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weatherjunkie

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  1. weatherjunkie
    From what I have gathered the increased easterly winds in the northern hemisphere at 200mb in the polar latitudes have caused the sudden stratospheric warming, or as you like to call it the Major-Mid Winter Warming; to my knowledge it hasn't been this strong during this time of year since 1978. This would set up high latitude blocking over the Northern Atlantic and hopefully some more winter cold outbreaks. By the way, awesome discussion. I still learning how to put the pieces of the puzzle together like the momentum fluxes and frictional torques. I hope that these discussions continue.
  2. weatherjunkie
    We've seen fantasy range SSW forecasts before, only to become less aggressive as it approaches. It looks promising, and while the stratosphere is generally easier to predict than the troposphere, it is far from over. I do like the model agreement. We are still in that day 10+ area so the only thing we can do is wait and see. There is also another factor to consider and was perhaps mentioned in this thread but I'm too lazy to look . A recent article (2012) showed a correlation between MJO phases and a SSW. When in phases 7-8 during winter there is an increased probability of an SSW during days 1-12 following the MJO orbit. This is where we currently are according to WH phase plots. Now if this does happen we would have to see how it propagates downward, which is highly dependent on the willingness of lower levels to cooperate...best case scenario is we feel the effects by mid-February, which I suppose is better than nothing.
  3. weatherjunkie
    Excellent introduction It will be interesting to see how the strong Nino matches up with the +QBO. I'd place bets that the strong Nino with wave breaking events in the N. Pacific and perhaps N. Atlantic that will eventually win out but I think it will be rather difficult. As you've stated, the chances of a SSW are heightened with a Nino. Should be a fun battle. Cheers from across the pond on another insightful thread. There is much to be learned about the troposphere-stratosphere dynamic.
  4. weatherjunkie
    Was looking optimistic over the last few days but less so today. Can't complain though since the E US has been quite cold and snowy. We wouldn't need a full SSW to keep it that way the rest of the winter. The PV has been entrenched into Canada for a while and another lower stratosphere split at some point in the next two weeks would most likely keep things cold. I like the wavebreaking we're seeing in the N. Atlantic. GFS showing warming events coming from that region and hopefully it'll be enough to knock the PV down some more. I've already convinced myself not to pay attention to the 6z forecasts...too much hope that gets dashed away in subsequent runs.
  5. weatherjunkie
    To expand slightly about one of the points recretos makes is the +MT torque event projected by day 10. Even if this doesn't work out too well this go-round, there are indications (outside of dynamical model forecasts) that the MJO will fire into phases 6-7-8 by the third week of January and these phases increase the likelihood of a +EAMT event. So we could be seeing several round of warming coming from there this month.
  6. weatherjunkie
    Maps are absolutely amazing. Keep up the good work! Looks like the long range is promising. All eyes on the downwelling possibilities but also to the strength of the warming. It may take another round of warming in late January-February to completely topple this strong PV. Going to be looking at the last week of January for another +MT event out of Asia to knock this off for a while. We'll see how it goes.
  7. weatherjunkie
    I'm glad to hear that you haven't abandoned ship with it. I'm sure quite a few of us appreciate the effort that you put into this kind of work and it would be of amazing value to the weather community. I look forward to seeing what you come up with.
  8. weatherjunkie
    The QBO is solidly west between say 20mb and 70mb. Judging by its pace over the past several months, I'd say any flip to the east based side will occur well after winter. However, there should be weakening of the westerlies starting at the top of the stratosphere and working there way down, so perhaps this affects the PV later on down the road for late winter. I'm on board with those that think long term the PV remains pretty strong. However, the latest forecasts charts hold promise for the more immediate time period regarding some blocking with a brief PV split/elongation. We'll see how it goes...
  9. weatherjunkie
    This is some great, great stuff. Can't wait to see what comes of this. On a side note, how has your MJO reanalysis/composite project gone? That one looked quite interesting as well.
  10. weatherjunkie
    This is incredible and I'm sure many will thank you for taking the time to do this. Keep us updated
  11. weatherjunkie
    The first chart simply measures the intensity of wave amplitude at various levels of the atmosphere and at certain longitudes. Basically what we see today from the ECM between hour 0 and hour 240 of its forecast period is much stronger wave 1 activity at the top of the stratosphere centered around 70N. The biggest question we have right now is not if we see a SSW but when and how do the subsequent displacement and fragmentation lead to colder/stormier pattern. It looks to be case of various levels of the stratosphere doing different things as the GFS/ECM show variations in what happens to the polar vortex as you make your way from 1mb to 100mb, which is to be expected when the PV becomes significantly weakened.
