Another Nor'easter 3/12-13; likely light to moderate snow...

[RU848789]

Been discussing this threat quietly in the 3/7 storm thread and finally decided to pull the trigger on starting a new thread, even though the Monday into Tuesday storm is looking more likely to go out to sea than hit us. However, there is still some chance of getting hit by this one and the storm is almost certainly going to be a powerful one, so if we do get hit, it'll be quite impactful. Also, keep in mind that if it does hit, we'll likely have some of the same surface temp issues and precip type issues we've had the past two storms, i.e., could be some white rain or even a mix, but if intensity is great enough, it could be an impactful snowfall. Anyway, the rest of this post is essentially from my last post in that thread.

Consensus from 00Z model runs is generally out to sea, but only 100-200 miles from being a significant storm, and the UK (2nd best model) does show a modest hit for our area, and we've seen several storms this winter at this timeframe (~72 hours out - looking like a Monday into Tuesday storm) shift NW in track over the last 72 hours and end up being hits for us.

So same bottom line - not worth sending out the Bat-Signal yet, but this one still has some potential to hit us (as model errors are at least +/-150 miles at 72 hours) and it it does, it'll be very impactful, as it looks to be quite a powerful storm, and therefore bears watching. Plus, the northern jet stream energy is still in the Pacific, off the coast of BC, meaning it's not being well-sampled data-wise, which only increases model inaccuracy at this point.

Also, the 6Z models are in and the GFS is a near miss (100-150 miles from the benchmark), the NAM is way out to sea, and the RDPS (Canadian mesoscale version of the 12 km NAM) is a modest hit for 95/coast, i.e., there's still potential there, but obviously not an imminent threat.

Edit: just saw the NWS discussion, below. They're a bit more optimistic for this storm than I am, so I think it's thread time, even if it ends up being a miss, which is more likely than a hit, plus this way I don't incur the wrath of he who shall not be named, lol.

https://www.weather.gov/phi/
https://www.33andrain.com/topic/831-winter-2017-2018-the-grand-finale-part-2/?page=12

National Weather Service Mount Holly NJ
412 AM EST Sat Mar 10 2018

LONG TERM /SUNDAY THROUGH FRIDAY/...

500 mb: The interactions of two digging short waves in central North
America Monday will ultimate determine our snowfall potential. The
lead short wave in Missouri midday Sunday, is modeled by the GEFS to
sharpen as it crosses the Carolinas on Monday. Meanwhile a meager
looking short wave over central Canada on Sunday amplifies
southeastward and negative tilted, heading into the Great
Lakes region Monday evening, then either ejecting the Carolinas
short wave east northeast out to sea, or absorbing it into what
should be a large closed low over NYS-New England on Tuesday.
That closed low then weakens eastward off the east coast by
Friday night with ridging to follow next weekend.

I dont think the models are cohesive here. The NAM is late to
the table on this one but am expecting much more NAM development
by this time tomorrow. For now its trying to set up an inverted
trough for Tuesday as our primary snow event. The UKMET was my
favored model since its been consistent for two cycles, and
closer to the coast, which is what I expect again this winter
with this upcoming system (SST`s offshore still above normal).
The GFS UK ECMWF all seem to be onto the rapid intensification.
That said, forecast uncertainty continues and haven`t said too
much yet about what may happen.

Monday...Cloudy. Snow or rain/snow mix changing to snow as the
boundary layer temp cools, all this to the southeast of PHL.
Amts and northwest extent yet tbd.

 

[LevaosLectures]

Optimistic? God man.

 

[Sweet Pea's Corner]

101.5 looking like a southern special.

 

[e5fdny]

Bump for the obvious reasons.

