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Carvers Gap

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  1. Carvers Gap
    I actually still like the February 5-10 window. Here is the side-by-side comparison of the past two runs at 500. 0z was actually colder with the initial front on the 5th. And again, without a -NAO it is going to try to lift out. This is at 18z on February 5th. One positive is the trough and initial front sped up a bit and deepened quite a lot compared to the previous run. The run-to-run change at 2m was actually net colder on the Euro OP for d5-8 when compared to 0z. I would post the R2R maps of those days, but I think you can get the picture by looking at the comparison at 500 at 186. New run is on the left. For once, the overnight run during this time frame actually improved.
  2. Carvers Gap
    Well, sometimes the tropical polar vortex at the surface will split first and work its way into the stratosphere. And at other times, the stratosphere polar vortex will split first and work its way down which is top down. Both work, but the first one has a more immediate reaction. The top down changes can take 2-3 weeks(sometimes immediate thought) sometimes to impact the troposphere and sometimes an SPV doesn't affect the TPV at all. That is why I like that animation that you post. You can see where the split is occurring.
  3. Carvers Gap
    Looks like 2-3 are firing pretty well. I kind of agree with you that the phase four area is firing. You are likely going to be right on that.
  4. Carvers Gap
    Which means modeling is going to be all over the place if that occurs. Can you tell, Holston, if that is a "top down" split? Sometimes we can get immediate reactions from those and sometimes not. I know in the spring of 2018, it took about 2-3 weeks to really impact the troposphere if I remember correctly...Basically, what I am getting at is if the TPV is affected and when?
  5. Carvers Gap
    Whew, I should have kept looking at that data.
  6. Carvers Gap
    @John1122, thanks for that verification site. Man, I missed the first half of the TN basketball game working through that. LOL!!!
  7. Carvers Gap
    GEFS just reaffirms that modeling is really struggling with the LR. Beats down the SER like the EPS did. Man, it is cold at the surface. I can't possibly understand why it is said to have a cold bias. J/K. Man that is a lot of blue and purple on Tropical Tidbits.
  8. Carvers Gap
    With it being late in the season and it taking a beating...that PV is going to be ragged. Will be tough for it to reconsolidate. Holston, we want to be under the warm anomalies, right? I know that sounds counterintuitive, but I "think"(???) that it is colder under those warmer strat areas....
  9. Carvers Gap
    Seriously great site, @John1122. I could spend days there. This is line graph data from the same site. I would set forth the idea that four time periods are skewing normal model tendencies during the past 90 days(early Nov, mid Dec, early Jan and mid Jan). Looks like there is a big bust in December where models missed by 10-15 degrees and early and mid January where models busted by 7-10+ degrees during week one and two. Overall, January misses have skewed model tendencies...as we know January has not been a good month for modeling. I know the big bust in early January was where modeling was too cold. I am assuming the miss in December is also the same based on the idea that we have been head faked twice and Christmas being warm was a huge miss. For example, the December 13th 12-day forecast would actually verify on December 25th which we know was warm. I might assume Novembers model numbers were actually too warm as twelve days after October 30 were a period of severe cold. December and January were both well documented bad time frames for modeling as was early November when modeling completely missed the cold. What would be interesting is to see the rest of the year. Not sure how to dig those up. Interestingly the GFS ensemble was better than the Euro at spotting cold last November from the d12 range. It was nearly two degrees better than the EPS(albeit bad scores for both). As suspected, the GEFS spotted the cold snap in mid November. So overall, I would suggest normal model tendencies are skewed and potentially might misrepresent modeling as being "too cold" because of an anomalous two month warm period(December to January). So it is a tale of two contrasting biases. In early November(when the pattern changed to cold) the models were too warm. During December and January, modeling was too cold during near record warmth as modeling almost always has trouble with extremes. So, those maps above have two months of cold bias and one week of warm bias. So, makes sense they are skewed. So, I think we have to consider current model tendencies but be wary of using past performance as and indicator of future performance. For example, I think many assumed modeling in December(that predicted warmth) was possibly wrong, because its past performance had been too warm in early November. The warm December forecasts verified. It is possible that the same thing will happen in reverse where modeling busts high. Not saying that will happen, but the antecedent performance of November certainly did not continue into December. In other words, sometimes modeling mistakes can move from a cold bias to a warm bias vey quickly as occurred in November.
