MAG5035

Have about an inch of new snow so far this evening from the LES/upslope snows and occasional bands that have had success getting off the Laurel’s tonight.

That tropical tidbits map that includes sleet with the snowfall makes the 3k NAM look halfway competent with this event. It was showing less than 1.5” south of I-80 in almost all of central PA on model sites that separate that out as recently as 6z this morning. The 12z run still didn’t even pick up on any Sus Valley snowfall, even in Harrisburg.

Dry slot is here and 3.5” is the total. Never mixed either, so the other stuff can stay away until it’s cold enough upstairs again later tonight and tomorrow haha. Melting down my rain gauge collector inside to see if I can get a rough ratio on the snowfall.

GFS for sure if Cashtown’s saying he has almost 4”. That was about the only model that was consistently showing that kind of snow that far into the LSV while keeping the widespread advisory totals in the rest of central PA.

Moderate snow and 29ºF, winds are up some as well and the flakes are a little bit more rimed. The mixing line is very close, but so is the dry slot. 3.2” now with 0.8” in the last hour.

I don’t see any snow angels lol. Radar and snow obs into Northern MD should make for a pretty good chance to get that 1”+ there and keep the Feb 4, 1995 record for latest 1”+ of the season at bay.

Moderate snow and 29ºF. Measured 2.4”, making 1.5” in the last hour.

Same here, it’s piling up pretty fast. I started with nothing on the ground.

0.9” one hour into the snow here. Moderate to heavy rate and 28ºF. It’s actually a pretty dry snow so far too.

I still think it’s going to snow everywhere in the LSV on the front end, there’s snow being observed all the way into northern VA. Even with surface temps a couple degrees above freezing the column should wet bulb down. Biggest question mark is York/Lancaster and how much can get on the ground if it starts as snow. Think the biggest thing there is if the best rates go north of there initially. Otherwise Harrisburg area looks good for getting to the 2” advisory threshold IMO. The stuff over here started fast and has stayed pretty heavy.

Snow has just commenced here, 30/24ºF.

511 cams showing it snowing all the way to the WV state line on I-79 in SW PA with grassy accums starting, with the highway caving about 15 miles up the road in Waynesburg. The 6z 3k NAM and RGEM already looking pretty bad there (had 0 snow in SW PA). Will have to see how that translates to the Sus Valley when the precip gets there.

Despite a good bit of virga so far, I think upstream radars (I’ve been watching PIT and Charleston, WV) are looking okay. The stuff that is likely reaching the ground is crossing into SW PA now and that is a couple hours sooner than what the HRRR has been showing as that has been suggesting a mid-late morning start in C-PA. There are some mPing snow reports north of Pittsburgh as well, so PIT radar is indicating the atmosphere is moistening up. I think the HRRR might be under modeling the precip shield a bit. The short range/high res models have been really inconsistent among themselves and still are with the snowfall swath. I’ve personally tossed the NAM and RGEM and favor the HRRR as the short range model for the snow swath positioning. With the globals I still think the GFS is too generous in the southern tier but the 6z Euro looks pretty close to what I’m thinking and also jives okay with the HRRR swath (Euro a little bit more solid). I also think CTP has a solid snow forecast out right now. The reality with this is that the ceiling has lowered with regards to high end amounts, thus their decision to go all advisories.

Most guidance has been supportive of at least a couple inches generally from the metro north, which I’d feel okay about. The big question is the south of the metro and how much warm advection precip can actually manage its way up into the rest of SW PA early, like especially prior to and near 12z. It’ll snow anywhere if there’s a more expansive precip shield that gets into PA early enough. Even without much of that, the main part of the system with the direct southerly flow straight from the Gulf of Mexico could still yield a start as snow with pretty heavy rates even in further SW PA but obviously time would really be limited there before the column temps get routed and then the dry slot arrives.

Nice looking cyclone. Too bad the low didn’t stay on I-10 til it got over to about I-95 haha.

Looks like the 0z 3k NAM is at least looking a lot more like the HRRR, finally. Still pretty generous on pingers and ZR but it’s finally addressing the CAD setup in south-central east of the Alleghenies.

Snowboard is deployed. Some early clearing has allowed for some rad cooling and temps are down to 26/23ºF currently. I just want at least 4 inches, some pingers to anchor the pack, and shut it down with the dry slot. All I ask for out of this system haha.

