Snowfall NYC subforum Jan 6 and OBS if needed

[SnowGoose69]

1 hour ago, Allsnow said:

06z euro going to be south of 00z. This threat is on life support now. 

The problem is this is all reliant on that one little piece of energy at 500 that swings down over NNE at the wrong time around 90 hours.  With so many little piece of energy pinwheeling around there is no way to know at this range if that timing is correct, 6-12 hours off and this could go 50-75 miles more north or south.  

[RU848789]

Would love to know how the NBM increased snowfall north of 276/195 up through 80 and even 84 at 07Z vs 01Z when every single model I have access to (GFS, Euro, ICON, and the ensembles for these) showed a significant decrease in snowfall for this area at 06Z vs 12Z. Only one model at 6Z, the ICON, has NYC at >1" (and the 0Z UK and CMC also had NYC at <1"), yet the NBM has NYC going from 2.4" to 3.5" from 01Z to 07Z.  @wdrag?  I know we had a conversation yesterday morning about inconsistencies with the NBM (between its high snowfall vs. the WPC low precip at the time), but this seems even worse.  

Edit: well, the 07Z NBM clearly thinks there will be 0.2-0.3" QPF for NNJ/NYC, as its QPF estimate is identical to the latest WPC QPF from 12Z today, below...

[NEG NAO]

3 minutes ago, RU848789 said:

Would love to know how the NBM increased snowfall north of 276/195 up through 80 and even 84 at 07Z vs 01Z when every single model I have access to (GFS, Euro, ICON, and the ensembles for these) showed a significant decrease in snowfall for this area at 06Z vs 12Z. Only one model at 6Z, the ICON, has NYC at >1" (and the 0Z UK and CMC also had NYC at <1"), yet the NBM has NYC going from 2.4" to 3.5" from 01Z to 07Z.  @wdrag?  I know we had a conversation yesterday morning about inconsistencies with the NBM (between its high snowfall vs. the WPC low precip at the time), but this seems even worse.  

Maybe because the models you don't have access too (which are quite a few) that they incorporate into the NBM continued the north trend ???

[MJO812]

Just now, NEG NAO said:

Maybe because the models you don't have access too (which are quite a few) that they incorporate into the NBM continued the north trend ???

I think they are lagging behind and will fixed this.

[NEG NAO]

7 minutes ago, MJO812 said:

I think they are lagging behind and will fixed this.

we are still almost 3 days away from the event - we are still on the rollercoaster ride we are only dealing with a 50 mile or so difference here between several inches and less then that........also how do they " fix this" solution? it is computer generated from their input at the time......

[wdrag]

10 minutes ago, NEG NAO said:

Maybe because the models you don't have access too (which are quite a few) that they incorporate into the NBM continued the north trend ???

What about dendrite-snow ratios in subfreezing airmass If qpf zero, then I say no snow.  We just dont have it all...

Also there is snow today s of I80. 

[NEG NAO]

1 minute ago, wdrag said:

What about dendrite-snow ratios in subfreezing airmass If qpf zero, then I say no snow.  We just dont have it all...

Also there is snow today s of I80. 

which locations are you talking about with zero qpf ? 

[wdrag]

Just now, wdrag said:

What about dendrite-snow ratios in subfreezing airmass If qpf zero, then I say no snow.  We just dont have it all...

Also there is snow today s of I80. 

Basically I cant pretend to know all of NBM, nor do I think can anyone not directly tuned into what goes into it-certainly not me. 

 

Todays WPC 4AM products make more sense to me including prob 4", and the null qpf line give or take 30 mi.  

I do think the 06z models are too suppressed for the strength of the sw and confluence in my mind is lifting north.  QPF did not respond. Not a strong northerly flow Monday morning helps as well... reducing influx of dry air. 

[NEG NAO]

1 minute ago, wdrag said:

Basically I cant pretend to know all of NBM, nor do I think can anyone not directly tuned into what goes into it-certainly not me. 

 

Todays WPC 4AM products make more sense to me including prob 4", and the null qpf line give or take 30 mi.  

I do think the 06z models are too suppressed for the strength of the sw and confluence in my mind is lifting north.  QPF did not respond. Not a strong northerly flow Monday morning helps as well... reducing influx of dry air. 

exactly and we have been on this rollercoaster ride from one or 2 model run cycles in a row up and down and we still are close to 3 days away until showtime ....

[wdrag]

4 minutes ago, NEG NAO said:

which locations are you talking about with zero qpf ? 

Here is the BOM qpf and snow at 07z/3 ..  where zero qpf, should be no SNOW unless a BOM developer can explain.  This needs a fix... cannot have both.  

 

I guess I can make it a reach on 0 qpf but snow, though makes no sense to me, is that one of the inputs is model snow but not that model qpf??  That is a reach on my part.  

 

Anyway, I have to go to work and will check back at 7P...  I hope we're still in the fringe game at that time.  

 

One good think about all this BOM review.. the NWS wants us to use this as BASE and then adjust based on our model intelligent perceptions and collaborations.  So they have us looking.  Also good that all this is documented so we can look back Monday evening, at least I will.  

Good job on the part of all participants. 

 

 

[donsutherland1]

31 minutes ago, NEG NAO said:

which locations are you talking about with zero qpf ? 

Hartford is one example on the 12z with 0.4" of snow.

[MJO812]

Sref further south. Nam will most likely be south.