 

[RU848789]

And as if right on cue, today's 12Z NAM moved the track from about 250 miles SE of the 40N/70W "benchmark" (spot where very impactful snowstorms often travel through while heading NE up the coast), which is way out to sea, to a track only about 50-75 miles SE of the benchmark, which brings a light to moderate snowfall to our area. It's one run of one model, so don't get too worried. Yet. If the other models follow suit, then people can start to get concerned about another snow/mix storm. And when I say follow suit, it's not like the NAM is actually influencing the other models, it just happens to always be the first one to come out (since it only runs 84 hours as opposed to 240-360 hours for most of the rest.

Edit: and the 12Z GFS is now a moderate hit for the whole area (3-6" range with the higher amounts toward the shore), as it moved NW a bit also (it was a light hit at 6Z). Let's see what the UK and Euro say, but the movement NW with the track looks to be real, so far. Almost every storm has done this, this winter - nobody seems to know why...

 

[RUPete]

I guess it's all about the trends. Trends were good last night, hopefully they don't head in the other direction today.

 

[Proud NJ Sports Fan]

Philly and South is fine by me

 

[MikeR0102]

Please no. My back still hurts.

 

[bac2therac]

remember with the last storm...takes moderate to heavy rates to get things to stick. Kuchera maps going to be more appropriate for this again with such a borderline event. Looks like GFS does show it closer. Giving everyone south of I 95 a potential for 6-8 inches but maybe half that on Kuchera and then 1-3 to the north.

also the 12z NAM verbatim is just an inch or two so that is nowhere near a moderate hit

Most people are concerned about impacts on the paved surfaces and roads not what falls on grassy surfaces and their outdoor grill tops. Timing will be crucial, GFS has this event starting overnight but I have seen models with this event concentrated on Tuesday so that could also have an impact

so 54 hours out and the models still awful and inconsistent in the medium range as I have been saying..almost every storm has had bad mid range models and they play catchup to the right solution within 36 hours so looks like important runs tonight and tomorrow.

 

[rurichdog]

I'm ready for some global warming.

 

[RU848789]

remember with the last storm...takes moderate to heavy rates to get things to stick. Kuchera maps going to be more appropriate for this again with such a borderline event. Looks like GFS does show it closer. Giving everyone south of I 95 a potential for 6-8 inches but maybe half that on Kuchera and then 1-3 to the north.

also the 12z NAM verbatim is just an inch or two so that is nowhere near a moderate hit

Most people are concerned about impacts on the paved surfaces and roads not what falls on grassy surfaces and their outdoor grill tops. Timing will be crucial, GFS has this event starting overnight but I have seen models with this event concentrated on Tuesday so that could also have an impact

so 54 hours out and the models still awful and inconsistent in the medium range as I have been saying..almost every storm has had bad mid range models and they play catchup to the right solution within 36 hours so looks like important runs tonight and tomorrow.

Likely to be a little colder with this one, plus much of the precip may fall at night, greatly reducing the melting concerns, so 10:1 ratios are possible. They got much closer to 10:1 in the areas that got a lot more snow, as there was less melting aloft. But if this hits during daylight and rates aren't good, it'll be white rain that doesn't accumulate, like the 3/2 storm for many.

First point of order is to see if the storm actually comes close enough for significant snow - it's much more likely not, but not a given. 12Z CMC and Euro also made big moves NW with the track and show similar light to maybe moderate snowfall. Verbatim wouldn't be a big deal - would need the storm to move another 50 miles NW for that, which is possible. Now people need to watch this one more closely.

Also, with regard to your comment on impacts being related to what falls on roads, I completely agree, which is why I can't figure out why you thought last March's storm with 4-8" of snow, then 3-4" of sleet, was a bust - the impact on the roads (snow removal, driving, etc.) was the same as it would've been if 12-18" of snow fell. Shouldn't matter, except from an "elegance" perspective, that it was sleet instead of snow.

