MAG5035

32/28ºF with the initial precip on the doorstep here.

I’m gonna throw out a map at some point I think, though I better do it soon since it looks like the first snow moves into the central counties by 12-2am. Might wait to see some early 0z stuff. 

I still consider the bust potential at least moderate in the corridor between I-81 (including Harrisburg metro) and the Laurels. Rates will be crucial with the first half or so of this event occurring during the daytime in that area with the temps near freezing. High res models kind of hint at this with their more elevational look to snow totals in the ridge and valley. On top of all that is that this is the region of central PA most likely to see that inverted trough related band set up somewhere. That feature’s about the only thing the Euro has been modelling consistently with this system. I think where that sits the longest will put down a narrow stripe of 8-12” within what I currently think will be a general 4-7” for this corridor. 

Still definitely some bust potential for York/Lancaster counties as well in terms of the top end potential. Obviously short term/high res guidance like the HRRR and NAM throttle this part of the Sus Valley, while the globals do not. GFS has tightened a bit, only clipping the far end of Lancaster with double digits. I’m weighing a bit more toward high res stuff at this point but this is where how far inside that coastal low can get becomes very important. 

15 minutes ago, WmsptWx said:

Watches expanded westward, ho.

I was wondering what they were going to do about the non-watch counties between the Sus Valley and the Laurels, since there’s more than modest support that a low end warning can be achieved. Somewhere between here and Harrisburg is also where that NORLUN feature is most likely to set up as well. 

Looks like Perry and Cumberland went right to the warning. 

40 minutes ago, pasnownut said:

after looking at 0z guidance so far, I'm setting my bar at 12" in northern Lanco. 

I also realize that I might be riding the pain/pleasure line, but am loving it all the same. 

With outliers continuing to bow twds the new King GFS, I wouldnt be totally surprised to see 1 or to ticks W, especially if the Euro course corrects and keep the tuck theme going strong at 0z.  trough axis is what I'm watchin now, as we know the storm is going to be a doozy.  

 

The GFS is still the furthest NW of any guidance, tucking the low back nearly ashore in Ocean City, MD before the fade to the benchmark…which is even more than the NAM. Unless the new 0z Euro pulls a fast one here in a bit we’re still looking at the same US vs Non-US modelling battle for another run. Things are coming much more in line across the board in favor of the bombing coastal, but Euro/Canadian has been taking this more direct from the Outer Banks to the benchmark with less of a tuck back toward the Delmarva. And that’s the key to both the more excessive totals and also getting any kind of double digit stuff back into any of the LSV. 

1 hour ago, Blizzard of 93 said:

There is also usually a secondary jackpot outside of the main area depending on where the best bands set up. A low that’s deepening to that level will push some heavy bands well inland.

My thinking on this right now is all of C-PA is looking good for at least a higher end advisory event to low end warning totals in the LSV where the watches represent currently. Basically a 3-6” event for everyone is my general baseline right now. NW of I-81 the key to easily meeting or exceeding that range relates to the inverted trough and the meso banding associated with that… as well as how well the initial precip develops as the features start to phase in. For I-81 and points southeast exceeding or perhaps significantly exceeding warning criteria becomes more related to how close the bombing low tucks in towards the Delmarva coastline. 

If there are going to be excessive totals with this (18-24+ type stuff), I think the low would have to take a track from interior NC THRU the Delmarva and up right along the NJ coastline for that theoretical swath to make it deep into the Sus Valley. Which probably isn’t going to happen. We have a good 500mb western ridge alignment but the axis is a bit east of Boise (ideal C-PA ridge axis). So I do think this low probably will stay a little bit offshore. I think York/Lancaster have the best chance of seeing anything double digit in our subforum, or Chester obviously since we do have a regular in here from there. 

Modeled trajectory now generally takes this rapidly developing low up from roughly Hatteras, up just offshore of the Delmarva, tucking to varying degrees depending on model, and then fading east to the benchmark (40/70). It’s easily meeting the criteria for bombogenesis on most guidance now, with the 3k NAM deepening 41 mb in 16 hours. The most intense banding would stay pretty tight with that rapid intensification scenario and track. The inverted trough is what keeps the light-moderate going back far into PA, which is aided some of course by this coastal being closer in than what most non-GFS guidance had until well..today. If we didn’t have that feature but still the rapidly bombing low we would have a truly sharp cutoff between a lot and nothing, which would probably reside right in the middle of the Sus Valley. 

Well that was one of the more absurd NAM-ing’s I’ve ever seen  over in Delaware/NJ/Philly/NYC. Wow.

