MAG5035

Nonsense or not this is the third run GFS in a row today that has shown a fairly impactful event running the whole way up.. starting all the way down in New Orleans with accumulating snow. Still not impacting C-PA or most of the LSV, but this is way more wound up than anything else. 0z vs 18z GFS. I’m using a 10:1 map so I can do the 48 hr total and separate out the other LES and light snows leading up to this. 18z Euro did try to come toward this scenario a bit, having a snow swath down to the Gulf Coast (starting in FL panhandle) but not as robust and mostly offshore. I dunno, progressive and positive tilt along with a lack of phasing probably argues towards the Euro end of things. On the other hand, could argue this has room to come west given axis of what is now a massive western ridge is along the Pacific Coast. New RGEM and Canadian don’t dig the responsible shortwave anywhere near as far down as GFS/Euro and it comes out faster and fires the coastal by Sunday morning off the Mid-Atlantic coast. This actually does impact C-PA with lighter snows but really impacts New England, pretty much a late blooming coastal solution for us with no snow anywhere near the Deep South. Certainly a lot of differences for an event that’s already starting in the outer reaches of NAM range.

It’s certainly a bit of a long shot but the big storm option is definitely on the table. There’s a lot of energy dropping in amplify this trough and it’s darn near an all out phase and explode type east coast storm. I have the 18z solutions below and you can see the distinct shortwaves lined up, but still on a positive trough axis. The trough eventually goes negative but it’s takes time and doesn’t seem to phase features cleanly/completely, which still yields some kind of event but not a storm of the nature that has occasionally been thrown out by mainly the GFS. Some things to consider, regardless of any eventual storm evolution this looks to be a fairly potent trough and closed 500mb low that develops over or just under PA. I think that alone will probably generate a swath of snows somewhere in central and/or eastern PA as the trough goes negative. Another thing to consider is temps. Tomorrow will be cold and windy but this is a quick cold shot that moderates rapidly for the first half of the week. Temps will likely be mild (5-10ºF above normal) first half of the week right up to the early stages of this digging trough and associated coastal potential. If we do get a storm it will be preceded by mild to marginal temps, esp in the Sus Valley. So when it’s probably 50ish there the day before, don’t be surprised.

One thing to keep an eye on is the MJO, which has been in the null phase for most of the last few weeks (not a major influencer). Models are forecasting it to finally strengthen, with most sending it solidly into Phase 6 later next week (esp GEFS). Euro guidance was more toward the border of Phase 6/7. Phase 6 is more often than not one of the eastern US torch phases with a high degree of corellation. Given some lag time this would generally suggest another warm period coming at some point possibly late month. Ensembles are definitely NOT showing much signs of that today temp-wise in the D10-15 range. So this will all be interesting to watch evolve. EPO/WPO are forecast to go pretty negative in that 10-15 day range along with a -AO/NAO. One of the few more recent examples of it not mattering much being in the warm phases was 2014 and 2015, and the main drivers of the cold those winters were in fact a persistently strong negative EPO/WPO.

The timeframe around the 15th or so has fairly consistently looked like it could be the best attempt at amplification we’ve seen so far this winter, which is definitely not saying much. Whether or not we can get some better phasing of features there remains to be seen, and probably will for a good while yet considering the range and model performance lately. There’s some potential there though, and during a period next week which should be at least seasonably cold. But in the meantime while we’re warmer and occasionally raining the next few days, 30 year anniversary of the Blizzard of 96 highlights might have to fill the void. Regarding the lack of bigger coastal snowstorms as of late in our neck of the woods, the Northeastern US apparently hasn’t had a RSI (NESIS) rated event since March 12-16th, 2023 (I had to do digging just to remember what that one did). There’s a slight chance the event right after Christmas might’ve snowed enough over more populated areas (NYC) to be a minimally rated one and hasn’t been added yet, but the point still stands. The last major rated NE storm was the Jan 31-Feb 2, 2021 storm.

2.7” was the general average around the yard I got for last night, so not too bad of an event. Only 18ºF out currently.