 

[bac2therac]

Euro is an inch or less..why are you saying moderate

and yes its a bust when they are calling for 18 inches of snow and you get 4 plus two inches of sleet

 

[RU848789]

Euro is an inch or less..why are you saying moderate

and yes its a bust when they are calling for 18 inches of snow and you get 4 plus two inches of sleet

I said "light to maybe moderate" and was referring to the CMC and Euro with the CMC showing a bit more - why are you nitpicking such fine details anyway as we're 2.5 days out? And last year many, including me, got 6-8" before the change to sleet, then 3" of sleet which is the equiv of 14-18" of 10:1 snow vs. the 12-20" forecast for most of 95.

 

[MadRU]

Ok so back to the original topic. The timing of this? Sunday night to Monday or Monday to Tuesday?

 

[bac2therac]

I said "light to maybe moderate" and was referring to the CMC and Euro with the CMC showing a bit more - why are you nitpicking such fine details anyway as we're 2.5 days out? And last year many, including me, got 6-8" before the change to sleet, then 3" of sleet which is the equiv of 14-18" of 10:1 snow vs. the 12-20" forecast for most of 95.

because the nitpicking is pointing out your little bias you have so when a 1-2 output becomes moderate thats what I mean about embellishing a little...its a minor point but thats what I notice. You also said the NAM was moderate and as far as I know it was minor. The Euro ensembles verbatim have a bit more...a few inches...so that is a positive if you are looking for snow. And there is a trend of a shift west with most models. As for mass equivalence..thats not how the public views things, just as when they hear 3-6 they immediately think plowable when it fact it may be 1-2 on pavement and nuiscance stuff. Most people are concerned about the basics. You tell them 12-18 they expect 12-18 and yes calling for 12-18 and get 4 and then a couple inches of sleet is a bust....the meterologists missed the sleet..thats a bust..how is not, its just like if it rained instead

 

[bac2therac]

Ok so back to the original topic. The timing of this? Sunday night to Monday or Monday to Tuesday?

more of Monday night into Tuesday impact event but not certain.

 

[MadRU]

more of Monday night into Tuesday impact event but not certain.

Thanks Bac

 

[RUPete]

Honestly, we need this thing to crap out. Still too much damage that needs to be addressed and still too many people without power.

 

[Tango Two]

Snow Possible Monday and Tuesday

Decision Support Briefing #1 As of: 4 PM Saturday March 10, 2018

What Has Changed?  Period of impact now looks like Monday into Tuesday


More Here:
https://www.weather.gov/media/phi/current_briefing.pdf

 

[RU848789]

because the nitpicking is pointing out your little bias you have so when a 1-2 output becomes moderate thats what I mean about embellishing a little...its a minor point but thats what I notice. You also said the NAM was moderate and as far as I know it was minor. The Euro ensembles verbatim have a bit more...a few inches...so that is a positive if you are looking for snow. And there is a trend of a shift west with most models. As for mass equivalence..thats not how the public views things, just as when they hear 3-6 they immediately think plowable when it fact it may be 1-2 on pavement and nuiscance stuff. Most people are concerned about the basics. You tell them 12-18 they expect 12-18 and yes calling for 12-18 and get 4 and then a couple inches of sleet is a bust....the meterologists missed the sleet..thats a bust..how is not, its just like if it rained instead

No bias, just trying to convey the threat and didn't think you were going to be ridiculously nitpicky, forcing me to provide details I didn't think were necessay. The Euro showed 1-2" for most which is light, but showed 2-3" for NYC and much of NE NJ, which is moderate (I think of 2" as the demarcation between light and moderate). I don't just post for your house or even just CNJ. And the CMC showed a general 2-3" for the entire area, which is moderate. And the NAM was light for most of NJ and moderate for parts of North Jersey. So, yeah, I'd say light to maybe moderate fits.

And of course for last year, the snow forecast for areas that were predicted to get 12-20" and got 4-8", like most of CNJ, was a major bust, as I said ad nauseam last year. I'm only saying that the overall forecast for impact was not, as most in the area got 4-8" of snow and 2-3" sleet, which is equivalent to 10-18" of 10:1 snow, which isn't far off the 12-20" forecast Even your 4" of snow and 2" of sleet (6.6" of snow equivalent at 3:1 ratios typical of sleet) is 10.6" of 10:1 snow and your report is certainly on the low end for CNJ (I can repost the maps and reports if you like). My main point was the 4/2 snow/sleet is the same mass as 10.6" of snow, so by your logic, which we agree on, they're identical impact.