  12. weatherjunkie
    I would like to take a stab at some of these questions if you don't mind. I'm also from the Philly metro area...small world I guess . 1. The affects of the warming are highly dependent on what happens to the polar vortex as a result of the warming. Most of the charts we see on the GFS show a split vortex by the end of the long range. This split will have to be monitored since one piece may setup over Canada/Greenland and will create quite a problem if we wish to see a -NAO. We would prefer to see the split where one piece heads to Siberia and the other to Europe which would allow HP over Greenland and a -NAO. For now we understand a warming is coming but the exact details of what happens to the PV remain a mystery and won't be really understood until middle January. 2. The MJO is a tropical atmosphere model which is dependent on deep tropical convection. The general principle is that the MJO affects large scale patterns in both the tropical and subtropical latitudes but is not as influential when it comes to high latitude patterns, although to say it has no affect would be erroneous. In fact, there have been numerous instances where the MJO was in an unfavorable phase and directly opposed to cold in the E US but the warming affects were dampened due to the more favorable Atlantic/NAO blocking. This is certainly a possibility if we can get blocking established prior to the MJO reaching phases 3-4 but at the moment this doesn't appear so and I do think we will warm up a bit come mid-january. It's the old battle of Atlantic vs Pacific and which one is more important for the E US in the winter. 3. Pretty much the same answer as 1 except the AO will almost certainly drop strongly negative as high pressure pushes away the PV from the North Pole. The fragmentation of the polar vortex is still uknown and details are hard to come by at this range. Right now if we were to take the GFS at face value in the 2+ week range we would likely see an east based -NAO which is better than positive NAO but would favor above average snow into the Great Lakes instead of I-95. Hopefully this clarified a few things.
  13. weatherjunkie
    What a pleasure it is to find such a thread every winter. Monitoring this kind of stuff if incredibly quite interesting and those who have posted in here have done a marvelous job in both explaining model outputs and potential impacts on sensible weather. To add some food for thought, it has been proposed that in order to help propagate the warming down from the top of the stratosphere to the troposphere, EP flux vectors must point to the poles in the troposphere. EP (Eliasssan-Palmer) flux is used to help describe eddy forcing of zonal wind anomalies. When EP vectors are pointed to the poles, wave propagation is enhanced and the polar jet is decelerated. These poleward propagating EP-fluxes are generated by tropospheric planetary waves which lead to our SSW events. Essentially when pointed polewards in the troposphere the zonal mean wind state is weakened allowing for some warming to make its way down. Of course, we also have to get the warming down from 10 mb where the 0z GFS shows 60+C temp change at the north pole. So far seeing displacement from 30mb to 100mb from strong wave 1 and weaker PV but the intensity of the warming is dampened as you go down which won't give it a final blow unless we see more events. But then again, the degree of displacement should be sufficient unless you're out for blood against the PV, which in that case we will need more for the kill. Here's a study which brushes over the EP flux. http://center.stelab...mazaki_koji.pdf Some more background on the EP http://www.rsmas.mia...Palm Theory.pdf Source of EP flux forecast that I could get my hands on http://ds.data.jma.g...x.html#monit_nh
  14. weatherjunkie
    Looks like a rather sizeable +MT event coming out of NA. Height rises penetrating to near the Pole from 30-100hPa and troposphere. Another punch for sure to the PV. We already know that the lower strat PV is beat up, so anything from here on out is pretty much overkill. Still not seeing a technical SSW, but we're good to go for high latitude blocking whenever the troposphere decides that it is time.
  15. weatherjunkie
    Quick synopsis of the latest data: GFS/ECMWF showing PV propagation to the pole at almost all levels, with the GFS being quite aggressive in indicating PV recovery while ECMWF still tries to retain some form of a split at the mid-levels and a weakened upper strat PV state. Both do however exhibit signs of a wave two type pattern. Zonal charts from the ECM indicate strong rebound of westerlies from 5-30 hPa between 60 and 80N. Momentum/heat fluxes weaken significantly by day 10 according to the Euro from planetary waves 1 and 2. Temp anomaly obs indicates downwelling of the +anomalies that were a product of previous warmings. This should help to drop AO in the short term. Most lower strat charts and tropospheric models indicate transient -NAO signals, so we again wait for chance of sustained cold. But hey, EP fluxes are neutral toward the end of the forecast period instead of equatorward, so that's some good news.
