MAG5035

The key to bigger amounts in the southern half of PA and specifically the LSV continues to be the placement of the initial band of WAA snows that breaks out and how expansive it is. 18z Euro gets it into northern half of PA initially Making for a shorter period of snow/frozen up front for the southern counties/LSV, but still good rates especially south central when the primary area of precip associated with the best forcing/southerly flow arrives. Hr 46 and 47 The heavy snowfall rates precedes the changeover/dry slot and moves through C-PA from SW to NE during the late morning-early afternoon hours. 10:1 Snow totals from the Euro 18z run. The Kuchera is lower around the edges of the snowfall swath, especially in SW PA and JST but the LSV is also about an inch or so higher using 10:1.

Most of the coating of snow I had this morning has melted here. Really elevational snowfall… it goes from little to none on the main part of PSU Altoona’s campus to 1”+ barely a mile up the road and 3”+ at the top of the mountain. Just a couple degrees of temp and a couple hundred feet of elevation made a big difference.. If it works, here’s a time lapse video from Penn State Altoona to the top of Wopsy Mountain (about 4-5 miles) E32B3C95-35EC-494B-BBC2-B0C4315486EC.MOV

Coating on the ground and 33ºF with light snow here , still some more patchy snow trying to push in from the NW 511 cams showing some grassy accums starting in the York/Lancaster area. Definitely doing better than I thought it would in the Sus Valley this morning.

Radar’s looking pretty good up your way right now.

Steady precip has started to blossom and overspread from the SW and mercifully it has quickly turned to wet snow here. This after a damp and dreary afternoon that saw about a tenth of light rain/drizzle and temps floating between 32-33ºF. Anything on the ground overnight would be welcome here after the disorganized mess this system has been today. HRRR seems to have been handling predicting the evolution of this generation of the precip shield associated with the strengthening coastal low fairly well this evening and suggests a 2-4 hr period of heavier snow overnight in the central counties trying to push a changeover into some of the Sus Valley. My thoughts from earlier haven’t changed (keeping accums elevational and NW of I-81), but I could see some flakes making it into Harrisburg eventually before daybreak. HRRR accums.. I think it’s a relatively reasonable map.

I do like this storm to target the heart of the CTP region with a decent warm advection snowfall. The other ensemble blends are pretty similar to the Euro’s. Storm is close enough that the Euro’s hourly products (out to 90) can see pretty much the whole event. The hourly was suggestive of a band to 1-2”/hr snowfall to come across C-PA during the late morning/early afternoon Wednesday prior to the mixing/dry slot. My concern at the moment is for the southern tier LSV. Models like the Euro and NAM (at range) are having the bulk of this WAA snowfall swath roughly turnpike and north there and missing with the best rates at a time when it will easily be cold enough to snow there. Something to watch as this gets more into the short range. I still think everyone in the LSV sees at least 1”+ out of this.

I haven’t been super impressed with today’s event in C-PA the last couple days. The separation between the decent area of moderate snows currently traversing Ohio and NW PA (with the weak parent low) and the later blooming coastal low is a killer for the central counties. Persistent good rates are needed where it’s cold enough to snow with the marginal temps and radar is fairly disorganized in this realm for now, though trying to blossom. Later on this evening is where we will see how quickly the precip shield organizes with the coastal. This especially looks good on meso guidance NE of UNV to IPT and NE PA but it remains to be seen for the I-99 corridor (AOO to UNV) and also if any change to snow can push toward the Sus Valley. Presuming we get a good shield set up, I think most accumulating stuff stays north and west of Harrisburg and will be pretty elevation dependent in that part of the ridge and valley (pretty much the region boxed in by I-99/I-80/PA Turnpike/I-81). Probably 1-2” type deal with advisory amounts starting NE of UNV.

