RU848789

Walt - I know you know a ton more about meteorology than I do, but I have a ton of knowledge about heat transfer/physical chemistry (PhD in chem eng'g) and I'd quibble with one point in your post. Once there is a layer of frozen precip on the ground (and there will be) the 2M surface temp becomes largely irrelevant to whether falling snow will accumulate at the surface, since the "actual surface" is snow, which, by definition, has a maximum temp of 32F and can't ever get warmer than that (will melt at 32F). If you're talking about bare paved surfaces (plowed or treated), then the actual surface will quickly warm to the 2M surface temp and further snow accumulations on the paved surfaces could be more difficult, unless, of course the falling snow rate exceeds the melting rate at the surface and with moderate snow or heavier, that will occur, as melting rates after dark at 33-34F should be <1/4" per hour.

NWS (Philly and NYC offices) reduced snowfall a bit for areas along and south of 78 (and 495 east of Manhattan), including for NYC, based mostly on less QPF while temps are cold enough, according to the AFDs. None of the advisory counties changed and the advisories still say 2-4" for NE NJ/NYC/LI, but the maps have less within that 2-4" range. A little surprised as I didn't think the 0Z models had backed off on snowfall amounts, but what do I know, lol.

Euro comes in a bit snowier than today's 12Z, like most of the other 0Z models. Nice. Might actually get 2-3" out of this in the 95 corridor.

It all depends, obviously, but if one gets 2" of snow and 0.3" of sleet, then that's about 0.3" frozen LE and if the amount of rain that then falls is <0.3", most of the rain would be absorbed, making for a fairly dense mass of slush - in areas to the NW where it will likely go below 32F later at night, it could make for some cement. Shouldn't happen along the 95 corridor and SE of there, as temps don't look to fall back below 32F until Sunday night. Still, I just want to see some white stuff for more than a few hours, lol.

The Euro backed off a bit on snowfall for the 95 corridor and towards the coast vs. the last couple of runs. Interestingly, the NWS offices kind of flip-flopped with their forecast snowfall, with the Philly office decreasing snowfall vs. yesterday's forecast, while the NYC office upped the snowfall forecast a fair amount. The two offices are moderately far apart at the boundaries between the offices (Passaic/Essex/Union/SI vs. Sussex/Morris/Somerset/Middlesex) - hopefully these discontinuities are cleared up before the event or someone will be wrong, lol.

latitude sometimes really matters. Recall 3/1 and 3/3 earlier this year, where most of us in northern Middlesex County got 9-11" of snow, combined (I got 10.5"), while folks 5-10 miles south in East Brunswick and Sayreville only got 2-4" of snow/sleet with some rain. I even drove around the morning after one of those to see the gradient from Metuchen (5.5") to Highland Park (3") to New Brunswick (2") to East Brunswick (1").

Yep, even 5 days out, every global model is showing some snow for the Philly-NYC corridor and even towards the coast, with the usual SE to NW, less to more snow gradient being likely. Surprised nobody posted the relevant model output - here you go. Note that most of the snow for the 95 corridor looks to fall between early afternoon and late evening, depending on the model - I included maps through Sunday morning to include total snowfall through New England. If I could lock in the 2-3" the Euro shows for me now I would (let alone the 5-6" on the GFS/CMC).

Ended up with about an inch on colder surfaces, with nothing on paved surfaces, so no impact at all from this little event. Nice surprise to see at least a little snow - was very pretty out there overnight and should be gone soon...

I have to do this at least once a year, lol, but it's frustrating to see the inconsistencies in the model outputs that are available to the public. I get that it's awesome to have a ton of great info, which is way more than we had even just a few years ago, but it would be even better if these inconsistencies could be addressed. Specifically, Pivotal shows only snow (without sleet) and freezing rain, while Tropical Tidbits shows snow + sleet (with the sleet counted as 10:1, snow to liquid ratio vs. the ~3:1 actual ratio), but not freezing rain. And if you look at them vs. each other, say, for Morristown, the Pivotal maps appear to be counting a large amount of the precip as sleet, whereas the TT maps appear to be counting a similar amount of that precip as freezing rain, not sleet. But which one is it, freezing rain or sleet? Huge difference, obviously. On the maps below (assuming the number in Morris County on Pivotal is Morristown), TT shows 12"+ of "snow and sleet" (at 10:1 ratios even for sleet), while TT shows 1.55" of freezing rain (15" of snow at 10:1) and 0.8" of just snow (not including any sleet). Again, which is it or is it some combination? The 4th graphic, from Cool.Wx, shows Morristown getting 1.5" of freezing rain, after about 1" of snow and 0.2" of sleet, so maybe most of that precip is ZR and not sleet. That would be catastrophic for much of NNJ, far worse than 4.5" of sleet (1.5" of liquid at a 3:1 ratio, equiv to 15" of 10:1 snow), which would be no picnic either. And, of course, the GFS shows all rain for MMU, while the NAM3K is in-between the NAM and GFS - now I know why mets get paid, even when they're wrong, lol. For my own backyard in the Edison area, TT shows about 6" of snow/sleet, whereas, TT shows about 0.2" of ZR and essentially zero snow. Should I assume the other 0.4" of frozen precip that TT shows is all sleet, which Pivotal doesn't show? Of course, one can look at the soundings at specific timepoints to estimate p-type and then assume the next few hours are that same p-type for the total that falls in that interval and then add all of them up, but that's tedious and why we all like model maps. Anyway, just a rant for today, as I try to figure out what's going to happen tonight. The alternative is to just watch it all unfold and not worry, but it would be nice to have more insight...

