OT: Minor to Moderate Snow/Mix Likely Sat Evening (2/8) through Sun am

[DJ Spanky]

We've got sunshine and partly cloudy up here in north jersey. Currently at work for a major upgrade, should be through by early afternoon at the latest. Got a couple of people up from SC for this, fortunately they were just down the street in a hotel for Thursday's storm.

 

[MadRU]

We've got sunshine and partly cloudy up here in north jersey. Currently at work for a major upgrade, should be through by early afternoon at the latest. Got a couple of people up from SC for this, fortunately they were just down the street in a hotel for Thursday's storm.

 

[RU848789]

It blows my mind that the HRRR and RAP are still given credence, I thought those were both put out to pasture years ago from a viability standpoint. They’re such short term models that you’re almost better just using surface analysis and current observations to determine what happens next rather than risk a short term model whiff. I wonder if those are still used by pros.

Actually, it's the NAM that's slated for discontinuation with the FV3 intended to replace it, but it hasn't been that great so they've held off. HRRR is often good inside 18 hours and is good for mesocale events like t-storms (I use it a lot for that) and we're there now, so it's certainly an outlier, but its idea of more snow than sleet can't be dismissed, just like the NAM's idea of much more sleet than snow can't. Time to watch...

 

[bac2therac]

The 0z nam was a kick in the nads for snow

 

[RU848789]

Here's the HREF (high res "ensemble" forecast, which is a mix of most of the high res/short term models and is pretty well respected). It can include sleet but has an algorithm to predict snowfall; also precip is much less from NE to SW, i.e., NYC looks to be getting 0.7-0.9" of precip while Philly is looking at 0.4-0.5".

 

[RU848789]

It's hard to follow 3 major stations on Saturday so on the weekends I only watch CBS 3 and 6ABC. Both had Philly in the coating to 1 inch map area but not far from the 1-3 NW of here.
Inside of the 12 hour start time so I doubt any major changes but it's still unsettled. I think everyone's accuracy on the timing of the start will dictate who will have the best forecast now.
Anyway. It's cloudy with sun breaking through. (yes just temporary). Almost zero wind so it sounds like a bike ride in a few hours. Some miles, hills and over the Ben Franklin Bridge to visit the Battleship NJ, it been a while.

The 12Z NAM you don't want, as it's almost all freezing rain, although a fair amount less precip on the NAM for Philly than for EWR (0.6" there vs. 0.25" in Philly); the 12Z NAM is almost all sleet at EWR (about 5" of snow worth) plus 0.1" freezing rain.

 

[WhiteBus]

The 12Z NAM you don't want, as it's almost all freezing rain, although a fair amount less precip on the NAM for Philly than for EWR (0.6" there vs. 0.25" in Philly); the 12Z NAM is almost all sleet at EWR (about 5" of snow worth) plus 0.1" freezing rain.

Agree. Freezing rain is dangerous in many ways. From slip and falls, to accidents to trees/branches taking out electric lines. Nothing positive about freezing.
Passed the frisbee golf course in Fairmont Park. Yes, there were people there playing but the wait to start was just one group. Get away from the computer and get outside. It's a nice winter day!

 

[bac2therac]

the rgem and ggem were both less snowy for central jersey to go along with the gfs and nam tragic outputs...more and more of a signal to a sleetfest and freezing rain/rain

with each run the hrrr is slowly cutting back on snowfall amounts and qpf in general

 

[RU848789]

Fascinating debates going on by pros/experts on AmericanWx and other weather sites regarding how fast the WAA aloft (warm air advection) will move north during the storm to turn the snow to sleet and then possibly freezing rain (or even rain), including discussions of the relative merits of the NAM vs. the HRRR and RAP high resolution/mesoscale models for predicting this, since the NAM has consistently been showing a fast changeover to all sleet (but not freezing rain or rain) for most of our region (except well N of the Tappan Zee) vs the HRRR/RAP which have been showing a much slower progression of the warm air and changeover to sleet. I have no clue which one will be right, but it'll be interesting.

https://www.americanwx.com/bb/topic...g-sunday-nyc-li-s-of-i78-on-the-edge/page/24/

Also, @rurichdog I asked one of the better mets on line about whether he uses the 540 thickness rule for predicting the snow rain line (with snow north of the 540 line on the 1000-500 mbar thickness map for those not familiar with it and rain south of the line, often) and this was his response. I asked whether the 1000-850 maps were readily available...

