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Yarmy

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Everything posted by Yarmy

  1. Yarmy
    Just had another very heavy - if brief - snow shower. Those North Sea surface temperatures making a difference, I think. Have about 4 inches now using my fingers into the top of the car measurement method.
  2. Yarmy
    FWIW, that shortwave modelled by GFS last week (which apparently handles Greenland better) as going E/NE to Northern Scandinavia and beyond has just delivered me between 5 and 10 cm of solid white precipitation. Models, eh?
  3. Yarmy
    Impossible for them really. I don't think any us believe the monster undercut will really happen so they don't want to panic anyone (especially those in SW England). On the other hand, if they don't say anything and it does come off, they'll be crucified.
  4. Yarmy
    Snowing again here. Not that heavily though.
  5. Yarmy
    Moderately heavy snow here replacing the overnight 1cm that had melted. Roads and paths too wet to settle, but grass, roofs and cars are getting covered. Edit: Spoke too soon. Beginning to stick to the roads. We're past peak temp for the day, so hopefully the front will stall right here and as temps continue to drop.
  6. Yarmy
    That comes as a surprise to those of us living near the West Norfolk coast.
  7. Yarmy
    Stay safe, friend, and don the factor 30. UPDATE: Bin lorry has made it through the 1cm drift. Phew.
  8. Yarmy
    Worth keeping in mind that North Sea surface temps are quite elevated at the moment so any wrap round could benefit from that. (Was that a ramp? My first since joining NW, if so)
  9. Yarmy
    Blimey, a week of cold, plenty of snow potential to come, yet still rampant pessimism. A couple of days ago, there were certain op runs and ens members showing the Atlantic blasting through on Tuesday and a raging PV thereafter. The only trend I can see is the cold spell being extended. Yet just because the UKMO mega blizzard is probably a glitch, it's the end of the world. A quick trawl through the New Year's Day T240 archives will be a salutary reminder of where we could have been.
  10. Yarmy
    In my short time here, both these runs seem to be regarded with some disdain relative to the 00z and 12z, but I'm not sure if there are verification stats for the separate runs.
  11. Yarmy
    Must. Remain. Calm. And. On. Topic. Today's 12z T84 v Yesterday's 6z T114
  12. Yarmy
    Indeed, but worth remembering we are back into FI then and the GFS had our potential snow machine Shortwave heading E/NE a couple of days ago.
  13. Yarmy
    Apologies, 35% of what?
  14. Yarmy
    Looking at the verification stats for the main players: http://www.emc.ncep....l/aczhist6.html (BTW, is this the most up-to-date place to find them?) Does anyone have the dates of previous SSWs (or even minor warnings) to plot against that? Might give us an idea of how the models do in those circumstances. What stands out for me is that they seem to usually do better in the NH winter then summer (more solar energy = more volatility, I suppose). Also, they seem more consistent in the SH. Edit: Should also note how much they have improved over the decades. Remarkable.
  15. Yarmy
    FWIW, GFS 00z Yesterday for Mon 14 at 7am 06z Yesterday for Mon 14 at 7am 00z Today for Mon 14 at 7am 06z Today for Mon 14 at 7am Differences, but not a million miles apart, then... 00z Yesterday for Wed 16 at 7am 06z Yesterday for Wed 16 at 7am 00z Today for Wed 16 at 7am 06z Today for Wed 16 at 7am No point looking beyond T102 for me, even for trends. My strategy is to look up to then and stop, then read the meteorological arguments given here (even when they soar over my head) for future evolution.
  16. Yarmy
    I didn't think MOGREPS was for public consumption?
  17. Yarmy
    Canada. French Canadians, though. :-)
  18. Yarmy
    The Canadians evidently have a lot of confidence in their Strat NWP extensions http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-11-00097.1 It will be interesting to see the verification stats for this period when it all plays out.
  19. Yarmy
    At T48 the ECM/GFS/UKMO/GEM are all very similar: http://www.meteociel.fr/modeles/ecmwf/runs/2013011000/ECM1-48.GIF Given that these patterns are unlikely to change significantly, why are we confident to see a resolution tonight or even tomorrow night? At this point on, it looks like a bifurcation to me: http://en.wikipedia.org/wiki/Bifurcation_theory I'd hazard that we might even have to watch the whole thing unfold in real time, before we know for sure (the NOW model ).
  20. Yarmy
    lnformation Theory Lecture http://videolectures.net/mlss09uk_mackay_it/ It's actually quite entertaining, and I did study it 20 years ago as a student although I remember little. The context here is machine learning (heuristics) which is suggestive to me of 'learning from the past' which logically we might expect to be a part of modern nwp models. Given that only recently have the models begun to use data up to the top of the Strat that this indeed is why the uncertainty is so high. Complete speculation on my part, but there you go.
  21. Yarmy
    What a bewildering (but fascinating) time for a newbie to start chart watching! Anyway, I have GFS/ECM/UKMO open in 3 windows and as I step through I can see the divergence emerge after T48. At T72, ECM begins to do its own thing, but GFS and OKMO are still close (to my novice eyes). UKMO GFS It's then that things begin to really change, but it seems a shame to me that neither UKMO nor ECM provide the 6h or 12h updates at that stage as GFS does so you can really watch the evolution in detail. So the question it leaves me is, leaving the models aside, are there any compelling physical reasons why that low would track E/NE rather than SE?
  22. Yarmy
    Agree. I think it's the 0Z T144 and it is wrong on Meteociel.
  23. Yarmy
    Uncertainty, in a nutshell. Comes from Information Theory. I actually studied it in a Maths course many moons ago, but I only first heard it used in relation to forecasting by Ian F on here.
  24. Yarmy
    I'm currently reading a book on weather which says the first ever computerised precipitation forecast was produced in 1967 by the Met. Just goes to show that predicting ppn is several orders of magnitude more difficult than pressure patterns (which as recent events show is hard enough!).
  25. Yarmy
    Unless anyone here has access to the model source, mad FORTRAN skillz, a strong familiarity with the equations of Messrs Navier and Stokes, and a desire to go through several hundred thousand lines of code then any speculation as to how the SSW is being handled is somewhat moot, I think.
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