  10. Carvers Gap
    Good find. I wouldn't argue with many of those, but I think(am nearly certain) the EPS has a really strong warm bias from d10-15 and also for the Weeklies. It is usually significantly warmer at 2m than any of the American model output. Not sure how those are generated, but the 90d timestamps might be skewing those. I can say from personal experience, the EPS has a warm bias in d10-15. Maybe the miss earlier in January and over Canada last week is skewing those maps as the past 90 days of modeling have had some wicked busts where modeling verified much warmer than modeled d10-15. Additionally, I would think that modeling would have some sort of correlational coefficient rating based on where features verified on a map - I would be interested to see those as well.
  11. Carvers Gap
    It has been a fight all winter. I am looking for some cold pattern persistence! LOL.
  12. Carvers Gap
    The thing I am seeing today is a bigger presence by the EPO ridge and a deeper trough somewhere east of the Rockies after Feb 5th. I really have run with the premise that the trough does not hold. But if that trough were to old like the EPS is showing, that would allow for really cold air to enter into the US. Give me that pattern on the EPS and 2m temps take care of themselves. No idea if that type of extreme look would verify. If I remember correctly, the CFS and EURO had similar MJO trajectories this morning - for once. I like that look, but do I trust the CFSv2? LOL. Anyway, at this latitude there are about 100 ways to achieve worse pattern. Right now, I am just pointing out with modeling how things could lead to a decent window.
  13. Carvers Gap
    Couple of images to explain my thinking regarding the EPS. 0z is on the right. 12z is on the left. The first image(figure 1) is hour 198 which is February 5 @ 18z. Notice the core of the colder air is further west vs being over Quebec. Notice that the cold north of Alaska is stronger. That stronger area of BN heights near Alaska likely weakens the downstream trough. Notice how at 0z they(the two areas of BN heights) are similar. JB likes to point out that there is only so much energy to go around. Again, I don't do 2m temps on the EPS as they are often very biased towards warm. I look at 850s. That said, the 2m temps later in the run are impressive. So, the trough at 500 is later by roughly 12-18 hours now that I have had time to dig into it. You can compare the two images. Instead of the cold digging with the feature in Quebec, it digs into the Plains and pushes eastward. Almost all modeling is bouncing back-and-forth between placing the lowest heights in the northern Plains or Quebec. You can see the difference. Figure 1 Figure 2 shows what I consider to be fairly important improvements. Notice the stronger heights at 330 are centered over Minnesota instead of Montana and Quebec. That might mean the EPS is just splitting the difference between the two cold pools OR it actually now sees the cold in the Plains. Either way, the result on this run is the positive axis of the trough being moved quite a bit further East. With the area of lowest heights centered in the northern Plains, the cold air presses further into the SE and nearly eliminates the influence of the SER in our forum area, even bringing BN heights into west TN, Arkansas, far western KY, and Missouri. That also means the storm track would theoretically slide eastward and run from Houston through TN to Massachusetts verbatim. In reality that front probably presses further east at the surface due to the cold being centered so close in the Plains relatively speaking. That is a cold pattern. Also note the ridging In Alaska along with the ridging building into the coastal areas of Pacific NA. Another difference is the lack of Atlantic ridging. That may very well have allowed the trough to be displaced eastward. But the biggest takeaway from LR(and really LR at that) is that the EPS takes a big bite out of the SER and centers the cold further East. Figure 2 Lastly, I thought I would compare the Weeklies to actually EPS stuff now that it is in range. This is the 7day 500 anomaly for February 4-11. Figure 3 is from the Euro Weeklies derived on January 20th. Figure 4 is the same time frame from the 12z EPS today which is a run eight days later. While not perfect, the cold and trough axis in the lower 48 is nearly the same place. Just showing that the Weeklies are doing fairly well right now in week 3. Also note that the actual trough is being modeled deeper on today's run. Figure 3 Figure 4
  14. Carvers Gap
    In my book that is a split given where it began at hour 0. But I am comfortable with different terminology. So, instead of split I will use an Eastman term: process upset. Used in a sentence it would work something like this....The SPV at 50mb is experiencing a major process upset.
