MAG5035

12z Euro track is just a hair too far inside for the LSV for the 23rd storm, putting the rain snow line between Harrisburg and York/Lancaster. The Euro ensemble mean has a much better look for CTP as a whole, clustering the lows more along the coastline… making for less of a C-PA divider in the snow dept. 12z Euro op (132hr) 12z Euro ensemble cluster (132hr)

I do like the overall look of things as we get toward the end of the month into early February. Seeing the cold anomalies in Canada replacing the sea of red positives is a good start even though the press focuses west/central US initially. We did kind of just go through this in December, where we were initially targeting significant cold being here by mid month and we didn’t get it until after mid-month and the really cold stuff waited until 2 days before Christmas. We’re likely looking at the same kind of progression here if it does eventually get cold. I think enough cold will eventually press our way but big question will be if we can knock back the SE ridge enough to finally get on the cold side of the storm track for a change. It doesn’t appear that way for the 19th storm (other than maybe brief interior ice in the beginning) and the next one around the 23rd or so is still debatable, although I continue to think that one has a better chance to at least have some kind of a mixing event up front if it cuts. Overall we’re likely going to have to take a couple more lumps storm-wise the next 7 days or so. Other question is sustainability if we can get the cold period. MJO could be a factor in a bad way if it eventually propagates into the P4-6 realm (talking beyond 15days at this point for this). That was a big reason our Christmas week cold got cut short. Models generally seem to want try to turn it back into the null phase before it goes from phase 3-4 for now but that evolution will need to be monitored. That’s likely to be a player on how mid-late February fares down the road.

I had been thinking about that mentioning the 06-07 winter. Considering CTP’s area as a whole, that one started even worse than this one as places like UNV were just about as well off as the Sus Valley. I thought it also had the latest inch recorded in the lower parts of the LSV but I couldn’t remember the exact date.. it was within a couple days of that Feb 4. 1995 record though. 94-95 winter is definitely not good company to be in but 06-07 did turn overall the back half of the winter with the V-Day ‘07 debacle and St Patty’s Nor’easter (both NESIS rated storms) as the headliners. That Feb 12-15, 2007 event was the first actual widespread event of the season for C-PA. Even the 95 event that gave MU its latest inch of snow ever was enough for a low end NESIS rank.. as well as likely being responsible for most of H-burg’s 9” that winter haha. Pretty much what I’m trying to say is that it’s really hard to get out of a winter in our region without at least some kind of more significant event even in the worst winters .

A big key to how this sets up going forward will be the positioning of the ridge in the West and/or East Pac… something that should be noted as definitely not set in stone as one can see from the 12z comparison of Op models. Funny part about this is the 12z GFS (on the right) in this hour timeframe is delivering C-PA snow from that 2nd potential system thats been showing up near the 22nd-23rd. I think that one probably has a better chance at frozen than the 19th/20th system although I wouldn’t sleep on that one either. At any rate, GEFS generally supports its op focusing the trough in the west while the Canadian op (maxed at h240) is more similar to the GFS today. The other ensembles of the Canadian and now the Euro EPS generally show the overall trough moves out instead of digging into the SW US. The latter two are definitely good looks, as is the Euro op itself. The temps still aren’t especially cold which I’ve brought up in previous posts and I’m sure has been mentioned elsewhere. Even with that Euro trough in the D8-10, negative departures aren’t that crazy and they’re more in the south than at this latitude while Canada is really warm wrt average. Even if this pattern evolves favorably following the 19/20th system, it’s likely not going to have anything crazy cold wise initially. It would still be plenty workable in our region though for snow potential given the time of the year. Unfortunately for @Voyager, the only really sure thing does seem to be temp departures in the SW US. 10 day average temps from D5-15

