RU848789

Here's a PSA for snowfall measurement: clear the board after the change to sleet and sum the snow and sleet measurements together; otherwise you'll likely get some compaction. This is from a great article on snow measurement in The Conversation based on NWS guidelines. Or maybe we'll get lucky and get no sleet, lol. More complicated cases of measurement So, let’s consider three common scenarios. Here in the eastern U.S., we often have to deal with snow that changes to rain during the course of a storm. Imagine 6.0 inches (15 cm) of snow falls, then an inch (2.5 cm) of sleet which compacts the snow to a 4-inch (10-cm) depth. Then, on top of that falls an inch of freezing rain which further compacts the snow to 2.6-inch (6.6-cm) depth by the end of the observation period. What should be listed as the daily snowfall? The snow depth? In this situation, when the snow transitions to sleet, the snow board should be cleared and the maximum depth of snow recorded – 6 inches (15 cm) in this case. Do the same with the sleet and this will add an inch (2.5 cm) to the snowfall – technically, “solid precipitation” – total. Freezing rain is never added to the daily snowfall total because it is in liquid form when it reaches the ground. Thus, the daily snowfall is 7.0 inches (measured to the nearest tenth of an inch) (17.8 cm), while the snow depth at observation is rounded up from 2.6 inches (6.6 cm) to 3 inches (7.6 cm). https://theconversation.com/how-is-snowfall-measured-a-meteorologist-explains-how-volunteers-tally-up-winter-storms-175628

Yeah, looks like it's almost in Cape May

As of 8:30 am snowing moderately and we have 3.1" otg (1.1" last hour) and it's 11F.

NWS maps hard to follow these days. This is a weird range map at odds with the colors, plus it starts at 7 am, so it's not the event map, which is below, starting at 4 am, so I don't think they cut amounts. Wish they'd only issue event maps - users can look and compare to what they have so far.

As of 8:00 am 2.6" otg at 11F, so 0.6" the last 30 min - can't imagine not making it to at least 8" with at least 5 hours of >1"/hr rates before any changeover (and hopefully the changeover is after that and rates are more than 1" per hour until then). Started around 5 am.

As of 8:00 am 2.6" otg at 11F, so 0.6" the last 30 min - can't imagine not making it to at least 8" with at least 5 hours of >1"/hr rates before any changeover (and hopefully the changeover is after that and rates are more than 1" per hour until then).

As of 7:30 am snow intensity and flake size have increased and we have 2.0" otg at 11F, so 1.25" last hour. This stuff has to be 15-20:1 ratio snow, it's so light and fluffy.

Ok boyz and grrrrrllls - as of 6:30 am we have 3/4" of the most exquisite pixie dust snow imaginable otg at 11 frikkin' degrees F! Let's get a foot or more! Woke up for a minute at about 4:50 am and snow had just started then.

But you're clearly not going on the latest models, which is the annoying point . Upton didn't lower anything and Mt. Holly just raised snowfall forecasts by a couple of inches across the board in their warnings as per my other post (they had cut too much).

You're simply trolling. Look at my post on the model stats for New Brunswick, which should get a little less snow/more sleet than NYC. The lowest of 8 models at 0Z was 5.6" and the average was around 9" with 1 to maybe 2" of sleet on top and a glaze of ice. For NB.

