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  1. All factors count, with that in mind it is necessary to look at this event from all levels and not just at the 850 and 500 hPa levels. SSW split the Stratospheric PV. That propagated down and was assisted by wave 2 to dominate the entire atmosphere from surface to upper Stratosphere. That opened the Arctic to HP. Wave 2 prevents the PV from reforming. As the timings draw closer to surface reactions you only have to look at the Upper Tropospheric charts to observe how the Scandi HP can develop and hold position. Observe the 150 hPa. HP dominates the Tropospheric PV and holds the Atlantic via the block. It is these observable charts that encourage deep confidence with what the 500/850 hPa charts show, to actually come to fruition by next weekend. To take that further, you can follow the 150 hPa level charts to see when retrogression will or will not follow towards Greenland and to predict when the cold spell will end. Add a 2 day lag from 150 hPa level to 500 hPa for best results. Remove the guess work and the confidence in long range prediction is increased.
  2. If it transpires with this actual outcome below and with a WAA of this magnitude. You will see the formation of an Omega block on a magnitude not seen since 2010. You’ve got to realise that the more energy that goes up then the stronger the block when it closes off. This would be a very very special event.
  3. Anthony has picked out a composition that results in best -NAO for the Eastern US. March 2013 would have featured had it resulted in a colder outcome for our cousins in the states. Watch the migration of the Euro HP- Travels west over UK, into the Atlantic and up towards Greenland. Gave them a late winter in 2001 with large amounts of snowfall. 2018’s -NAO is to travel NE from the Atlantic towards Scandi and then NW towards Greenland. Synoptics are very different. Outside influencing factors are also different. I believe the US will get their West based -NAO in week 1 into week 2 of March, as the tropospheric PV moves Westward and breaks out into lobes.
  4. The ECM sees the reversal. It’s just not within the range of the 10 day model outputs of this past weekend. My post was in reference to those that were writing off the SSW effects by not seeing the tropospheric response showing an Easterly with every output. When the time table was always pointing towards 21st-25th Feb, if all proceeded as expected. Minor displacements in the Stratosphere give us a -AO, I expect the same and much more from this event. I felt that if the ECMWF’s Stratosphere and Troposphere modelling were in sync, that it would show the formation of a significant-AO. That didnt happen and therein lays my sole criticism of the ECM. As for the GFS, it sees the signal, it just doesn’t know where and what date to proceed with the correct solution. Ive put a timetable of my expectations and upcoming events and expect to die on my sword for trying to be an SSW oracle. All good.
  5. Absolutely 100% agree with you as to the ECM’s current model output. It is not even registering the bare minimum of a -AO from this event as the effects of the SSW are out of its range at present. Minor displacement event at the beginning of Jan 2018 Required 12-14 days to register a -AO on the ECM . We don’t even have a reversal registering at the 10 hPa level at 60 N as per Berlin. Which will show by tomorrow or Tuesday at the latest. So it stands to reason that in reality it does not know that it’s coming. As seen on the 10 Day model forecasts of this weekend. Propagation towards the surface on the 14th/15th. WAAs to occur around the 17th-20th Pacific and Atlantic routes. Shortly after we should see an enforcement of -AO from the WAAs. 21st-25th for -NAO. Scandi HP to show first until wave 2 dismantles the US vortex and hunts down the meandering Asian lobe. Once that is complete we would be expecting to see retrogression of HP towards Greenland by the beginning of March. As the HP on Tropospheric level gains more in roads into US Trop PV. Apologies for using your post Sebastian to vent on the failure of some to merely stand firm and watch the developments occur.
  6. UKMO has a strong -AO at 144z. The GFS is now onto the correct solution. Scandi HP developing. Retrogression to Greenland is on the horizon. (20th approx)
  7. “How I learned to stop worrying and love the SSW” Dr Strangelove. I have always attempted to keep my explanations of the atmospheric processes in the most basic of terms. Simplistic, yes but wanting them to be very understandable too. SSW creates a split at the 10hPa level commencing over the next 24 hours. As seen below. Inside the gap of the split vortices there becomes an opening for High pressure to locate to that position. We have seen several times this winter, the development of a -AO. Displacement of the PV off its natural peg hole- Greenland. The wave energy burns out and we see a return of the PV back to its natural position. What we have now is not only displacement but also destruction of the PV and no return to its default position. The SSW downwells enough that it allows upwelling from the surface (wave 2) access to an altitude and position that would be unattainable without the SSW. That easterly winds exist in all levels from Mesopause to the surface. Firstly at the pole= -AO and the lower latitudes. Above see how the HP moves into the gap of where the upper Trop PV existed. We have a cross polar link up. Allow 2 day lag to make the same positions at 500 mb level. Then by the 17th Feb the -AO acts as an elbow into the face of the US daughter vortex and pins in down. While at the same time the vortex is attacked again leaving more certainty that the PV will not reform or reposition at its default for approx 4 weeks. That is if it can recover from such a brutal assault. The ECM has a better handle on the upcoming surface reactions. Strat/Trop PV is gone and so the -AO opens the way for a -NAO to develop. As seen below I feel the GFS is struggling to interpret to upcoming developments and is messy in comparison. Hope this explains the quiet confidence of the SSW effects and the incoming surface responses based on logic, physics and the process.
  8. Very marginal 1/2 km, it will change again tomorrow for sure.
  9. The ECMWF has wave 1 tantalisingly close to full reversal. As it is so close many will have to watch stats up to and after the event. Wave 2 is going to require the same observations
  10. What are your thoughts on Tropospheric responses? Decoupling between Trop and Strat PV by 10-14 days. Then reliance on WAAs to disrupt the Trop wave pattern into several extending lobes towards the lower latitudes. As to where I’d only be guessing, very difficult to calculate.
  11. Who is willing to predict the NH Tropospheric scatter from this reversal. If the GFS is reading to split correctly and both lobes are hit with down welling it is effectively a continuous atmospheric shotgun blast.
  12. Pleasantly surprised with the energy contained inside the two initial pulses from wave 1 at the 1hPa level. GFS is predicting PV relocation towards Eastern Canada a non to common event if it does transpires. Patience is a virtue of stratospherics but all worth it when we arrive at this point.