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Glacier Point

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Everything posted by Glacier Point

  1. Glacier Point
    .. a risk during February, not now.
  2. Glacier Point
    Increasingly, from upper air data and forecasts, I'm seeing the prospect of any sustained mild spell this side of Christmas, and probably beyond being closed out. The upper vortex post split being modelled sends the pv over the Atlantic and Siberia with very little left on the Pacific and North American side. In order for a mild SW feed to be sustained, you would like to see the vortex strong and organised west of Greenland. The trop outputs are good at the moment for cold, but take a look at the upper atmosphere plots and things are developing nicely from a coldies point of view.
  3. Glacier Point
    Day 10 GEFS H5 anomaly; Noteworthy as it shears off the remnants of the pv over Canada and digs it south-east through the eastern US forcing height rises over Greenland which looks much the favoured option at this stage. That paves the way for a tanking in the AO. Oh and look, 4 wave pattern emerging.
  4. Glacier Point
    It's actually getting shredded and then coming under displacement pressure from the Pacific side. The 12z GFS variant is to take the lobe of the pv over Canada and stick it over Iceland. The balance of 06z ensembles were trending to break fragments off and send them into the Atlantic reinforcing a Greenland High. Worth coming to a view on where the 12z suite is going in this respect t180 - t240.
  5. Glacier Point
    In the Winter Preview I said I was looking for signs that seasonal models were starting to move towards the composite analogues. Well, here it is..
  6. Glacier Point
    GFS 06z advertising what can happen if the split in the pv is strong enough, it dislodges the segment over Canada and the 2 wave pattern naturally attempts to drag the upper tropospheric low through the trough extending across NE states forcing an extreme rise in heights over Greenland. The northerly you see at the end is a natural conclusion as the larger part of the vortex stabilises in its displaced position. That would be a long, long road back to anything mild. However, much to resolve for the models. Crucially it's all about what settlement the split parts of the pv can arrive at, and how intense the split is. This is not a time to be buying much into model solutions or even ensemble means beyond t192. Remember also that there are further attacks to the pv in the pipeline, well into December which are even now outside the comprehension or range of the NWP.
  7. Glacier Point
    Something else going on at 1 hPa not obviously related to lower level developments.. GFS again going for a rapid rise in temperatures towards early December over Russia.. 2nd December 6th December We saw last year warming pools in this area move their way into the Pole.
  8. Glacier Point
    If you didn't need any more instruction as to why following individual operational models beyond day 7 is folly, take note.. TODAYS GFS AND ECMWF ENSEMBLE MEANS ARE IN GOOD AGREEMENT WITH THE LONGWAVE PATTERN FEATURING STRONG RIDGES OVER THE BERING SEA AND NORTHEAST ATLANTIC AND AN AMPLIFYING TROUGH ACROSS THE EASTERN HALF OF THE NATION. THE VERY LARGE POSITIVE 500-HPA HEIGHT ANOMALY CENTERS AT THE BERING STRAIT (MORE THAN 300 METERS ABOVE NORMAL) AND SOUTHEAST OF GREENLAND (MORE THAN 200 METERS ABOVE NORMAL) ARE WELL AGREED UPON BY ALL ENSEMBLE MEAN SOLUTIONS. OPERATIONAL MODEL RUNS WERE NOT USED IN CREATING THE MANUAL 500-HPA BLEND DUE TO POOR CONTINUITY. Taken from: http://www.cpc.ncep....day/fxus06.html and FWIW, the 8-14 day anomaly pattern is a stonker. http://www.cpc.ncep....14day/500mb.php
  9. Glacier Point
    Definate 'low resolution' issue with the GEFS. At t180 we have reasonably tight cluster around a ridge solution centred around Iceland. Through t192-204 that drops out significantly and a lot of spreads suddently develop. Don't think that's related to a synoptic evolution, more inability to deal with the dynamical processes going on.