[EastonSN+]

8 minutes ago, donsutherland1 said:

Hartford is one example on the 12z with 0.4" of snow.

Hi Don, I believe Central Park stands at 11.6 in of snow for the last two seasons and this season so far. There is a chance that DC can reach a foot which would eclipse the 3-year Central Park snowfall total. I wonder if this has ever happened where DC's 3-year snowfall average has eclipsed Central Park.

[MJO812]

On 1/1/2025 at 7:24 PM, Rjay said:

There's nothing wrong with 18z runs

Alot of people don't believe the off hour runs. In this case it was wrong .

[BoulderWX]

4 minutes ago, MJO812 said:

Sref further south. Nam will most likely be south.

Yup - as often happens, we see the overcorrection north on the models for a couple of suites only to settle somewhere in the middle of the guidance or in this case the southern end of it. 
 

 

[donsutherland1]

1 minute ago, EastonSN+ said:

Hi Don, I believe Central Park stands at 11.6 in of snow for the last two seasons and this season so far. There is a chance that DC can reach a foot which would eclipse the 3-year Central Park snowfall total. I wonder if this has ever happened where DC's 3-year snowfall average has been Central Park.

NYC is at 12.6". I believe you missed the 1.0" that fell on 12/24.

As to your question, it has on 11 occasions. The most recent such period was 1987-1989 with DCA's 3-year average coming to 24.8" and NYC's to 18.6".

[the_other_guy]

It really isnt a roller coaster. The storm misses south and may graze us. Everything else is model noise

[LVblizzard]

With that new lobe of confluence showing up and pressing down into Quebec and Maine, we need this storm to buck the trend of slowing down and speed up again. If it’s too slow then that lobe comes crashing in and squashes the whole thing towards DC.

[Stormlover74]

6 minutes ago, the_other_guy said:

It really isnt a roller coaster. The storm misses south and may graze us. Everything else is model noise

We're back where we were 3 days ago

[pstar3182]

1 minute ago, Stormlover74 said:

We're back where we were 3 days ago

It's always groundhog day, eventually. 

[NJwx85]

The PV dropping down through New England killed this storm and the one that would have come the end of next week. The energy coming out of the plains won't dig enough and the pattern is flat and overall progressive. It comes down to bad timing. 

 

[RU848789]

1 hour ago, RU848789 said:

Would love to know how the NBM increased snowfall north of 276/195 up through 80 and even 84 at 07Z vs 01Z when every single model I have access to (GFS, Euro, ICON, and the ensembles for these) showed a significant decrease in snowfall for this area at 06Z vs 12Z. Only one model at 6Z, the ICON, has NYC at >1" (and the 0Z UK and CMC also had NYC at <1"), yet the NBM has NYC going from 2.4" to 3.5" from 01Z to 07Z.  @wdrag?  I know we had a conversation yesterday morning about inconsistencies with the NBM (between its high snowfall vs. the WPC low precip at the time), but this seems even worse.  

Edit: well, the 07Z NBM clearly thinks there will be 0.2-0.3" QPF for NNJ/NYC, as its QPF estimate is identical to the latest WPC QPF from 12Z today, below...

A couple of folks on 33andrain, including one met, have said that the NBM is time lagged, i.e., the 07Z NBM would only include model inputs through 0z and not the 06Z models.  That would at least explain why the NBM snowfall for 07Z is greater than the 01Z NBM for areas N of Philly and much greater than the 06Z models would suggest, since they're generally much lower than the 0Z models were.  To me, that makes the NBM a much less useful tool, if that's correct, as it would always be 6 hours behind. 

@MGorse- sorry to tag you again, but can you clarify if this is the case, i.e., what time model inputs go into a particular NBM run?  I'd also be curious (see the quoted post) if the 12Z WPC QPF output is simply the 07Z NBM QPF field (they're identical), which is based on 0Z model data - that seems to be very old data, then.  

[MJO812]

Yep Nam south

[Brian5671]

Dry and Cold.   BORING

[LibertyBell]

51 minutes ago, EastonSN+ said:

Hi Don, I believe Central Park stands at 11.6 in of snow for the last two seasons and this season so far. There is a chance that DC can reach a foot which would eclipse the 3-year Central Park snowfall total. I wonder if this has ever happened where DC's 3-year snowfall average has eclipsed Central Park.

this is actually normal when you dont have many coastal storms.

there are two primary west-east track, one is to our south the other to our north

 

1989-1990 had way more snow in DC too

the 1980s were in general much snowier both to our south and to our north.

Look up these storms

 

Vet Day 1987

February 1989

December 1989

in that last one we got rain and thunderstorms while DC got snow

[ILoveWinter]

Just can't catch a break here. I think it's comical that we go from cutters or storms with no cold air in place to an overly suppressed set up. I can deal with the first two but the confluence induced dry walls are the worst.

[LibertyBell]

1 minute ago, ILoveWinter said:

Just can't catch a break here. I think it's comical that we go from cutters or storms with no cold air in place to an overly suppressed set up. I can deal with the first two but the confluence induced dry walls are the worst.

but it's normal

 

[MJO812]

I will continue to look at the video I took of the light snowfall from Christmas Eve to make me happy.

[North and West]

.

[Allsnow]

2 minutes ago, MJO812 said:

I will continue to look at the video I took of the light snowfall from Christmas Eve to make me happy.

Another “epic pattern” failure