 

[sport2231]

If anyone wants to just know the basics...

Some sort of snowfall looks much more likely every 6 hours with the models runs. As of right now, does not appear anything beyond a nuisance snow. But as we learned in the last storm, it doesn’t take much of a change to go from that to much more.

If your following the trends, each model brings it more west and closer to the coast.

This is certainly something to watch over next 24 hours

 

[RU848789]

And as if right on cue, today's 12Z NAM moved the track from about 250 miles SE of the 40N/70W "benchmark" (spot where very impactful snowstorms often travel through while heading NE up the coast), which is way out to sea, to a track only about 50-75 miles SE of the benchmark, which brings a light to moderate snowfall to our area. It's one run of one model, so don't get too worried. Yet. If the other models follow suit, then people can start to get concerned about another snow/mix storm. And when I say follow suit, it's not like the NAM is actually influencing the other models, it just happens to always be the first one to come out (since it only runs 84 hours as opposed to 240-360 hours for most of the rest.

Edit: and the 12Z GFS is now a moderate hit for the whole area (3-6" range with the higher amounts toward the shore), as it moved NW a bit also (it was a light hit at 6Z). Let's see what the UK and Euro say, but the movement NW with the track looks to be real, so far. Almost every storm has done this, this winter - nobody seems to know why...

Back to the models, the 12Z Euro and CMC both show light (1-2") to moderate (2-3") of snow for much of the area, so overall, the threat looks to be light to moderate, as currently modeled.

However, there are indications we could get more than that - the 3 km high resolution 18Z NAM is showing an area-wide 4-8" by hour 60 (1 am Tuesday) and the storm is nowhere near over at that point. While the 12 km (not high res) NAM is only showing 2-4" for the area after 84 hours. Huge discrepancy and for the same model core, but the reason is likely the better way the high res handles vertical velocities and convection, which are the key to generating high snowfall rates.

Long way to go still, so need to buy milk and bread yet, but we're very likely going to get some snow now, IMO. How much is the question. And it's the first model of the 18Z suite out (only a couple other models run at 18Z), so we'll need to wait until tonight's 00Z model runs to know if the NAM is a blip or is leading the way.

Edit: the 18Z GFS is hot off the presses and shows a generally light snowfall, as the northern and southern pieces of energy phase too late, leaving the storm to strengthen after our latitude, hammering S/E New England. It's never easy...

One other point worth noting. This has moved from a Monday morning through evening storm to a Monday night/Tuesday morning storm, as it has slowed down on the models. That means snowfall would be able to accumulate without any melting from the strengthening March sun, such that once snow accumulates on surfaces, including roads, which it will, if intensity is there, we'll see much closer to 10:1 ratio snowfalls.

 

[Sweet Pea's Corner]

People care about what is going to accumulate on pavement not grass. I charge according to what is plowable on pavement not grass. So if it snows 5 inches on pavement but 12 inches on the lawn I will charge for 5 inches. Same as if it goes to sleet from snow. I will charge the amount the has collected on the pavement not what the equivalent would be if it didn't change over. No one cares if it snows 5 inches and then 2 inches of sleet. It's 7 inches total not 13 inches if it didn't change over. That is all.

 

[RU848789]

Very interesting and insightful discussion from the NWS-NYC this afternoon, below. Really like the part I bolded below, as we've seen this film before. As I've tried to explain many times, numerical weather prediction (NWP) is still quite an inexact science, with models routinely struggling to accurately project where storms will develop and how those storms will evolve. Not surprising, when you realize at 3-4 days out, the pieces of energy that eventually form a nor'easter 3-4 days later are several thousand miles from here and there are so many global atmospheric variables that can and do affect the evolution of the forecast, greatly increasing forecast uncertainty.

