December 16-17, 2020 Storm Observations and Nowcast

[nycwinter]

1 minute ago, RU848789 said:

SIAP, but here's the latest from the NWS...if the underlined part about the snow/sleet/rain transition line being further SE than expected comes true, folks from Trenton to NYC will likely see mostly or all snow (and at least 8" and up to 12" and maybe more if the back end delivers), but that's certainly not a given. At current rates, we'll have 6" by 10 pm, the earliest any models showed sleet. We'll see...

 

Area Forecast Discussion
National Weather Service Mount Holly NJ
555 PM EST Wed Dec 16 2020

NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Evening Update...

The storm is well underway now, with steady to heavy snow, sleet,
and rain having overspread all areas. Made a few tweaks to the snow
amounts to reflect some observations, but we`re well past the point
for any meaningful changes. In general the onset and ptype
transition have gone about as expected and the forecast continues to
track well for such a big event. If anything the cold air has held
on a little longer than expected and certainly longer than a lot of
this morning`s hi res guidance indicated, leading to some higher
totals across portions of southern New Jersey. This includes here at
the office where some massive snowflakes and snowfall rates of 2 to
3 inches per hour have been observed leading into the transition,
which was happening here around 5:30 PM after about 4 inches of
snow. That transition line continues to march north and there have
been no changes to headlines or the overall forecast philosophy,
with the sharp gradient appearing it will end up just slightly
southeast of forecast especially in New Jersey.

In addition to the ptype transition, satellite and radar also show
the dry slot rapidly approaching from the southwest. This should
lead to precipitation rates falling off significantly or
precipitation ending completely for areas such as Delmarva and parts
of southern New Jersey over the next few hours. Further north, snow
rates are starting to come up significantly, and these areas remain
in line for the highest totals. No noteworthy changes to the
forecast to the north and west with a widespread 10 to 20 inches of
snow still expected. Dry slotting should be less of a factor to the
north, but banding will produce local variations in totals.

Late tonight as the low starts to pull away, a final wrap-around
band of precipitation may bring some additional snow to many areas,
especially towards central and northern New Jersey. This could add
on an inch or two of accumulation within a couple of hours during
the predawn hours. In addition, falling temperatures later tonight
could lead to a refreeze of any water or slush, yielding continued
treacherous conditions into the morning.

No changes to the wind forecast either, with winds steadily ramping
up from south to north. A 60 to 70 kt easterly LLJ will continue to
bring a lengthy period of gusty winds as it partially mixes down to
the surface, especially along the coast and within the heavier
precipitation. Gusts up to 60mph remain possible along the immediate
coast this evening and into tonight, with 45 to 55mph gusts possible
in the coastal plain and 35 to 45 mph gusts elsewhere. Storm total
QPF continues to look mainly at or below 2 inches, possibly a bit
higher along the New Jersey coast and towards the Poconos. Dry
slotting should help keep liquid totals manageable in most areas.
Outside of nuisance/poor drainage flooding, no hydro issues are
anticipated. Marine and coastal flood headlines remain in effect,
and are covered in their respective sections below.

hmm channel 7 map shows 9 inches by midnight in the city..

[SI Mailman]

the southeast trend of the sleet line would be good news for me since I'm on the edge of good totals and taint.  

[nycwinter]

2 minutes ago, RU848789 said:

SIAP, but here's the latest from the NWS...if the underlined part about the snow/sleet/rain transition line being further SE than expected comes true, folks from Trenton to NYC will likely see mostly or all snow (and at least 8" and up to 12" and maybe more if the back end delivers), but that's certainly not a given. At current rates, we'll have 6" by 10 pm, the earliest any models showed sleet. We'll see...

 

Area Forecast Discussion
National Weather Service Mount Holly NJ
555 PM EST Wed Dec 16 2020

NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Evening Update...

The storm is well underway now, with steady to heavy snow, sleet,
and rain having overspread all areas. Made a few tweaks to the snow
amounts to reflect some observations, but we`re well past the point
for any meaningful changes. In general the onset and ptype
transition have gone about as expected and the forecast continues to
track well for such a big event. If anything the cold air has held
on a little longer than expected and certainly longer than a lot of
this morning`s hi res guidance indicated, leading to some higher
totals across portions of southern New Jersey. This includes here at
the office where some massive snowflakes and snowfall rates of 2 to
3 inches per hour have been observed leading into the transition,
which was happening here around 5:30 PM after about 4 inches of
snow. That transition line continues to march north and there have
been no changes to headlines or the overall forecast philosophy,
with the sharp gradient appearing it will end up just slightly
southeast of forecast especially in New Jersey.

In addition to the ptype transition, satellite and radar also show
the dry slot rapidly approaching from the southwest. This should
lead to precipitation rates falling off significantly or
precipitation ending completely for areas such as Delmarva and parts
of southern New Jersey over the next few hours. Further north, snow
rates are starting to come up significantly, and these areas remain
in line for the highest totals. No noteworthy changes to the
forecast to the north and west with a widespread 10 to 20 inches of
snow still expected. Dry slotting should be less of a factor to the
north, but banding will produce local variations in totals.

Late tonight as the low starts to pull away, a final wrap-around
band of precipitation may bring some additional snow to many areas,
especially towards central and northern New Jersey. This could add
on an inch or two of accumulation within a couple of hours during
the predawn hours. In addition, falling temperatures later tonight
could lead to a refreeze of any water or slush, yielding continued
treacherous conditions into the morning.

