Two Mdt to high impact events NYC subforum; wknd Jan 6-7 Incl OBS, and mid week Jan 9-10 (incl OBS). Total water equiv by 00z/11 general 2", possibly 6" includes snow-ice mainly interior. RVR flood potential increases Jan 10 and beyond. Damaging wind.

[Tatamy]

34 minutes ago, NittanyWx said:

With surface temps in the mid 30's, you'd take the under.  Clown maps are exciting to look at, but you do still need to check those temperature panels and soundings...

Your point is well taken.  I was speaking in general terms.  Make no mistake that if even if half of that accumulates on city streets and sidewalks that would be a lot.  The fact that much of this falls at night will help.  I used to work in the city on the west side and recall a number of times where snow was falling at the roof top level (six stories up) and was falling as rain at street level.  It really does take a significant cold air mass to get accumulations especially in Manhattan.

[LibertyBell]

1 minute ago, jm1220 said:

We have to hope the confluence/blocking can be strong enough to force the storm track SE. If that’s too weak I agree the track will probably be unfavorable for snow in the city and E. The western trough isn’t good unless it can act as a kicker-the SE ridge will try to pump and cause a hugger/inland track. That confluence is our hope to force the low to be kicked east. 

What was going on before that showed a more suppressed track for several runs?

[EastonSN+]

3 minutes ago, jm1220 said:

We have to hope the confluence/blocking can be strong enough to force the storm track SE. If that’s too weak I agree the track will probably be unfavorable for snow in the city and E. The western trough isn’t good unless it can act as a kicker-the SE ridge will try to pump and cause a hugger/inland track. That confluence is our hope to force the low to be kicked east. 

Yup. I posted a couple times that the storm to the west can help kick this storm east before it gains too much latitude. Only UKMET and GEM show a rainy outcome for most. 

That said, it doesn't LOOK like Bluewave, Nittany or Walt are too confident for accumulating snow for CPK.

[LibertyBell]

2 minutes ago, Tatamy said:

Your point is well taken.  I was speaking in general terms.  Make no mistake that if even if half of that accumulates on city streets and sidewalks that would be a lot.  The fact that much of this falls at night will help.  I used to work in the city on the west side and recall a number of times where snow was falling at the roof top level (six stories up) and was falling as rain at street level.  It really does take a cold air mass to get accumulations especially in Manhattan.

Theoretically if that's the case then the amount of snowfall could vary a lot based on elevation.  There are hills in northern Manhattan and also on Staten Island that could get snow while the more commercial areas get rain?

 

[WestBabylonWeather]

2 minutes ago, LibertyBell said:

Theoretically if that's the case then the amount of snowfall could vary a lot based on elevation.  There are hills in northern Manhattan and also on Staten Island that could get snow while the more commercial areas get rain?

 

North shore LI can get snow while south shore rains to. And it sucks 

[MJO812]

Eps is north 

[LibertyBell]

2 minutes ago, WestBabylonWeather said:

North shore LI can get snow while south shore rains to. And it sucks 

Maybe Bald Hill will get significant snow lol

[MJO812]

Great for interior

[Tatamy]

16 minutes ago, LibertyBell said:

Theoretically if that's the case then the amount of snowfall could vary a lot based on elevation.  There are hills in northern Manhattan and also on Staten Island that could get snow while the more commercial areas get rain?

 

It’s not based upon the elevation.  It’s based upon the urban heat island effect.  There can be snow with the event anywhere in the city however how much of it sticks is very dependent on surface temperatures.  You then have to incorporate temperatures up in the atmosphere to this equation.  Many models are calling for mixing or even a change to rain.  Throw in the presence of a warm ocean and the nearby LI Sound.  Many parts that play into this scenario.

[SACRUS]

[MJO812]

Interior areas look great for this storm.  The coast will struggle with mixing most likely until the storm moves away.

Modeling can change but I think a few slushy inches for the coast most likely with alot more inland.

[NEG NAO]

1 minute ago, MJO812 said:

Interior areas look great for this storm.  The coast will struggle with mixing most likely until the storm moves away.

Modeling can change but I think a few slushy inches for the coast most likely with alot more inland.

what is your definition of "the coast" ?

 

[Allsnow]

2 minutes ago, MJO812 said:

Interior areas look great for this storm.  The coast will struggle with mixing most likely until the storm moves away.

Modeling can change but I think a few slushy inches for the coast most likely with alot more inland.

Two camps for the 06z eps in the spread. 

[MJO812]

Just now, NEG NAO said:

what is your definition of "the coast" ?

 

What ?

[jm1220]

10 minutes ago, WestBabylonWeather said:

North shore LI can get snow while south shore rains to. And it sucks 

I grew up on the S Shore and know that all too well. It's still too early and a lot can change but personally I'm pessimistic about this one. I'd keep expectations tempered near the coast. Maybe we can pull a surprise and the confluence can help us in time but it might be more helpful for places like Boston. We've seen that big last minute NW trend with these and this setup with the western trough looks to me like that could happen again. 

