MAG5035

Here was last night's 0z HREF 24hr snowfall, which is short range ensemble guidance that NWS factors pretty heavily into their snow maps, and you can see why CTP opted for watches in Adams, York, Lancaster. Thought this was the 12z run but good thing I double checked bc it hasn't run 12z yet on the SPC site. Would imagine whatever the 12z shows will factor into whether they opt for warnings in the watch area. Considering the full suite of guidance, they're pretty locked down on the general location of the best swath of snow but there does still seem to be quite a divide in guidance though when it comes to amounts of said swath . Looking at the 12z GFS and GEFS, it's barely an advisory event in the watch counties and a general 1-2 in the rest of the Sus Valley, RGEM same way although that particular model has generally been SE the whole time on the lead up. 06z Euro/EPS supports Sus Valley wide advisory event but borderline at best on upgrading the watches to warnings. It's the short range guidance like the NAM/SREF/HREF that have been robust on warning totals and the 09z SREFs are most robust on NW extent with solid advisory amounts all the way back past I-99. So all things considered, I think what CTP currently has out snow-map wise is pretty good representation right now with location of the swath of best snows and perhaps tempered expectations on the top end accumulation wise.

0z GFS again with the broad coverage but not much in the way of 6"+.

I said earlier I'd consider it a win if I saw 1-2" back this way and that it just had to suck me back in haha. I'm thinking the central counties' (NW of I-81) chance at seeing anything notable hinges on any interaction between the two shortwaves that can generate an area of snowfall further back.. something to the tune of what the 18z GFS tried to do.

Thermal gradient could argue for that closer surface low track ala the NAM.. which has the low into the southern Delmarva vs the GFS/EURO staying notably off the coast. Not like we're stuffing this system down with a significant arctic air intrusion that can push the baroclinic zone offshore. (actual cold air comes in behind this sytem). DC's coming off a day where it's 50ish tomorrow and temps during the event aren't overly cold even in the LSV. Ugh, this system just had to suck me back in lol.

Measured 0.5" of new snow at daybreak, which easily melted off non-snow surfaces this morning. Just did some measuring to get the state of the snowpack in the yard. Mostly ranges 6-9" with an area of shallow snow <3" on the one corner and an area of 14-17" on the downwind side of the house and between the house and the shed. Before the snowpack softened yesterday, that last 3.5" Tuesday evening was windblown and the wind continued Wednesday with some significant blowing and drifting.

The Euro's take: Not focused like the NAM with the big amounts but a broader precip shield. Euro and esp GFS illustrate what I was suggesting in last night's post with getting the northern and southern shortwaves close enough to interact and cause a more expansive shield back NW of I-81. Wouldn't be heavy but I'd consider 1-2" a win back this way if it happened. This is starting to look like an advisory type event roughly I-81 east and I-78 south.

Heavy snow, roads caved already.

Snow has arrived here, on a ripping southerly wind.

My take on this Sat night/Sunday system is the most likely area for accumulating snow in C-PA is probably going to run I-81 and esp SE of I-81 (could be an I-95 axis). This storm could sneak back a bit more but I don't see alot of amplification (much more progressive than our last system lol) and the northern and southern shortwaves stay separate. I think the best chance NW of I-81 is if there's a bit of interaction and enough amplification that we can generate an area of lighter snows between the two shortwaves. Some model runs were playing around with that a bit so we'll see. I personally think we'll see something like that but its not going to be anything heavy. Good news is if we fizzle on this we're probably not waiting too long for the next one in what looks like a very active storm track. Obviously "potential" in the pattern is only realized if it actually comes to fruition but this 10-14 day period coming up is teeming with it, as evidenced by the 18z GFS run. We have legit arctic air on the playing field now unlike December and most of January and if it actually gets released into the eastern CONUS at some point in this period it's probably going to be something of a magnitude we haven't seen since the 2014-2015 winter.

I'd sign up for the opening 10 days of that 18z GFS run coming in right now, good lord.

I thought about hitting the slopes today, glad I didn't.

I'll be curious to see the NESIS ranking of this storm. My guess is it's a solid/higher end 3, judging by the snow reports it had a pretty wide ranging 10-20" swath that got into the outer metro regions W and NW of all the big cities, with NYC/LI being the one big city metro that got into that 10-20. DC looked like it rode the edge of the 4-10" swath, while Philly was more into it but some suburbs there had big totals (. Same with Boston, there actually wasn't too much in the metro but a lot of mid-high teens reports in the suburbs. The 20-30" swath obviously located in a much more populated area than the December storm, which I think was a big reason it only ended up being a 2.

I figured haha, that's how big storm rumors get spread. People on social media don't read details like the date of the map and share blindly.

That's for the storm that just happened.

Lot of uncertainty in the models in the mid-range. Euro just went from plenty cold to straight up rainer between 0 to 12z runs with the wave it had out around D7. Actually it seems like all guidance really backed off the cold in this particular timeframe where there is that potential following wave after whatever materializes Sunday. It does look like this is going to be a gradient pattern setting up as guidance isn't completely dumping the PV into the east like it was a few days ago. Going to likely be some back and forth with where this gradient sets up.

Snow has lightened up. An average of measurements is about 3.5" new. So the new storm total snowfall is 12.5" now. Edit: Adding last pic of the night, driveway was bare late this afternoon when this band moved in.

Definitely the longest lasting nor’easter I can remember. Got any cheap sleds for sale? Haha this looking like one of those rare good stretches for snowmobiling.

I will, I did achieve double digits finally. Just call @2001kx and I the clean-up crew haha. Think he said over in the storm thread he had 4.8” new. I’m prob getting close to at least 3” but it’s blowing and drifting like crazy.

At this rate the deform bands might leave C-PA just in time for Friday’s event lol. At roughly 65 hrs off and on with this storm now, and I’m currently getting by far the worst conditions I’ve gotten the whole event.

Just got home after being out and about this evening. Best average I got is about 2” of new snow, but pretty variable as it’s wind driven and drifting. Took a drive to our camp in NW Huntingdon County before dark and roads are all a snow packed mess again after being clear this afternoon. Getting crushed right now. This stuff is very fluffy and the stiff breeze is blowing it around.

Lol some of the best rates of the whole event here and not even in the heaviest echoes yet.

Some climo stuff from the AFD this afternoon. Check out the excerpt about State College.

Moderate, wind driven snow now. The double digit total may be back in play now given the look of the radar.

Snow moving back in lol.

I think even if the southern wave doesn't work out there's a northern branch shortwave and likely arctic frontal passage to be watched for there... and it would probably be a pretty potent one too given the arctic air on the table. Euro's the only one with this bigger storm attm, but it's been keeping this solution plus enjoying solid support from it's ensembles.. so def more than a fluky run or something like that. We'll see how things progress. Did notice guidance isn't completely dumping the PV into the Great Lakes/NE today after whatever this system ends up being.. keeping the core of stupid cold -35 to -40ºC 850mb air just above over on the Canadian side of the North Central/Great Lakes. GFS drops it down more getting -20 to -25ºC 850mb air into the commonwealth. Euro cold but not quite as cold, which isn't too bad as that set up could be better in terms of getting a gradient pattern with some well tracked systems. Euro ran another system out around D8 or so.