Carvers Gap

Yeah, very different circumstance to get you snow vs MBY in many cases. The EPS now has the pre-Christmas trough. That is a legit window now I think. PNA spikes positive temporarily for that model on the Euro. We don't need weeks on end of a great pattern, just need a window where it can occur. Today is the first I have seen ensembles move off their spots. Operationals are so different, that something had to give. I generally don't expect snow around my neck of the woods until January or February. We can get it earlier as we have had two great pre-Christmas snows(after going decades without those), but the norm is a six week window from Jan 1 to the middle of February. So anything right now is a bonus. If that 50/50 low is legit, that is important for the eastern half of the forum area.

When is the last time we looked at 12z suite and are like, "Wow, the Euro looked better than the GFS?" Been a couple of weeks, but that is a great looking pattern. Ridge off the west coast popping an albeit likely temporary PNA ridge which sharpens the downstream trough. Then a 50/50ish low is parked in the right spot with energy in the southern jet timed with the northern stream. Lovely look, but ain't no way that is locked in at that range. The great thing even though that is unlikely? The pattern isn't benign.

To clarify...how you draw up a major EC storm. Again, that probably isn't right but that 50/50 has been showing up on multiple runs of multiple models. Just need timing for something to come along behind it with enough spacing.

Posted about the same time you did. Probably isn't right at that range, but that is absolutely how you draw it up.

Post 1: My takeaway from the 12z run is the Pacific (the irony, right?) actually is the driver for colder weather on this run. No idea if true. The Euro at 0z was slower with the MJO and the pattern was slower...but with a similar progression. The GFS is faster in getting the MJO in winter phases, and it shows on this run. I don't have a preference in terms of accuracy at this point. I do have a preference in terms of winter wx!!! Forgot to post the above...so will just post both posts in this one. Post 2: Well, the Euro doubles down on a double block with the NAO strong negative. Looks remarkably like the CMC. Now, I think what modeling are seeing are increasing chances for cold in the East during the last ten days of the month, and possibly into early January if we are luck. Almost all modeling returns to the western trough after that though. Then I would guess that we see another week or two of warm weather followed by another loading of cold which surges eastward. That kind of looks like the pattern for winter and looks remarkably similar to last winter. Good pattern for those in the western 2/3 of the state if that is indeed the pattern. Fun thing to watch. If that NAO forms, I am seeing a low get forced into the NAO block. It slows that low just north of Nova Scotia. That is a recipe for a big storm as it would suppress the flow and force a storm to climb the coast slowly and then stall. Maybe a 50/50 low? Timing appears to be off right now with so few systems in the pattern, but if one were to get in the pattern....look out.

Impressive Alaskan block setting up shop right before Christmas on the 12z GFS run.

Cosgrove noted in a post about a week ago to keep an eye on GOA lows. If they ever move southwest into the Pacific, it sets the stage for the EPO to pop and allow cold air to rush into the Lower 48. That is what is happening in this run.

Pretty impressive run by the 12z GFS unfolding after d9. Long way out there, but that is 17-18 level EPO stuff there if memory serves me correctly. Late December in mid-January. Super dry but incredibly cold with single digits for nearly a week straight for lows with no snow on the ground. Not that cold so far on the run...just looking at the direct path from the Arctic southward.

Thanks! Looks like an EPO ridge creeping towards the WC. That is the same general look as other models, but a bit slower in its evolution which doesn't surprise me given the Euro's tendencies. The breakdown of ridge pattern over the East(even if just temporarily) is what I am looking for evidence of.

Holston, do you have the control for d10-15l?

Thanks, Holston. Progression is slower but smilier. Like seeing the AN heights in the southwest. If it continues to connect with the ridge in AK, that forms an EPO. Big change today was the GEFS with big changes after d10. Honestly, those are fairly substantial changes on the EPS...just not in ur favor. Need that ridge out of the Aleutians. However, some great cold snaps during La Nina winters tend to work around that big high there. And of course, sometimes it just goes warm! LOL. Thanks again.

Of note the 0z and 6z GEFS have cracked - meaning they are no longer repeating the same pattern endlessly. Of note, a -NAO is now showing up on the model. If true, it means the operational has led the way. The 0z GEPS is not too dissimilar. Good news on the ensemble front. I can't see the d10-15 EPS on WxBell.

@Holston_River_Rambler, I may do a post in the historical winter thread on 17-18. You are more than welcome to chime in. The swings that winter were WILD!!!! We had a stretch of about seven days that were roughly -20F below normal....and then then hit 82 in February...got an SSW....and then there was light, but measurable snow at TRI twice during April. That is classic La Nina. Easily one of the most frustrating winters in terms of snow, but watching the GFS nail the strat warm from 16 days out was something to behold.