Op runs are going to waver greatly run to run out in that range but overall signal from all ensemble guidance has been persistently there for a reversal of the current regime to build a western ridge axis that goes up through AK, shutting off the onslaught of storms into California and developing an eastern trough.And they’ve been consistent doing that starting Jan 20th and after too (not pushing it back) as it’s gotten more in more into range with Jan 20th basically being at D10 now. Teleconnection forecasts have been running pretty positive EPO (-PNA) D5-10 and then reversing to neutral/negative D10-15. AO remains negative and NAO trends neutral/negative. 12z GEFS vs Euro EPS D5-10 comparison (using 5 day avg 500mb anomalies) 12z GEFS/Euro EPS D10-15 (5 day avg 500mb anomalies) If I threw the Canadian ensemble in there too it’s basically right in line with the GEFS/Euro EPS. It’s the kind of major shift we’ve been looking for in the Pac. That time in late January is the bottom of the curve in terms of climo temp wise so while winter’s been a bummer so far, it looks like we’ll be setting up a period of potential at a good time. Extended stuff like the Euro weeklies take this general pattern into early-mid February (the actual primetime Mid-Atl snowstorm season). So I’m confident this change does happen, but what will be interesting to see is how long of a period of opportunity we have….Is it like a 10-14 day window or can we actually get a more extended period? That may eventually depend on factors like the MJO and if it continues to do a 4-6 run after it’s currently forecasted run through a few of the colder phases (mainly 1-2 for now).

I’ll agree with the first sentence of that, the last couple weeks haven’t exactly been a standard boilerplate Nina in the west. As for the rest of that, there’s likely a Nino coming next winter but obviously predicting eventual magnitude/impacts in the eastern US at this point is a “hot” take at best at a point in the current winter where I’d likely consider saying something like the rest of the winter will definitely be a blowtorch in the eastern US a hot take also. Also, I dunno where he’s from or when deer season is there but my first year hunting when I turned 12 was Fall 1998 and it still is the warmest weather I’ve ever hunted in for rifle season. That was the December like the whole first week was in the 70s. So problem with his anecdote was he was probably talking December 98, which was during the start of the big Nina period of that timeframe lol. If he’s talking Nov/Dec 97 (during the actual super nino period) I dunno where he’d be hunting deer in shorts at.

Back edge is here, managed a healthy 0.7” haha. Nice to see it white again though. 511cams showing it snowing pretty decent in most of Harrisburg now.

The turnpike has caved from Breezewood through about Tuscarora Tunnel area. Pretty heavy rates by the looks of the 511 cameras. This heavier area of precip should get into the Harrisburg area pretty soon and I’d imagine it should be heavy enough to fall as and/or quickly become snow.

Well, we’re snowing and at 31/27ºF here with dusting so far. Wasn’t really any virga issues from the arriving echoes on CCX radar. So we’ll see how this goes. I haven’t been particularly impressed with this threat but it seems like radar trends are good (better than HRRR presentation) and this should send a 2-4hr period of precip across C-PA generally from I-80 south, with a relatively narrow swath of light accums. Would imagine T-1” will be the rule with some of the western/central ridges maybe seeing 2”. Mesowest LSV temps in the mid-upper 30s from H-burg south so onset might be an issue with regard to p-type.

I was intrigued so I was just reading through the last several pages in there since last night. Now I understand why Jebman came into our thread to bless us with some of his good winter mojo lol.

Agree on our side of the northern hemisphere and Western Europe, however the other side is a whole different story that probably shouldn’t be overlooked. Lots of cold anomalies spread across a large part of the Asian continent (most of Russia from west to east, China, eventually Japan, etc) during the next 7-14 days. If it’s super warm on our side, it’s typically really cold somewhere else on the other side. 7 day mean temp (D1-8) 7 day mean temp (D8-15) We are and will continue to work a decent negative -AO regime throughout the period (next 15 days) so one of my concerns regarding any eventual flip back to an overall colder pattern here is possibly considering the fact that the bulk of the cold dump into mid-latitudes is occurring on the other side of the hemisphere and not ours. On the other hand, there is still “cold” to work with that in the right setup to get us to snow…even with the bigger storm potential late next week. This is January after all. We’re just not in a cold regime overall until some wholesale changes occur. That’s likely going to hinge on what kind/magnitude of MJO forcing we have going forward (even the circle is better than another 4-5-6 run). I feel like we will eventually come back around to a much better period but it may take a couple weeks longer to get there. That doesn’t mean we can’t have opportunities in the meantime either.