"In an event like this with massive mid level WAA I never really look at thickness. I typically only do it for all snow type events where its marginal temps and then I use 1000-850 which until recent years practically no online websites even had anyway, you basically needed to be an NWS employee and have AWIPS til about 10-15 years ago to view it. It usually works way better in a marginal temp event than 1000-500. I think in the January 2008 storm the 1000-850 argued the area would see no snow at all. I recall a MET posting that on the old forum"

https://www.americanwx.com/bb/topic...8-on-the-edge/?do=findComment&comment=7625967

 

[RU848789]

Agree. Freezing rain is dangerous in many ways. From slip and falls, to accidents to trees/branches taking out electric lines. Nothing positive about freezing.
Passed the frisbee golf course in Fairmont Park. Yes, there were people there playing but the wait to start was just one group. Get away from the computer and get outside. It's a nice winter day!

Sedgley is about as old as the course at RU - love that place. Playing later today - I try to play 5 days a week even in winter - I hate "exercising" but I don't mind it at all when I get some exercise playing a sport; same for soccer which was cancelled for tomorrow as some of the guys don't enjoy playing in the snow (we did that last Sunday and I had a blast, but there was some whining lol).

 

[RU848789]

the rgem and ggem were both less snowy for central jersey to go along with the gfs and nam tragic outputs...more and more of a signal to a sleetfest and freezing rain/rain

with each run the hrrr is slowly cutting back on snowfall amounts and qpf in general

But the Euro/UK were both better at 12Z and the HRRR decrease was kind of expected as it was a pretty big outlier - it's now fairly similar to the Euro/CMC. The NAM may end up right, but it's still fairly lonely with partial support from the GFS (but it's lower resolution could be messing up those graphics from what I've been told). There's no doubt though that there's been a trend for less precip (so less snow/sleet) SW of NYC and especially SW of about New Brunswick and a trend for more sleet than snow SW of NYC.

It's possible one could see 0.4" QPF in philly as half sleet/half ZR, 0.6" of QPF in NB with 1/4 snow, 1/2 Sleet and 1/4 ZR and 0,8" of QPF in NYC with 1/2 snow and half sleet and little ZR. That's not a prediction, per se, but just showing the trend one is likely to see for less precip and more non-snow as one goes SW from NYC to Philly.

 

[RU848789]

Summary: Still a very difficult forecast timing the change from snow to sleet to freezing rain and maybe even plain rain for some (especially near the coast) near the end of the storm. Start time has been pushed back a bit to around 5-6 pm in the Phillly/SNJ area to maybe 7 pm for CNJ to about 8 pm for NNJ/NYC and the precip will come in like a wall with heavy precip immediately and coming down moderately to heavily for about 5-6 hours, ending by midnight to 1-2 am. No matter when the changeovers are, driving is likely to be very difficult during the storm with 1" per hour snow (or the equivalent amount of sleet) falling and then some freezing rain for many and the sleet/snow will all accumulate with temps generally at or below 32F for the storm.

When the changeovers to sleet and freezing rain (and maybe plain rain) occur will hugely impact the amount of snow/sleet on the ground, although the frozen mass on the ground will be similar, assuming about 0.1" or so of freezing rain and little rain (except near the coast), so the impact on driving and removal will be similar (except no visibility issues for sleet). There are models like the NAM and GFS that show little snow and mostly sleet for CNJ while there are models like the HRRR/UK that show mostly snow and a bit of sleet for CNJ with most of the models in-between those extremes with some snow and some sleet. I don't have enough expertise to know how this is going to play out, but can at least provide some potential scenarios based on the NWS forecast, below.