  10. Glacier Point
    Such a lot to keep tabs on at the moment. This stratospheric vortex has really had a hard life. First it can't manage to propogate downwards. Then it gets nibbled and then munched by wave 2 activity. Then a warm plume develops over the Pacific which may or may not work its way towards the Canadian sector. Then we have a large increase in westerly winds over 30-40N which might further enhance tropaves and wave 1 and wave 2 actvity in the next 2-3 weeks. Then, up pops GFS12z which increases temps at the very edge of the stratosphere by 20C in the space of a day or two over Asia at the extende range. Over the top ?
  11. Glacier Point
    I can buy the idea of some moderation in the 'tropospheric fire' as the +AAM signal peters out although our analogue guidance tends to keep the colder pattern for longer and plotting a course through a period of intense pressure on the stratosphere from beneath is going to be higly problematic. However, stratospherically, I suspect we'll be kept glued to developments because the instant the upstream ridge decline / movement poleward takes place, that will be the cue to wave 1 activity which will set the clock ticking for the next phase of intense blocking centred on mid January through early February.
  12. Glacier Point
    Worth speculating on position of the post split vortex scenario.. First thing is that the initial split may not be the end of it. We've seen wave 2 showing some unpredictability and I suspect we've not bottomed out on vortex splitting, probably not until around 5th December will have the full picture (that's an awful long way out). Thereafter, the general trend to take the warm plume over the North Pacific in towards Canadian sector looks very plausible and is the one I would go for. That means any reformed (and weaker) pv will be displaced towards Greenland, Svalbard, Barents. Curiously, the trospheric response may actually be for ridging in these areas as the dominant ridge over Canda disrupts the flow over N. America locking down the -NAO pattern. Even if it is west based, December's wavelengths tend to favour an elongation of the ridge across to Iceland preventing the returning southerly jet from pivoting northward in the Atlantic.
  13. Glacier Point
    GEFS 06z mean has Europe going into the chiller week 2 FWIW and the ECM 00z has us not far behind at around 4C below normal over mainland Europe. At that range it doesn't take much to shift that cold pool further north. ECM 00z mean also depicting a half decent cross polar flow. This is the 06z however, but you get my point - anything beyond t144 (more especially when hemispheric pattern change is occuring when mode performance drops off) should be ensemble mean / spread based first. The operational GFS means didly squat beyond this time. The key players here, stable ridges over the North Pacific and North Atlantic, should be your guidance here.
  14. Glacier Point
    sneaky peak from the winter forecast for vortex projection Jan and Feb.. a solid signal for ridge towards Canada. Everything this year seems to be happening quicker.. the reaching of minimum stratospheric temps for example. Wouldn't be surprised to see this taking root in December and this I think is the axis of the winter stratosphere.
  15. Glacier Point
    Tonight's CPC 8-14 dayer, rock solid: Mentions stable blocking structures N. Pacific and N. Atlantic. It should be noted that 12z operational ECM was too progressive wr/r/t N. Pacific (loses the ridge too quickly). We should now be looking for slow evolution in this pattern. The high latitude ridges will be persistent with the tendency of the Pacific ridge to shift its position northward and westward in time supporting a full blown -AO phase later on. Our ridge in the Atlantic may wobble around, first NW towards Greenland for 5 days and back again for another five, potentially becoming part of a very strong -NAO phase mid December when the polar vortex will be under full scale attack. This phase hasn't even got into the model's range yet. Weatherwise, becoming increasingly cold.
  16. Glacier Point
    Keeping an eye for the future....look how the break off the pv over Siberia washes through the cold trough centred over NE China and is heading towards the Pacific on the GEFS. That should work its way westwards on the back of the Asian Jet and set up our Aleutian Low - forcing the ridge over Aleutians poleward and locking us into a -ve phase AO during mid to late December. Probably 10 day type oscillations in the blocking strength for the next 30 - 45 days, thereafter all eyes on end Jan. Could well be very interesting. CFS monthlies now starting to entertain the idea of a cold December (up to 4C below for parts of Europe). January now in the firing line and some movement there today towards a colder pattern as the models get to grips with dramatic developments. All those initialised prior to this (or those unable to spot it) will be junk status. GEFS also starting to develop the idea of the Pacific ridge turning poleward and towards Siberia in response to Wave 2 activity in that region, in turning pulling the developing ridge to our north further NW allowing for pressure to go into free fall over Europe. For those about to mither about a west based -NAO, not really a problem in December, more of a problem in Feb. Also fairly sizeable Asian Mountain Torque now showing its hand - might be worth keeping an eye on stratosphere within the next 10-12 days.
