It's not coming 1/31-2/1 2026

[MJO812]

Brutal close misses

[donsutherland1]

17 minutes ago, RU848789 said:

Don - you shared the table below of NBM snowfall inputs last week, but I simply can't imagine how the new NBM is more than the last run and how either of them could be right even with the wetter SREF inputs, as I think everything else should be near zero, except for low amounts from the EPS.  And if it were just an academic question it might not be a big deal, but the NWS regularly refers to it in their AFDs, so clearly they use it, which I don't get.  Any insight?

 

I suspect that there's a programming issue of some kind. Last winter, there were a number of cases where the NBM showed measurable snow even when QPF was 0.00". I raised the issue and was told it would be addressed in the next version (v. 5.0). I suspect that issue is skewing the numbers. For the upcoming system, the 19z NBM showed 0.02" QPF for Philadelphia. Its snowfall forecast was 4.9" (4.3" if 24-hour snowfall is used). That's a wholly unrealistic snowfall estimate.

[Brian5671]

new GFS shunks DT with close to 0-NC then OTS

[nycsnow]

Just now, Brian5671 said:

new GFS shunks DT with close to 0-NC then OTS

Even cape cod don’t really get anything…. What an awful storm lol 

[MegaMike]

33 minutes ago, RU848789 said:

How does the NBM go up for the Philly-NJ-NYC region after every 12Z model was a whiff (other than the SREFs)?

 

 

 

 

 

From hour 61-84 the NBM snowfall (it's different per variable) product composes of the GEFS (30 members; weighted 24.75%), EPS (50 members; 41.25%), GFS (weighted 4%), and SREF (10 members; weighted 30%). Likely, either the SREFs, and or EPS, beefed up snowfall a little bit... The GEFS/GFS still look poor.

[Brian5671]

10 minutes ago, MJO812 said:

Brutal close misses

In the end it won't be all that close.

[RU848789]

8 minutes ago, donsutherland1 said:

I suspect that there's a programming issue of some kind. Last winter, there were a number of cases where the NBM showed measurable snow even when QPF was 0.00". I raised the issue and was told it would be addressed in the next version (v. 5.0). I suspect that issue is skewing the numbers. For the upcoming system, the 19z NBM showed 0.02" QPF for Philadelphia. Its snowfall forecast was 4.9" (4.3" if 24-hour snowfall is used). That's a wholly realistic snowfall estimate.

Don - thanks, as always, although I'm assuming you meant to say that's a wholly unrealistic estimate, correct?

[donsutherland1]

Just now, RU848789 said:

Don - thanks, as always, although I'm assuming you meant to say that's a wholly unrealistic estimate, correct?

Yes. I've fixed the typo. 

[Stormlover74]

[nycwinter]

since it appears it wont be that close nothing to be upset about time to move on to the next storm..

[Wxbear25]

Yeah... Realistically speaking, the only ones really in the game at this point are Cape Cod and Nantucket

Montauk is kinda, sorta maybe a little in the game and points west of that are almost definitively done for

gonna keep watching through 12z tomorrow since thats when the s/w will be over the US fully for the first time, but, barring pretty massive changes, this goose is cooked for 99.99% of our sub-forum

[donsutherland1]

Below is the NWS forecast for parts of North Carolina and South Carolina. Since 1950, eight storms brought 4" or more snow to Wilmington, NC. Just one of those storms brought measurable snowfall to New York City. 

[RU848789]

6 minutes ago, MegaMike said:

From hour 61-84 the NBM snowfall (it's different per variable) product composes of the GEFS (30 members; weighted 24.75%), EPS (50 members; 41.25%), GFS (weighted 4%), and SREF (10 members; weighted 30%). Likely, either the SREFs, and or EPS, beefed up snowfall a little bit... The GEFS/GFS still look poor.

Thanks, but even if one takes the GFS, GEFS and EPS over the last 3 runs for Philly, for example, the average is about 1/2" and those models contribute ~60% to the NBM according to your post with the SREFs having 30% input - if that's the case to get from 1/2" for 60% of the input to the 4.8" seen for Philly on the latest NBM, that implies the SREFs would need to be 12+" for Philly at only 30% of the input, which seems impossible, as the SREF snowfall (10:1) from the last few runs has been in the 2-4" range for Philly, unless that snow is at 30-40:1 ratios (and Kuchera is showing 20:1 inland).  But I will say I didn't realize the SREFs were counted so strongly and it at least explains probably half of the NBM numbers for inland locations.  

 

[MANDA]

35 minutes ago, Brian5671 said:

new GFS shunks DT with close to 0-NC then OTS

With the 500MB pattern the way it is forecast to be and has been forecast to be for days this is not a surprise.  Closing off upper low along the GA coast moving ENE, tilt of the trof which was not at all favorable, kicker feature and a sloppy surface evolution this was going to be a reach for anything decent up here, except for maybe a NJ coastal grazer and maybe central and eastern LI and even that is failing.