I have mostly been liking what I’ve seen from guidance in terms of trending towards a stronger Canadian high that is in a decent position and doesn’t necessarily retreat rapidly either. Looking at 12z suite GFS had a stronger high than the Euro (1035ish vs 1030ish). Comparing ensemble means GEFS and EPS have similar strength to the high (1030ish) with the GEFS mean suggesting a somewhat better positioned high. The Canadian suite is interesting, the op manages to be the furthest west solution while the ensemble mean is in line with the others and is most suggestive of transferring a low to the Delmarva coast. The Euro ensemble has some clustering as well. Obviously, if this managed to secondary that far down the coast.. that would fare well for extending frozen/mixed precip in C-PA. Even without much transfer to the coast, I feel there should be enough of a wedge in place initially to see measurable snow (at least 1”+) in all of the LSV. Globals don’t always see CAD the best, especially more at range. So it will be interesting to see how the short range high res models handle things when we get to that point. Right now, the ensemble blends seem pretty good in terms of mean placement of the major features. We still have some time for getting details sorted out. GEFS: EPS v Canadian ensemble

Yea it’s a similar type setup but I don’t know how the direct comparison is going to end up panning out. It will almost certainly be a warmer version of that type of gradient pattern, at least with the next couple events upcoming the next 5-7 days. The Feb ‘94 gradient pattern was preceded by a really snowy and frigid January. Yesterday and the current date in 1994 had all-time record cold and lows from -10 to -25ºF over most of the commonwealth. Probably a bit understated to say that we don’t quite have that kind of airmass coming into this stormy period. We still don’t have much anomalous Canadian cold yet through these next couple events. Getting some high pressure set up prior to the Wednesday event should at least help get the O-fer the winter crowd in here their first measurable snow if not first 1”+ event. Basically the possible difference I’m trying to lay out here (at least to start) is that gradient pattern was attacking much colder available air and an established snowpack. The current upcoming pattern is going to have to establish pack in the upper Ohio Valley, lower lakes, and our region where there is currently zero snow. So while I see the next two events getting a lot of that done, some portion of our southern tier is probably going to be part of the gradient zone between snow/mix and predominantly rain vs Feb 94’s which delivered a bunch of ice/sleet events well down into the Mid-Atl region (DC/northern VA/etc) with a much colder available airmass. Models actually establish some anomalous Canadian cold toward the week 2 timeframe with some SE ridging eventually trying to persist but with better cold available trying to press from Canada. So that week 2 timeframe could end up more favorable overall for the LSV and probably northern Mid-Atlantic for frozen events if we keep an active pattern.

You got the WS-5000 station right?

Still no 0z GFS tonight, they can keep it unplugged lol. Here’s 0z Euro for the Sunday storm And for Wednesday’s storm: Euro achieved this with the 2nd storm despite taking a straight up primary up the Ohio Valley to Erie with little secondary development. Progged an okay high to the north allowing for a pretty big thump up front. Using Kuchera here, the 10:1 actually had higher amounts on the fringes of the accumulation swath.

Not sure why my WB hasn’t loaded any of the 0z GFS in yet but in the meantime.. here’s the early prediction sure to go wrong just issued from CTP.

It wouldn’t have my vote lol

Getting multiple strikes of lightning/thunder.

Cold front’s on the doorstep. Looked like there were several mPing reports of small hail toward the Pittsburgh area and western PA with it so we’ll see if I can get in on any of that. Hey it’s frozen.. a T is a T lol.

Indeed, the classic benchmark for C-PA snowstorms is the ridge axis thru Boise, ID, which this doesn’t have. Although the Sunday system doesn’t either, I think the shortwave that dives into the SW behind it (which becomes the Wed storm) acts to eject that out instead of amplify.. which could explain the trend for Sunday to be a bit of a weaker system and one that gets to the coast easier. Even if Wed does cut, I think there will be a somewhat better antecedent cold air mass in place for that with enough high to the north to support frozen up front at least. GFS had the weakest high to the north to go with a dominant primary and thus had the least frozen/mix. Whatever secondary coastal low evolves will also dictate how long that can hold. Even the big Euro run yesterday featured a primary to a coastal secondary with this, the transfer just happened much faster and today’s run has a stronger primary that’s overall a bit further west today.

0.89” of rainfall today, temp still 38ºF. Looks like most precip is done here until possibly fropa later this eve. Maybe can manage to score whatever upslope/LES that manages to blow off the Laurels tomorrow to go with the wind advisory.

GFS takes a primary along to the Lakes with the coastal for the Wednesday event as well. True central goes from ice to snow at the end but obviously not ideal. Canadian has front end snow that goes to mix/rain in the LSV as the coastal low goes by for Sunday event (not to the Wednesday one yet)

Yea the most consistent actually. Weatherbell has newer tools in its meteograms section to see trends. Here’s Euro EPS v GEFS, I’m using UNV this time. EURO EPS GEFS The initialization timescale is a bit different between the two since the GEFS includes 18 and 6z runs and the Euro EPS only uses 0 and 12z, but you can see the Euro EPS started dialing this Sunday event in with the 0z run on the 16th, while the GEFS finally started seeing it better this morning at 6z, though you can see it has seen the event to a degree. . Conversely, the GEFS started seeing the potential 2nd event before the Euro EPS. These products are available for the op models too. And of course the GFS op’s first run that had measurable snowfall with the Sunday event at UNV was the 12z run today.