National Weather Service New York NY
408 PM EST Sat Mar 10 2018

LONG TERM /MONDAY THROUGH SATURDAY/...

A familiar pattern with NWP is a signal for a coastal storm in
the Day 5-7 period, losing the signal in the Day 3 to 4 period,
and then coming back with it in within 48 hrs of the storm. This
appears to be a function of NWP struggles with phasing of
northern and southern stream energy.

This appears to be the case again, with operational models and
good percentage of GEFS/EPS ensemble members having trended
closer to the 40/70 lat/lon in the last 24 hours with a bombing
offshore low. The main players in this forecast lie in the
degree of amplification of a PAC shortwave descending down the
front range of the Rockies today and sliding east through the
Tennessee River Valley/Southeast US Sunday into Monday, and then
its interaction with a large polar low descending into the
Great Lakes Monday into Monday Night. SBU CSTAR ensemble
sensitivity lies in the evolution of the omega blocking over the
Eastern Canada, and the downstream effects of the evolution of
the deep eastern PAC trough over the next 24 hours. Would expect
models to have a better handle on this in the next 24 hours as
the these elements are better remotely sensed and initialized in
the models.

Based on the above reasoning and ensemble qpf probs, moderate
potential exists for an advisory level snow (3+ inches) for the
Monday Night through Tuesday time period, with a low potential for
strong winds and warning level snows(6+ inches), particularly east
of the Hudson River. Thermal profiles support mainly snow, but solar
insolation, boundary layer temps, elevation/maritime effects, and
precipitation intensity are always complicating factors for snow
accum this time of year. Monitor subsequent forecasts through the
weekend for the latest on this storm.

 

[RU848789]

People care about what is going to accumulate on pavement not grass. I charge according to what is plowable on pavement not grass. So if it snows 5 inches on pavement but 12 inches on the lawn I will charge for 5 inches. Same as if it goes to sleet from snow. I will charge the amount the has collected on the pavement not what the equivalent would be if it didn't change over. No one cares if it snows 5 inches and then 2 inches of sleet. It's 7 inches total not 13 inches if it didn't change over. That is all.

Give it a try, because for you it's just as hard to plow (or for me to shovel) 5 inches of snow and 2 inches of sleet as it is to do the same for 12" of snow. Mass is the only variable that matters for that, while depth doesn't matter at all. It's just people aren't knowledgable enough to know the difference - try charging them for mass when it's dense and depth when it's fluffy, lol.

 

[RU4Real]

try charging them for mass when it's dense and depth when it's fluffy

I worked my way through school using a similar philosophy.

 

[RU848789]

I worked my way through school using a similar philosophy.

lol, good one..

 

[Sweet Pea's Corner]

If that happens there is a slight adjustment in price to cover heavy snow. It just doesn't happen as much. I'm probably speaking more of the total accumulation on grass then pavement.

 

[RU848789]

If that happens there is a slight adjustment in price to cover heavy snow. It just doesn't happen as much. I'm probably speaking more of the total accumulation on grass then pavement.

Well yeah, pavement is all that matters for impact really (unless it's on trees and brings them down or maybe visibility), thats' a given IMO. My argument with bac was on mass vs. depth on pavement and I think mass should be all that really matters - problem is we have an historical bias that only cares about depth.

 

[WhiteBus]

Was this thread necessary??

 

[RUJMM78]

People care about what is going to accumulate on pavement not grass. I charge according to what is plowable on pavement not grass. So if it snows 5 inches on pavement but 12 inches on the lawn I will charge for 5 inches. Same as if it goes to sleet from snow. I will charge the amount the has collected on the pavement not what the equivalent would be if it didn't change over. No one cares if it snows 5 inches and then 2 inches of sleet. It's 7 inches total not 13 inches if it didn't change over. That is all.