Just for giggles and the people I share weather info with on a Rutgers sports board, I put together the data set below for New Brunswick, as most posters there are alums and/or live reasonably close by, so NB can be a decent surrogate for much of CNJ and for 95 from Trenton to NYC. Anyway it's total QPF, snow QPF from the 10:1 maps and ZR QPF and sleet QPF, from subtracting the snow/ZR from the QPF (and sleet depth at 3:1). I'll be curious to see which model at 0Z tonight did best, since I'm just 5 miles NE of NB. Thinking my 10.4" snow/sleet prediction is decent (NWS was 11.9" last night when I made my guesstimate and is now 10.1") and I still think (have for a couple of days) 8-12" for CNJ/EPA between 78 and 276/195, as well as the 95 corridor from Philly to NYC is a good call. Have a great storm all. I might paste all the snowfall maps too if I get motivated more. HRRR: 1.5" QPF - 11.6" of snow (1.16" QPF) - 0.12" ZR = 0.22" QPF as sleet or 0.66" sleet (assumes 3:1 ratio) NAM: 1.4" QPF - 5.6" of snow (0.56" QPF) - 0.02" ZR = 0.82" QPF as sleet or 2.46" sleet (assumes 3:1 ratio) ICON: 1.5" QPF - 6.3" of snow (0.63" QPF) - 0.00" ZR = 0.87" QPF as sleet or 2.61" sleet (assumes 3:1 ratio) RRFSA (new NAM): 1.3" QPF - 12.4" of snow (1.24" QPF) - 0.06" ZR = 0.0" QPF as sleet or 0.0" sleet (assumes 3:1 ratio) GDPS (CMC): 1.8" QPF - 9.5" of snow (0.95" QPF) - 0.0" ZR = 0.85" QPF as sleet or 2.55" sleet (assumes 3:1 ratio) UK: 1.1" QPF - 10.2" of snow (1.02" QPF) - 0.0" ZR = 0.08" QPF as sleet or 0.24" sleet (assumes 3:1 ratio) Euro-AIFS: 1.3" QPF - 12.2" of snow (1.22" QPF) - 0.0" ZR = 0.08" QPF as sleet or 0.24" sleet (assumes 3:1 ratio) Euro: 1.2" QPF - 7.2" of snow (0.72" QPF) - 0.1" ZR (this was a guess as the Pivotal algo is suspect) = 0.38" QPF as sleet or 1.14" sleet (assumes 3:1 ratio)

With the 18Z models now out and generally (Euro/AIFS/RGEM/UK/CMC/HRDPS/HRRR) a bit snowier/less sleety than at 6Z and 12Z gnerally showing 8-12" before any sleet at 10:1 (which would be 10-15" at 13:1 ratios) I feel more confidence in an 8-12" snowfall for 95 from Philly to NYC and all of CNJ/EPA N of 276/195 and S of 78 (and more N of there). The two model exceptions were the NAM/GFS, which showed 5-6" (at 10:1) for CNJ (6-8" at 13:1 ratios) and then a lot of sleet (2"). I'll definitely take the Euro/AIFS/RGEM/UK/CMC/HRDPS/HRRR over NAM/GFS every day of the week (with the GFS the worst, going from most snowy to least snowy over the last 24 hours). We'll see soon I guess.

That's incorrect. Mt.Holly is only 5" south of 276/195; 6" north or there and contiguous with Upton...

Thanks, fixed the post...

But I'd take the over at Bryant Park nearby if someone else is measuring, lol.

Edit: updated as I had the 2:24 am map up (thought it was pm D'oh!), although the new map still has most of CNJ in an 8-12" swath, so changing the warning to 6-10" for Morris-Hunterdon-Somerset-Middlesex-Mercer-Salem-Gloucester- Camden-Northwestern Burlington-Cumberland-Delaware-Philadelphia- Western Chester-Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks seems unnecessary. Just keep it at Morris-Hunterdon-Somerset-Middlesex-Mercer and SEPA and at 8-12" and put the SNJ counties at 5-8" with Monmouth/Ocean. 'm missing something, as almost every model shows 6-8" of 10:1 snow for CNJ (8-11" with 13-14:1 ratios) and some show 8-11" of 10:1 snow and the NBM is still showing 9-10" (at model ratio); only the NAM shows 4-6" of 10:1. And then add another 1"+ of sleet and sticking with their 7-13" range (or 8-12" which I like better)would've been fine, IMO. Also, as I've said since their first map came out, they should've started with 8-12" and adjusted upwards if needed; starting at 12-18" for everyone was a recipe for walking it back for 2+ days. I don't get it - and I think 6-10" for CNJ, for example, might be on the low side a little.

Great point. Here's the NAM GIF for the last 36 hours with essentially nada in LR.

If meteorologists weren't so fixated on snow depth, but instead focused on frozen mass, 2" of sleet, alone, which is equivalent in frozen mass to 6" of 10:1 snow, would qualify for a warning. Same impacts on transportation and shoveling/plowing, plus it melts more slowly due to the much lower surface area to volume ratio. It doesn't have visibility issues, though, and it's not as pretty, but it's just about as impactful on the public.

