psuhoffman

I changed the setting so that others can share their screen and I welcome anyone who wants to take over and lead the discussion for a while to do so. This does not have to be just me leading all the time. I would love to hear others input as well.

I will be on again at 9:30 and will stay on for as long as we have something interesting to talk about. Just use the same link as earlier today.

That was fun. I wish we had done one before there was a threat to just chat and get to know each other. But I got Covid then the holidays…but maybe we can do a more laid back chat after the storm to discuss long range and just chat more relaxed. I’ll set up another for this evening to discuss the 0z as it comes in and the huge north trend in the precip!

got it, you should have it now

I just checked and sent out the link to everyone I had. If you still didn't get it please email me again. [email protected]

I just sent the invite to the emails on my list. If you didn't get one please let me know.

The WV is often the easiest way to see the mid level flow and moisture transport. Start of the loop you can pick out the mid level low and associated flow. It’s still positively tilted here (flow has a west to east component to it). Here it’s SW to NE but by the end of the loop you can see the flow is “backing” or taking on less W to E component. It’s almost neutral here. If the flow actually takes on some E to W component that’s when it’s negative (against the predominant W-E mid lat flow). The sooner the flow backs the more likely the system will be more amplified and come further north. Or at the least have a more expansive precip shield due to better moisture transport into the cold sector north of the low track.

https://www.tropicaltidbits.com/sat/satlooper.php?region=us&product=wv-mid The WV loop is a thing of beauty. The flow is really backing in the TN valley. This has a classic look for the mid Atlantic! Btw I still like to look at the WV sometimes just to get a feel for the flow. I’ll never forget being in the psu weather center the day before the Jan 2000 storm trying to argue with the meteorologists on duty that it was clear from the WV and IR that the mid and upper levels were way more amplified and the flow was backing much more than any of the nwp was showing over the Miss Valley. They were pretty dismissive…”it’s only 24 hours, the models would be picking up on it” lol

I can do a zoom chat 4:30 this afternoon. If there is enough interest I could do another later this evening as the 0z guidance comes in. I’ll email everyone who signed up the link. If you didn’t sign up but are interested please email me at [email protected] and put Amwx zoom in the subject so I can search/filter and I’ll add you and email the zoom link.

You’re right that it’s not typical. And I know you’re kidding but we do have some who think there are numerical patterns and while storms that fringe the NW zones are rare they can happen in bunches. There were a few in 1980 for example. Hence the rare year Richmond and DC had more snow then up here. Not saying it’s likely now…just that there is chaos at play here. I’m not worried. I do think there is a good chance I get fringed tomorrow but it will even out over time so it’s ok.

It can happen. I only got 2.5” from the Jan 2019 storm. There was a storm in Jan 1987 that gave DC a foot and fringed up here. Jan 2010 also was like that. The orographic banding and super high ratios you described is why there will typically be that “deathband” up here. The added terrain lift along with colder temps typically causes better snow growth conditions here. I often have 20-1 ratios. But those factors won’t happen if we’re in the subsidence zone and that can happen if the storm track is far enough south. Right now the track is iffy if there will be enough mid level moisture transport into this area. One more tick north like last night and we probably would see the typical orographic effects up here but there needs to be good enough moisture to take advantage of that.

Zoom chat tomorrow?

If it still looks good I can set up something tomorrow.

No one is debating that it’s getting warmer and snowing less. But you exaggerate and talk about nothing else. No one in here has the ability to wave a magic wand and fix it. So all you’re doing is harassing people who mostly agree with you.

The bar on your posts can’t get any lower.

@WxUSAF btw this is the scenario to test “can we get cold”. If we get a PV split, pna/epo ridge with the cold currently built up in Canada and don’t get some serious cold period from it…then it’s time to just give up.

If it does good for them. I’ll get snow up here eventually. I’ll live if I miss a couple storms. Doesn’t mean I won’t be a little irked seeing deck pics from central VA while I have bare lawn but I’ll get over it.

On the coming “waves” in the next week… these are the type systems that depend on discreet details that won’t be known until the last minute. And to make matters worse there is often a nice band that develops in response to where the confluence/subsidence cuts off the precip. There is likely to be a very sharp cutoff and models won’t nail that until within 24 hours. I’m not going to waste you’re time pretending I know where it will be but obviously places southeast seem favored ATT. The next threat will develop as a wave forms in response to the jet on the front side of a digging amplifying trough. This is somewhat similar to waves we got in 2014-15. Where this ends up will depend partially on how the PV split happening at that time evolves. The whole trough is pinwheeling and amplifying around that process. It’s way to volatile to try to pin down at range but I do think the idea of a healthy wave in response to this process is correct. Long range I like this evolving pattern quite a bit. I know I poo pood pac with no high lat help recently but that’s now what I see happening now. All guidance is now showing a significant TPV disruption happening due to a wave 2 hit this week. The TPV elongates with a lope getting displaced south on our side. The euro has backed off a raging +AO. The numbers might not look great but I’ve said the numerical index can be deceiving. Below are the Gefs end EPS both show the elongated tpv (red). Both have ridging in the HL. The gefs connects a ridge bridge all the way across the top because it completely splits the tpv. EPS severely elongates and displaces the tpv but both have plenty of ridging up top to do what we need which is displace the tpv and get cold discharged into the mid latitudes. The pac pattern puts the trough in the east. That high lat wouldn’t be good enough if the pac was garbage but that’s a good combo there. Again trade offs. Great pac longwave pattern and decent high lat is a winning match. This look reminds me a lot of 2014 and 2015 where the details up top helped enough for a pac driven longwave pattern to work. 2014 with enough ridging poleward in the epo side and 2015 with a displaced tpv on the Atlantic side. This is kind of a combo of both. This is not a hecs look. But this is the kind of look that would produce boundary waves and some would be suppressed enough. This isn’t the kind of pattern nwp is going to pick out threats at long range though. Remember most of the snows in 2014 and 2015 weren’t on our radar at all past 72 hours.

