MAG5035

I do feel the same way, but I don’t completely discount the NAM’s robust warming higher up near the 850mb level either. But same stuff as 12z. The money 3hr frames for ZR are 60 and 63. Using my nearest station at KAOO as an example since I’m in the thick of the heavy ZR over here. HR 60: Surface -6ºC, 925mb (~3k ft) -6ºC, 850mb +2ºC HR 63: Surface -2ºC, 925mb -3ºC. 850mb back to 0ºC Even with that basic breakdown at the major layers I look at that and ask what part of that suggests that particular station sees 0.78” as freezing rain? I think something toward a NAM scenario might get a few hours of sleet into the central and *maybe* western counties. But Pitt’s advantage is the 850 low tracks favorably on the NAM for western (and serviceable to central counties) plus overall flow is on the cold conveyor belt side of the low. We don’t have an Ohio Valley low with SW flow intruding in this situation and trying to overcome that with a secondary to the coast. The warm advection comes from the tremendous easterly flow aloft with the coastal low. I can’t really think of a situation in the past that has presented the NAM type scenario of that much mix/ZR into western PA so that would be a new one to me if it happened.

Yea, ultimately unless this low track can bump east to at least maybe tracking through Philly.. the big thing for the LSV is how much can they get up front as that region is going to be subject to being advected out all the way to the surface with strong ESE flow from the inside tracking low, with York/Lancaster being the most vulnerable to an earlier transition. It was my original presumption that if this low was going to stay on the right side of the Apps that we would see the best pressure falls closer to the coast and the low pressure doing the same. That late shortwave dropping down from the Lakes does kind of force this thing’s hand to come straight up instead of escaping east or northeast, so hopefully we can see that. There is still time.

We can debate how far into PA the warm air aloft punches but I simply do not buy the NAM’s expansive freezing rain. This isn’t really a setup for a deep swath of ice IMO, the high moves east as this storm approaches and this becomes a matter the low track and the cold boundary. The mix period will come and depend on how far in the screaming 850mb jet adverts >0ºC air aloft. 925mb and surface eventually will get compromised for a time too in some of the LSV (esp further south and east) which will probably invite a change to rain but that could be after best precip. Let’s go on a deep dive, we’ll do the Euro and NAM side by side. Surface 850mb winds 850mb temps So okay the NAM has a stronger 850mb jet deeper into PA and more robust advection. Let’s look at 925mb temps. Look how cold the 925mb layer is, no way that is a widespread ZR profile. Surface temps from KAOO west to Pitt are still in the mid 20s in this frame. We could be talking more widespread sleet maybe at some point in the storm if the more robust warming aloft of the NAM comes to fruition but not straight heavy freezing rain from H-burg to Pitt. This strong 850mb jet and inside low track has been a concern of mine, but to counter this the storm is progressive. There’s no blocking up front to slow this down/cut it off and add more time to advect in warm air. This storm is also deepening pretty decently as it is approaching us so that warm nose will get however far it gets into PA but then as the low gets into (or hopefully just SE of PA).. the maturing system will be cooling the column top down. This whole event’s in about a 12 to maybe 18hr duration range.

I saw this gem shared on my F-book feed. S&S needs to get their head in the game lol

6z NAM pretty similar to the 0z NAM still, but here's a look at what the 3z SREF had. Very similar to the Euro ensemble Additionally, PBZ and CTP already have just thrown up winter storm watches for large chunks of both CWA's... likely a hat tip to continued high confidence in most guidance of significant snow in at least the central and western counties. CTP's watch area looks like pretty much everything from the Susquehanna mainstem west. Below is the watch for central/south central counties, north central's is tied in with the Wind Chill advisory and no mention of mixing. No early morning update yet in the CTP AFD regarding the storm.

0z Euro EPS >3” Probs >6” Probs 10:1 Mean

This is in the range where the high res Euro can cover the event hourly. The 6hr precip can be misleading with a quicker moving system. If you use the 1hr QPF by precip type/MSLP you’ll have a much better idea of transition times and precip ending. It looks like most stuff lifts out by about 10am (15z). That track through eastern Penn is rough for the LSV, hopefully it can sneak at least to moving over SE PA/Philly. But even as it looks now the LSV has a 6-8 hour period of snow followed by a transition to rain and then slot out. Here’s the 84 hr with the 1hr Ptype/MSLP

Here was the 0z GEFS 6+ probs.

I’m just not sure winds that high mix to the surface. I could def see some 20-35mph gusts occurring in the Sus Valley pretty easily. I dunno about 50+ though.

I’ve been watching the consistent heavy snows on guidance over here and thinking how you couldn’t get any better of a Sunday Night than getting buried while watching the Steelers drop KC on SNF haha. But I’ll be sweating the game and getting the first 6 inches on the ground I’m sure lol. And on that note, it’s too bad this game wasn’t in Pittsburgh. It would be right in the thick of the storm.