At some point soon something’s gotta give with this US vs non US guidance in terms of the top end potential. 

GFS and NAM totals would be an all-time snow event for the Delmarva and at least a top 10 type event for NJ and NYC. 

5 hours ago, pawatch said:

39 degrees and rain. Not much rain overnight .21”

Appears first line of storms last night was a big miss.

Hows the rivers and the ice? Anybody having any problems yet?

Models are being the models again. You think in this day and age there would be more consistent models…terrible! 

I saw videos earlier today of the ice on the move on the West Branch at Renovo. 

https://www.facebook.com/nova1962/videos/818644964578280/?idorvanity=105222725398

30 minutes ago, mahantango#1 said:

It looks like they are factoring the NBM in pretty heavily into their forecast, which is probably the best move right now.

That’s a comparison of the regular NBM and the v5 NBM which is the parallel one that is eventually going to be the regular operational NBM this spring. The v5 version doesn’t incorporate SREF due to its impending retirement I believe at the end of the year. Actually I’ll just show the relevent slide from NOAA’s presentation on the v5 as to the differences in it and how the blend is made up. 

https://vlab.noaa.gov/documents/6609493/7858320/NBMv5.0+Overview+for+Evaluation.pdf

8 minutes ago, Itstrainingtime said:

Euro just made a not insignificant move in a positive direction. To clarify, it's much wetter in the LSV. 

It is trying to tuck the low more than 12z and it def made a big step closer to the GFS once it’s further out to sea. GFS still earlier with phasing/storm development that translates to the big amounts it puts out. Main mechanism for us is still the inverted trough, which was more robust with that run. Our “benchmark” for a coastal low is on top the Delmarva or at least right along/near the coast. 

It would be an all-time coup for the GFS if its persistent bomb solution came to fruition. But aside from all that.. again there continues to be solid support on most guidance and ensembles for a widespread light to moderate event via the ULL/inverted trough in C-PA even if the coastal ultimately does pop off and track way SE out to sea. I think we’re all in solid shape for a 2-5” type event right now, with the potential for a bit more within eventual placement of mesoscale features associated with the inverted trough setup. 

What will need to be watched for in the more likely, lighter snow event scenario is timing and rates. This event doesn’t look particularly cold, especially in the earlier stages. Timing seems to be centering on first half of this event possibly occurring during the day Sunday. Later February solar’s getting to a point where a light snowfall rate with temps near freezing won’t accumulate as well. Obviously, more moderate rates will likely be fine, as will whatever snow lingers into a good part of the night Sunday. That could add a bit more range where folks that end up stuck in the light rates see more like an inch vs being in what will likely be a couple of heavier bands that could help deliver a higher end advisory or more.

Or the GFS could be right, that would be good too. 

58 minutes ago, Voyager said:

While all eyes are focused on Sunday, I've got a WWA for a mixed bag of wintry precipitation tonight. Penndot is even brining some of the major roads (PA309) here in the Skook.

It looks like primary wintry threat in the advised area is going to be some elevated freezing rain accrual and perhaps a bit of sleet, as some low level CAD takes a bit of a hold tonight and advects temps near freezing near the surface and 925mb from the NE. 

Flood watches here tonight, something I haven’t seen in a hot minute. This first batch of rain has already delivered over a half inch here in the last two hours or so. Think the main thing is ice jam potential but looking at the flash flood guidance it is actually quite low. We basically melted out completely here the last couple days, so that top layer of ground is saturated and probably not completely thawed either. Good chance for some sharp rises in the local waterways. Otherwise a much needed rainfall.

2 hours ago, Itstrainingtime said:

CMC brings the Norlun Trough feature further east into the western part of the LSV. They are notorious for being both very fickle and can carry quite an impressive punch. If it materializes, that's probably the ticket to a 6" snowfall this far west. 

This has actually been the most consistent part of forecasting this the last couple days, the inverted trough/NORLUN feature plus the general lighter snows having to do with the upper level feature dropping through. The last couple model runs have been fairly consistent across the board with delivering a light to moderate snowfall. The 0z suite is solid in C-PA, Euro included, with ensemble support for such things.

What is still wildly different is the evolution of the coastal itself. 0z GFS threw down like 30” on a big part of the Delmarva, while the 0z Euro has 1-2” at best there and way offshore with the developing coastal. 

6 hours ago, Itstrainingtime said:

ICON, GFS and CMC all dropped a big fat turd tonight. Amazing how quickly everything was coming together early today and even more quickly how things have soured tonight. 

