psuhoffman

safe travels

Since we finally have a legit tangible threat I think its worth noting a trend I have observed the last few years wrt the guidance. There has always been a general time period when guidance was likely to converge on a consensus and then from that point on its only the details that usually need to get ironed out. Where the fringe ends up. Meso scale banding. Exact rain/snow line. But the large scale features and general track is locked in. Obviously there are exceptions where a huge across all guidance bust happens but thats rare. The old timers remember in the 90's and early 2000's when that "convergence" didnt typically happen until 36-72 hours out. More recently that convergence on a general solution has been happening between about 100 and 140 hours. We are still outside that range where guidance will shotgun solutions within a very wide permutation of outcomes every run. Trends in the ensembles are still way more important at this range then any one op run. Once the various globals begin to converge on a solution, likely not for another couple days at least... then we can start to worry about details. And once convergence happens it still doesn't mean there won't be changes...just that those changes likely wont be 500 miles! Until then it really doesn't matter what any one op run says. Once we do see that convergence around day 5...we don't want to see a track that is hundreds of miles away from what we need. The old "NC bullzeye is fine day 5" thing has not worked for us lately. The error from day 5 isn't what it used to be. But we are still way outside that range. On a more specific note regarding THIS setup... The pattern is absolutely loaded heading forward. About as good as we can hope for. There will likely be multiple threats. But even with the blocking this is a more difficult setup for guidance to resolve because we are at the mercy of stream phasing. These are not STJ dominant systems. This is a MUCH better pattern than a typical NINA but its still not fully a split flow STJ dominant Nino pattern where guidance might be able to pick out these storms from 10 days out. When dealing with the kinds of multiple interactions we are here its unlikely the final solution is known from as far out. Reminds me of January 2000 when we knew the pattern was ripe but the guidance was keying on the wrong waves from range and we ended up getting a few nice storms but none of them was well resolved until the last minute. Guidance has improved a LOT since then so I highly doubt we get any last second surprises like that but it wouldn't shock me to see something we previously "gave up on" sneak back up on us in the 3-5 day range. But I think it would take monumental bad luck, even for us...to get through the coming 2 weeks without any meaningful snow.

My point was with that pacific look it shouldn’t be that warm in the east.

He also predicted a snowy December and that I would have above normal snow for like the 14th time in the last 15 years.

It’s way out there so not worth panicking yet…but worth noting since it’s on all 3 ensembles day 14-16. The pac progresses to a favorable configuration with an Aleutian low and pna ridge. But the warmth from the pacific overwhelms the whole pattern and even with a trough in the east it’s game over. In 48 hours once the cross polar flow cuts off the pacific air brought in by the pna ridge eradicates all the cold from N America. Hopefully it’s wrong. If it’s correct that might be the most troubling thing I’ve ever seen. If an Aleutian low/+pna/-NAO doesn’t work because pacific warmth overwhelms the pattern around New Years…I dunno what were even doing anymore. I’ve said this over and over but 90% of our snowstorms didn’t come from cross polar flow arctic patterns. Most -epo patterns that bring down the arctic hammer dump the cold too far west. The full latitude pna epo ridge that dumps cold directly into the east is extremely rare but also can lead to just a cold dry period. 90% of our snow came from a combo of favorable pna and high lat blocking to facilitate a favorable storm track in a moderate temperature regime that used domestic typical winter cold and the snow fell with temps very close to freezing on days that likely would have been a high of 40-45 had it been sunny instead of snowing. If we need some perfect pattern that somehow incorporates cross polar flow AND blocking we’re just fooked most of the time. That’s a super rare thing that isn’t going to happen much. We have to be able to snow from a good storm track with a typical domestic cold thermal regime or we’ve lost most of the ways we used to snow.

It was the only good snow that winter in northern VA. My senior year at Oakton HS. It was in the mid 30s as the snow began then temps quickly fell to 33 then 32 as the intensity increased. Eventually towards the very end of the storm that evening temps dropped below freezing. I think the temp splits for the day were 37/29 at IAD and 39/31 at DCA.