Here’s a look under the hood of the ensemble guidance at a location. Using MDT here. 18z GEFS 18z Euro: This really brings out the difference that remains in the ensemble camps in an area (LSV) that figures to be the biggest tossup trying to establish where the R/S line might setup and if most LSV sees mainly rain, mainly snow delivering sig accums or something in between. Recall the favorable low clustering the GEFS has. Despite that, GEFS presents 11/30 measurable with only 2 of those big hits with the other 9 minor measurable. Euro EPS has way more supportive (reflecting a colder column overall) with 50/51 (plus the control) showing measurable with almost half of those being a moderate snowfall.

The GEFS is still somewhat reflective on what the op was doing thermally despite the good clustering. The result is the snow swath it has focuses more on the northern half of PA. Probability of 850mb temp being above 0 via the individual members: 24 hr snowfall swath (mean): And I’m just doing analysis here, I’m not necessarily favoring one thing over the other right now. I mean gut says a fairly strong low tracking to the Delmarva and up (esp if it gets along the actual coastline instead of just inside) would deliver snow to all of central and at least a good portion to the Sus Valley… but we’re not working with any anomalous cold temps surface or aloft (850s are actually + anomalies). GFS could end up being more correct thermally even though with the low evolution it caved to the rest of guidance that featured a more dominant coastal low. Just putting the options out for consideration.

GFS wasn’t super far off from 12z (it’s 12z run and vs Euro) in terms of its coastal track, which came a little bit further inside at 18z. It still should have hung decent snow on central/western PA on that track. The big difference was thermals. Notably warmer aloft preceding the event than the Euro, which may have to do with it holding more of a surface reflection west of the Apps coming up and pushing just enough of a warm nose into all of southern PA to make it messy and delay a changeover back to snow as the column cools with the deepening coastal low. It is an important thing to consider with this system, as we won’t have much surface high support and will be relying more on where the gradient is and the developing coastal low to eventually start pulling favorable thermals back toward itself as it quickly comes up the coast. These are the details to get sorted out the next couple days but I’m sure it’ll take getting into NAM/HuRRR range to really get some kind of good handle. Big thing for now is at least the GFS continues to develop the decent coastal low getting to the Delmarva region. This had about been the only model that consistently wasn’t doing that (keeping primary west of the Apps to the Lower Lakes) the last few days until today.

Your welcome I edited my post but they had a bigger long term yesterday talking about tomorrows system and the Sunday system and all they did was remove the part about tomorrow system today (now in the short term) and kept the part about Sunday there. I’d expect an update for that section in the next couple hours, as they usually do in the later afternoon.

If you were reading the long term portion of their discussion, that has yet to be updated this afternoon (still yesterdays disco). Edit: They had a bigger long term yesterday which also included tomorrows system and removed that and kept the portion of the discussion referencing the Sunday system.

Boy this sure escalated quickly today. I had been reluctant to really pull the trigger on Sunday’s event until I saw some kind of clarity between the GFS/GEFS and everything else, especially in this situation where the GFS was simply taking a primary cutter west of the Apps with little or too late secondary development for us ( a viable outcome considering how the season has gone). Definitely significant that it finally came in line for the most part with Euro/Canadian guidance that had predominantly a coastal low. Presuming that holds in ensuing cycles… focus can start on how much of C-PA this may impact with snow. I still see the LSV (esp Adams/York/Lancaster) as fairly vulnerable in this setup. A slightly inside track from VA into the Delmarva/southern Jersey is would likely straddle the R/S line very close or into southern PA (LSV) during at least a portion of the storm. Obviously a bit more progressive/SE would help that particular area. Those details will get sorted out the next couple days. The next one (25th/26th) is definitely one to watch as well, as that will likely take a similar track coming fairly quickly behind Sunday’s system (3-4 days). The gradient might shift a tad south for that system as well. This is a prime opportunity to score once or twice in the next week. There’s likely to be a swath of big snows on the ground for whoever is lucky enough to see it delivered from both systems.