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Yeoman

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    January Medium/Long Range Discussion

    in Mid Atlantic

    Posted

    5 minutes ago, frd said:

    Great illustrations !

    You know I was speculaing , not wish casting, whether this sudden turn we made from no winter arriving to, yeah it s coming and it could get nasty is the same way things evolve for our area with snow. A sudden flip and then one event after the other. We would not see it is coming until almost the last minute.      

    The twitter bot is a real person?

    • Confused 1

    January 12-14, 2019 Storm Threat

    in Mid Atlantic

    Posted

    20 minutes ago, mattie g said:

    While I’d be slightly disappointed to see the GFS lose out on this fight, I wouldn’t sniff at 1-3” to start a pattern change.

    Rumor is the GFS is highly compromised due to the shutdown therefore I suspect it will be spot on. 

    • Haha 2

    January 12-14, 2019 Storm Threat

    in Mid Atlantic

    Posted

    1 minute ago, NorthArlington101 said:

     


    In my meeting with Jason Samenow I mentioned this and he said it’s true. There are issues they haven’t been able to fix due to the shutdown.

    Both Jason and “Angela” are CWG journalists.

     

    Sounds like their source was grasping at straws, unless EMC has no testing/QA process for data format changes.

    My guess is most if not all resources are/were being used to get the Fv3 to production by 1/15, with little emphasis updating the GFS regardless of the shutdown

    • Like 1

    January 12-14, 2019 Storm Threat

    in Mid Atlantic

    Posted

    2 hours ago, Ji said:

    From wes to me....wes always delivers bad news


    Jay Hatem Angela wrote a really good and important article on how the GFS has been degraded because of the shut down. Evidently, EMC workers were deemed non-essential and there was an international format change scheduled to standardize how weather data is formatted that was being implementedright as the shutdown was declared. EMC has no one there to ake the necessary changed so that the newly formatted data can get into the models. It still gets data but not as much as it should be getting. A degradation of model scores (accuracy) commenced around Christmas. Therefore, it's probably wise to lean more on the Euro and its ensembles then the GFS. That's why Jason noted that there was a slight chance of a snowstorm. The Euro and its ensembles mostly miss us or give us a dusting. That doesn't guarantee no snow storm as it could be wrong as we're still far enough out in time that no model has a lot of skill.

    Not sure where "Angela" got her info, but I find it hard to believe that a change to the most critical aspect of a weather model performing properly just happens on a whim with no extensive period of testing and verification before going live. I call BS..

    • Like 2

    January Medium/Long Range Discussion

    in Mid Atlantic

    Posted

    1 hour ago, psuhoffman said:

    That guy. 

    I made a New Years resolution to not waste time arguing with people who claim things that actually have happened can't happen or are impossible.  This doesn't pertain just to weather. 

    That actually happens enough in your life to require a NY resolution? Time to find some new friends.

    • Haha 1

    January Medium/Long Range Discussion

    in Mid Atlantic

    Posted

    A fascinating read from over at 33andrain from a member. Bottomline, the models need time to take into account what is happening, I think whether you believe in the strat/MJO/tropical forcing interactions at play or not,the massive effects from the SSWE and extreme EAMT you have to at least think that the modeling, even in this day and age, is suffering from making proper outcomes due to all the complexities coming together recently. Just MHO. 

    I just posted this across the pond for a slightly different audience - only slight editing:

     

    REALLY GREAT NEWS!

    Now some of you will not realise the significance of this:

      31b.PNG.766453981ee279078fb4debe0bf441dc.PNG&key=a30b74bf8346ec94580e8901a892f0e72319f57ced1abd3198024ed2443b6da0

    Those of you who have been reading my posts and those from the likes of [mention=1304]Tamara[/mention], [mention=70]Isotherm[/mention] [mention=447]Snowy Hibbo[/mention], myself and others who comment on the key teleconnections will know that we've been banging on about +ve EAMT (East Asian Mountain Torque) in particular. We could see this event unfolding a few weeks ago as part of the GSDM (global synoptic dynamic model), the GWO (global wind oscillation), GLAAM (global atmospheric angular momentum) and both FT (frictional torque) and MT (mountain torque) which all link in with tropical forcing, the ENSO state and the MJO. These charts are produced 2 days after the actual position - so this afternoon's chart (above) shows the position as on Dec 29th.  In my previous posts I said that EAMT was already rising strongly and that could be seen in the pressure distribution over eastern Asia (I showed the StormSurf charts, most recently yesterday).  Well, EAMT is not just rising but it's sky rocketing as can be seen by the red line in the chart and looks set to climb quite a bit higher, in fact with that 2 day chart time lag it already is.