I prefer keeping my snow blower in the garage which means keeping snow storms away from East Brunswick is the desired track I want to hear in the coming days.

 

[T2Kplus10]

Was this thread necessary??

It's not.

 

[RU848789]

Was this thread necessary??

Why would you even ask that question? No threads are necessary, but some people like these. If you don't, maybe ignore them.

 

[RobotHunter]

26" last storm and looks like a hurricane came through with all the trees and branches down....can't handle another inch of snow

 

[BigEastPhil]

TV 12 Forecast tonight (Michelle Powers) has a mix I believe occurring Tuesday per the Futurecast.

 

[zappaa]

Lots of pain and suffering going on around here.
People with damaged homes, cars and still no electricity.
Anybody rooting for another storm on top of the last one is off their rocker!

 

[DJ Spanky]

I don't think anyone is really rooting for us to get hit by another storm.

 

[e5fdny]

Was this thread necessary??

It's not.

Yes it is.

Possible new meteorological event/game/etc. = new thread.

 

[Scarlet dollar]

Lots of pain and suffering going on around here.
People with damaged homes, cars and still no electricity.
Anybody rooting for another storm on top of the last one is off their rocker!

Not rooting for one, but sure would like to know what to prepare for. I thank numbers and Bac for keeping us informed. And for those that don't think this should be a thread, simple. Don't read it.

 

[RU848789]

Back to the models, the 12Z Euro and CMC both show light (1-2") to moderate (2-3") of snow for much of the area, so overall, the threat looks to be light to moderate, as currently modeled.

However, there are indications we could get more than that - the 3 km high resolution 18Z NAM is showing an area-wide 4-8" by hour 60 (1 am Tuesday) and the storm is nowhere near over at that point. While the 12 km (not high res) NAM is only showing 2-4" for the area after 84 hours. Huge discrepancy and for the same model core, but the reason is likely the better way the high res handles vertical velocities and convection, which are the key to generating high snowfall rates.

Long way to go still, so need to buy milk and bread yet, but we're very likely going to get some snow now, IMO. How much is the question. And it's the first model of the 18Z suite out (only a couple other models run at 18Z), so we'll need to wait until tonight's 00Z model runs to know if the NAM is a blip or is leading the way.

Edit: the 18Z GFS is hot off the presses and shows a generally light snowfall, as the northern and southern pieces of energy phase too late, leaving the storm to strengthen after our latitude, hammering S/E New England. It's never easy...

One other point worth noting. This has moved from a Monday morning through evening storm to a Monday night/Tuesday morning storm, as it has slowed down on the models. That means snowfall would be able to accumulate without any melting from the strengthening March sun, such that once snow accumulates on surfaces, including roads, which it will, if intensity is there, we'll see much closer to 10:1 ratio snowfalls.

NWS-NYC has put a snowfall map up; none from NWS Philly yet...

Looks like that insane run of the 18Z 3 km NAM may have been a blip. So far, tonight the 00Z model suite is coming in with some modest consensus for a light to moderate snowfall (models generally showing about 1-4" across the area with the higher amounts usually near the coast) Monday evening into Tuesday morning, as the low pressure system is forecast to be just far enough SE of the benchmark to keep the heaviest precip offshore. In addition, at this point the cyclone isn't expected to be that strong in our area, but is expected to stregthen and hit eastern LI and SE New England with major snows. Still waiting on the Euro/UK, though.

With snowfalls this light, the snow would not accumulate during the day, but with the snow likely to be falling while it's dark, the snow ought to be able to accumulate fairly easily, with temps close to 32F, although paved surfaces warmed during the day will be harder to accumulate on, even at night. However, keep in mind that the potential is still there for more substantial snows to hit our area - would only take a slightly further NW track and few hour earlier strengthening of the storm. A complete miss out to sea is also still possible. Not really worth reprinting the 4 pm snowfall maps from the NWS at this point, since they're out of date and will be updated in a few hours.