MAG5035

CTP's latest update on Mon/Tues. I'd be ecstatic with that clean of a storm and 4-6"...but personally expecting a much messier outcome. I'm always a proponent of the cold hanging in better in C-PA than modeled, especially in the interior counties.. but CTP is really bullish inside the area boxed in by I-80 and the turnpike (N-S) and US 219 & US 11/15 (E-W). That area in particular is going to be the hardest to forecast, and clearly CTP is favoring a colder column and perhaps factoring climo in with the track. 12z Euro still the coldest aloft while having the most expansive freezing rain, which I still don't get how the p-types get ZR out of a large portion of the interior central showing solidly below zero at 925 and surface.. and even 850. Issue is, column also warms between 850mb all the way up to 700mb in this zone at least briefly with 700 temps right around 0ºC or slightly above in roughly the eastern half of PA on some guidance. So I think even if the mostly frozen precip did happen here that it could be more sleet than snow, which would easily knock those bullish totals down. Otherwise, my main points from last night's post are pretty much unchanged. I personally think CTP should consider watches for some south central counties (all current non-watch counties NW of Franklin/Perry counties as that would be the region with the best chance to achieve a stripe of .25"+ ice in the very possible event that we get more of a freezing rain/sleet deal vs the more snow/sleet event being portrayed there in CTP's forecast.

As for conditions here it's still 23ºF with a solid freezing drizzle and some occasional snow grains. Untreated stuff is starting to get a really nasty thin glaze on it.

Yea the 0z guidance generally did not help the cause for more frozen precip further southeast in PA tonight. Models trended tighter to the apps tonight with the NAM actually taking the low right through western PA and the Euro getting underneath but showing reflection up into WV on the west side of the apps. GFS is mostly SE of PA but def edged tighter. Having the surface low really close isn't going to cut it here and obviously we're cooked if the NAM was actually right. My argument for a more frozen outcome than being modeled is heavily dependent on the low pressure actually staying SE of PA with some room to spare. That would allow a fighting chance for the surface cold air to bleed into PA more and also a SE track would imply the thermal boundaries aloft are shifted SE as well to where it favors more frozen. Already mentioned about the high earlier with how the portion that stretches north of us across Ontario/Quebec seems weaker and also a bit further north than a couple days ago. This was one of the keys for holding the cold air east of the mountains and helping keep the low SE. Should note that Euro looks the strongest of the models with that particular feature. I would consider the runs at least thru 12z (and probably thru 0z) to see where we're at today and also to have a good look at where this initial wave of precip running up Sunday night is going to be placed before making any rash decisions. But in light of how things look tonight this is shifting towards these main things as it stands. 1- How much ice does the LSV (SE of I-81) see before a potential change to rain. 2 - What the dominant mix type (freezing rain vs sleet) is going to be in the portion of central PA NW of I-81 including places like IPT, UNV, AOO, JST, Carlisle, Bedford, etc. and if some snow can still occur (more possible the further NW one goes). And 3 - How much potential mixing cuts into the more predominant snow potential for the rest of the north-central and NW portion of C-PA (NW of IPT over to Clearfield, St Mary's, Bradford, etc). This still has time to shift back the other way to some degree and the position of the cold air boundary is going to be extremely important, especially with how well the models represent it. This low is basically going to ride this baroclinic zone and it's not going to be something that easily yanks the cold air east towards a rapidly deepening surface low in time.

Thursday was actually the one I was more worried about cutting/p-type issues vs the current upcoming Mon/Tues event . The current system is occurring in the middle of a seismic shift of the NAO and AO neutralizing and possibly going somewhat positive from being like -4 and -6 respectively. With the EPO/WPO tending positive, PNA trending positive, and no intense NAO blocking to counter...our luck is probably going to run out soon with our nice run with a lack of major cutters.