Details: The updated NWS maps for snow/ice are below, as well as a couple of other selected media maps, some with more snow/sleet forecast than the NWS (News12/TWC) and some with similar amounts (Channel 4/Channel 7 with the gratuitous shot of Dani Beckstrom for @Knight Shift and @bac2therac), but I'll only discuss the NWS below. The NWS forecast shows a bit of an increase in snowfall amounts for the NWS-Philly counties from Sussex down through EPA/CNJ vs. yesterday with areas N of 78 forecast to get 2-4" of snow/sleet and up to 0.1" of freezing rain and most of CNJ forecast to get 1-3" of snow/sleet and up to 0.1" of freezing rain as per the updated advisories, below. Less snow is forecast south of 276/195 (up to 2" snow/sleet possible, but most locations <1"), but up to 0.2" of freezing rain is forecast south of 276/195 near the 95 corridor vs. up to 0.1" of freezing rain south of 276/195 and towards the coast (but no freezing rain forecast at the immediate Monmouth coast, which is why they have no advisory), as per the updated advisories. Here are some guesstimated scenarios based on the NWS forecast.

• For much of CNJ between 276/195 and 78, we might expect the following, assuming 1" per hour snowfall rates (or 0.1" per hour precip rates on a liquid basis), mixing with sleet 1 hour into the storm would lead to maybe 1" of snow and 1-1.5" of sleet (3-4.5" of snow equivalent) and maybe 0.1" of freezing rain for a total of ~0.6" of precip and 2-2.5" of snow/sleet otg (meeting the 1-3" snow/sleet forecast).
  • The freezing rain would simply be absorbed into the snow/sleet making it more slushy, but freezing rain on bare untreated surfaces will produce a glaze, so I'd recommend actually waiting until the storm is over to shovel or to put salt down if shoveling after the snow/sleet are done.
  • Also, note that temps won't go above 32F for most until about sunrise so road conditions are likely to still be difficult well into the morning, but temps eventually will reach the upper 30s for most with some afternoon sunshine, allowing melting, although temps will quickly drop back below 32F around sunset and reach the low 20s by early Monday, freezing solid whatever slush remains.
• For areas south of 276/195 it might be something more like 1/2" of snow, then 1" of sleet then 0.2" of freezing rain and 0.1" of rain, leading to about 1-1.5" of snow/sleet otg and some melting/compaction due to the plain rain so it'll likely be <1" snow/sleet otg at the end.
• For areas line north of 80 that get, say, 3 hrs of snow for 3", then about 1" of sleet, that would put about 4" snow/sleet on the ground, perhaps topped off with up to 0.1" of freezing rain. And of course, anyone who gets 0.6" of precip as all snow, that would be 6" or so of snow on the ground at 10:1 ratio.
• Last, but not least, my guess for my house in Metuchen is 1.5" of snow, then 1" of sleet (~3" of snow equivalent in that sleet) for 2.5" snow/sleet on the ground, then 0.1" of freezing rain on top. We'll see...

https://forecast.weather.gov/wwamap/wwatxtget.php?cwa=PHI&wwa=winter weather advisory
https://www.americanwx.com/bb/topic...s-of-i78-on-the-edge/page/18/#comment-7624862

---

URGENT - WINTER WEATHER MESSAGE
National Weather Service Mount Holly NJ
320 AM EST Sat Feb 8 2025

Sussex-Warren-Morris-Monroe-
Including the cities of Stroudsburg, Morristown, Newton, and
Washington
320 AM EST Sat Feb 8 2025

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 3 PM THIS
AFTERNOON TO 6 AM EST SUNDAY...

* WHAT...Mixed precipitation expected. Total snow and sleet
accumulations between 2 and 5 inches and ice accumulations up to
one tenth of an inch.