It’s super rare but not impossible. Richmond got more snow than up here in 1980 for example. But I’m not worried and if it happens oh well. Things balance out in the long run.

But the pac looks good…isn’t that what everyone wanted???

Gefs went 2014 look in the long range. The key is it keeps enough of a ridge over the top to displace the TPV into N Amer enough to suppress any SE ridging. We don’t need a great look up top if the pac is great, just need it to not go to total dog poo like the eps says. A great pac ok HL works. A great HL ok pac works too. But we’ve taken turns with one or the other in total dog crap phase.

Regarding the trailing wave threat next week. Yea usually trailing waves don’t work. Know what else usually doesn’t work…just about every setup other than a juiced stj system plowing into a high locked in by a 50/50. That’s the only high prob setup we have. Everything else is us rooting for a low probability thread the needle scenario to work out. What we need is enough enough energy left behind by the initial NS wave and enough separation for the trailing wave to amplify after the front clears. It happens. We got snow this way in a Nina in Jan 2001. But it’s low probability, like just about everything else we track.

@BristowWx @cbmclean Depends what “throw in the towel” means. I always expected below avg snow. But I didn’t expect a total dreg dud year like 2002/2012/2017/2020… In 2019 I did call TOD on winter in late December. But I didn’t do that lightly or as a joke like some do every year it doesn’t snow by Xmas. There was a very specific set of circumstances (raging positive AO during a long term +AO phase, anomalous mid latitude pac ridge, and a N. amer void of cold, enso neutral) that when that pattern sets in around New Years in those phases the results have always been atrocious. Every time. That’s the recipe for our absolute worst winters. And it’s a pattern that takes months to break usually so it was game over. What we’re dealing with now is bad. But it’s not necessarily totally game over. There is cold around. The pattern has been variable it’s just we’ve seen different things take turns wrecking our snow chances. Now it seems the pac improves but the Atlantic will play Scrooge. But that’s the kind of thing where eventually we could line stuff up for a decent run. If a period of Atlantic blocking returns while the pac is somewhat less hostile we could pull out some snow. Blocking tends to return later in winter in years we had a -NAO in December. But we should set the bar low. This is a Nina which will limit any recovery. Ninos can pull off amazing endings after awful starts like 1958, 1960, 1966, 1987, 2015 because with a stronger stj all we need is to get a period of cold and we can go on a tear. In a Nina that’s muted somewhat. So even if we get a 2-3 week cold period we’re still likely talking modest snowfall results. Something like 1999 or 2009 is doable where we eventually got a decent snowstorm later in winter. 2000 is an example of where you can get lucky with a 10 day favorable pattern in an otherwise awful year. Then there is 1976 where it was awful and totally snowless and then we lucked into a 6–10” snowstorm mid March. Those were all awful Nina’s where we still managed at least one legit snowstorm. Actually even in a bad Nina odds greatly favor us licking our way to one snowfall somehow. But are we going to turn this into a good snowfall year that we remember fondly, highly unlikely at this point.

One last thing to consider…there are a lot of combos the pac pattern can take but most aren’t good. It’s not a 50/50 thing. It’s more like 70/30 in terms of what works for us. That’s just a fact of our latitude and it’s only getting worse as it warms. Specifically we need there to be some amplitude to the jet in the pac to prevent zonal pac puke from infiltrating the conus. So we need a pac ridge somewhere…but it has to be positioned just right. Too far west and the trough is out west. Too far East and the vortex can get into Ak and destroy our cold air source. An Aleutian low is good but slightly too far west and it causes a -pna and too far east and it floods pac puke across the US. The type of perfect pac pattern like 2014-2015 that can give us snow absent much help on the Atlantic side is really rare. It’s a perfect alignment of various features. Absent that we can overcome a mediocre alignment in the pac with some help on other places. But if the pac is “ok” and everything else is bad that’s not a winning hand either imo.

Well the 12z eps went along with the op. But hey it’s a +pna…I hope people don’t complain when it’s still 50* due to the fact the high latitude pattern went to crap! Look at that, nice Aleutian low, +pna, great pac, and we’re torching. Because a +++AO will offset the pac the same way a - - -pna will offset a -AO.