[LibertyBell]

10 minutes ago, Tatamy said:

It’s not based upon the elevation.  It’s based upon the urban heat island effect.  There can be snow with the event anywhere in the city however how much of it sticks is very dependent on surface temperatures.  You then have to incorporate temperatures up in the atmosphere to this equation.  Many models are calling for mixing or even a change to rain.  Throw in the presence of a warm ocean and the nearby LI Sound.  Many parts that play into this scenario.

wow that makes it sound like an early spring event.

Would rates also factor in-- the higher the rate the more chance it will be snow (and also if it occurs mainly at night?)

[LibertyBell]

1 minute ago, jm1220 said:

I grew up on the S Shore and know that all too well. It's still too early and a lot can change but personally I'm pessimistic about this one. I'd keep expectations tempered near the coast. Maybe we can pull a surprise and the confluence can help us in time but it might be more helpful for places like Boston. We've seen that big last minute NW trend with these and this setup with the western trough looks to me like that could happen again. 

Remember 2014? ;-)

 

[NEG NAO]

5 minutes ago, MJO812 said:

What ?

give examples the terrain around the metro varies - for example when I lived in Silverton Toms River a mile from the water - Northern Ocean County back in the 80's there were storms where we got an inch or less and when I drove inland 7 miles there were several inches on the ground I define the coast as only a few miles under 5 from the water down there

[Allsnow]

 

[LibertyBell]

6 minutes ago, NEG NAO said:

what is your definition of "the coast" ?

 

Mine is anywhere within 25 miles of the ocean.

[LibertyBell]

1 minute ago, NEG NAO said:

give examples the terrain around the metro varies - for example when I lived in Silverton Toms River a mile from the water - Northern Ocean County back in the 80's there were storms where we got an inch or less and when I drove inland 7 miles there were several inches on the ground I define the coast as only a few miles under 5 from the water down there

ah so it varies and you can't use a single mileage for everyone....see I consider Manhattan has part of the coast.

[NEG NAO]

3 minutes ago, LibertyBell said:

ah so it varies and you can't use a single mileage for everyone.

yes and in NJ there are natural boundaries such as the Raritan River in Northern Middlesex County and this storm has shown model outputs from various models showing that area as the rain snow line

[Tatamy]

2 minutes ago, LibertyBell said:

wow that makes it sound like an early spring event.

Would rates also factor in-- the higher the rate the more chance it will be snow (and also if it occurs mainly at night?)

Rates do matter however the precip type is ultimately dependent on temperatures aloft.

[NittanyWx]

Looking forward to modeling tonight/tomorrow midday as we start getting more robust sampling of this western system.

 

I'd say up to this point odds have been slightly skewed towards more suppression vs cutter based on synoptic pattern, we now should start being able to discern which is the more likely risk with better certainty starting with the 0z tonight and 12z tomorrow.

 

The region is threading a needle between trying to have enough western amplification/east canada 50/50 to get this storm north (but not too much), trying to deepen the low (but not too much) and if you do both, also trying to avoid warm air nose near the 700mb level.

 

Delicate balancing act with several moving pieces.  It's going to be hard at the coastal plain (city, LI, coastal NJ) for this to deliver much more than a light/low-end moderate event I feel because of marginal temps (being overnight does help a bit) but whether this is a notable interior event where sfc temps will be colder we should start getting an idea on soon as we start defining track risks with more conviction.

 

You guys know I've been someone who felt this period could work for over two weeks now, but as I said then and will continue to say now, a few things need to go right still and not all of them have done so yet.

[Allsnow]

This time last week the storm we are currently following was forecasted to be a warm rain event to Maine. The airmass and setup has certainly improved 

[Nibor]

1 minute ago, Allsnow said:

This time last week the storm we are currently following was forecasted to be a warm rain event to Maine. The airmass and setup has certainly improved 

After last year I forgot that can happen. 

[North and West]

Yeah but this kinda Christmas is never guaranteed. 

Maybe it’s the ayahuasca we’re smoking, but I thought suppression was the issue? (I only do that with memories)


.

[donsutherland1]

From the WPC's Probabilistic Winter Storm Severity Index tool: Moderate Impact

 

[suzook]

8 minutes ago, Allsnow said:

This time last week the storm we are currently following was forecasted to be a warm rain event to Maine. The airmass and setup has certainly improved 

Very good point. January has arrived, and so has some cold. I feel the last few years any snow in December is a gift. 

[Dark Star]

30 minutes ago, NEG NAO said:

what is your definition of "the coast" ?

 

Normally, Union and Middlesex Counties in NJ receive the same type of precip as mid town Manhattan (anticipated debate to follow)...