  17. Glacier Point
    Forecast will be filmed this week, available some time after.
  18. Glacier Point
    Following this through.. The 1st wave 2 attack is now registering for the 20 day lag centred on 30th November. GFS 06z showing a massive ridge penetrating the Arctic at 30 hPa. The possibly modification of the angle of ridge showing up at the end of the GFS run: If we were right about the wave 2 activity (and so far this looks like an extremely good call and therefore excellent 'tool' added to our kit bag), then no reason to suggest that the continued disruption of the vortex throughout December will take place (possibly with a reduced level of 'forcing' as the +AAM signal diminishes a touch). That in itself sets an interesting prospect - further tropospheric feed back and development of Aleutian low in response to hemispheric realignment - more wave 1 activity (vortex displacement) into January ?
  19. Glacier Point
    ... the final piece of the jigsaw slots in nicely. For the observed and projected mean temperature profile for late November into December, with an assumed ridge (warmer) to the Northern Pacific region and cold core located to towards Greenland and NW siberia, our analogues are as follows: Rolled forward, no great change suggesting a displaced vortex scenario.
  20. Glacier Point
    Disagree there Phil. GEFS t168 shows a sudden rise in pressure mid Atlantic: ..we're starting to get trough disruption in the semi-reliable period. The 00z and 12z GEFS mean height anomalies are indicating the southern Greenland / N.Atlantic +ve height anomaly as being the largest in the NH.
  21. Glacier Point
    Consider a 20 day time lag from strong ridge development through to wave 2 activity registering in the stratosphere.. Current GFS projection at 30mb Pattern centred on 20 days previous This would appear to correlate with the stratospheric ridges, more particularly North Pacific. Rolled forward another 5 days, should we look for the angle of attack to change, perhaps from a ridge originating in Siberia ? Before another wave (wave 2) of attacks in the North Pacific timed for mid December based on current GFS ensemble means ? Questionable how much of a vortex will be left by then.
  22. Glacier Point
    .. thar she blows.... Angular momentum showing an upturn, heralded by strong +ve frictional torques. Quite likely that we'll se some further spikes in tendency in relative angular momentum over the next 10 days or so.
  23. Glacier Point
    The ensemble mean data consistently pointing towards an anticyclonic phase as next week's trough migrates eastward and fills / disrupts. Thereafter, the trend (with excellent teleconnective support) is to introduce a stronger mean ridge towards the north-west (favoured spot southern tip of Greenland to Iceland) during final week of the month delivering T2 anomalies around -0.5C through -1.5C. With a strengthening ridge in the North Atlantic, the flow will pivot around this drawing in a more northerly or north-easterly component. Modelling has generally rushed this synoptic evolution IMO, but possibly CFS v2 week 3 and 4 a little slow in bringing the evolution, but gathering support for this type of set up for late Nov / early Deccember which asks some rather immediate questions of ECM,GLOSEA and EUROSIP seasonal forecast (CFS starting to sniff the coffee). Note the persistence of the Kamchatkan / Aleutian ridge there.
  24. Glacier Point
    I wouldn't worry about cold source Nick. Another very consistent NAEFS 00z, in tune with 12z and CPC prognostic developing moderate level anomalous ridge over southern Greenland / North Atlantic week 2 and dropping the longwave trough to our south as heights build to the north. Given the excited state of the NAO this year, ridge to our NW should be sharp enough to draw down Arctic air source into Scandinavia.
  25. Glacier Point
    Interesting to look at analogues for cold stratosphere Novembers.... Current data: Analogues: Rolled forward into December.. This seems to suggest a bit of a reversal and also look where the warming is centred. The warm bubble starting to appear on long range forecasts is in this locale and it reaffirms my view that polar stratosphere will have a very displaced look about it this winter, with the Pacific side warmer, at least to start. We are still on course for a lot of 'action' around early December (modelling late November) in the stratosphere thanks to lagged influence on wave 2 activity.
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