---

URGENT - WINTER WEATHER MESSAGE
National Weather Service Mount Holly NJ
320 AM EST Sat Feb 8 2025

Hunterdon-Somerset-Middlesex-Mercer-Carbon-Lehigh-Northampton-
Upper Bucks-Lower Bucks-
Including the cities of New Brunswick, Trenton, Allentown,
Morrisville, Flemington, Doylestown, Bethlehem, Chalfont, Jim
Thorpe, Easton, Somerville, and Perkasie
320 AM EST Sat Feb 8 2025


URGENT - WINTER WEATHER MESSAGE
National Weather Service Mount Holly NJ
320 AM EST Sat Feb 8 2025

New Castle-Salem-Gloucester-Camden-Northwestern Burlington-Berks-
Delaware-Philadelphia-Western Chester-Eastern Chester-Western
Montgomery-Eastern Montgomery-
Including the cities of Wilmington, Media, Camden, Cherry Hill,
Norristown, Glassboro, Pennsville, Honey Brook, Pottstown, West
Chester, Reading, Oxford, Philadelphia, Moorestown, Kennett
Square, Lansdale, Collegeville, and Mount Holly
320 AM EST Sat Feb 8 2025

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 6 AM
EST SUNDAY...

* WHAT...Mixed precipitation expected. Total snow and sleet
accumulations up to two inches and ice accumulations up to two
tenths of an inch.

---

URGENT - WINTER WEATHER MESSAGE
National Weather Service Mount Holly NJ
320 AM EST Sat Feb 8 2025

Western Monmouth-Ocean-Atlantic-Southeastern Burlington-
Including the cities of Jackson, Freehold, Wharton State Forest,
and Hammonton
320 AM EST Sat Feb 8 2025

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 2 AM
EST SUNDAY...

* WHAT...Mixed precipitation expected. Total snow and sleet
accumulations up to two inches and ice accumulations around one
tenth of an inch.

Minor NWS-Philly map updates, decreasing snow a bit SW of an Allentown to about Long Branch line, in line with decreased precip, as far as I can tell (as I just discussed in a previous post) and increasing snowfall a bit, north of 78. The ice accumulations were increased a bit along and NW/SE of 95 south of about Woodbridge.

 

[bac2therac]

But the Euro/UK were both better at 12Z and the HRRR decrease was kind of expected as it was a pretty big outlier - it's now fairly similar to the Euro/CMC. The NAM may end up right, but it's still fairly lonely with partial support from the GFS (but it's lower resolution could be messing up those graphics from what I've been told). There's no doubt though that there's been a trend for less precip (so less snow/sleet) SW of NYC and especially SW of about New Brunswick and a trend for more sleet than snow SW of NYC.

It's possible one could see 0.4" QPF in philly as half sleet/half ZR, 0.6" of QPF in NB with 1/4 snow, 1/2 Sleet and 1/4 ZR and 0,8" of QPF in NYC with 1/2 snow and half sleet and little ZR. That's not a prediction, per se, but just showing the trend one is likely to see for less precip and more non-snow as one goes SW from NYC to Philly.

Well the euro and ukies maps were not kuchera

Knowledgeable mets are sending the warning signal

Sleetfest

 

[bac2therac]

HRRR and RAP are caving rapidly

18z Nam is sleet to rain

 

[bac2therac]

Cutting back qpf now in .3 to .4 range

 

[WhiteBus]

🙏for a rain finish. Oh billy, billy billy...

 

[rurichdog]

Skies getting dark. Here it comes...whatever it is.

 

[WhiteBus]

Skies getting dark. Here it comes...whatever it is.

Where are you? You do know it's near sundown.

 

[WhiteBus]

Radar has this closer to 7pm.

 

[RU848789]

Minor NWS-Philly map updates, decreasing snow a bit SW of an Allentown to about Long Branch line, in line with decreased precip, as far as I can tell (as I just discussed in a previous post) and increasing snowfall a bit, north of 78. The ice accumulations were increased a bit along and NW/SE of 95 south of about Woodbridge.

Last NWS map before the storm presumably, although precip has broken out in far SNJ/DE. Not much change other than my point-and-click is now showing me getting 3.4" of snow, which I can't quite believe, although I am in the 3-4" swath of far northern Middlesex County. While there have been some trends towards less precip SW of NYC and especially SW of NB and towards faster warm air aloft intruding and turning the snow to sleet faster, the NWS appears to be not convinced since their maps haven't really changed and their discussion still has some confidence in a thump of snow for much of CNJ and all of NNJ before any changeover.