Damn, now we have to worry about the sun angle...at 15F, lol.

Just caught up and surprisingly, didn't see the NWS snow/ice maps, so here they are. I had also summarized all of the NWS-Philly/NYC warnings elsewhere, so sharing them here. Nice to see the NWS finally bringing snowfall forecasts in line with the models and most other forecasters - I think a general 8-12" of snow and sleet for most S of 78 and more N of there and NE through NYC and the LHV/CT is pretty good. The NWS has me at 11.9" of snow/sleet, which I think is still a little high, so I'll go with 10.4" for Metuchen. NWS-Philly Counties For Sussex-Warren-Carbon-Monroe-Lehigh-Northampton, the warning is for 11-15" of snow/sleet, but no freezing rain (ZR) For counties in PA/NJ south of 78 (except coastal counties south of Ocean), i.e.,Hunterdon-Somerset-Middlesex-Monmouth-Mercer-Salem-Gloucester-Camden-Burlington-Ocean-Cumberland-Berks-Delaware-Philadelphia-Chester-Montgomery (and Newcastle/Kent in DE), the warnings are for 7-13" of snow and sleet with up to 0.3" of freezing rain accretion, especially SW of Trenton as per the ice map below. For Atlantic/Cape May counties and southern DE, the warning is for 4-8" of snow/sleet plus about 0.1" ZR NWS-NYC Counties For W. Passaic, the entire Hudson Valley and the coastal CT counties, the warning is for 12-16" of snow For NENJ (Union/Essex/Hudson/Bergen/E Passaic), NYC and LI, the warning is for 10-14" snow/sleet plus a light glaze of ZR

The NWS finally dropped their snowfall forecasts (new and previous attached) to a somewhat more reasonable level, especially S of 78 where sleet will likely be at least at a moderate level. Likely tied to the NBM drop.

I think everyone knows we have warnings up for everyone covered by the NWS-Philly and NYC offices. A summary is bulleted below, as I find wading through the full text to be tedious; the first 4 bullets are the counties under the NWS-Philly, while the last 2 are under NWS-NYC. One can argue that these numbers are a bit aggressive vs. other forecasters, but the NWS hasn't wavered, really, other than knocking down snowfall forecasts a bit south of 78 due to some sleet and adding in some ZR. There are also some models that show 10"+ amounts given good ratios (like 12-15:1), so it's not like the forecast is crazy, just higher than most; their latest map s arebelow. With temps below 20F for most and some wind, it'll be frigid and salt won't work as well, plus there will be some wind (20-25 mph) so some drifting is possible. For counties S of 276/195 in SEPA/SNJ/N DE, the warning is for 8-12" of snow/sleet plus about 0.3" of freezing rain (ZR) For Atlantic/Cape May counties and southern DE, the warning is for 6-10" of snow/sleet plus about 0.1" ZR For Sussex/Warren/Poconos/Lehigh Valley, the warning is for 12-18" of snow plus a light glaze of ZR For Morris-Hunterdon-Somerset-Middlesex-Monmouth-Mercer-Ocean-W Montco and Bucks, the warning is for 10-15" of snow/sleet, plus about 0.1" of ZR For W. Passaic, the entire Hudson Valley and the coastal CT counties, the warning is for 12-16" of snow For NENJ (Union/Essex/Hudson/Bergen/E Passaic), NYC and LI, the warning is for 10-14" snow/sleet plus a light glaze of ZR https://forecast.weather.gov/wwamap/wwatxtget.php?cwa=PHI&wwa=winter storm warning

This is going to be one of the most impactful winter storms this country has ever seen. Here are the snow and freezing rain (ZR) maps for the US from the NBM (model blend). A foot+ of snow from Texas to Maine is insane and crippling 1"+ ice storms south of that snow for many may be even more impactful. Also, if you look at these same maps from 3 days ago, below, you can see how much further south the big swaths of snow and ice were (when most of us were worrying about suppression) – they’ve moved northward about 150 miles, as the modeling and the actual system have evolved, but that’s not an unusual track forecast error that far out. But I’m sure it’s disappointing for the folks who are snow lovers who thought they were getting a foot of snow and who will now likely be getting up to 1” of ice.

Sleet also melts more slowly than snow, given its much lower surface area per volume ratio.