Maybe they come back?

One thing I've noticed - there's an additional piece of energy showing up tonight that swings through early Saturday. If that comes to fruition it's lights out. We won't have the separation needed for any trailing energy to come up and get us as the flow dampens out behind the Saturday thing. 

There’s a lot of energy pieces in the 500mb flow to sort out. It looks like the main piece is phasing in later on guidance now, firing the coastal more offshore. That deep 500mb shortwave still passes over us, so could still have some lighter snow in that scenario. One thing that I saw hints of in various intensity across the overnight op guidance is presence of an NORLUN/inverted trough type feature… something that just occurred in New England a week ago. That’d be a more localized thing, and probably something hard to nail down the exact location of. 6z GFS had the feature a good bit further west vs 0z GFS, for instance. 

Then there’s the 84 hr 6z NAM with the wave coming through a full 24 hours early, full disclaimer on it being the 84 hr NAM. But I certainly wouldn’t say the models have a handle on this yet. 

In what has been a pretty good indicator of warmer times ahead for us the last few winters, Mammoth Mountain point and click has 59-93” in the grids from now through Thursday lol. 

I do like the weekend timeframe if we can line something up at the proper time. There looks to be 2-3 different waves this week… Wed, Fri, and then the Sunday system that has occasionally shown up as a snowstorm. The first two waves favor rain with some potential for mix NE. 

31 minutes ago, Blizzard of 93 said:

Lol, this worthless storm is infuriating me to the bitter end… I

I don’t think that I have EVER seen a freaking change over happen well to my South east prior to my change over to snow in Marysville.

Normally the change over happens first in Altoona, State College, Newport, Marysville, MDT, then Lancaster l, etc…

Not tonight!

 

 

We’re cooked in the low levels up thru 925mb or so, the easterly/northeasterly flow from the low going to the south is drawing sub zero 925mb air thats in place from that direction.. hence the backwards changeover.

Actually a pretty decent band of precip running along the I-80 corridor from State College over to pretty much NJ, and there’s accumulating snow on the cams on I-81 and 80 near Hazelton and down I-81 as far as at least the US 209 exit north of Pine Grove. 

17 hours ago, Itstrainingtime said:

Please understand, I wasn't being critical of you in any way. I don't do that. It was just ironic that the GFS jumped on to something it largely wanted no part of even when the Euro did.

No worries, I didn’t at all take it as any kind of criticism. I did think it was funny that I pretty much gave this storm 2-3 days up to the 48-60hr range for it to come back north and then of course it does right after I made my “it’s probably not happening” post. 

So now a period of steadier precip happening with this looks fairly likely, certainly from the turnpike south but perhaps as expansive as from I-80 south. Big issue now that’s happening with guidance overall is suggesting the lower column might not be cold enough. GFS has obviously been the coldest solution in that regard, but high res NAM, HRRR, Euro to a degree present that this might start as rain and possibly remain so for a majority of the event. While surface temps probably won’t be as warm as today (likely more high 30s to low 40s), there’s depth to the low level warmth in the column all the way up to about 850mb. 925mb (3000 ft) temps are progged as much as +5-6ºC prior to precip onset on most guidance. That makes a rain start pretty likely. Colder sub 0ºC air at that level eventually tries to advect in from the NE as the storm deepens as it gets off the coast. GFS does it the fastest, hence its snowier solution. Euro draws it in late, which leads to measurable snows more in eastern PA. High res guidance like the 3k NAM isn’t drawing it down in time. 

4 hours ago, Itstrainingtime said:

And then...came the 18z GFS.

I mean I’ll gladly be wrong haha, though I didn’t completely shut the door on precip making it into southern PA. The 0z GFS is going harder than the 18z did, with a warning event in the Sus Valley and advisory all the way up through the C-PA I-80 counties. The northern feature is notably sharper and more involved than the 12z and 18z run. 

0z vs 12z

Models like the NAM and RGEM which hadn’t been anywhere near getting anything into PA now have lighter precip into the southern third of PA on the 0z run, although p-type is mainly rain with those models. 18z Euro, which was one of the few that got precip into PA was the same as well being similar in precip coverage to 12z but more rain. So temps are still a potential issue as they will be fairly mild Sunday. The GFS’s stronger solution would likely take care of that problem as that solution obviously has the heavier rates. You can see how a lighter event might still have issues though with the marginal surface temps. We’ll see what happens the next couple runs. 