NAM really doesn’t differ much from everything else track wise, it might actually be a bit SE of the 18z Euro but there is a big difference thermally aloft. The difference is it seems to want to transport >0ºC 850 and 925mb air much deeper and quicker into PA than the others. NAM might be a bit deeper into PA with it but they all have had this insane 60-80kt+ easterly 850mb jet strafing eastern PA so maybe it thinks that warm layer makes more inroads. Gotta remember we’re in hot take range with the NAM yet but this tremendous easterly jet probably should be kept in mind. I’ll be more interested in the NAM probably say 0z tomorrow. Speakling of the wind, I have seen the likes of the GFS have stupid high surface winds and I do notice the NAM has similar surface winds in eastern PA. I could def see 50-60 mph surface winds along the coast but that type of stuff doesn’t normally translate to the surface all the way to Harrisburg no matter how windy it is at Canderson’s house lol. I don’t really see that as a good thing if it happens either because besides the obvious wind related issues, the due easterly fetch right from the Atlantic would probably modify the surface and boundary layer. Just some things to keep in consideration. Otherwise, the other ops and ensembles have been pretty solid today and the previously mixy GFS has gotten a good bit more blue with the p-types today so far while the Euro has continued to hammer a large portion of C-PA. I’ll be riding with that consensus unless/until something changes. This event likely will eventually have mixing issues in some of the LSV for a time as I think this will take the inside track but probably closer to the coastal plain and if we’re lucky closer to the Delmarva. But this should hit hard on the front end and the NAM’s probably too far out to resolve that well yet.

Wasn’t he travelling somewhere?

That’s a different interpretation than WeatherBell’s snow map. The GFS on WB has the whole LSV in the 5-7” with no weird reduction like that map. I mean according to that DC is still seeing 6”. If that’s a Kuchera map I wonder if that one (assuming that’s a Pivotal map) calculates it differently. Kuchera is ideal to use in a stable cold snow column. When it’s on the fringes where there could be mixing and/or marginal surface temps (which I’m seeing a good bit of 34ºF in the LSV while still in the main precip) the equation that calculates Kuchera could put out an unrealistically low ratio even if primary p-type is snow. Counter to that, if you have a truly frigid column.. your going to see unrealistically high ratios. At any rate Pivotal and WeatherBell must calculate that differently. Here’s WB, most of the LSV stuff is right up front. I’ll also note that 10:1 in the LSV is pretty similar to this Kuchera.

Euro ensemble stuff. Really ramped up accumulation probs in true central and western. Unfortunately also looks like it’s solidified with what the op is trying to sell sending the surface low up into eastern PA. Accum mean: Individual surface low tracks (using 0z vs 12z)

Might as well throw in the Canadian ensemble.

Lol it really is though, the snow mean is down across PA (generally 4-6”) but over a majority of it. I assumed there were several members following the GFS op in punching a lot of mixing into PA but I was definitely wrong in that assumption. I see like one such member, the rest are snow and some don’t really hit PA. Good news I guess is that there isn’t any members that are trying any funny business like making the low more dominant on the other side of the Apps. My educated guess is that the operational models are presenting this system as stacking and occluding as it arrives into the Mid-Atlantic region and giving the models fits in terms of the temp fields aloft and p-type and just evolution in general. For example, I simply don’t see the whole western part of the state sleeting like the Canadian has with the intense precipitation. I would imagine this should be more of a case of how far inside the tracks and how far in the low level warmth punches. And again, this warm punch is brief and happens after the main initial slug of precip. The storm is stacked with the really deep 500mb low moving overhead and should rapidly reestablish a snow friendly column, even with the surface low over PA. The problem is just with the best total QPF residing with the comma head, which would be west of the LSV with an inside surface low track.

CTP is likely playing climo likelihood of this ultimately running nearer to the coastline and ensemble support for now, which is a safe bet. It was also mentioned on their AFD of the antecedent cold in front of the system, which will be quite notable. Just realized my grids here have a high of 16 on Saturday, the day before this rolls up. That’s cold. With everything now on board, considering the differences between models.. none of them are really terrible for anyone in this subforum. Even though the GFS/Canadian is trying to Miller B this more than the Euro, it still has robust coastal development well before it gets to our latitude, and it still delivers good up front. But with that setup, you have to wonder with such a strong coastal low about how well those globals are handling P-types at this range. This thing’s progged to be a bomb (low 980s) on the GFS and Euro. Thats nothing to sneeze at. I would think that would quickly overwhelm any surge of warm air in the column from a presumptive remnant OH Valley low and present a snow-mix-snow scenario.