That’s some really disjointed action going on however Pivotal generates their maps, especially comparing Huntingdon County to Franklin haha. Here’s the Weatherbell ones. I only took it out to 30 to focus on the main part of the event. The total snow out to 72hrs is picking up the eventual backlash/upslope snows in western PA Thursday behind the system. GFS 10:1 GFS Kuchera, it actually makes a bigger bullseye. As much as I’d love this solution the GFS is probably a bit too cold and SE. But on that topic, one thing to watch tonight is the snow swath as this comes up. Near the Ohio River (about 20-30miles either side) has been making a sharp dividing line on guidance, especially from Louisville to the confluence with the Mississippi. The NAM is uniformly above the river being the furthest NW, while the GFS snows on most of western and northern KY with the initial warm advection precip that eventually turns into what it does here on the front end. So if there’s a massive bust later this evening in the NWS Paducah realm in western KY, for example… where GFS has their equivalent of warning type snowfall for nearly the other half of their CWA that has no winter headlines…that might be an indicator of the GFS being on to something.

I dunno if I’d call it straight-forward haha, at least the part that ultimately matters (snow on the ground). GFS is getting good snow to the LSV and even SW PA because it focuses the preceding warm advection snowfall there instead of a thinner stripe across northern PA as the higher res short range models and the Euro have been showing. I tend to think there will be better coverage with a system like this to deliver something closer to a Euro type solution but I’m not currently buying the full GFS type scenario that has some of the best totals actually in southern PA and some of the Sus Valley. I mentioned in my post in the last page that will have to see how radar trends go tonight and how well the meso guidance is modeling it. The WAA stuff is the key part of seeing any notable accums (advisory type amounts) in southern PA.

It’s been that way on the Euro as well, esp in SW PA and the Laurels. Kuchera calculates ratio off of the warmest temp in the column and the method can sometimes be an issue in fringe areas. Highly marginal 850 temps are likely to blame and it is coming around the key few hours of heavy precip in the late morning that are immediately preceding the mixing. JST gets 3.0 in 3 hrs off of a 10:1 rate from 15-17z, with an intense burst of nearly 2” of one hour. Highly doubt with those kinds of rates that JST only gets 0.8” total snowfall.. unless of course they are sleeting (a possibility). CTP has mentioned in their disco the last couple days that they’ve liked an 8-10:1ish ratio… mainly due in this case to the max forcing occurring below the DGZ.

Here’s the business end of CTP’s short term disco this afternoon:

The NAM has had a solution like this since yesterday, pretty insistent on 850s warming faster in southern half of PA and not providing much snowfall even in the AOO-UNV part of C-PA where the other model guidance has been suggesting some of the best potential totals. The HRRR holds that layer longer getting the period of snow into at least some of the Sus Valley. This is in reference to the main heavier area of precip associated with the deep southerly fetch and best forcing. The real killer in the LSV’s snow potential and possibly to some degree in this particular area, and I’ve mentioned this a couple times the last few days… is the positioning of the WAA snowband that breaks out. Because the timing of that feature is such that it would definitely snow anywhere in here. Unfortunately that has trended to favor the northern half of PA, leaving the main slug and a shorter time window for front end snow before the column gets warmed. I still think the NAM is a bit fast with that, and I favor more toward the HRRR’s take holding in the CAD and the low levels a bit longer. I also don’t recall the NAM doing all that well in this situation either when it came to the Dec 22 front end snows that managed to get into some of the Sus Valley. At any rate as it looks this afternoon, I think if CTP upgrades to any warnings it’ll be for the northern half of that watch area, where the early WAA snow is focused on most short range guidance. A 2-5 advisory is probably going to be good for the rest of the watch area. They’ll probably maintain advisory for the rest of their CWA for various impacts NW-SE ranging from 1-3 down to T-1 and trace of ice potential. Still going to have to monitor radar trends as this gets closer, because if there is a more widespread area of WAA snows that breaks out ahead that doesn’t focus on just northern PA, then there could be a better chance for some of the southern tier to see more snow.

CTP has headlines up, I was wondering how much of the central they were going to consider for watches. 4-6” is the snow amount forecast for the whole watch area. It has been looking like 6” may end up being the ceiling for the most part… reflective on the new probability products CTP has where best 6+ probs (30-40%) have shifted north to center on the UNV to IPT part of true central.

Gotta remember those tropical tidbits maps include sleet with their totals. Here is the 12k and 3k NAM with 10:1 snowfall 12k NAM 3k NAM Most of central below I-80 and Sus Valley have some amount of pingers and some ZR. I was going to credit the NAM for seeing the separated/disorganized nature of yesterday’s storm pretty early on in the short range.. and now it pulls this for this system, which I don’t buy the lack of front end snow below I-80 currently. That’d be a huge bust for the middle of PA where CTP has their highest forecasted totals.

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.