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Yarmy

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Everything posted by Yarmy

  1. Yarmy
    So maybe the criticisms of the FV3 have been a bit premature. The FV3 on the 0z is actually weaker than the GEFS up to about 10 days before the now familiar extreme divergence:
  2. Yarmy
    Unstable flow over a warm North Sea. A shame it's T300 and not T30.
  3. Yarmy
    It wouldn't be an issue if folk just practised a bit of self-moderation. Ask yourself, does anyone really need to read "Eyes down for the 12z!!!!" every other post?
  4. Yarmy
    The original image is for 2018/2019 and is cached by Netweather. To show an updated image, you have to append a random query string to the URL as I've done here: I added ?v=otbc but you can put anything, e.g. ?v=20191128105830. Edit: The above is for 65N, and the below is 60N.
  5. Yarmy
    Different network of observers. SIDC had 20 or so fewer spotless days the last time I looked. Some of the spots counted were very weak and very short-lived.
  6. Yarmy
    Sorry, the context was not to compare with the FV3, but to point out that all the strat models flipped massively inside one day. It comes from the Lee et al. anticyclonic wave breaking paper.
  7. Yarmy
    Almost, but not quite. 268 is the SIDC count, so you need to use the current SIDC count to compare. The current number of 249 spotless days on spaceweather.com is the Boulder count. The current SIDC count is 243 (190 up to the end of Sep then 29 for Oct and 24 in Nov days since then). So Dec 21st or so, assuming no spots appear.
  8. Yarmy
    Further to the Simon Lee tweet above about things sometimes changing rapidly. From his wave-breaking paper: We don't have access to archive GEFS or the ECMWF medium-range, but we do have the GFS Op archives on Meteociel. First, the GFS 0z T384 10hpa from Jan 29 2018: ...and the next day at T360:
  9. Yarmy
    And yet here comes a cold spell following a near record high strength SPV. The SPV is on average at the peak of its strength come the end of Dec, so any prediction as such is going to be reasonable based simply on climatology. Nobody knows for sure though, as shown in the Simon Lee paper above. The Feb 18 SSW was not forecast by any model even at 12 days out.
  10. Yarmy
    Also would need some of the energy to separate and go under the block. I had a scan through the 0z GEFS to see if any members had that, and just about the only one that did was Perturb 11: So highly unlikely, you'd think.
  11. Yarmy
    The first chart there I think is a good reason why only looking at the 60N U-component mean can be a little misleading, as discussed above. The steepest gradient is - as far as I can tell - right on the 60 degree line of latitude. Looking at the GFS op for the same time:
  12. Yarmy
    I don't know about historically, but the GFS 6z is currently verifying better than the 0z, 12z, 18z: T120 T144 The differences are almost negligible though. The issue is not so much the difference between individual runs, but that the GFS performs significantly worse than the ECM, UKMO, and even the GEM. So for all the expensive upgrades, they still can't seem to catch up.
  13. Yarmy
    NCEP EMC Global Model Verification WWW.EMC.NCEP.NOAA.GOV
  14. Yarmy
    What is the x-axis scale on that chart? I initially assumed hours, but that can't be right. Is each tick 6 hours?
  15. Yarmy
    Enormous spread on those Glosea ensembles after about D14. That's not a criticism, and it's to be expected at that range. In the shorter term, it shows a weakening of the SPV which is in concert with all the other output we see? It would be nice if we got to see the temp and GPH anomalies as the U-component of the zonal mean at 60N/65N doesn't tell the whole story.
  16. Yarmy
    @DiagonalRedLine constructed an excellent jargon glossary some time ago here: Keep in mind that often terms are used quite loosely. Abbreviations too, are overloaded, e.g. SW can mean south-westerly, south-west, shortwave, stratospheric warming depending on the context.
  17. Yarmy
    But we had this posted a week ago, so um... Who knows? My guess would be a significant warming, but not necessarily an SSW.
  18. Yarmy
    Daniela Domeisen is currently presenting at the ECMWF workshop. She's talking about trop impacts of SSW. A couple of notes: 1. There is, on average, a -NAO response to SSWs. However, this average is dominated by a strong -NAO signal in 2/3rds of cases. In the other 3rd, there is no signal at all. 2. The likelihood of a downwelling (and a subsequent -NAO) depends on the state of the troposphere at the time of the onset of the SSW. If there is a strong Euro block in the trop at the onset of the SSW, then this is much more likely to result in downwelling and a -NAO.
  19. Yarmy
    For what it’s worth, this is the current state of the art ECM seasonal’s hindcast for 1995/1996 initialised with November 95 data: Twitter MOBILE.TWITTER.COM Difficult for it to be more wrong. The above was prompted by Ant Masiello speculating on Twitter about how the GCMs would have forecast DJF with a similarly cold stratospheric base state. Anyway, I think a fairly mobile first half of Dec is a strong possibility. Thereafter is anyone’s guess.
  20. Yarmy
    I've been watching this. Ted Shepherd's presentation was very technical and difficult (for me, anyway) to follow. Amy Butler is on now, and her presentation is much more accessible to the layman. Hopefully, they'll put all the videos up later.
  21. Yarmy
    The Holton Tan effect has to be considered too, though. The abstract for Labitzke et al 2006: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.393.7345&rep=rep1&type=pdf The gist is that WQBO+Solar Max promotes a weakened SPV, as does EQBO+Solar Min. But of course, it's never quite that simple.
  22. Yarmy
    The average height of a man in the UK is 5 foot 9 inches. That does not mean that men in the UK are generally 5 foot 9 inches tall. But anyway, it's meaningless to compare spotless day counts by calendar year, which is the point. Moreover, nobody should be using spotless day counts anyway, as the record is not homogeneous over time. The International sunspot number should be used as that is adjusted to account for differing number of observers in different time periods and the rest.
  23. Yarmy
    11 years is just the average. Cycles can vary in length from 9 to 13 years. SC23 lasted 12 years and 4 months, SC22 9 years and 11 months: Cycles durations | SILSO SIDC.OMA.BE Table of minima, maxima and cycle durations Cycle Minimum Maximum Duration in Nb Year Month SN Year Month SN Years + Months 01 1755 02 14.0 1761 06 144.1 11 04 02 1766 06 18.6 1769 09... Also, the cycle could begin at any point in a given year. For these two reasons, it is meaningless to compare the spotless totals of individual calendar years. Jan Janssens at STCE uses the following definition for the start of solar min: the month in which the 10th spotless day appears. That's somewhat arbitrary too, but it gives a much better view of the solar cycle progress.
  24. Yarmy
    I believe that those are hindcasts for 95/96 from the current seasonal models. In other words, it’s what the current models would’ve predicted then. Someone responded to a question Ant Masiello asked on Twitter: Twitter MOBILE.TWITTER.COM
  25. Yarmy
    The Meteociel charts are a few random GEFS members at 10hPa for T384. Matt Hugo is showing 30hPa charts for (yesterday's) ECM at T240. Nitzan Cohen (a Swedish TV weatherman, apparently) is showing the 50hPa chart for the ECM T240. None of them is showing a split.
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