No changes to the wind forecast either, with winds steadily ramping
up from south to north. A 60 to 70 kt easterly LLJ will continue to
bring a lengthy period of gusty winds as it partially mixes down to
the surface, especially along the coast and within the heavier
precipitation. Gusts up to 60mph remain possible along the immediate
coast this evening and into tonight, with 45 to 55mph gusts possible
in the coastal plain and 35 to 45 mph gusts elsewhere. Storm total
QPF continues to look mainly at or below 2 inches, possibly a bit
higher along the New Jersey coast and towards the Poconos. Dry
slotting should help keep liquid totals manageable in most areas.
Outside of nuisance/poor drainage flooding, no hydro issues are
anticipated. Marine and coastal flood headlines remain in effect,
and are covered in their respective sections below.

the sleet area may just be in only brooklyn southern queens and not in uptown in manhattan

[Rjay]

12 minutes ago, bluewave said:

Heaviest snow of the event so far in SW Suffolk. Estimated visibility 1/4 to 1/2 mile.

Ripping

[justinj]

33 minutes ago, MJO812 said:

I haven't seen it snow this hard with gusty winds in years.

Beautiful outside

 Upton

.HEAVY SNOW DEVELOPING OVER SOUTHERN
FAIRFIELD...HUDSON...PASSAIC...
UNION...BERGEN...ESSEX...QUEENS...RICHMOND...BRONX...KINGS...
ROCKLAND...SOUTHERN WESTCHESTER...SUFFOLK...NEW YORK (MANHATTAN) AND
NASSAU COUNTIES...

Heavy snow will develop over the area through 7pm. Snowfall rates of
1 to possibly two inches per hour are likely to develop.

I have. I believe it was March 22 2018 Islip airport which is two miles from me had 5” in one hour. They had 9” of snow in two hours

[Gravity Wave]

Keep in mind the sleet line was supposed to stall out for a while once it reached Sandy Hook. It's already behind schedule along the Jersey shore.

[dmillz25]

About 3” now it’s Accumulating fast

[TJW014]

41. Still raining. 10 miles to the north, heavy snow, with about 3" on the roads

[bluewave]

2 minutes ago, Gravity Wave said:

Keep in mind the sleet line was supposed to stall out for a while once it reached Sandy Hook. It's already behind schedule along the Jersey shore.

Slower along the Jersey Shore for the time being and faster near the Delaware River.

[weatherpruf]

12 minutes ago, MJO812 said:

My friend in central NJ has 5 inches 

What do you consider CNJ? I'm in CNJ we have nowhere near that here. Maybe 2, 2.5. CNJ goes from like Jackson all the way to just north of the GSP bridge; areas to the west could have that much; i'm to the east. Flakes also just got bigger, which usually is a bad sign.....but I'm not hearing the sleet line is moving north yet.....

[sussexcountyobs]

As of 6:45 pm, just measured 1.4" new. Current temp is 18.7° with moderate snow falling.

[chrisNJ]

Eyeballing 4” or so in Hillsborough 

[dWave]

10 minutes ago, nycwinter said:

the sleet area may just be in only brooklyn southern queens and not in uptown in manhattan

Thats what they were forecasting anyway, so perhaps it may not make it to BK, southern Queens for the most part.

[jm1220]

4 minutes ago, Gravity Wave said:

Keep in mind the sleet line was supposed to stall out for a while once it reached Sandy Hook. It's already behind schedule along the Jersey shore.

When the precip starts to peter out later tonight the mix will come north faster. That's what's happening in PA. 

[SnowGoose69]

NYC had .17 liquid this past hour

[SomeguyfromTakomaPark]

Very legit band coming through nyc metro. 

[TJW014]

According to KDIX radar, we've had 2.5" of liquid here since the start of the storm.

[weatherpruf]

16 minutes ago, nycwinter said:

the sleet area may just be in only brooklyn southern queens and not in uptown in manhattan

If it its sleet in Brooklyn it will usually be sleet by me and RU's area as well. It's going to sleet, it's just matter of time, for a lot of us here. When? That's the question....at least it isn't rain.

[sussexcountyobs]

Just now, CarLover014 said:

According to KDIX radar, we've had 2.5" of liquid here since the start of the storm.

?

[Allsnow]

5 minutes ago, weatherpruf said:

What do you consider CNJ? I'm in CNJ we have nowhere near that here. Maybe 2, 2.5. CNJ goes from like Jackson all the way to just north of the GSP bridge; areas to the west could have that much; i'm to the east. Flakes also just got bigger, which usually is a bad sign.....but I'm not hearing the sleet line is moving north yet.....

It’s stopped at Toms River. We will be fine. Areas in eastern pa will flip way before us.

 

mod snow 3 inches 

[North and West]

.

[MJO812]

4 minutes ago, weatherpruf said:

If it its sleet in Brooklyn it will usually be sleet by me and RU's area as well. It's going to sleet, it's just matter of time, for a lot of us here. When? That's the question....at least it isn't rain.

I will let you know when I change over

[TJW014]

2 minutes ago, sussexcountyobs said:

?

 

[lee59]

Temperature slowly rising here, up to 29degrees

[tim]

...here on ELI 29.8* ..moderate snow..

snow started around 3:45..stuck immediately to everything..

not sure but either we 'taint or we ain't"..hoping for ain't..

[sussexcountyobs]

1 minute ago, CarLover014 said:

 

Definitely not correct on qpf

[krisb]

Ripping in this nice band in SE Nassau. Nice big flakes. 

[jysamuel]

Hi everyone - longtime forum stalker finally decided to join

 

Heavy snow here on the Staten Island south shore - a balmy 25° and close to 3.5" here. Roads are a mess!

[chrisNJ]

Sleet in Harrisburg per TWC after 3”.  Screw zone?

[jm1220]

That yellow band just got here-wow!! Dumping.