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Glacier Point

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Glacier Point last won the day on January 10 2019

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About Glacier Point

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    horses, horses, horses, italy, food, gardening and the landscape, oh yes, and the weather
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    Forecaster Centaurea Weather

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  1. The GWO provides a useful measure here of both extratropical and tropical responses. I suspect with increase of upper westerlies, GWO will orbit in low amplitude within the El Nino attractors for the remainder of the month, next cycle of the MJO through the Indian Ocean likely to coincide with a big spike in AAM tendency (circa 18 days from now).
  2. RMM plots are something of a blunt tool - and will not capture neither lagged influence of poleward westerly momentum transports nor low frequency influences. The suggestion is that the MJO may appear to be weaken during late January, but other measures may be far more instructive.
  3. Velocity potential component suggests more of a Phase 8 type projection to the MJO, which would also fit GWO cycling to falling AAM tendency. Phase 8 for January: That's a very weak signal there. Phase 8 for January with El Nino filter (which is relevant): That's not far removed from current week 2 modelling, and Euro ridge type solution there: Kind of underlines my antipathy towards January for anything meaningful. However, if the tropical signal persists into February, then look... Phase 8: Phase 8 with ENSO filter:
  4. @Jules216 2006/07 cited as being a carbon copy of this winter. Yes, in lots of respects. Similar MEI / ENSO structure. Similar QBO evolution. Similar warm phase early / mid winter characterised by monster +AO during December / January with coupling between trop and strat PV. And now, similar MJO evolution. Fair to say 2006/07 has been on the radar for some considerable time. Hopefully we'll see a 2007 style reversal in the AO for February. Be interesting to see if the lower solar conditions this time round deliver anything more tangible for colder outbreaks further west than in 2007.
  5. Blog – Centaurea Weather CENTAUREAWEATHER.COM If you have any questions on this, probably best take them to winter discussion thread to avoid going off topic. Thanks
  6. Unless it turns out that the +IOD has been overly dominant (we are extremely hampered by low sample size in determining this - and possibly a hint that low solar has been over-cooked as driver), it's been more a case of nothing overly supportive of cold pattern. The best indicator out there has been the MEI. That's been bumping around borderline El Nino for the last few months: ESRL : PSD : MEI.v2 WWW.ESRL.NOAA.GOV US Department of Commerce, NOAA, Earth System Research Laboratory, Physical Sciences Departmant Weak El Nino / warm ENSO neutral climatology is against cold patterns for Northern Europe during the early part of the winter, more conducive later on depending on other factors.
  7. New blog entry up which will hopefully paint a broader picture. This winter has always for me been about February having most wintry potential. The evolution in the MJO and wider low frequency signal for the remainder of January looks like favouring central Pacific tropical forcing, so expectation would be for the current MJO wave to behave as per GEFS, high amplitude phase 7 weakening and more sustained low frequency signal to take over in phases 6, 7 and 8. That ties in with enhanced wintry potential for very back end of January but more likely February. I'm getting a very 2007 vibe right now, so worth seeing how facets of current modelling might evolve as we head towards end of the month and into early part of February. First, MJO signal: Notice how 2007 wave developed in late January in the Western Pacific and persisted as an artefact signal for the rest of February in phases 6-7. Overall velocity potential for month more phases 7-8: And now forecast: Charts end of January 2007: Note the Alaskan / Chukchi Sea ridge development there. This looks solid in the modelling right now, and is expected to be a recurring theme over the next few weeks: Also looking solid is the positioning of the stratospheric vortex shifted towards Siberia and away from Greenland / Canadian Sector. The two together suggest a high potential for transient ridge development in the North Atlantic to interact with this ridge and force blocking structures in the polar region sufficient to diver the jet south. Very much the evolution in February 2007. 850 hPa profiles are going to be hampered by lack of in situ cold air over Scandinavia and Eastern Europe, although this should change with time under this pattern. Still likely that marginality will be the key buzzword, but at least and more realistically, potential for something to watch going forward, and one big back end winter easterly to chase.
  8. 12z EPS depicts a very elongated vortex all the way up to 50hPa towards the end of the run. A starting point if you’re looking for an upward split.
  9. The way end of week 2 EPS and GFS look, wave 2 bottom up splits could be in play.
  10. Blocking signatures starting to show up in high latitudes consistent with precursor pattern as per above. Next Wave 1 attack expected early in the New Year and EPS beginning to pick this up with warming over Siberia projected and our now familiar displaced vortex centre. Would expect this continue to build and a SSW very possible during second half of January.
  11. GFS op advertising the direction of travel for the New Year given current thinking..
  12. One of the outcomes manifested by the unusual occurrence of a record strength +IOD event outside of a strong El Nino.
  13. My thoughts would be as highlighted. Think of loading a dice. Currently 35-65 against. The more we progress down the road of +IOD / +ENSO climatology / weakening of the wQBO, the greater the loading in favour of colder outcomes. +EAMT might be overdone on 5 day averages, an angular momentum uptick / GSDM may be more low amplitude that first thought.
  14. I reckon it will flatten out soon into New Year. There is a narrow window for a wave 2 induced pattern (high pressure centred close to UK) arising from a recent enhanced trade / reduced westerly across the central Equatorial Pacific and spike in tendency in angular momentum. Worth noting the direct correlation with this in the polar stratospheric pattern. However, that won't last long. GFS suggesting a westerly wind burst across the central regions of the Equatorial Pacific in the next week. That will increase angular momentum and trend more to a wave 1 pattern (both tropospheric and stratospheric) with associated lowering of surface pressures in the North Atlantic and dropping of Arctic air mass into the mid West States of the US. That should fire up the jet across the North Atlantic displacing any mid latitude ridge across North-west Europe. Strong presumption for jet angled NW-SE into Europe with moderate level +ve heights to our north within this regime. GEFS 06z ensemble mean makes perfect sense to me within that broad context. What does strike me from current modelling is the propensity for scrambling of the mid layer flows across the North Atlantic, probably the low solar conditions beginning to take effect. Therefore, heights likely to be greater to our north than analogue guidance would suggest - but still overall signal is for troughing across NW Europe beyond next week's ridge.
  15. and add cfs week 3 to that .. However, before champagne corks start popping, interpretation of this z500 pattern requires strong health warming in translating to T850 and T2: 1) no source of deep cold across Europe and temperatures likely to be well above average prior to this; 2) trough access likely to favour milder Atlantic air mass across much of western Europe, including the UK. Bottom line - looks good, and something to draw interest but from my perspective, nothing to see here suggesting cold nirvana in the next few weeks.
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