@Maestrobjwa you asked for a specific example where something in the past might not work today. This was one that kinda popped into my head. Feb 8 1997. 6.8” at IAD. A general 4-8” across the whole area. Somehow is snowed during this pattern… A weak piece of energy cut across under the pseudo block in southern Canada and managed work out. But there was no real cold anywhere in the east south of New England. It was 41 the day before and 37 for a high that day at IAD and most of the snow fell at 32-33 degrees. This stuck out because it was one of the last examples of a snow from a feature that used to work a lot. A south central Canada block with an otherwise +AO/NAO. There are quite a few examples of that look in the snowstorms I studied in the 1940s-1990s. Then they went extinct. We had a couple patterns like this more recently and we got a perfect track storm but temps ended up too warm. One was late January or early Feb 2020. Within that got awful winter we had a week with a Hudson Bay high and a system came along and off the coast. But the temps even in mid winter were just blah and without any thermal gradient to aid lift from WAA the system was just a weak POS that gave us some drizzle and scattered rain and mix showers along the NW fringe. A nothing burger that at the time stuck out to me as similar to ways we had salvaged a small to moderate snow in an otherwise bad season and mediocre pattern. But as I’ve said recently we just don’t seem to have any prayer in a bad pattern anymore. No way to luck into snow from some micro feature within the bad pattern. Lately unless the pattern is good we’re torching with 55 degree temps and no prayer of snow. Kinda doubt that pattern from 1997 supports snow anymore.

Imo what’s “winning” is complicated and depends. I think from a distance without knowing the synoptic details I would be happy with a 4” snow event as a general rule. But again, if 24 hours out were looking at a HECS and it falls apart to just 4” we all know none of us is feeling great from that. Then there is the macro v micro. In the micro I’ll be happy with a 4” snow on Dec 23. But at the end of the winter if all I got for the whole season was say 17” (which is a bottom 10% winter here) because we had a couple great patterns and all I got out of them was a few minor snowfalls…it’s a fail for the season. Getting a small snowfall is fine but at some point we need to cash in big and max out a good pattern if we want to have a good season. To make a baseball analogy…going into a good pattern like this is kinda like having the bases loaded with nobody out and you’re 4-5 hitters coming up. Let’s say they hit a sac fly and an infield single that gets in 2 runs. In the micro that’s fine. They did ok. Then your bottom of the lineup strikes out. Later the heart of the lineup comes up with 2 on and again they manage to get one run in. In the micro fine. But at the end of the game when you lose 5-3 you look back on that and realize you needed a 3 run homerun or a base clearing double somewhere in there. I’m fine with singles as long as once in a while we get that home run. Or at least a double! There was an arctic front in the 80s that dropped 7” in an hour some places in northeast MD with thunderstorms. So anything is possible.

Careful….You’re tip toeing near a rabbit hole that got some pretty mad at me last year In seriousness though…something I’ve anecdotally observed over this 6 year run that’s been the “worst in history” wrt snow…while the pattern has been awful much of the time, what’s actually made it worst ever was when we did get patterns that historically were plenty good enough to snow they were also mostly frustratingly underperforming. That said we are just at the precipice of this coming pattern but if we did manage to waste a -4 AO, -epo, neutral pna pattern coming up that will go into my memory bank as another check mark in the “uh oh” column for sure. I’m optimistic we cash in somewhere coming up, just saying.

In general yes so high elevation valleys are the best location for ice. The Shenandoah and some of the valleys in WV get awful ice storms. But higher elevations also advantage from upslope flow which can cool the low levels. It can also enhance precip which further cools all levels.

Considering the time range and all the noise between now and then that needs sorting out, the Gfs was pretty close to the same solution as the cmc. Yea I get that for many here the fact one is wet and the other 2 feet of snow is lol but synoptically a slightly colder antecedent airmass in front, slightly less amplified primary, and the Gfs would have been the cmc solution.

That was my childhood, waiting for 803 to be called.

Unfortunately I think we underperformed. Had a pretty good pattern from like Jan 20 through March but never really got a flush hit. Lots of minor events and a big ice storm though.

Late January 2007. Every guidance showed a nice 3-6” event from a rather weak wave along a stalled boundary only 24 hours out. Everything except the NAM. We were tossing it since surely that one relatively new and so far unreliable model couldn’t be right against all else. Wanna guess what happened?

Radar https://weather.us/radar-us/usa/19960107-212000z.html h5 and other daily data https://psl.noaa.gov/data/composites/day/

I was up in PA that one winter and got 14” but where I am now got 23” according to the coop down the street.