There is a wicked cold snap earlier in the 17-18 winter which is hidden because it straddled two months. End of December and beginning of January saw the N Fork freeze pretty much solid here. We had nearly a week where we didn't get above freezing. Don't think it snowed at all as the PNA/EPO was almost to the Arctic(or more). Was very frustrating to have that much cold and very little snow. Classic La Nina cold outbreak. Spring 2018 was crazy. I need to go look at that thread again. I may have been in JC picking up a water heater during April with snow showers coming down.

LOL. Man, I am afraid to go look at those threads - I was living large that year! As you know, Kingsport normally gets hosed when it comes to snowfall in the TRI. @Holston_River_Rambler, the EB? LOL. Seriously, our elevation is lower due to being right on the river. My house sits about 100-150' higher than the river plain, and I prob get 25% more snowfall than downtown. Then again, I am upwind of the heat dome.

We bough a 4WD after that winter as a family vehicle and haven't had to use it since!!!! LOL. Our van was useless for two months in 14-15.

I generally like the Australian. Nah, LOL. It is the coldest which is why I say that. I talk about the MJO, but I truly hate to look at it on modeling - meaning going to the MJO region and looking at charts for convection. @nrgjeff, which model is it the handles the western Pac and IO better? I would guess Euro but not sure that is a slam dunk answer.

So the Euro Weeklies are wonky again. Literally, the mean ensemble repeats the exact same look through the end of January with almost the exact same details repeating week after week. That has always been a red flag to me, because that isn't real life. It doesn't go below normal at any point. Here is the wonky part. The control goes below normal during the last week of December and stays BN for the entire run! The entire run.... On a sad note, the last two runs of the CFSv2 have left the cold camp. It will probably be back. That is why I don't share a foxhole with that model. It is a waffler. LOL. But I like it on cold runs. The GFS operational and Euro control are the keep in the castle of cold. Those are our holdouts. Stay strong, 0s and 1s.

That is insane!!!!

Yep, that is what we have been saying on this forum for several days. Debatable about the coldest air being over here. Yesterday, that was the general trend. Today, though very cold in NA, the coldest remained in Siberia for most of the models I could find. Nothing set in stone at all. I look for one of two mechanisms to drive it both, -EPO or -NAO or a cutter which wraps cold air in behind it. I am probably missing something. Teleconnections looked good this AM after d12 or so. I think we are likely looking at an amplification which doesn't hold. However, if we can get 4-7 days of good, cold Arctic air...we have a shot.

Modeling has been awful this fall at catching trough amplifications. Ensembles will likely miss the troughs embedded in this pattern at range. I don’t use them as a primary source in order amplification as they smooth it out at range. Ensembles will be last on board. What I am looking for is not a flip to long term cold which I think is unlikely thought not implausible. So, same plan as last year. Trying to find cold shots within the pattern. As PSU noted in a great post yesterday in the MA forum, we live in an area where snow is the anomaly. It is easy just to say it is doing to be warm and not snow. The “not snowing part” is true for 95% of the days of winter or more. So, it is house money to go warm-up and rain. That is the norm. Tough part is being able to spot a trough amplification before ensembles do. So, I don’t see myself as a hobby forecaster, but someone who is hunting winter wx.

Add the 12z Canadian to the mix as it is now picking up significant AN heights over Greenland. So that is the GDPS and the GFS which are now picking up blocking which forms around d8. Again, a lot of this is speculation until we can get it inside of d7 where skill will increase with each day at that point. The NAO is NOT a given and is notorious for head fakes, but to have it on two models with cold air already in place over NA...this raises the chances for an eastern trough amplification after the 19th. I am not saying this is a pattern change as I am not sure what pattern we are changing at this point. We have noted many times that mega ridge in the East during winter are often precursors to strat warming and cold air getting into the Lower 48.

12z GFS basically splits the SPV and likely a part of the TPV right around Dec19th. Part of it heads south into the Lower 48. Very likely anything after that is in-correct, but a wild, wild run.

Meanwhile the 12z GFS is pretty much bringing it this run. What a block.

Two words...NE TN. Location matters. A lot of folks outside of TRI won't think about 14-15, even on the Plateau. I probably had almost 30" of snow here in January and February alone - and that is in Kingsport which is less snowy than the other TRI. We score a bit differently than the rest of the forum area. SE KY and SW VA folks can relate to the differences of the micro climates. Kingsport does not do well with NW flow events(Bristol and JC do well), but does very well with events along the Atlantic provide we can get under a deformation band west of the Apps. Usually when it is colder in western areas of the forum, it is often warmer here. Last winter was an extreme example. Memphis got hammered for days. We saw very little.