In terms of surface features, the GFS has much more high support than the Euro does, with the Canadian being more similar to the GFS in that regard. GFS vs Euro 186hr Also, the feature preceding this (around Tue-Thur timeframe) looked to be a big difference in guidance. This was originally the feature I thought was going to be our amplification and storm potential (and the one I was worried about targeting south of us). On the GFS, you can see this develops way south and out to sea, but it is a much more significant feature and ends up eventually phasing the northern stream into a 50/50 type low. It’s just enough to pull down some cold (and place the surface highs in a more favorable place) and deliver the snowier GFS solution. Euro doesn’t do this, so while the low track of our system we’re watching is relatively similar when it gets to the coast, there’s no cold. Surface comparison at 144hr, you can see the Euro doesn’t even have much of an offshore system compared to the GFS 500mb comparison at 156hr. See the big difference downstream where the GFS phased a low and the Euro doesn’t. It actually ends up not mattering with the 500mb low still going just under us in both cases (a good thing) as we still have the Canadian ridging having the 500mb feature undercutting but this downstream thing may be a key thing in having any kind of cold in place to work with. This is way more detailed analysis than i usually do for this range, but I suppose it’s good to illustrate all the differences in features and that we’re likely going to be hashing out just the general details of this for several more days with continued run to run differences in modeling.

I wouldn’t say it’s progressive, we really shorten the wavelengths in this period and we have Canadian ridging that allows this to undercut, and potentially even cut off. I think the big problem we’re going to come across with this potential system is going to be temps, something I’ve alluded to the other night in my post about the pattern during this timeframe. The 500mb feature positioning looks great for us considering the shortened wavelengths. 12z Euro v GFS height anomaly Here’s the temp anomaly though for 12z Euro v GFS around the time of this storm being on the coast. The SE is below average because it pulls enough cold down for - anomalies in that region but there’s no anomalous cold to be drawn down from Canada. The result if likely going to be a marginal event if this system comes to fruition.

I like to snowboard in the stuff so I’m definitely a pack person. The 3+ days of 55-60 and fog/rain wrecked the base that Blue Knob had managed to get on top of the half decent natural pack that we had for Christmas. They posted they’re closed until further notice (whenever they’re able to make some more snow). That’s PA’s highest skiable mountain (3100’ish) too. The wild swings are definitely a bummer in that regard.. so is the mixed storm after mixed storm. After the December 22nd event dumped 4-6” around here and THEN 1.5” of rain on top of that, I’d have to say I’m over mixing events. Pretty sure the Dec 15-17, 2020 storm was the last bigger storm that was a clean snowstorm around here. While I’m on the general subject I might as well touch on snowfall averages since I’ve seen some discussion about it the last couple days. It’s been a real mixed bag (ha ha) when it comes to snowfall with respect to average to date so far in C-PA. You go from parts of the LSV that haven’t seen much more than a trace yet to some portions of the Sus Valley that saw snow in the Dec 22 event that are below but not super far below average. Using some detailed climo data via the PSU Dept of Meteorology’s page, the 9.9” the PSU climo site (State College) measured for December was good for 42nd snowiest out of 128 to date for DJF (ranking was as of Dec 31st). So essentially, approx 70% of Decembers spanning back 128 years didn’t crack 10” for the month back in the State College area. Kinda shows even back here that a modestly snowier December is more the exception than the rule. Another region that is likely quite below average snow wise so far is the Laurel’s, where these events that put down decent snow/sleet in the central counties put down more in the way of mix/ice up there. But especially affecting that is the lack of LES/upslope via a NW flow. That’s been a thing the last several years in that particular part of PA, which I personally have some thoughts/theories about. I mean we’re talking about a part of PA that sees a lot of snow, but the co-op site in the Laurel’s for example has been notably below its longer term average esp since the 2014-2015 winter. Only one of the last 8 winters was average, with none above average and the rest below. If one wants to see an actual notable trend of less snowy (with respect to average) the last several years, this region of PA is seeing it… and that of course affects the ski resorts there (Blue Knob, 7 Springs, etc). MDT in that same timeframe has seen 5 above average winters, 2 below average (still around the median), and the 1 all time turd (2019-20). I’m not sure why 19-20 isn’t included in there (probably Covid related) but we know how bad that winter was for snow.

