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Carvers Gap

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  1. Carvers Gap
    I think the 12z GFS at least shows why we have been watching this timeframe for seemingly weeks. Get cold air into the pattern with an STJ and the 12z GFS is a potential option. There was an additional wave which I think makes four along that front which hugs the coast. Long way out there, but something to track for now.
  2. Carvers Gap
    12z GFS still on time with a strong cold front and ensuing trough around Feb 5th. Something to watch, as noted in the previous thread, is whether energy will make a run along the incoming front. In this case there were 3 waves of precip long the front. First was rain and the last was snow as the Arctic front passes. We have scored on those during the past decade, usually 2-4" type snow events. Obviously at this range, a lot can and will change. Things to monitor will be whether the cold actually modifies as the event nears or will it maintain that strong frontal passage. Another thing to watch will be the angle of the front. If it sort of gets a positive lean to it, that raised the likelihood of something riding the front, especially if the tail is slow to move along in Texas. In other words, we want it to drape across the SE as a frontal boundary. Will be interesting to see where the rest of the run leads. As for this weekend's look, still not sure I buy the suppressed look but certainly looks that way as of right now. The energy that digs in behind it would likely induce snow shower activity.
  3. Carvers Gap
    Mostly rain here today. Had a few flakes mix in around 8:00AM. @PowellVolz shared in the discussion thread that Ober Gatlinburg is seeing some mixing there and also shared a great radar look @4K' where the changeover appears to be occurring. Phrase for the day: Cold rain.
  4. Carvers Gap
    Thanks for the new thread, @John1122. Looks like this is pinned to the top, so I will place afternoon ensemble discussion here.
  5. Carvers Gap
    Cold rain! Great share. Was/is definitely a marginal event.
  6. Carvers Gap
    ***Heads-Up**** Looks like John has the Feb/March thread up and running. So, I suggest we keep discussion for this week's marginal events in this thread(Dec/Jan) and then transition February discussion over to the the thread he created. Looks like it is pinned to the top now.
  7. Carvers Gap
    Cool. Had a few wet flakes hit the windshield this AM, especially as we climbed away from the river. Rates helped the mix. Nothing major as it was still mostly rain. OG has done fairly well with these elevation events lately, well compared to the rest of us.
  8. Carvers Gap
    During the social media era, the -NAO has been pretty lousy. We have had a few winters with it during the past decade that have been stellar for sure. I do think you make a good point that it will likely return. Pretty much knew after that long stretch this past year that it was going positive this winter. Problem with a -NAO during summer is that it has the opposite effect - hot.
  9. Carvers Gap
    We have spoken about the QBO some. Conversation has been spirited but constructive. We are now in the easterly QBO descending phase(reference NASA) of the QBO which is also called negative. As of January 26th, 30mb is roughly neutral, 40mb is negative, and 50mb is negative. Below is the QBO chart developed by Barnston, Livezey, and Halpert. D'Aleo shares a similar graphic from time to time. He did again today and it is worth a share. We are almost(if not there now) in the upper left hand quadrant of the graphic(East QBO and solar min). When you look at both the 6z GEFS and 0z EPS, you see something very similar in modeling beginning about hour 330. That tells me that the QBO is likely having more influence. Notice the east based -NAO and the positive in the GOA. Not a perfect fit, but pretty close. Anyway, there is precedent within QBO understanding for the upcoming pattern. It will be interesting if blocking continues to be shown at higher latitudes.
  10. Carvers Gap
    Which tells me that the lack of an Atlantic block is a problem. Speaking for MBY in NE TN... 09-10 was a good winter and had a -NAO. 11-12 wasn't terrible as we had thunder snow here. 13-14 was a good winter and had a -NAO. 14-15 was a good winter and had a +NAO but I wonder if that was still a winter with good blocking in the AO region? Seems like it had a -QBO as well. I don't think the NAO is a "cure" for our winters as the Pacific is notable and important driver. However, I can make a really good case that the lack of Atlantic blocking at this latitude has been a problem for several straight winters. I think it is a problem especially for those on the eastern side of the forum as NW flow tends to modify by the time it gets here. Need a block to actually bottle-up that cold air and keep it from sliding out. All of that said, if we want a good February one path towards that is to see a -NAO develop and block the cold shot next week from leaving. If it slides out, it is a textbook example of why some Atlantic blocking(even if weak) is important. Without something to slow down system 50/50 low or a block, the cold slides out and is very dependent on timing as things are humming along. The HB block has at least formed confluence near our area.
  11. Carvers Gap
    Also, I like the idea that a wave or area of slp could potentially run along the leading edge of a trough like the one modeled to come through next week. Whether that happens remains to be seen. The Euro has it at d10 which is a dubious range to refer to actual specifics I admit, but it does provide an example of what "could" happen. That looks has also been on the GFS a few times which is dubious at most time ranges. LOL. Assuming next week's trough is legit, the way we score would likely be with energy on the front end, clippers, or energy as the SER slips underneath it. Again, something to watch on ensembles is how much cold air will be available. Looks like the trough will have moderate staying power of 4-5 days. Could be less or more depending on your model of choice. On some modeling the trough will lift out after one shot. On others it gets a second shot of cold air that digs it further. That second shot will likely decide how long the ridge holds as it could dig more into the West. Right now(we have seen that change before), the cold looks substantial which means the cold could press into the SE despite the SER(reference to JB and just prior knowledge for that nugget) late in the run. So now we wait, track some marginal events, and hang out on the forum. Model mayhem is well underway. Don't like what you see? Just wait a run or two.
