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marksiwnc

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    caernarfon, Gwynedd
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  1. It was snowing in penygroes this morning deffo. Although Llantrisant is quite far from here lol
  2. Snow has been Falling to low levels in NW Wales this morning. And it has gone a lot colder. Mountains are completely white
  3. I'm hoping that I've got a decent chance of snowfall tomorrow night and Friday. In NW Wales as I'm 8 miles from the sea to the north although if the wind travels over Anglesey then there's 20-25 miles of land before hitting here. Hope so
  4. The Arctic Oscillation (AO) is currently positive and is predicted to first trend positive week one and then trend negative back to neutral week two. The weakly positive AO is reflective of mostly negative pressure/geopotential height anomalies in the central Arctic and mixed pressure/geopotential height anomalies in the mid-latitudes. With mixed heights over Greenland and Iceland but positive heights across the mid-latitudes of the North Atlantic, the North Atlantic Oscillation (NAO) is currently positive. With heights predicted to rise slowly near Greenland the next two weeks, the NAO is also predicted to slowly trend negative. With strong oceanic ridging/blocking cold temperatures have become widespread across the Northern Hemisphere (NH). In general, Eurasian temperatures are predicted to follow the AO trends first turning milder and then colder again. Much of North America is in a clear trend to milder weather as a strong polar low is predicted over Alaska that will result in a mild, southwesterly flow of air downstream over much of North America. However the mild trend will be briefly interrupted by an Arctic outbreak at the end of this week. With near normal poleward heat transport, the stratospheric polar vortex (PV) has remained relatively strong. However the weather models are predicting the PV to become more disturbed over the coming weeks. A more highly perturbed PV could have an important influence on surface weather but for now that remains highly uncertain. I have been anticipating a stratospheric PV disruption beginning in the latter half of January that will have an impact on the weather; however, as far as I can tell the stratosphere and troposphere remain mostly uncoupled. Therefore weather patterns are more transitory and that will likely continue unless there is a significant disruption to the stratospheric PV. Impacts It is my opinion that the stratospheric and tropospheric PVs were coupled in the fall and through much of December. In December they were coupled in such a way that resulted in cold temperatures in western North America and western Asia. Later in December they were coupled that the PV was strong in both the stratosphere and troposphere that resulted in an overall milder pattern across the NH. But since the end of December the stratosphere and troposphere seemed to have gone their separate ways. The polar cap geopotential height anomalies (PCHs) warmed in the troposphere characterized by blocking in the northern latitudes of the two ocean basins that resulted in colder temperatures for both continents. In contrast the PCHs have stayed cold in the stratosphere and for now the Global Forecast System model (GFS) is predicting that the two remain mostly uncoupled. In the absence of coupling between the stratosphere and the troposphere the weather is likely to remain transitory. North American weather is sensitive to variability in the atmospheric circulation in the North Pacific. So far in January there has been strong blocking/positive geopotential height anomalies near Alaska resulting in cold temperatures downstream in Canada and the United States (US). However the pattern is predicted to reverse with a deep polar low centered over Alaska that will result in a southwesterly flow of mild, maritime air from the North Pacific across much of Canada and the US. My expectations are that this pattern will be transitory as well with a cooling trend towards the end of January. Across the larger Eurasian continent, the weather has been more stable with cold temperatures across Siberia and warmer temperatures across South Asia. The cold air from Siberia has been transported to the southwest into southwest Asia and Southeastern Europe by blocking in the Barents-Kara seas. Closer to the blocking/positive geopotential height anomalies across Northern Europe including Scandinavia and the United Kingdom (UK), temperatures have been milder. Variability in the pattern is expected but the overall pattern looks to persist in my opinion. My expectations have been for the stratospheric PV to become more highly perturbed the second half of January. There are signs that the stratospheric PV will become more perturbed in the coming weeks but I feel that it remains highly uncertain how much and what will be the impact on the weather. I don’t see an ideal pattern to excite strong upward Wave Activity Flux (WAFz)/poleward heat transport in the next two weeks. Until the stratosphere and troposphere become coupled, in either direction with strong or weakly coupled PVs, my ability to anticipate multi-week changes in the weather is limited. Brief update by judah
  5. You two can stop winding us up now. Lol hopefully your correct but I don't know. Certainly the models (especially GFS)! are shocking this winter. Maybe a sign of things to come in the future of weather forecasting for the British Isles
  6. Let's just hope the ECM is correct and that high pressure will continue to rise in the Atlantic so everyone can have snow. I'm not feeling confident on snow in my area Thursday/Friday even is there's weather warnings
  7. I was thinking why the weather warning was showing for the West really. I can't see anything below 100meters. That's just a guess mind you. Seems like forecast temperatures have risen a few degrees than originally thought
  8. Tbh you can almost laugh at these charts. I'm hoping the ECM and UKMO is correct but I can't see the GFS being wrong when showing mild. It almost guaranteed to be correct knowing our luck. Here's to hoping...... Forecasters nightmare every week
  9. Just a quick question. With waters quite warm around the UK and the burst of frigid cold coming down would this not promote some polar lows? If polar lows do develop then surely the outlook could be anything. I remember a low dropping from Iceland was a possibility yesterday could this low be a polar low development and the models are not able to pick it up until last few hours???
  10. Not the news we wanted but we have to accept it. Hopefully the models may give us some cheer in the new year with cold,crisp and at times the chances of snow country wide... Cheers Ian
  11. Ian f did mention that they (met) thought that a zonal period was probable between the high switching from our East to our North East I believe. I think this might be the way this pans out. Hopefully it would be able to dig a bit further north west.. hope gp puts a post the next few hours to see where he thinks we could be heading. give us (sacra members) some good news boys
  12. Hahaha watching the models is like a game of bingo when all array of options are on the table lmao. I just hope that yesterday's mumblings regarding a possible MJO 7/8 for that sudden change in all outlooks.... anyway eyes down for your first numbers hahhahaha
  13. The recent weather patterns changed after the last cycle so who's to know... no not corbyn. Nathan rao is the name hahahahahahahahahaha (obviously joking)
  14. Well I'm with gp on this one. I personally like the connection between weather and the moon cycles so I'm edging towards around 29/12 for new pattern due to new moon cycle. who know tho yeah
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