It’s still snowing quite hard, I’m pretty sure I have in the ballpark of 2-3” total but it’s been blowing around so much that it is going to be hard to get good measurements. Temps just prior to the squall arrival were up as high as 31.5ºF and now 45 minutes later it’s 21ºF. Looks like a rough go of it on the roads right now. This is the closest 511 cam to my house, about half a mile away.

It’s here, whiteout and gust to 39.4mph

This snow squall band continues to have occasional lightning strikes in it.

Have about an inch on the snowboard so far, getting into a bit of a lull ahead of the snow squall line. Winds have been surprisingly feisty for most of the duration of this early steady snow with a lot of 25 mph+ gusts. So snow’s been blowing around a good bit.

27ºF and steady snow arrived here in the last hour, with a fresh coating so far. We usually do pretty good with these kind of events here right off the ridgeline. CTP expects about 2” here in Altoona and I think that should be pretty attainable between the steady snow and the expected snow squall line.

HRRR really maintains the snow squall line pretty much all the way through PA overnight. Passage timing is about 130am or so for AOO/UNV/IPT and during the 3am hour for the LSV. Gonna be moving quickly but could put a half inch or so down in spots. Pre squall snowfall really falls off a cliff once east of I-99. West of there and especially up in the Laurels will be a wintry go of it this evening.

Models have not done well in the mid-long range this winter, which might sound like a captain obvious thing to say but typically they’ll get a general idea of the overall pattern in the 6-10 day range. I don’t personally think the highly touted AI models have done notably better either. I’m sure it’s an expectation thing with folks that with everything available that forecasting just HAS to get more accurate. My opinion on AI modelling is while I’m sure it excels at pattern analysis, it’s still only as good as the initial data/information you’re putting into it. Which basically puts it in the same boat as the standard physics based models. You still need accurate observation data/sampling, and preferably.. the more data points the better. Anyways, I think the high changeability on modelling stems from a few things like blocking (NAO), which models never do well with. MJO is also in the null phase and forecast to remain there for the foreseeable future, so there’s no real coherent signal from that realm. I’d be more willing to buy what the MU guy is trying to sell about January if we were staring down a strong and long lasting pulse into phases 4-6, but we’re not. Another reason is simply our general area has been in a spot where the high variability of the models has had the biggest impact on actual forecast weather differences. I did originally like the storm potential around the 8th/9th a few days ago, but I do believe the models are starting to register on the EPO and WPO going positive in that timeframe to go with a -PNA. The WPO has been solidly negative the last few weeks and a big reason why there’s been plenty of cold available in Canada. That’s probably going to overcome the -NAO and is why we’re now seeing eastern ridging and a more rainy looking scenario with systems around then. But that doesn’t look to last, we keep the negative NAO and the WPO/EPO is forecast to go right back negative. So while that period next week isn’t looking as great, I think things still tend to look at least seasonably cold overall in the longer term and we’ll have opportunities. My big issue with this winter has been actual storms (Gulf sourced/coastal), we’ve had a real lack of them this season dating back through the fall.

Despite pretty high winds, the most impactful weather has shifted over to the snow bands that set up late this evening/early this morning in combo with the winds of course. Opted for a late night snow chase on a band that set up in northern Blair/NW Huntingdon a couple hours ago and it ended up being worth it. Some folks probably saw their biggest snowfall of the season to date under it. 2-4” was common on the I-99 corridor roughly between Bellwood-Tyrone, carrying over into Huntingdon County. Very impressive for a LES band being off the Laurel’s. I-99 between Tipton (Exit 45) and Tyrone (48) PA 45 in Spruce Creek, PA (NW Huntingdon) This band missed here by about 6 miles or so, there’s only about a half inch of wind blown snow here at the house.

That’s right around where I bottomed out about 7-8am this morning (about 993.2mb). Up to almost 999mb now.

46.1 mph is the high gust so far on my gauge at home, which is already higher than anything it got from the other Friday’s high wind warning. For high gusts so far at official stations I’m seeing 54mph at MDT, 56mph at CXY, 50mph at AOO, 45mph at UNV, 64mph at JST, 62mph at LBE and 58mph at DUJ