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Catacol

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Posts posted by Catacol

  1. 2 hours ago, Scott Ingham said:

    What do you think to the gwo looking like it’s hardly been touched? 
     

    Me personally I’m excited for the next tropical wave and consequent rise in AAM off a good base state! 

    I think it would be hard to find a better setup than that about to unravel. Only solar is out of ideal kilter but on its own, irrelevant.

    -MJO amplified and back in the west pacific in the final third of this month 

    - GLAAM has remained high, further surge expected. +EAMT?

    - Vortex is weakened and possibly about to split

    - Scandy has been cold since the autumn. There is cold nearby to tap into

    - eQBO firmly embedded, ENSO Nino with +IOD now done and dusted


    These are the keys for me. I’m not moving from what I said a few days ago. Cold for a long time..


    Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5005813
    • Like 2
  2. 2 hours ago, Met4Cast said:

    There was a discussion a few weeks ago on this actually. The 00z runs appear to flatten the patterns more quickly only for the 06z and 12z runs to slowly re-amplify the pattern again.

    Not sure if this is a genuine observation or just a bit of confirmational bias creeping in but it is something i've noticed over the years of model watching.

    12z runs are verifying better than 00z at the moment, suggesting that amplified solutions are coming up trumps. Fits the GWO orbit.

    • Like 7
    • Insightful 1
  3. ECM has just thrown out the most potentially snow charts across the UK from days 8-10 that we have seen since 2018. I'm in a rush - I dont have time to read the many pages of comments, though I will predict that some are very happy at these and some are bemoaning the marginal 850s in the south and sounding the doom-bell.

    850 predictions at day 8 are utterly irrelevant. Look for the pattern. Cold trough, channel systems bumping into it. There are snow opportunities likely from both convective shower streams off the north sea as well as cold/warm boundary frontal events.

    This is about as good as it gets. Happy days says this pig in sh*t. Enjoy your own day if you can and remember (contrary to my initial post yesterday!) that 12z forecasts are verifying better than 00z at the moment so let's build on this morning's foundation later on. 


    Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=5002777
    • Like 2
  4. 32 minutes ago, Continental Climate said:

    A good post in my view. If you look at the output say 5 days ago there was a much more robust signal for greenie blocking and the infamous shuffling high to the north was meant to just meander around giving us a prolonged cold period. That signal has evaporated. I've not heard a single mention of a shuffling high for days. Some people are quite rightly frustrated this signal has been dropped. This spell has been watered down last few days in my opinion. Will it get colder yes, will people get snow yes, will this be a period of snowy weather lasting longer than 6 days unlikely now in my opinion. There is no denying the blocking signal has faded last few days. 

    A fair point - but I'm not sure the prognosis at the moment has really deviated from the overall shape of things that was probably best expressed by Tamara a couple of her posts ago. We have the wave break now that is being pushed up to high latitude at the end of the week, we then have the cold trough dropping in. We will likely have a slower breakdown from this than the models predict (because observationally models speed up breakdowns than is usually the case once it happens) and then we have - with the less favourable MJO phases and a drop in AAM - an anomaly chart like this to wrestle with:

    image.thumb.png.3a784a7fe12807f52414dec46160ee99.png

    First of all it is a very long way off - but if we take it at face value it reflects the progression of the drivers stated above but does not really give us a scooby as to what the synoptics will be. There is certainly a pressure contrast that is still suggestive of weak -NAO but quite where the cold/warm boundary will sit is very uncertain.

    Then -  looking at the latest GEPS that, to my eye, has been a bit more accurate than GEFS from the 00z run we get this out in the very far reaches of ensemble modelling:

    image.thumb.png.e5db6a7067e9fc1b0921141a0b9b733d.png

    High pressure starting to build back into Greenland in line with the Nino background and drivers pointing to renewed momentum and amplification which then ties in with the EC weekly move back towards this:

    image.thumb.png.7b32392940c981255df6a1df5407c9fb.png

    So - some degree of relaxation of the cold was inevitable at the end of next week, but it does look temporary and - in any case - quite where the boundary between the warm and cold air will be is utterly impossible to nail down now. I think the overall pattern as described in that post of Tamara's remains solid.


    Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=5002814
    • Like 1
    • Thanks 1
    • Insightful 1
  5. Countdown to @Scott Inghamday is on - now 168 hours away.