I’ve given it a couple days but I do believe this Sunday storm possibility is pretty much cooked for us. The streams look to stay separate and this southern stream wave looks to shoot straight out under us. Still a possibility precip gets into the southern tier below the turnpike, as the op Euro and GFS still suggest but other guidance doesn’t get anything into PA. Some EPS support for the Euro op with measureable snow into PA while the NBM has virtually no swath of snow now.. as GEFS, Canadian ensemble and short term guidance like the NAM et al don’t get precip into PA. AI Euro an outlier showing a more substantial snowfall in the Sus Valley and warning amounts in Philly/NJ. Overall, it’s something I’d put at like 20-30% for a chance of a period of lighter snow in places like Gettysburg-York-Lancaster.

Other issue in the event we get precip into southern PA could be temps. They look to top out near 40 Sunday and then likely only cool to around freezing during the timeframe of any impacts of the storm. P-type should be snow as I think the column would cool enough but I think surface temps would make any impacts (roads, non snow surfaces) minor. 

Nice day with 48ºF here currently. Some melting but dewpoint’s around 30 and it’s not all that windy today. Eastern PA holding onto chillier temps as progged,  while temps did overachieve in the central and western parts of the state today. SW PA is way into the 50s. 

I see a lot of guidance the last couple runs are killing the storm threat for the weekend taking it way south, but I’m gonna remain indifferent to that prospect for now. Sure it could happen, but we’re also currently in that time range where models like to do such things for whatever reason. We went through a good bit of this with the 1/25 storm as well. So I’m not writing anything off yet. 

It’ll def be warmer this week overall and much more comfortable compared to what we’ve been dealing with, though the only “warm” day with respect to average looks to come tomorrow. If temps manage into the 40s that’ll make for daytime highs that aren’t much more than a few degrees above average. Western and actual central probably get there but a lot of guidance suggests the Sus Valley doesn’t even get out of the 30s. Tuesday night temps will stay up and probably have more of a + departure but we’re already bleeding cold air back in by that point behind what is now mostly a dry frontal passage. Rest of the week looks like a continuation of below average temps, although much closer to normal. 

Then we’ll see what this weekend system does. Snow prospects look to hinge on degree of secondary development to the Mid-Atlantic coast as we will likely have a more marginal cold airmass to work with. Overnight Euro was more of a cutter hence the brief mix to rain solution. GFS and Canadian further south with the primary and has the defined secondary low (esp Canadian solution). I’m thinking high probability this isn’t a clean system (strictly snow), but also good possibility of at least front end snows. Immediately beyond that potential system this weekend we look to more significantly moderate temp-wise for a time next week. WPO is forecast to head significantly negative again in the longer term, reloading Canadian cold. Continued +EPO/-PNA in the progs may mean that focuses out west at first, I think we’ll continue to be more vulnerable to cutting systems in that timeframe (next week). 

We should welcome precip in any form and any kind of a more active storm pattern, because we’ve been building a pretty sizeable negative departure the last 6 months in basically the entire East. If we get this weekends system, that would make 3 full weeks since the last significant precip maker. 

90 day precip departures

180 day departures

3 hours ago, Itstrainingtime said:

MU ain't playing around with the wind threat:

NW winds of 20-40 mph with gusts up to 60 mph will buffet the region on Sat. In addition, temps will plunge into the teens Sat morning with wind chills as low as -15°F throughout the day and -20 to -25°F at night. Exposed skin could develop frostbite in just 10-15 minutes. Roadways may be littered with debris from the high winds, as well. Uninsulated/unprotected pipes may freeze or burst, and widespread power outages are also likely. Stock up on extra water, food, blankets, coats, flashlights and other supplies late this week. Make sure you have a backup generator too. In the event of a power outage, the internal temp of your house may drop to unsafe levels in just 12-24 hours. Finally, fill your vehicle's gas tank to prevent fuel lines from freezing.

Geesh, I guess not. I’m probably in the minority here but I’m not really all that impressed with the wind threat if we’re talking strictly from a mph standpoint. Most guidance and that includes the high res stuff like the HRRR that normally ramps up surface winds barely support advisory winds much less anything of the variety that would cause widespread power outages. But I could get on board with a wind advisory for 45-50mph I suppose. Basically a typical wind event in other words, it gusts to 60mph at @canderson’s house in those anyways haha. This event also has a more northerly trajectory to the wind as well being more NW or even NNW.. less of a direct downslope component to enhance wind gusts IMO. 