8-10 days out disclaimer and etc etc, but here’s probs for 3+ via the 12z Euro ensemble. The ensemble mean itself seems to support less of a C-PA dividing (or avoiding) swath of snowfall that the op and control have.. for this afternoon at least. Good ensemble signal though.

As far as sensible weather, the only storm threat I’m really going to detail at much length currently is the system slated near that Sun/Mon timeframe. Looks to be a quick system that could deliver a broad area of light to perhaps moderate precip. Should note this has mainly been a GFS/Canadian thing as the Euro has not really shown much of a system or associated organized precip. To that point, the former have a bit of a stronger shortwave. 18z GFS tracked features a bit north of the 12z Canadian, thus showing more of a mixed bag and less snow for C-PA. Thats gonna be important because we don’t have much cold to work with. There’s some Canadian high involved but it’s quickly moving as well. Pretty much, if the weak surface low tracks south enough it should be just enough for a snow event. Going forward, I do see the potential late next week as we briefly amplify an eastern trough. Def would be looking for a coastal in that timeframe (D7-10) but I don’t like the ridge positioning in the central US and a western trough pressing. To me.. it honestly looks like that specific kind of window of opportunity for the folks further down the eastern seaboard to have better odds of seeing the first actual coastal snow event of the season than it does for us in a pattern that’s…workable.. but by no means ideal. Just my initial thoughts on it, there’s a lot of time to go. Still trying to make heads or tails of the longer term pattern.. and the models probably are too honestly. Really not liking the persistent (and strengthening) +EPO/WPO the models have been advertising though. What makes this work, at least for the next 6-10 days is the broad Canadian ridging centered near Hudson Bay. These strong systems via the very active and suppressed Pac jet crash into this when the impact the West Coast and pieces of the energy cross the US undercutting the ridge. So from a storm track standpoint, that gives us a chance. It’s kind of a Nino-esque pattern really. The problem with this setup is temps, even though it should be noted we’re at a time of the winter we can overcome that in our particular region. You look at any longer range guidance and ensembles lately and you can see the widespread + anomalies in most of the CONUS and Canada in 2m and 850 temps (generally higher + the higher in latitude one goes). The exception comes briefly in the timeframe of the late next week amplification opportunity when there is some decent - anomalies centered in the SE US. What this is generally suggesting is there’s no true cold/arctic air for the CONUS to tap into. Sure it’s “cold” in Canada but it’s an airmass that is significantly above normal for that region. Looking globally it really seems a lot of the significant cold anomalies reside in on the other side of the hemisphere in Asia (Russia/China) getting into the medium/long range of operational model guidance. It’s definitely a hard pattern to figure out, though they never seem to be easy lol. I figured something was going to give between the MJO being progged to go into 8-1 and the uglier Pac teleconnection forecasts. Instead the models are more solidly forecasting an 8-1 (probably 2) run and keeping the strong +EPO/WPO. They do seem to have it screwing around more (stall/looping in the edge of 7/8) before actually getting into phase 8, and I mentioned in my previous post that this isn’t an instantaneous thing either. It’s probably going to take another several days for models to really see and incorporate this if in fact the MJO does makes this run. It’s possible the eventual influence of this (which presumably would be a much colder/below average pattern in the eastern US) is still outside or on the edge of the D15 range. Just going back to last month it ended up taking about a week or so longer than it had been originally looking in late Nov/beginning of Dec. So that’s my best take on the pattern for now.

At 1.06” for the rainfall for today with this event. Temp is all the way up near 56ºF right now which I’m sure is +30-35ºF for this time of the year here. It’s gonna take a cold rest of the month and/or one heck of an arctic outbreak to even out the + departures we’ll have accrued this first week of January by the time temps come back down to normal-ish late in the week.