Been busy and mostly away from the computer good part of the day. Was a nice freezing drizzly 21-23ºF here today. I'm still not really sure what to make of the precip type situation with this. It seems like models have weakened the portion of the high pressure stretching north of us over to Quebec to a degree. Really been making this more of a straight-up gradient vs much of a traditional CAD wedge with Western/NW PA in a much better situation than the LSV or even the central counties below I-80 currently. Track of the surface low continuing to be mostly under us would figure to support more frozen. Kind of suspect about GFS and NAM pretty much routing sub-freezing surface temps out of all the Sus Valley. Euro is simultaneously the coldest column and iciest outcome freezing rain wise. I don't understand why it's still printing out such a big stripe of ZR, especially in the central counties. KAOO at -4ºC surface, -5ºC 925mb, and -1ºC 850mb at Hr 66 after 0.3" of ZR from 60-66 is not a ZR profile, no way. At least the thermals on the warmer models make a bit more sense vs the p-type. C-PA is right smack in the middle of the baroclinic zone and potential transition zones and determining where everything's going to setup is very difficult at this point. I still lean to the colder end of the spectrum and it definitely appears that CTP does too. Just something about that low tracking SE of the region with plenty of surface to try to press and bleed in. However, the aforementioned high pressure appearing a bit weaker on the end of the "banana" that stretches over to Quebec would seemingly limit driving down a CAD wedge east of the mountains to hold in the LSV SE of I-81 later in the event. On the other hand, models like to underestimate the CAD. Going to have to monitor how temps go tomorrow and how that front running wave of precip tracks Sun night into Monday ahead of the main wave to get a better lock on the positioning of the temp gradient.

I'll gladly take the milder temps and active storm track we have right now over having the extreme cold. Especially since we are still cold enough to mostly maintain the pack that's on the ground. We've had conflicting signals via the teleconnections for a lot of this exceptional NAO/AO blocking period with a mostly -PNA and a solid MJO magnitude that's been floating in the Phase 6-7 region. (currently 7) Want to know what they usually translate to, especially in 6? Not going to get into a whole thing and stat lesson on the significance % maps but regions in that blue or purple shows high correlation to the temperature pattern. That's why phases 4-6 are frowned upon greatly in the eastern US, esp during a Nina. Phase 7 is a warm phase in the east too, but not as strongly. But the gradient pattern we're in and the arctic air not completely dropping in to the east makes alot of sense when this is considered. I think it's a blessing in disguise personally. You don't have such strong NAO/AO blocking then you guys are talking about still having the AC on. You don't have the conflicting MJO signal and it's conceivable its frigid in PA and we're lamenting DC and VA getting all the snow. And I guarantee you guys wouldn't be so disappointed we're missing out on it being -10 if that happened.

Yea, I've been considering that aspect. Typically an amplification as major as one taking extreme winter weather pretty much to old Mexico and the Gulf Coast generally wouldn't bode well for us in the eastern US but we still have the sprawling high pressure and the cold air to the north and the low attacking it from the Gulf. Majority of guidance and ensembles keep this surface low below us, initially on the west side of the Apps in the SE but eventually going to the Mid-Atlantic coast. Not a wound up deep low either. So this is definitely looking like a pretty high impact winter storm for C-PA, but details on P-type are anyone's guess really at this point. I still personally prefer more frozen (snow/sleet) solutions, like the GFS. Should note there is a huge difference in surface temps GFS vs Euro (8-10ºF) during the height of this. Even with that, I don't really buy the Euro's expansive ZR, especially outside of the southern tier where the column would suggest sleet more than ZR. Why do I prefer the colder solutions? Despite the core of the arctic air not pushing into our region, it slides east across Ontario and Quebec with that sprawling high pressure. So I think surface/low level cold is going to bleed down into PA pretty efficiently, especially with the majority of guidance keeping the surface low underneath us. It seems that 700-850mb zone is most likely region this busts above 0ºC and that's high enough in the column that i'd be considering sleet as predominant mix over ZR, although there's going to be a stripe of more significant ZR to deal with somewhere as well.. and our southern tier near the Mason-Dixon is a place to watch for that possibility .