Maybe someone, Don? can confirm when was the last time we had something major up here with a 500MB low digging to the GA coast?  Certainly nothing I can remember from the recent big ones.  Something that far south is going to peak and occlude way to soon and would be quite a feat to get a surface feature from off the GA coast to vicinity of the BM.  It can happen but upper trof would have to be going negative rapidly, very rapidly.

My friend in RDU is excited, been waiting a long time for something decent like this.

 

 

[weatherpruf]

speaking of misses....apparently the blizzard of 1966 was 60 years ago today...according to the snow map it slammed everyone except the nj coastal plain and nyc...according to the map at accuweather most of eastern nj was just minutes from big snows to the west....oswego recorded 50 inches ! philly, baltimore,  dc all got slammed too. how that missed the metro is a mystery, because the map looks like long island got hit...unless it was the dryslot from hell....or perhaps rain. we'd be gnashing our teeth with an outcome like that....

[RU848789]

32 minutes ago, Stormlover74 said:

I don't usually look at the 10% low and high probability graphics, but this one shows the huge difference in snowfall for the 10% chance that the high scenario plays out - not surprising given how steep the snowfall gradient is from SE to NW, which might be why the NWS is showing the snowfall gradient over the ocean.  The 10% low probability is a Blutarsky-esque 0.0" for everyone, as one might guess.  

[Stormlover74]

4 minutes ago, weatherpruf said:

speaking of misses....apparently the blizzard of 1966 was 60 years ago today...according to the snow map it slammed everyone except the nj coastal plain and nyc...according to the map at accuweather most of eastern nj was just minutes from big snows to the west....oswego recorded 50 inches ! philly, baltimore,  dc all got slammed too. how that missed the metro is a mystery, because the map looks like long island got hit...unless it was the dryslot from hell....or perhaps rain. we'd be gnashing our teeth with an outcome like that....

Looks like we got some of it too

 

[TriPol]

I feel bad for the people in Virginia who thought they were going to get a 40 inch snowstorm at the start of the week. 

[Dark Star]

7 hours ago, eduggs said:

If other guidance eventually matches the NAM and we get one more small tick closer, this would be a fun nowcast on Sunday for coastal regions. I'm doubtful we even get that close given the persistence of unsupportive modeling outside recent ECM runs. But it's still a low level chance IMO.

gone...

[Dark Star]

54 minutes ago, nycsnow said:

Even cape cod don’t really get anything…. What an awful storm lol 

I was stoked, but now accept the inevitible...

[Dark Star]

9 minutes ago, TriPol said:

I feel bad for the people in Virginia who thought they were going to get a 40 inch snowstorm at the start of the week. 

Not really, feel sorry for us...

[nycsnow]

3 minutes ago, Dark Star said:

I was stoked, but now accept the inevitible...

Looks like 6-12 we’ll have some chances, clipper parade 

[weatherpruf]

20 minutes ago, Stormlover74 said:

Looks like we got some of it too

 

that seems to make more sense...the accuweather graphic showed only gray areas....

[weatherpruf]

9 minutes ago, nycsnow said:

Looks like 6-12 we’ll have some chances, clipper parade 

you never know what will crop up, just like this last one; i remember in feb 2014 nothing looked good and then all of a sudden an 8-10 paste job materialized......that was it for that year, the next march storm actually got suppressed, leaving us with pixie dust and delayed openings we didn't need....those march storms often suck....

[MegaMike]

39 minutes ago, RU848789 said:

Thanks, but even if one takes the GFS, GEFS and EPS over the last 3 runs for Philly, for example, the average is about 1/2" and those models contribute ~60% to the NBM according to your post with the SREFs having 30% input - if that's the case to get from 1/2" for 60% of the input to the 4.8" seen for Philly on the latest NBM, that implies the SREFs would need to be 12+" for Philly at only 30% of the input, which seems impossible, as the SREF snowfall (10:1) from the last few runs has been in the 2-4" range for Philly, unless that snow is at 30-40:1 ratios (and Kuchera is showing 20:1 inland).  But I will say I didn't realize the SREFs were counted so strongly and it at least explains probably half of the NBM numbers for inland locations.  

 

It's frustrating, for sure. I think to be 100% satisfied with their documentation, they need to provide an example for one case study. ie... Provide a table of snowfall accumulations (and exactly what field/how they processed snowfall) for all ensemble members + diagnostic models, take the weighted sum of all ensembles/models, then show the final result superimposed onto their NBM map. 

When I ran the calculations as you did, my value was far off from what the map showed too. I do trust that their documentation is correct (consisting models and weights wrt time), but something else does seem missing. I may ask the developers when I have time, but I think Don already did this.