  12. Carvers Gap
    Personally, I don't think the PV splits quite yet. Looks to me like modeling is bringing it back together after a strong disruption. I also don't thing it was a head fake as the PV will be likely disrupted. A TPV split is a "be careful what you wish for scenario." Sometimes it really helps and sometimes it really hurts. But still, I doubt this is completely worked out. Great disco on the forum about it. Certainly looks like some response from the troposphere may occur. Also, do you all have the stats for the number of -NAO winters(DJF) that we have had during the past 10-15 years along with the dates? I think it is seven of the last eight winters that we have not had Atlantic blocking. I am going to examine whether the lack of Atlantic blocking is contributing to some of the less snowy winters that we have had recently.
  13. Carvers Gap
    As mentioned yesterday, the Euro op was likely in error in digging the trough into the West at d10. (We won't know if that was an actual error until that time frame verifies of course)This morning it moved it right on through. So far on modeling the trough is set to arrive around February 5th. As I have mentioned ad nauseam, it will be tough for it to hold with no blocking over the Atlantic. At this point the cold shot into NA is at d9, and we are not having to wait for d11-15. JB mentioned last night that the cold source would likely be strong enough to press eastward(even if the trough centers in the front range eventually - even with varying degrees of SERs present on modeling. The 6z GEFS has has muted the SER. The EPS has has well but not to the GEFS' degree. Right now, the GEFS is leading the way with the EPS again struggling with a pattern shift - that is a twist. Will post more later. The good thing is that the cold air shot is within d10 right now, so we should be able to get a better look at how it sets up(vs a washed out ensemble). Two questions are in my mind now: 1. How much, if any, blocking develops as it is now being hinted on modeling inside of d10? That would fit with QBO understandings. 2. Does the Euro bend and head towards the MJO as it did in November? In November, the Euro never caught up.
  14. Carvers Gap
    18z GEFS is a slight improvement and obviously very cold after an operational like that. The SER forms later and actual surface temps remain normal under the SER with such powerful temps to the NW. Again, as mentioned above, that is a workable look even late in the run.
  15. Carvers Gap
    Additionally, it may be that modeling is beginning to "feel" the disruption of the PV which will induce blocking. Nothing is a given this winter....
  16. Carvers Gap
    I don't like the western trough deal on ensembles late in each run, but that is the consequence of no Atlantic block. However, the way the gradient stretches out(on ensembles) would probably still mean the boundary would move to our south some. Looks to me like mid-Texas to DC would be the boundary on ensembles. Storms would run that boundary speaking of later in the run. The 18z GFS is probably an outlier run(to other models...similar to other GFS runs) due to how it keeps reinforcing the eastern trough. All of that said, I am most interested to see if other subsequent runs of the GFS and other modeling begins to catch blocking over Greenland. Probably the single, greatest feature that makes this an outlier is the block over Greenland. I will also be interested in seeing the MJO forecasts during the next few days. What we can hope for is that the 18z GFS is catching a trend as it sometimes does. But we can enjoy it until 0z. I say that, because the GFS has been flipping from blocking to no-blocking like flipping a light switch. The 18z GFS does illustrate how a little help from the Atlantic could hold the eastern trough in place.
  17. Carvers Gap
    Accumulation amounts in the eastern half of Tennessee generally range from 4-14" snow with the greater amounts over the Plateau. Much of the eastern half of the forum area has 6" plus. edit: eastern half defined in this case as mid-state to the Smokies
  18. Carvers Gap
    AT 354, all of NA is BN. I suspect the GFS in phases 2 or 3 of the MJO with that look. I would be hard pressed to find a better run this season IMHO. Yes, it is the GFS so everyone knows the rules. But one can still admire that run.
  19. Carvers Gap
    What is interesting is that as the features on the map have retrograded a bit(trough taking peak in the West), AN heights have also backed into Greenland. Something to watch. And if you watch the NA 500 anomaly map evolve at 192, notice how the trough doesn't get stuck like it does on the Euro. Then, watch the differences. https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=namer&pkg=z500a&runtime=2020012618&fh=264
  20. Carvers Gap
    The 18z GFS at 252....-NAO much?
  21. Carvers Gap
    It is interesting. I think the American suite brings the PV back together. So many unknown variables right now - more than usual!
  22. Carvers Gap
    Interestingly, the 12z EPS has a slight SER like the GEFS. I find that interesting because if the EPS is caving to the GEFS, then it likely means the GEFS MJO might be correct with phases 2-3 which is a win long term win. If one looks at the surface, EPS 2m temps actually beginning advancing cold air from the front range just like the GEFS. And at this range, lots of things probably still going to change. Good thing is the initial trough is still not track. Past that...crap shoot with so many things changing. Will be interesting to see where modeling goes after changes in the MJO today.
  23. Carvers Gap
    This run of the 12z EPS is really amped. All anomalous features over NA are deeper.
  24. Carvers Gap
    Out to 234, trough is heading into the East slightly ahead of schedule on the EPS. Some support for the cutoff but the strongly -EPO will kick it out. But with the moderate possibility the Euro is up to its old tricks on the operational, that operational run is probably not trustworthy after 198. By 258, very strong trough in the East...stronger than 0z. Now, how long will it hold? So we don't have a misunderstanding here, we know the possibility exists of the initial heading east and a secondary wave of cold diving West. Let's see where this goes.
  25. Carvers Gap
    12z EPS looks good out to 180. Looks quite similar to the GEFS and similar to its 0z EPS run. Bout to find out how much support that Euro operational run has....
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