  16. weatherjunkie
    GFS showing some nice warming over Greenland/N. Atlantic in the lower stratosphere with what I'm assuming is local wavebreaking action. As noted by a few, the top of the stratosphere is showing an significantly weakened PV. The problem is getting this to occur at lower levels and it appears the GFS wants to restrengthen the mid-stratosphere vortex a bit. More warming over Siberia is expected but EP fluxes remain unfavorable. ECMWF actually is showing a wave 3 signal in the lower stratosphere plots. It'll be an interesting few weeks...
  17. weatherjunkie
    Why is it that EP fluxes must be poleward? I understand that this aids in propagation of momentum and heat from the planetary waves to the poles (and deceleration of westerlies). How this transfers to the lower levels of the stratosphere and then troposphere is a concept I still struggle with. The only thing I can think of is tropospheric/lower stratosphere poleward EP flux to help decelerate westerlies and allow for the upper stratosphere warming to filter down. Speaking of decelerating westerlies. Looking at the ECMWF zonal mean forecast charts we see that by 240 the high latitude upper level westerlies are completely removed. Something else to keep an eye on.
  18. weatherjunkie
    In terms of a disintegrated PV, ECMWF isentropic charts show low potential vorticity in what would appear to be the heart of PV in the upper levels. Certainly another good sign. We will also have strong heat flux between both waves 1 and 2 from 60 to 90 N. It appears wave 2 will be the primary contributor of momentum flux in the next week or so as we see great increases in amplitude and perhaps that is why we are seeing some signs of wave 2 on the 10 hPa charts by 240. All in all you can't complain about the latest forecast outputs.
  19. weatherjunkie
    I believe what he was trying to get across was that the ECMWF was indicating a warming of 50C, not that the actual temperature reaches 50C. JB along with quite a few meteorologists in the US are having a rough time with their winter forecasts. JB in particular is having one of his worst seasons that I can recall. He has made forecasts and then has came out with new forecasts only to rescind them week or so later. He generally does decent in the long range (1 month +) but he's a bit off his game as of late.
  20. weatherjunkie
    Wave 1 is expected to increase height amplitude and temperature amplitude congruent with the expected warming. Very nice heat flux from wave 1 between 5 and 10 hPa and even wave 2 by 240 indicating it wants to get going a bit. Pretty solid momentum flux as well by day 10 from wave 1 but this occurs at the top of the stratosphere. Very strong momentum flux from wave 2 by 240 in the Euro but again it as at the top of the stratosphere. Looking at some forecasts, I expect to see IO convection increase at a pretty good amount around the 25th of January, perhaps setting off another Asian MT event to cap the month off and give the PV one more blow heading into February. This is the hope that I have for February in giving us the high latitude blocking that we all seek. As of now the warming will help but I'm sure most can't shake the feeling that we'll need 1 more warm push to set us free.
  21. weatherjunkie
    Looks like another solid MT event. Frictional torque and AAM tendency still on the rise, so perhaps some more umph in this event. Latest 10 hPa temp anomalies indicate significant warming in E. Asia/ N. Pacific relative to where our Ozone increase/wave breaking has occured. Looking at the forecasts for the upper stratosphere I still don't see much from the PV aside from movement toward Siberia. It seems like this will be a long struggle.
  22. weatherjunkie
    I suspect the low level wind reversal on the ECMWF is a function of the MJO pushing into phase 6 and given the composites I've seen the high latitude HP is allowed to build and amplify. Certainly phase 6 suggests -NAO given the W Pac tropical forcing.
  23. weatherjunkie
    That is what I had suspected. As always, your input is greatly appreciated. Yes, I see what you are saying. It looks like we'll just have to wait and see. At the very least it gives us something to monitor other than lack of cold and snow. Wave breaking potential also on the increase given the wave 1 amplitude (and forecast strengthening). Also seeing signs from forecasts of wave 2 strengthening.
  24. weatherjunkie
    The location of these warmings doesn't appear to bode well for the N. Atlantic. Again, I know the propagation of the warming doesn't translate directly from level to level, but this still doesn't appear to be good for a -NAO, am I right? MMW = major midwinter warming, but I'm unsure if the criteria is the same
  25. weatherjunkie
    wave 1 and wave 2 picking up in intensity...might get some extra help for the stratosphere
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