I remember all the hits too, unfortunately that’s a much smaller list. I’m lucky to have a good memory. Secret is I never studied and I’m not that smart…I just remember everything. I do think there is value in knowing how we’ve failed though.

That hasn’t been my experience. Just going back over some notably great patterns… 1996 we got some minor snow in November and early December from a pac driven pattern. But the great blocking set in around Dec 10 then we struck out on like the first 5 waves before the big storm finally hit in January. 2003 we did hit our first threat in December. Then we struck out on a couple and lucked into some back end snow after a big rainstorm on Xmas. But then we went almost a month in the middle of that winter with mostly cold and dry conditions before the epic February. We had a really good pattern in Jan-Mar 2005 but mostly struck out again and again until we finally hit on back to back snows in late February early March. 2009-10 we waited a couple weeks and then cities missed on 3 threats before the big storm. Then when blocking reloaded in January we missed on the first several chances again, which was when Ji went on that now infamous rant before we went on that heater in early February. But after we also missed 3 more threats to end that winter and Ji made another epic post that it made the winter disappointing to end that way lol. 2013-14 was the only exception where we seemed to hit everything. That was rare Imo and we got lucky. 2014-15 the pattern flipped to a -epo pna pattern in mid January then we suffered for a month while New England got blasted and we missed threat after threat. Then we went on an epic run Mid Feb and March. 2016 January the block set in then we wasted 3 threads. One was similar to this coming storm, muller b with not enough cold. Then a cutter. Then a suppressed storm and finally the big hit. Then we mostly wasted the same pattern for several weeks after also. We also missed 2 good threats in March that year. We under performed. March 2018. Amazing pattern. But we missed 3 times before the hit. Perfect track coastal with not enough cold. Then a miller b that developed late. Then a suppressed storm. I made an epic rant and we got the hit right after. This is subjective somewhat, but just pointing out from my perspective even when we’ve had great patterns and great winters we miss a lot and sometimes have to suffer before snow. I think we just block out the misses and just remember the hits when we look back.

It is a very similar look. In 2009 eventually a piece of the TPV did drop in and phase while there was a 50/50 in the way to prevent a cutter. But keep in mind it took a while. We had a cutter and a sheared wave after that date before finally getting the win. Great setup doesn’t mean “next wave is definitely a big snow”. Even in our best patterns we often need multiple chances before we get a hit.

It’s trending more negative day 10-15 than guidance showed it previously. Not more negative than the -4 stdv it is now. We don’t need the AO to be -4 to snow.

Now that the guidance has resolved the bigger picture Synoptics of the evolution this week, and it makes much more sense given the lack of any antecedent cold, we can start to get a clearer picture of what could come after. As the primary from this week stalls and slowly dies to our north in Canada cold will finally slide east across the Conus. For a time the flow is likely to be progressive and suppressive. Not sure about that first wave around the 20th. That might be a slider. After that it gets interesting Imo. A lobe of the TPV is going to slide south through a temporary weakness in the blocking and end up in Canada. But at the same time the wave breaking from the system this week and that TPV is going to pump the NAO ridge and the blocking strengthens again. After that is when I think is our best shot. The TPV stuck under blocking will provide ample cold source. The key will be exactly how that TPV is situated. Several ways to score. Waves look to continue to eject from the pac and one could run the boundary under the TPV. The big dog potential would be around the 23-27th if something from the NS rotates down around the TPV and phases. That’s risky though. If there happens to be a 50/50 at the right time that’s the setup for a big storm. No 50/50 and too much Atlantic ridge in front and it would be a cutter. Weaker boundary waves would be higher probabilities for frozen but lower high end potential. Just my 2 cents how I think this might play out. Most of what I described the key events happen soon enough that I feel reasonably confident in this general progression.

I see you found a mirror.

Ji hasn’t been that bad Imo, just a frustrated post now and then when a specific storm doesn’t work out. The other guy though…is just straight trolling and contributes absolutely nothing of substance ever.

Agree with Wiggum. Unless you just have a bet the Bay freezes over you don’t actually want the core of that kind of cold centered on top of us. Storms are going to ride the boundary. You want to be on the cold side but not too far. That’s an ideal look Imo.