Always though that map was odd - why have NYC Metro with higher ZR criteria than Sussex/Warren/Morris, where ZR is far more common. I'm sure some of that was due to the office boundaries, which is why I like the current ice storm warning criteria, which is at least more consistent from east to west (although I'd orient it more SW to NE than this with Union/Essex/Hudson and NYC/LI in the 0.25" criterion.

Maps are better than words, lol, but the 2" line is about from Nazareth to Randolph to Paterson to Yonkers, which is about 15-20 miles N of where it was at 0Z.

Ok kids, it's snowing! It's 32F with 1.25" of new snow on the ground on colder surfaces here in Metuchen with a little slush in spots on paved surfaces, which is not surprising, so on the whole, this should generally be a nuisance snowfall, with regard to travel impacts. Judging by the radar history, it turned to snow around 3 am, while I was sleeping and snowed at a decent clip until about 5:30 am, a little after I woke up. It's certainly a pretty snowfall and hopefully we'll get at least one more decent band. Snowfall rate has lightened up a bit since then and the 95 corridor does look to be on the NW side of the heavier bands. NWS forecast hasn't really changed much with 1-2" generally expected for most of the area. However, judging by the radar history, it looks like not much snow has fallen more than about 10-20 miles NW of the Route 1 from Philly to NYC. Could definitely see localized 3" amounts east of about a Hammonton to Hazlet line, where banding looks to be heaviest, although with temps slightly warmer there, wouldn't expect to see much on paved surfaces.

So much for 2-4" of additional snow, sadly. Got very little during the rest of the afternoon, with whatever fell mostly melting. However, since about 6 pm, we got another 1/2" or so, much of it in the last 2 hours with some occasionally moderate snow. 2.5" total now. Not quite 5-8", but it still looks nice and makes great snowballs! Could be another 1/2" or so is my guess, looking at the radar.

As of 3:30 pm, still have just 2" OTG, as it's been snowing fairly lightly the last hour and my guess is the snowfall rate was matched by the melting rate for an accumulation rate of zero. Anyone who thinks this storm looks healthy is delusional: a few hours ago, 2/3 of CNJ/NNJ was under 20 DBZ+ rates, while maybe 1/10th of that area is under that kind of rate. We may still get pivoting and more snow, but the last few hours have underperformed for most. On the bright side, at 3:30 pm, while the NWS-Philly dropped the warnings for most of eastern PA, they kept them for Mercer, Somerset, Hunterdon, Warren, Morris, Sussex, W. Monmouth and Middlesex for 2-4" of additional snow. They also kept advisories for the tier of counties south of those counties for 1-2" more snow, but dropped all advisories for Philly Metro.

Thanks, that's nice of you to say - good luck in your final work years too. Didn't realize that MSW was your area and yeah, leaving after 30+ years is a pretty big change (akin to a friendly divorce lol). Fortunately, it was on my terms and they want me to come back part-time (~10 hrs/wk) for 6-12 months to consult at a nice rate, which I'll likely do, as I think it'll be a nice transition and a little extra income won't suck. Lots of bonds, too, as you said: most obviously, I managed groups of 10-25 for the last 20 years and probably 70% of our department was in my group at one time or another, and in addition, there have been the weather notes, the DJ-ing (I've been DJ-ing our annual BBQ and holiday parties for over 20 years and will still do those in retirement at least this year), and the Rutgers football games (our crew of 14 includes 3 guys from work and their wives and with Schiano coming back there's actually hope for the future).

BL is the boundary layer, essentially the atmospheric conditions at the boundary between the air and the ground.

Snowfall intensity the last hour has been light to moderate, so only got 1/2" in the last hourd with 2" OTG as of 2:30 pm. Temp ia at 33F (been bouncing between 32 and 33F, just warm enough for some melting). The 18Z HRRR only has another 2" for most of CNJ/NNJ so I'm thinking most folks in warning areas aren't going to make it to the 5-8" range predicted for many of us if the model is correct. I'm at 2" now and 2 more would be 4", which I'd be happy with - of course the HRRR is nowhere near being correct all the time. Radar really looking ragged though vs. an hour or two ago. Let's hope this thing cranks back up.

Snowing moderately and 1.5" OTG as of 1:30 pm at 32F. Roads are slushy, but not too bad, as long as one goes slowly, as I just made a food store run (an excuse to get out, lol); 287 and Route 1 are just mostly wet with a little slush so far, but will likely get worse by 3-4 pm, assuming the snow continues and as the sun goes down.

