MAG5035

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. 

30 minutes ago, Bubbler86 said:

Not on these maps.  1-2" difference. 

 

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. 

6 minutes ago, Blizzard of 93 said:

I agree….this storm is fairly straightforward, do the GFS might be able to handle this one.

It has been very consistent with this event.

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. 

2 minutes ago, Bubbler86 said:

GFS and Euro leading the snow train.  KUCH is MUCH lower vs 10-1 one the GFS in the LSV but still the top like you said. 

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:

Quote

SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
High pressure parked over northern New England should supply
sufficiently cold air for precip to begin as snow over the
entire forecast area. However, a warm nose aloft will eventually
work in, changing the snow to mixed precip by late in the day.

After detailed discussion internally, external collaboration
with WPC and surrounding WFOs, and particularly the wisdom for
"Leveraging the uncertainty of ensemble guidance" - passed down
from our recently retired SOO (Science and Operations Officer),
we`ll continue to ride the Winter Storm Watch for at least one
more model cycle as the probability for 6 inches or more is less
than 40% (where it`s maximized) in most places surrounding
Interstate 80. 4-5 inches looks pretty solid in the current
Watch area, with similar or slightly lesser amounts being more
definitive outside of the Watch.

In either case, a few-several hour period of moderate to heavy
snowfall rates will likely lead to high impact for travel, but
we still need to draw the line somewhere when it comes to
actual amounts. Given our criteria of 6"/12 hour for a warning
and the aforementioned probs for that amount - Advisory Criteria
Amounts look more probable, but we don`t want to downplay the
"Impact", especially from the Central/NCent Mtns east across the
Middle and W Branch of the Susq Valley.

Strong synoptic support and anomalous moisture/IWV transport
from the GOMEX into retreating cold dome will produce an
initial, quick "2-3 hour dump" of snow with a high likelihood
of 1+ inch/hr rates across the interior zones. The main
uncertainty lies with how long the heavy snow/rates will last as
there will be an inevitable transition to wintry mix due to
tremendous WAA driving burgeoning warm nose aloft followed by
300-700mb layer dry slot arriving from the OH Valley by the
evening.

Several deterministic pieces of guidance and GEFS indicate that
the max Tw aloft will stay just below zero through 18z for much
of the CWA east and north of a line from KELZ to KUNV and KSEG,
with the PTYPE snow between 11-13 and 18-19Z.

Model soundings indicate the changeover is likely by late
morning over the Laurel Highlands and reach the mountains north
of KIPT by around 22Z. An examination of model time sections
indicates the strongest lift will occur well beneath the DGZ, so
expect snow/liquid ratios not far from 10:1. Ensemble mean qpf
currently suggests a widespread 3-6 inch snowfall is likely
across much of the forecast area, with significantly less across
the Lower Susq Valley, where a change to rain is likely after a
relatively short period of snow. 1+ inch/hour snowfall rates
are possible for a time Thursday, given the plume of GOMEX
moisture and strong forcing associated with coupled jet
structure.

12 minutes ago, GrandmasterB said:

The NAM is concerning even for State College. I think that's probably curtains for down here. Really the theme of the season, just can't get anything to work.

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. 

9 minutes ago, paweather said:

I’ll take it! 3:4

 

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. 

 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) 

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. 

1 hour ago, Atomixwx said:

Upon further review: Nevermind. We got about 3 inches of paste it would appear.

Sent from my motorola edge 5G UW (2021) using Tapatalk
 

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. 

30 minutes ago, Blizzard of 93 said:

Hopefully the Wednesday event has a nice organized precip shield that attacks the just cold enough air to produce a good snow thump.

The 12z EPS remains steady for Wednesday.

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. 

1 hour ago, GrandmasterB said:

Pains me to say it but...I kind of see Wednesday turning into tomorrow's event. Anyone close to that SE edge may see any accumulations march steadily northwest.  12Z Euro already starting that move.  Why bet against the seasonal trend at this point?

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

2 hours ago, Blizzard of 93 said:

Here is the combined 18z storm snow total for both events through Thursday am.

This looks a lot like the 1994 type of storm gradient that was mentioned by @psuhoffman recently.

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. 

1 hour ago, Mount Joy Snowman said:

The majority of the WU stations right around me are between .65-.7".  That final line that went through last night seemed to drop a little more out this way.  Still no gauge up for me.  Unacceptable, I know.  Just too much old growth interfering and nowhere to attach it that isn't too close to the house or in a relatively open space.  Think I might secure it to the mailbox.  Would that be weird?   

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.

1 minute ago, pasnownut said:

0z NAM going for peoples choice award.

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.