If the dryer and warmer aloft-faster trends verify, could be one of those storms where there's a significant difference between, say NB and places like Freehold, Trenton or Frenchtown to the S/SW/W, i.e., decently more snow and precip in NB. Maybe. Time to watch the radars and it's certainly plenty cold for snow/sleet with temps around 32F, but low humidity and dewpoints in the upper teens meaning the wet bulb effect will get most down into the mid/upper 20s for awhile. Going to be an interesting next 8 hours or so.


Area Forecast Discussion
National Weather Service Mount Holly NJ
400 PM EST Sat Feb 8 2025

NEAR TERM /THROUGH SUNDAY/...
With a cold and dry air mass currently in place, light precip
aloft so far has mostly evaporated/sublimated before reaching
the ground. Exception has been the far south, where light snow
and mixed precip has been observed in the Delmarva so far with
little impact. However, as the lows approach from both west and
south, expect precip to blossom across the region with strong
warm advection and difluence developing aloft to support it. The
strong warm advection aloft, and easterly winds at the surface,
should work on making this a mixed precip system, with initial
snow transitioning to sleet/freezing rain in nearly the entire
CWA, and to rain from I-95 and points south and east. Freezing
rain looks to linger longest across the western Philly suburbs,
so continue with highest ice accumulations in this area,
possibly up to around a quarter inch, but did drop snowfall
amounts a smidge across Philly metro as it looks like the warm
air really comes in fast aloft.

Further north, a burst of moderate to heavy snow looks likely
after sunset for the Lehigh Valley, Poconos and northern NJ,
possibly extending into the northern Philly suburbs and central
NJ briefly, before the change to sleet and freezing rain. Where
that lingers longest as snow, highest accumulations will be
found, with 3-6 inches expected in northernmost NJ, 2-4 inches
in the Poconos and the rest of north-central NJ, and 1-2 inches
in the Lehigh Valley, northern Philly suburbs and central NJ.
This prolonged period of snow, followed by sleet, should result
in less ice accumulation, closer to a tenth of an inch or less.

From I-95 on south and east, a transition to rain looks likely
overnight as the easterly flow works some warmer air inland,
though this appears to likely be a struggle, and it may fail to
change over in Philly until very late in the storm. That said,
still expect around a tenth of an inch of ice across the I-95
corridor and interior southern NJ and northern Delmarva. That
quickly declines further southeast where oceanic influence
should be more dominant, with ice of just a few hundredths of an
inch before warming occurs.

 

[RU848789]

HRRR and RAP are caving rapidly

18z Nam is sleet to rain

HRRR made a comeback as per the last 4 run trend below and the NWS hasn't backed down and have in fact bumped some folks up a little bit, like me. Don't get me wrong, I'm very concerned about getting mostly sleet as I'd like to see some snow and the trends have not been good for mostly snow for anyone really, but the NWS knows more about this stuff than I do and I just hope they're going to be right. I'd rejoice if I got the forecast they have for me of 3.4" of pretty dense snow and sleet that comes from 0.59" of QPF, with 0.06" of ZR on top of that. That's more than my guess was (2.5" of snow/sleet from 0.45" of QPF).

 

[Rhuarc]

Weekend storms don't get the same interest from me. Already home with no impact on work. This week should be more fun.

 

[ClassOf02]

NJ really is a fascinating location for these storms with the drastic gradients we often see. Looking like we are getting a minor amount of snow and we’ll see how much sleet here in Lambertville.

 

[RU848789]

The current radar at 6:30 pm is quite close to what the fairly snowy 21Z HRRR was showing for 7 pm pm, whereas the 18Z NAM at 7 pm looked weak and spotty. Doesn't mean the HRRR will be right and the NAM wrong, but that's the case so far, IMO. Snow should be into western NJ in 30 min...

 

[bac2therac]

🌭

 

[T2Kplus20]

🌭

Why is this even a thread? It's a rounding error "event".