  15. Carvers Gap
    @Holston_River_Ramblerlooks to me like that trough is going to lift out of the West fairly quickly. Have seen that trend on modeling. That is a textbook easterly QBO/solar min look. I actually am a fan of the PV being over the HB an pivoting down cold - and I may have that backwards but that is what sticks in my mind.
  16. Carvers Gap
    That run of the 12z EPS will work. The cold is centered in the Plains and not the Rockies. The cold would push on that boundary. IF true, that taps the GOM with that look late. See how the boundary drags into the Gulf? Fairly strong improvement IMHO and the ridge is closer to the West coast. The SER has really been pushed toward the EC.
  17. Carvers Gap
    At 288, more ridging into Alaska is evident. Core of the cold is over the Plains. Looks very much like a microcosm of November.
  18. Carvers Gap
    The interesting development on the 12z EPS is that the trough is a bit slower to lift out and the storm track would be optimum around 228. Of note, the ridge in the eastern Pacific is closer to the coast and stronger at 288.
  19. Carvers Gap
    Also, looks like the 12z Euro OP splits the SPV as well. I will let Holston unpack that.
  20. Carvers Gap
    The Euro digs the initial trough into TX this run. It is sort of a compromise between the CMC and GFS. It is worth noting that the big cold has slowed by about 36 hours due to the trough digging. The cool thing about the trough digging is that it allows for the storm that Holston posted above. I don't see anything at this point that makes me think the trough won't come East. The big EPO ridge should kick it out. Just about timing right now. But we don't want to see things getting pushed back and held at d8-9. Need to see it moving forward. Quick EPS update as in a bit of a hurry this afternoon: The EPS does not slow the front down. (Edit: Surface front slows down by about 18-24 hours...sorry, was in a hurry...500 has only slowed down by about 12) I am actually trying to decide if the trough digging is a bad thing. That actually might allow the trough to have more staying power. The EPS does sort of split the difference between the core of the cold on the 12z Euro and the 0z EPS. Instead of the core of BN heights over the GL, it is heading down the Plains into the SE. Model Mayhem...I keep saying it, but it is true. Still looks like a decent window for a storm.
  21. Carvers Gap
    @Holston_River_RamblerI think the EPS/Euro handle the MJO regions really well. But as we have noted, the GFS/GEFS probably handles the strat a bit better. Not sure what to think at this point. That will likely have impacts at high latitudes that modeling isn't seeing yet. Looks like that has been on there for several runs.
  22. Carvers Gap
    I just looked. Yeah, the 12z basically split it. It is even more noticeable at 30 and 50mbs. That is a big development if true.
  23. Carvers Gap
    One final note here before the Euro rolls, the EMON/EMOM is super similar to the Weeklies last night regarding the MJO. If you break the next three days into 1/3s: The first third is null. Second third is 4/5 and little of 6. Last third is null. That fits really well with a cold shot in early Feb, a warm-up, and then the trough pushes back East as the MJO stalls. All of that is at really low amplitude. The GEFS wants to head towards 4 and bend back to 3. This just tells me what we know from forecasts. The MJO is going to have 2/3 firing along with 6 at times. Going to be a battle and is likely why we see models waffling after Feb 10th. One can see when looking at the equatorial are in the IO, MC, and western Pac the MJO firing in the sequence that the EMON has. So again, looks like when the MJO goes into null gives us a clued as to when windows will be there for winter storms.
  24. Carvers Gap
    12z GEFS @ Pivotal Wx is done. Trough ducks west around the 9th or 10th, and then like the Weeklies, centers back towards East right at the end of the run. No idea if true, but that is a good trend if it were to continue. Good thing is that there is precedent for that.
  25. Carvers Gap
    The 12z GFS has a very strong EPO ridge during this run. The CMC isn't far off from that either. The CMC is just slower but would likely get the same result a couple of days later. We will see if this trends...both models have a better looking Pacific after Feb 5.
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