     

    I'll not go into the complexities but +ve EAMT events have an extraordinary influence on all levels of the lower and middle atmosphere and especially on the northern hemisphere global weather patterns and many of these assist directly or indirectly with setting up ridges and troughs and blocking patterns. Here are some of them:

     

    1. A "major contributor" to wave breaking in the stratosphere (there are other influences too, of course) and vortex attacks by creating huge uplift and vertically propagating planetary waves from the Tibetan Plateau and particularly (as discovered more recently) the Mongolian Mountains, which can reach the upper stratosphere and even the lower mesosphere before reaching the "critical level" which is effectively "wind shear" in the troposphere as shown in this chart.

    31e.PNG.8d2097980024e41d8012b9f47d6b0a44.PNG&key=dc0a0f0c4847dc42af9d3a869da71f86ed488bc513b1848311d9ce03ade06472

    In the stratosphere the critical level has the easterlies above it which are the reversed winds and the planetary waves cannot break through it and are reflected (or even deflected) back down and they break at increasingly lower levels.  This produces one or more attacks on the spv (stratospheric polar vortex) and prolonged events can send up further planetary waves with attacks from above and below.  The last surge in EAMT occurred  during Dec 4th to 12th and peaked around Dec 9th/10th.  A few days later we saw some attacks on the SPV.    

                                                                                                                                                                                                                              

    2. Now we have a further event which is likely to repeat the exercise and if there's any problem with the split or the downward propagation this may well deliver the final blow to the SPV in a few days.  In fact the timing is almost perfect with the split (if it happens) predicted for later this week.

     

    3. EAMT also influences the tropospheric patterns with lateral planetary waves influencing the jet stream and downstream patterns in winter across the North Pacific and into N America. This can help the jet stream to meander and/or buckle.  This action in association with other factors can have knock on effects setting up the pattern and distribution of troughs and ridges around the hemisphere.

     

    4. In the summer half of the year EAMT has a powerful influence on the Asian Monsoon.

     

    5. The planetary waves also spread polewards and this is where it gets very interesting.  Some of us will have heard of and studied Judah Cohen's theories on early Asian Snow Cover extent and the greater likelihood of SSWs.  He recently admitted that it is more complicated than that and it was not a perfect correlation but nevertheless it does seem to work more often than not..  Over some years and particularly more recently, research has strongly suggested a link between North Asian blocking and the priming of the lower tropospheric layers and the surface to be receptive to a down welling SSW.  In several of my recent posts I've been showing those Asian pressure charts and the extraordinary expanse of HP over almost all central Asia northwards, Russia and Siberia.  I've been looking at the timing of these events and I'm pretty sure that it's no coincidence that a combination of +ve EAMT, extensive Asian snow cover (well above average right now as I showed yesterday) and the blocking regime are all coming together to make the patterns receptive or even highly conducive to downward propagation of the SSW to the surface. This obviously needs to be explored much more extensively and research into earlier SSWs (including near misses and failures) need to be considered. Another factor is GWD (gravity wave drag) which is mostly generated by the the east Asian mountains as well. That will be one of my 2019 projects amd Malcolm and Tom are likely to participate and others will be welcome.

     

    Malcolm [mention=20040]Blessed Weather[/mention] and I have been studying these events and found that they fitted in perfectly to last February's SSW.  Here's the MT chart for back then:

    31d.PNG.57f23b7eda9b3b110aae9895f2f8726e.PNG&key=8492b16f6042f571bd3b3a3aac4f2cd2dd86f543750645fd972af474c6abcbad

    Note the 3 spikes in EAMT.  The first one around Feb 1st to 5th and the SSW was triggered a week later on Feb 12th. The second one around Feb 20th-25th and we saw the full propagation down to the surface and just a few days later with the "Siberian Express" rushing westwards and producing the "Beast from the East" in the UK and progressing around the hemisphere to N America about a week or so later..  The final spike was March 5th-10th and the "Mini Beast" followed about a week or so later and with further impacts on N America a few days later (and lasting much longer).

     

    Overall, some of this is still theory but the extraordinary influences of +ve EAMT events have been studied for over 20 years. Now more of you might realise why I'm so excited about this month's two +ve EAMT events.  The models simply do not have much of these influences factored into how they churn out their nwp solutions and it's why they often need a few days to adjust to changes in the background signals.  Before long we are likely to see some much more sophisticated models being developed. The next few days of monitoring the model output will be totally absorbing and fascinating. 

     

    Finally a Happy New Year to everyone and what a January we have in store for us!

     

    David     smile.png   

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