I started my winter weather emails at Merck in the late 90s and then I became head of one of our major synthetic chemical pilot plants in 2000 and part of that job is being on the Site Emergency Mgmt team, given the tons of flammable solvents and chemicals we have on site and use in that building; then in 2008 I was put in charge of process safety for the site, so continued my involvement with the OEM team. My weather notes started going to the OEM guys, in the early 2000s, especially since we were all involved in snow removal (our operators are involved in that as part of the contract) and they grew over the years, such that we set up a service to have them sent to about 500 subscribers in the company as of now. I just do winter weather and tropical weather and it's mostly for fun, but people seem to like them. So many people wanted me to continue with them after retirement that we have one of the admins taking my content from an email I send her and posting it for employees.

Looks like this is where the band has set up. Could be 6" or more in these locations and travel is going to be rough. Special Weather Statement National Weather Service Mount Holly NJ 1134 AM EST Mon Dec 2 2019 NJZ001-007>010-012-PAZ055-062-021745- Morris-Hunterdon-Sussex-Somerset-Middlesex-Warren-Monroe-Northampton- 1134 AM EST Mon Dec 2 2019 ...AN AREA OF HEAVIER SNOW AFFECTING NORTHEASTERN HUNTERDON... MORRIS...SUSSEX...WARREN...SOMERSET...MIDDLESEX...NORTHEASTERN MONROE AND NORTHEASTERN NORTHAMPTON COUNTIES... At 1132 AM EST, an area of heavier snow continues to slowly move across much of northern New Jersey. Snowfall rates up to an inch per hour will result in an increase in accumulations on untreated surfaces and also significantly reduce the visibility. Remember, bridges and overpasses tend to be colder and therefore be more slippery. Conditions can deteriorate rapidly in winter weather situations. Be prepared that untreated roads will quickly become slush to snow covered during heavier bursts of snow. Slow down and allow extra time when traveling. Locations impacted include... New Brunswick, Perth Amboy, Morristown, Somerville, Port Jervis, Newton, Montague, Mount Pocono, Somerset, Edison, Old Bridge, East Brunswick, Bridgewater, South Brunswick, Sayreville, North Brunswick, Carteret, Dover, Madison and Hopatcong.

It's been said by many before, including me, but if you work in the area and are at work now and can head home, I'd highly advise it, since snow at this rate will accumulate even on major highways and we all know what happened on 11/15/18 in a similar situation. I just advised the emergency management Merck folks in Rahway, who I used to work with (I retired last week after 30+ years) to consider sending people home early: my weather notes continue to be sent to about 400-500 people there, even post-retirement, which is kind of cool.

Snowing close to heavily now here at 32F with 1/2" on the ground as of noon. Gorgeous out there folks - go take a Jebwalk Accumulating well on all surfaces now, which is easy at this rate and with the low sun angle.

Started snowing lightly here around 10:30 am at 33F and had a dusting as of 11:00 am. Snowing moderately here now with 1/4" OTG as of 11:30 am - it took awhile to overcome the melting, especially with the very wet ground, but now snow is accumulating on all surfaces including paved ones; in addition, temps have dropped from 33F to 32F.

Thought summaries of the NWS Philly/NYC forecasts and the relevant snowfall maps might be helpful. Significant bust potential exists on the low side for NWS-Philly and on the high side for the NWS-NYC, IMO. This is really going to be a nowcasting event, i.e., watching the radars and the sky. Where do I sign up for the 4-7" forecast for me? So let's get to what the NWS-Phillly is saying. Warnings are now up for 5-8" of snow for Bucks, the Lehigh Valley, Mercer, Hunterdon, and Somerset, A warning is up for 4-7" for Middlesex Warnings are up for 6-10" for the Poconos, Sussex/Warren/Morris. Advisories are now up for 2-5" for Montco, W. Chester, Berks, W. Monmouth, Ocean, and Burlington Advisories are up for 1-4" for E. Chester, Delaware, Philly, Gloucester, Camden, and E. Monmouth. And what the NWS-NYC is saying. Warnings are up for 5-7" of snow up for W. Union, and W. Essex Warnings are up for 5-10" of snow for Passaic, N. Bergen, Orange, Putnam, Rockland, N. Westchester, and N. Fairfield Advisories are up for 2-4" for eastern Union, eastern Essex, southern Bergen, Hudson, Bronx, Manhattan, Staten Island, Queens, Brooklyn, S. Westchester and N. Nassau (and 4-6" for interior CT/3-5" for coastal CT).

Not true. As of this 2014 thread, the 6/18Z scores were slightly worse than 12/0Z, but much better than the 6-hr previous model run, which is mostly a function of being 6 hours closer to the event, which will almost always result in a more accurate forecast, given numerical modeling of chaotic systems, like the weather, where forecast errors always get worse the further out in time one goes. I also recall reading more recently that the 6/18Z gap had narrowed further, but couldn't find that in a quick search.