What I am impressed with is the COMBO of the winds and cold temperatures. Dynamically this will be the coldest shot of the winter to date. The more northerly component to the wind minimizes modification of the airmass source travelling over the Lakes, which already have a good bit of ice with Erie >95% covered.  Non-diurnal “High” temps for Saturday will occur before about 3-4am Sat morning. Sat daytime temps will struggle to get out of the single digits in most of the area. Laurels and some north-central might not crack zero.

You can see how there’s an appendage of non-modified Arctic air that reaches PA. I drew the rough surface wind direction. It mostly goes over the frozen portion of Huron and Erie. 

Saturday morning will probably be the worst for wind chills, though it won’t be good all day. I think most of that extreme cold watch has a good chance of being upgraded to the full blown warning.

Here’s the kind of wind chills the 18z HRRR put out after daybreak Saturday morning. I haven’t really seen those kind of wind chills since the Christmas 2022 cold shot. 

8 hours ago, Mount Joy Snowman said:

I heard some stat about State College having 8 straight days with temps remaining below 20 degrees (think it was just broken this afternoon), which is the longest such stretch since 1893, or something to that effect.  Wild.

UNV got to 25ºF today, with similar temps around town up there. So it stayed at 7 days, which is still tied for the 2nd longest streak to that 1893 streak of 10 days. AOO broke their longest yesterday (that station only goes back to 1950) and added another day today only reaching 18ºF. 

Quote

.CLIMATE...
State College tied the second longest run (7) of consecutive
days with max temp staying <= 20F for the period 1/25 through 1/31).
The last time this occurred was post-Christmas 2017 (12-28-2017
to 01-03-2018). The longest run of 10 days occurred in January
1893 from the 11th-20th. It will be a top 3 coldest last week/7
days of January (mean temp 1/24-1/31) for State College.

January ended up drier and colder than normal for nearly the
entire Commonwealth. It is worth noting that January 2025 was
comparable to January 2026 in terms of temperatures (it was actually
slightly colder last January at Harrisburg, State College, and
Johnstown compared to this year).

 

That’s interesting that for the month as a whole, last January was actually colder. 

On 1/31/2026 at 12:14 PM, Voyager said:

Good God... 

I know you guys love winter, but really, when is this pattern going to flip or relax, and why has it been so persistent? 

 

This winter has been tracking similarly to the last real consistently cold winters that we had back in 13/14 and 14/15, especially the latter. Main drivers then were heavily Pac influenced with a strong and persistently negative EPO and WPO much like we’ve had most of this winter so far other than when we warmed up for a couple weeks in early January. That alignment directs a continental source of cold air from Canada with no Pacific modification. The 13-15 winters achieved that without much help from any -NAO/AO, something we actually have had a good bit of this winter, and currently. The result has been a lot of cold in the east, and a historicially bad winter snow-wise in some parts of the west to date. 

So with that said, I’ll offer at least a little bit of hope. Starting to eye the following week after this week for some kind of period of modification after we probably get whacked with a couple days of arctic air comparable to what we just had next weekend. Looking at teleconnection forecasts right now, there’s a pretty sizeable shift progged to occur in the Pac realm occurring around the timeframe of that clipper and ensuing arctic shot. EPO and WPO both reverse to positive, and the monster +PNA we have reverses to negative. That combo will almost certainly inject Pacific modified air into the CONUS to some degree. How much negative NAO holds will probably have a hand in how that works into our part of the country. Nothing really reverses the -NAO/AO but some ensembles neutralize a bit more than others. So there could be some resistance here, especially with a solid snowpack in the Northeast. Resistance could in fact end up breeding more snow/mix events in our neck of the woods. But I’m currently thinking we’re looking at a milder pattern overall during that timeframe either way. And you can see the op runs of the GFS/Euro in the longer range sort of reflecting that shift. 

This week prior to the clipper won’t be all that bad temp-wise either, at least during the day. We will continue to have very cold nighttime lows with a deep snowpack and mostly fair weather (other than maybe Wed for some). 

System wise this coming week I don’t think we’re dead in the water yet for the Wednesday system, especially in the southern half of PA. NBM guidance has measurable from roughly the turnpike south and GFS generally in that ballpark. This certainly has time to trend back our way, though I think it would just be a lighter snowfall on the table. 

Solid agreement beyond that for a strong clipper tracking SE thru the lakes around the Fri-Sat timeframe. While staying plenty cold, low track north of PA might have the typical downsloping issues east of the mountains we’ve dealt with a lot this winter.. so we’ll see. As progged it’s a pretty strong system for a clipper, and it looks to usher in another reinforcing shot of arctic air.