Euro EPS v. GEFS probs. They are really starting to see the storm now. These are 6”+ probs

Euro did come inside a bit today vs it’s 0z run, although I think the bigger difference was it was a good bit more expansive on the western side of the snowfall swath. It’s also very sharp with it’s changeover line, mainly snow to light rain and little mixing. Lot’s of time to resolve that track in that situation. I think most of the LSV would still see mostly snow in that scenario, just that it would slot out and since the storm is stacked at the point it’s coming through the Mid Atlantic into SE PA… it won’t be long before the cold air is fully entrained into the system (if it already isn’t). The big thing there is just that the best forcing and deform are further west in PA with the inside track. GFS has had a different evolution, more of a straight Miller B type with surface reflection carrying up into the OH Valley, allowing for more of a mixing mess but still actually looked marginally better today with more frozen as there is strong coastal development. Euro has a bit of a jump to the coast in the Deep South but it looks like more of an A evolution. Truly huge differences between that and the Euro are out in the middle of the country. GFS has over 30” of snow at the confluence of the Mississippi and Ohio Rivers where Euro has essentially 0”.

Don’t suppose there will be too many complaints from most in the subforum about the 0z Euro. Swath is a bit west of 12z but still hammers C-PA. 3 and 6 hr QPF at 135hr shows one heck of a deform band sets up right up the Sus Valley thru IPT and into NY. 0z vs 12z

Looks like GFS is still way inside (a tad more than 18z) with mix getting pretty deep into central and the 985 low coming right up the gut of C-PA. Still front end for all and significant central and esp western PA. Guess we’ll see where the rest of the 0z guidance and ensembles set up. Def suspect of that GFS track, I mean it’s possible but certainly not common.

I’m not much of an expert of how the computer models work but I do know the individual ensemble members operate on set preconditions/parameters that slightly differ to generate a forecast that accounts for uncertainty, or as NOAA defines it, When considering the Euro control run, the control run of an ensemble is the “best estimate” of the initial state of the atmosphere. I know the meteograms on WeatherBell plot out a GFS control but I’m not sure if that’s factored the same as the Euro EPS. At any rate simply based on the above, given lead time and the amount of moving parts with this…not to mention that the feature that ultimately becomes the system isn’t on shore yet, I’m not surprised there’s a lot of differing solutions within the ensembles. I do think they took a significant step in seeing it vs the operational the last couple runs. Compared to the GEFS, the 12z Euro and EPS seemed more dialed in to each other and the control run looked similar to the swath the op had.

I’ll pass on the overall 99-00 Nina analog haha. It was cold but since 1980 it was the 4th least snowy winter at UNV (behind 11/12, 15/16, and 19/20). Unfortunately it has been pretty dry to this point snow wise while looking quite cold overall for the foreseeable future. I was only like 13 at the time but I do remember that winter having blocking but too far east and we missed out on some coastal storms being too far east or offshore. We get this potential storm that should turn that on it’s head. I can kind of see the similarity in the setup between the Jan 2000 surprise and this potential one but as it’s modeled at the moment I think this has a farther west 500mb alignment (western ridge), more amplified, and a much more established system coming across the country. The northern energy for 1/25/00 didn’t phase in until the coastal low was popped off the SC/GA coast. It then had to come right up the coast which was where modeling at the time was extremely late to the game picking up how close to the coast it will run. The lead up to this is different, having a pretty significant wave coming up across the country (that part has been consistently modeled the last several days). The big thing with the last pretty much model cycle or so has been the energy dropping in/behind this wave and allowing it to amplify and come up the coast. I think this has the potential to be a much more widespread storm then that one was.

Okay, I’m interested now. Is this going to be another case of the GFS picking this back up first in the mid-range like the Jan 3rd event? There’s a lot of moving parts to this, but we’re going to have the amplified pattern we need to pop one of these big time events. Using Euro here (and Madden voice if you wish), Parent shortwave(s) of this potential system arrive on the west coast (main one Washington and another higher up in BC by about H48, appearing to phase in to a very potent 500mb shortwave and rounding and dropping straight down toward the Gulf. 57 HR 99 HR So a lot of the early phases of this are already within the short range (certainly in NAM range) as far as getting the parent shortwaves on shore to the point of this dropping down the plains toward the Gulf… and this has been modeled pretty solid getting a decent swath of precip to that point. So you’ll see in Hr 99 I marked a few other things and their eventual directions being modeled between then and the next map (Hr 126). As the parent 500mb shortwave slows and amplifies there’s another shortwave that comes in on the BC coast, while the closed 500 low (PV) over the far north of Canada lurks. Dashed line denotes positively tilted ridge axis. This is where it gets extremely important. These features HAVE to drop down behind and force this thing to round the bend, or else we’re sitting high and dry as this potent feature gets forced east and out under us. Today, the likes of the GFS and Euro are doing the former, so we’ll see if that trend continues. There’s big time potential on the table if it does. HR 126

It’s got Bliizzak’s on for the winter so we can face off on a long snow covered stretch lol. It’s fun to drive, and it does do really well in the snow with the AWD.