 

[bac2therac]

That's not snow in PA per reports on that radar

And the hrrr is verifying as too cold

 

[RU848789]

NJ really is a fascinating location for these storms with the drastic gradients we often see. Looking like we are getting a minor amount of snow and we’ll see how much sleet here in Lambertville.

Many mets I've spoken to in person and on line say predicting for this area is "the big leagues" since it's so difficult to get the rain/snow line right as we have so many mixed precip events, plus there's a billion critics waiting to stomp on you if you get it wrong, lol.

 

[WhiteBus]

So, the current radar looks quite impressive to our west in PA and the 18Z NAM at this point looked very spotty with precip, so the storm is at least off to a good start and the NAM is not verifying so far, while the HRRR is.

What is impressive? Nothing has started here yet? I'm North of Philly and it's 34 degrees here.

 

[RU848789]

Encouraging for snow lovers...

 

[RU848789]

What is impressive? Nothing has started here yet? I'm North of Philly and it's 34 degrees here.

You're 34F with a wet bulb temp of about 25F, so you'll be well below 32F once the column above you moistens up, which cools the column via evaporation. That evaporation is why the radar shows snow aloft, but it's not reaching the ground. Might take 15-20 minutes for that to occur and then I think you'll see some snow to start as per the SPC post I just made. No idea how long that will last though.

 

[RU848789]

That's not snow in PA per reports on that radar

And the hrrr is verifying as too cold

You're correct, although that could be light precip leading to sleet, although the dual-pol radar does show what looks to be heavy sleet in eastern PA right now. But my primary point with the radar comparisons was the radar intensity/precip looking much more robust and close to the HRRR as opposed to the NAM. There have been two "trends" that concern folks who want snow - less precip on the NAM and some other models, especially W and SW of NYC and faster WAA driven transition to sleet like the NAM vs. what some of the models show. If I can't get all snow, at least I'd rather get the higher precip (QPF) and mostly sleet than low QPF and mostly sleet. We'll see about the QPF and sleet very soon, but initial indications are more precip, but also mostly sleet...

Here's the dual pol radar showing the bright sleet signature in eastern PA. Some pros have been saying all along that they think the colder air towards NYC would help keep precip around here as snow for longer, but that remains to be seen...

 

[WhiteBus]

You're 34F with a wet bulb temp of about 25F, so you'll be well below 32F once the column above you moistens up, which cools the column via evaporation. That evaporation is why the radar shows snow aloft, but it's not reaching the ground. Might take 15-20 minutes for that to occur and then I think you'll see some snow to start as per the SPC post I just made. No idea how long that will last though.

Well this tired guy better see something soon. My bed is calling me or vice versa lol.
It's funny the energy that your body takes out of you during the winter to keep your body warm is so much more in the heat of summer.

 

[WhiteBus]

You're correct, although that could be light precip leading to sleet, although the dual-pol radar does show what looks to be heavy sleet in eastern PA right now. But my primary point with the radar comparisons was the radar intensity/precip looking much more robust and close to the HRRR as opposed to the NAM. There have been two "trends" that concern folks who want snow - less precip on the NAM and some other models, especially W and SW of NYC and faster WAA driven transition to sleet like the NAM vs. what some of the models show. If I can't get all snow, at least I'd rather get the higher precip (QPF) and mostly sleet than low QPF and mostly sleet. We'll see about the QPF and sleet very soon, but initial indications are more precip, but also mostly sleet...

Currently light rain in Belmont Hills. Very light. Very late.

 

[RU848789]

Turning from sleet to snow in Allentown and the Lehigh Valley. Good sign.

 

[bac2therac]

32 and sleet/rain combo has begun

 

[dfr1966]

Sleet here in Kendall Park

 

[Joey Bags]

Sleet/ZR mix here in flemington. No flakes. 30.6 degrees. Not expecting much if any snow out of this, just a layer of concrete to wake up to.

 

[bac2therac]

Turning from sleet to snow in Allentown and the Lehigh Valley. Good sign.

Another weenie tag.🌭


Good sign for what?

A good sign would be warming so this goes to rain

 

[rurichdog]

Sleet & freezing rain in Hamilton.
Just started 5 minutes ago.