Just measured 3.4", with some lingering light snow still falling.

Lol @MillvilleWx might win "coldest snowstorm of the winter" down there in Midland, TX with the storm that becomes our Tuesday event. Yes those temps are in ºF

Looked like that upper band of snow is still over Northern Cambria on radar, not getting anything?

Right at 3" with snow lightened up.

Yea even though this still looks mixy you can see tonight's run gets the low to the coast under us and with that banana high to the north it def favors deeper cold and a more frozen outcome.

It's been crushing pretty good for a little while though starting to get on the edge of the best stuff. Glance at the snowboard out in the yard from inside using binoculars with the lights on looks like almost 3". How much back building happens is likely going to determine if I can get into the 4-6" forecasted range.

This is the type of enhanced stuff the next few hours that's either going to get us to our forecast totals or not, which should eventually push into the LSV. It's coming down pretty heavily now here.

Yep Radarscope.

Starting to see the bigger flake size with the enhancement showing on radar.

Got moderate snow and getting pretty close to an inch so far. Temps back to 25ºF

Steady light snow now, pretty grainy. 29ºF

Some light snow starting, temps around freezing.

I think CTP may be considering that route for some of the southern tier counties. They did have a brief short term update early this afternoon addressing having to bump up for more QPF and higher ratios and most likely for warning upgrades were the Laurel's counties Cambria and especially Somerset. Def concur with that as the most likely area for more widespread 6+ in the CTP CWA would be those two counties.. where the best overall QPF and high elevations conincide. There's definitely some support on the short term guidance for that and perhaps Bedford/Fulton/Franklin/Adams as well, IMO. Franklin and Adams need 5" in 12hr for a warning criteria so it's certainly in the realm of possibility.

12z HREF guidance.. regular mean and probability matched mean.

No biggie, your concerns were definitely valid. You can see today looking at temps across the state how we don't have any actual arctic air or at least extremely dry air in the state and that it does appear the boundary where the icing is occurring in the Ohio Valley looks to be setting up a bit NW with this first wave. This type of gradient stuff doesn't get usually resolved until we're in the short/near term. Still gotta get the snow on the ground too lol.

It seems like more focus is put on this initial wave tonight over the second one Friday and that "round 2" looks more like the feature we see showing Sunday. By the way I'm shocked where guidance has ended up with tonight's wave, SHOCKED I tell ya lol. This thing currently pegged for next Tuesday looks like a pretty significant storm. We have the GFS and Euro trying to cut it today. In the case of the Euro, trying to cut into a 1040 high that starts at hr 138 sitting on the Canadian shore of Lake Ontario. I'm not sure why it's such a freezing rain bomb given the thermals. Hr 150 which caps the height of a 6 hr period of significant precip (mostly ZR), has marginal 700 and 850 temps (still at or just below zero) and majority of 925 and 2m temps in the teens to low 20s. In other words, probably a sleet/snow bomb. Honestly like the Canadian's evolution here as general theme is a bigger storm attacking solid high pressure to the north. Speaking of themes, there have been a lot of attempts at cutting in this D6-8+ timeframe this winter. That's where the Jan 31-Feb 2 storm started.

Yea I saw that a bit ago, it's a pretty bullish forecast dependent on that second surge Thurs night/Friday. This first wave tomorrow night has been showing back up better on guidance well into PA the last couple runs while second wave has seemed to stay more below the mason-dixon. Still like bottom two tiers of PA counties having a solid advisory type snow for tomorrow night's wave. Even if Friday misses, that next potential event is already almost in NAM range on Sunday and then looking like something Tuesday (0z GFS was big for that one).

They sure aren't. My uncle lives there and he went through the 2009 ice storm. This pic isn't his but he lived a couple miles from the NWS there at the time and this was taken from the office. Pic Source: https://www.weather.gov/media/pah/Top10Events/2009/Ice Storm Jan 26-28 2009.pdf