    For those interested, verification stats for 00z runs are quite a bit ahead of the 12z runs at the moment, and when it comes to 168h prediction from 00z runs there is very little between the models at the moment and that includes GEM. Don't diss it!

    image.thumb.png.559ae88e68baef43a6930bf4045132c6.png


    Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=5000723
    • Like 2
  6. Bounce back to zero complete. 

    image.thumb.png.1abe2bb324b256ccb1da3f5680d8229f.png

    Not too much damage done - still significantly "Nino" as an /ocean/atmosphere coupling

    image.thumb.png.0dff35ee4f9f2d41601908a60c978dfd.png

    and momentum is on the high side still

    image.thumb.png.da2c1a031060835389bad0f8734608a4.png

    So. The challenge now is to work out just how significant the lagged impacts of the dip will be, timed for week 3 starting 22 Jan. Anyone looking at the EC weeklies can see the change, BUT we are likely to have embedded cold as this flatter influence returns. If we remember back to December as a case study the westerlies came through as expected, but the timeline was put back and the crash was quite a big one. Not so this time, and cold will be significantly stronger. 

    I think the battleground snow scenario for that week will gain traction. Too far out at present to see any evidence in NWP but it will come. Some warming of the overall pattern at that point is inevitable, but I dont think it will last long and we can cross fingers that it may only impact the south. Next rise in frictional/mountain torque will be in the wings and the MJO is forecast to be back in the western pacific soon after 21 Jan by both ECM and BOMM with GFS only a few days behind.

    image.thumb.png.4f92953e3f8c47f398375fcbea03fde8.png

    image.thumb.png.73e6beb2d8cf30fce42757c6fd8786df.png

    image.thumb.png.481c4f7cbb7f3f4a1f68f00ed359cadb.png

    So... no change really to the prognosis laid out before.

    1. Cool to cold, sometimes very cold this week, mainly anti cyclonic but some snow showers bound to pop up.

    2. Cold to very cold, sometimes severe cold? the week after, snow in the mix from both NE and SW potentially.

    3. Cool to cold in final week of Jan with battleground snow potential, low pressures deflected south with luck.

    4. Amplified into early February - Greenland again?

     

     

     


    Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=5000301
    • Like 3
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  7. 17 minutes ago, Drifter said:

    Looks deep cold to me? 

    Maybe we should put some numbers to the language so that when some shout “a deep freeze is now off the table” we know what we are talking about.

    As I see it taking into account usual U.K. winter synoptics:

    850s of 0 = Cool

    850s of -4 = Cold (has to be, given at -4 snow is in the mix)

    850s of -8 = Very Cold (rare, and snow over rain nearly ever time)

    850s of -12 = Severe Cold (very rare in truth, if you want lots of these go to Canada!)

    850s of -16 = Exceptional Cold (how often in the last 50 years?)

     

    On this basis I will say again - we are looking at a spell of very cold weather off and on for the extended. At times it will be cool to cold, and at best we might hit the odd moment of severe cold if the dice roll kindly. And snow is in the mix.

    Do some folk need to get realistic about U.K. winter? We will never hit continental levels of freeze potential.

    image.png


    Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4999153
    • Insightful 3
  8. Some things never change. It is as though model watchers wake up every morning determined to be gloomy.

    ECM 240

    image.thumb.png.807d647f4daf5d718cd4e1cdcb273364.png

    GFS 240

    image.thumb.png.e3aad51971c53f7b3aa616ea01b04f86.png

    GEM 240

    image.thumb.png.0dc99c6181178e84f719a8c463ec8d60.png

    I'd give my right army for charts like these in any winter. 

    My only comment would be to address the delay issue. Those long in the tooth on watching models know that high pressure is often, if not always, modelled to move faster than actually occurs in practice. So seeing the trough arrive a day or two later fits the observation. No issue with this provided we maintain low pressure to the south and dont see a sub-tropical high resurge. Any signs of this?

    Well - on the EPS not really at realistic range. Weds 17 and the midnight EPS still have pressure lowered over the continent

    image.thumb.png.83872b8abbe70d248c1f34cc0b89465d.png

    and yesterday's EPS the same out to 300h.

    image.thumb.png.6cb5cf90494905a58dbe2a814c044e89.png

    There are too many on here who get the magnifying glass out at 192h+ and see slight shifts as a disaster. There are always going to be shifts - it is absolutely impossible for one complex run produced out of Tb of data to be the same as another and these will sometimes "improve" or "downgrade". But one thing is for sure - getting hung up on 850 spaghetti charts at 192-240h range is 100% guaranteed to drive you nuts. As I said yesterday NWP is hopeless at getting 850s right even within high resolution range, and an 850 spaghetti does not really therefore give you much of an idea of synoptics.

    Enjoy the ride. This has a long way to run yet - hopefully a very long way to run. Patience, stamina and a very healthy dose of perspective required.


    Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4999081
    • Like 4
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