MJO has been a fairly big driver in the turnaround to warm the last several days and looks to potentially remain a factor as we get later into the month. You can see that it entered Phase 4/5 by Dec 22, right when the arctic blast crashed through us… and has spent the last week cycling 5 and 6. Now this teleconnection isn’t instantaneous, but when you consider how strongly correlated to eastern warmth 4-6 are during the winter months.. you can see why our cold snap was cut short when it could have lingered longer without this major reshuffle in the pattern. So we’re already into Phase 7 technically, which is a “better” phase… and the pattern responds as such after the Tuesday cutter as we get some Canadian ridging above and knock down the SE ridge.. allowing an attempt at perhaps a more favorable storm track and temps that could still be an issue.. but still doable for snow for us in the right setup. It seems the Jan 6-8 timeframe could present something either in the form of some kind of inverted trough feature with the lingering upper low from the midweek system or maybe a whole other system a couple days later. Hasn’t been much consistency yet on either feature. MJO forecasts going forward suggest an attempt at getting into phase 8 and maybe 1 and 2 depending on the forecast. I put up the Euro and ensembles for this post, which shows a sluggish move into 8 (GEFS similar) but the extended (monthly) Euro shows a more consise 8-1-2 run as we get from about mid month on. That would be ideal to help set up an eventual return of a widespread below average temp regime to the eastern US, something the ensembles seem to be introducing currently esp beyond D10. In the meantime, we maintain a half decent setup for undercutting storms with higher heights over Canada.. but the potential will get better in time temp wise if/when we get some better support in the Pacific realm (EPO). Right now we’re not really looking at true cold in the pattern initially even with a better looking storm track on our side of the country and a continued mostly -AO. That’s due to the low heights and suppressed jet in the northern Pac keeping an active pattern into the western states, not to mention the aforementioned above normal heights in Canada correlate to significantly above normal temps for that region as well. Once we build some western ridging and ideally reverse the EPO back to negative, we should tap back into a much colder air source. Whether or not the MJO does a full blown 8-1-2 run, I’m kind of glad the MJO has gotten this 4-5-6 run out of the way and didn’t stall in those phases in the process. As long as it stays out of there, we’ll have a chance to deliver a favorable pattern for cold and snow. And it appears barring any major changes the next couple weeks that we’ll likely stay out of it for at least most of January. Otherwise, you couple that 4-5-6 with the moderate Nina base state at any point in the next 1.5-2 months and it’ll be more of the kind of weather we’re seeing right now.

51ºF here, the first such day (50+) in the last 22 days. Definitely some melting but yard still maintaining pretty much full coverage in terms of the pack, for now.

Merry Christmas everyone! Temp has reached a balmy 15.1ºF, still a pretty stiff breeze. This arctic air mass has definitely been something else. TIme of the year (min sun angle) has a part in it but since the air mass arrived Friday Morning temperature trends have been completely non-diurnal. Christmas Eve here had a -3.5ºF low and a high of 10.8ºF, which was reached right at midnight last night. Mean temp yesterday was 2.5ºF, averaged from obs every min. Today had pretty steady temps with a low of 10.8 and high 15.3ºF. As mentioned yesterday, we spent about 18 hrs straight being below zero which covered max daytime heating hours Friday. And consecutive single digit temps ranged from about 1030am Fri til 1130pm last night (37 straight hours). That’s some pretty impressive stuff, it can get cold around here and obviously much colder in radiational cooling situations but you don’t see that kind of cold very often directly associated from the air mass. Temp/Dew/Apparent graph Dec 22 to Current

Low was -3.5ºF last night and just now getting above zero degrees. That made for an 18hr period that it was below zero here.. which is pretty impressive.

JST, which is at -8ºF currently, had a wind gust to 60mph at some point in the last hour. Current ob (about 10 min ago) is sustained wind of 35 and G44. Thats a -38ºF wind chill when applying just the sustained wind. I mean I can’t think of another arctic shot off the top of my head that combined actual temps of that caliber with such high winds.

PennDOT RWIS station on Cresson Summit on US 22 just west of Altoona. Max gust of 60mph, consistent gusting near 50mph. Ouch.

State of the snowpack as promised, you can also see it’s been windy here today with all the pine tree debris. Going outside to take this picture took my breath away.

Officially below zero now here, at -1.5ºF with a -10.7ºF dewpoint.