions in the tropical Pacific Ocean, as well as the corresponding (but not as well known) tropical Atlantic Ocean El Niño. However, this was not the only factor, nor was it the only place that sea surface temperatures (SSTs) were notably warmer than normal. Temperatures in the Mediterranean Sea, off the coast of Florida, and in the North Atlantic Ocean also made the news, and these elevated temperatures were implicated in significant weather events, particularly extreme rains and intense tropical cyclones. Many maps of SST show anomalies, which are the temperatures compared to a baseline mean temperature averaged over many years (commonly 30 years). While this common depiction is very useful, it is not unusual for temperatures to be warm in the summer (in this case, summer in the Northern Hemisphere). So, in this Data-in-Action article, the NASA visualization tools Giovanni and Panoply are used to compare SSTs averaged over the months of June, July, and August in 2022 and 2023. https://disc.gsfc.nasa.gov/information/data-in-action?title=Comparing Sea Surface Temperatures in June-July-August 2022 to June-July-August 2023&utm_source=newsletter&utm_medium=email&utm_campaign=earthdata-discovery-122023
  16. Oh God they are talking about the winter of 62-3 again, and again, and again, and again.
  17. Showcasing the death of the world’s glaciers By Audrey Payne Among the mountains of evidence that climate change is warming Earth faster than any other point in recorded history is the fact that most glaciers around the world are shrinking or disappearing. Melting glaciers and ice sheets are already the biggest contributors to global sea level rise, and according to the World Glacier Monitoring Service, ice loss rates have increased each decade since 1970. Yet, of the approximately 200,000 glaciers in the world currently, no database exists to identify which glaciers have disappeared, and when. The Global Land Ice Measurements from Space (GLIMS) initiative, an international project designed to monitor the world's glaciers primarily using data from optical satellite instruments, aims to change that. “Glaciers are indicators of climate change because they grow and shrink on longer timescales than rapidly changing weather, so they give a clearer signal about climate,” said Bruce Raup, a senior associate scientist at the National Snow and Ice Data Center (NSIDC) and director of the GLIMS initiative. “We know that glaciers are disappearing, but we’ve had no way to show that to people. So, we are making an effort to document glaciers that have disappeared and approximately when they disappeared.” https://nsidc.org/news-analyses/news-stories/showcasing-death-worlds-glaciers?utm_source=newsletter&utm_medium=email&utm_campaign=earthdata-discovery-122023
  18. A lot of comments again this morning in the mod thread about 'good or bad outputs' which are subjective and totally meaningless to ordinary mortals. They merely reflect the mindset of the thread.
  19. In fact at any time of the relationship is fragile if anything impacts the lapse rate such CAA within the layer for example. I would have thought you always need to take great care evaluating surface temps from the 850s unless other info is also available
  20. How do different pathways connect the stratospheric polar vortex to its tropospheric precursors? Abstract Processes involving troposphere–stratosphere coupling have been identified as important contributors to an improved subseasonal to seasonal prediction in the mid-latitudes. However, atmosphere models still struggle to accurately predict stratospheric extreme events. Based on a novel approach in this study, we use ERA5 reanalysis data and ensemble simulations with the ICOsahedral Non-hydrostatic atmospheric model (ICON) to investigate tropospheric precursor patterns, localised troposphere–stratosphere coupling mechanisms, and the involved timescales of these processes in the Northern Hemisphere extended winter. We identify two precursor regions: mean sea level pressure in the Ural region is negatively correlated with the strength of the stratospheric polar vortex for the following 5–55 d with a maximum at 25–45 d, and the pressure in the extended Aleutian region is positively correlated with the strength of the stratospheric polar vortex the following 10–50 d with a maximum at 20–30 d. A simple precursor index based on the mean pressure difference of these two regions is very strongly linked to the strength of the stratospheric polar vortex in the following month. The pathways connecting these two regions to the strength of the stratospheric polar vortex, however, differ from one another. Whereas a vortex weakening can be connected to prior increased vertical planetary wave forcing due to high-pressure anomalies in the Ural region, the pathway for the extended Aleutian region is less straightforward. A low-pressure anomaly in this region can trigger a Pacific–North American-related (PNA-related) pattern, leading to geopotential anomalies of the opposite sign in the mid-troposphere over central North America. This positive geopotential anomaly travels upward and westward in time, directly penetrating into the stratosphere and thereby strengthening the stratospheric Aleutian High, a pattern linked to the displacement towards Eurasia and subsequent weakening of the stratospheric polar vortex. Overall, this study emphasises the importance of the time-resolved and zonally resolved picture for an in-depth understanding of troposphere–stratosphere coupling mechanisms. Additionally, it demonstrates that these coupling mechanisms are realistically reproduced by the global atmosphere model ICON. https://wcd.copernicus.org/articles/4/1071/2023/
  21. https://confluence.ecmwf.int/display/FUG/Section+8.2.6+Madden-Julian+Oscillation+Output
  22. The links between the Madden-Julian Oscillation and European weather regimes Abstract Skillful weather forecasting on sub-seasonal timescales is important to enable users to make cost-effective decisions. Forecast skill can be expected to be mediated by the prediction of atmospheric flow patterns, often known as weather regimes, over the relevant region. Here, we show how the Grosswetterlagen (GWL), a set of 29 European weather regimes, can be modulated by the extra-tropical teleconnection from the Madden-Julian Oscillation (MJO). Together, these GWL regimes represent the large-scale flow characteristics observed in the four North Atlantic-European classical weather regimes (NAE-CWRs), while individually capturing synoptic scale flow details. By matching each GWL regime to the nearest NAE-CWR, we reveal GWL regimes which occur during the transition stages between the NAE-CWRs and show the importance of capturing the added synoptic detail of GWL regimes when determining their teleconnection pattern from the MJO. The occurrence probabilities of certain GWL regimes are significantly changed 10–15 days after certain MJO phases, exhibiting teleconnection patterns similar to their NAE-CWR matches but often with larger occurrence anomalies, over fewer consecutive MJO phases. These changes in occurrence probabilities are likely related to MJO-induced changes in the persistence and transition probabilities. Other GWL regimes are not significantly influenced by the MJO. These findings demonstrate how the MJO can modify the preferred evolution of the NAE atmospheric flow, which is important for sub-seasonal weather forecasting. https://link.springer.com/article/10.1007/s00704-020-03223-2
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