high risk

1 hour ago, bncho said:

Will this greatly improve the verification scores of the American models? Will the GFS be an actual model to consider once this new core is implemented?

         I'm not a huge fan of FV3, so I would hope so.   One big thing is that a fully-coupled GFS will be implemented later this year, which should be very helpful.   That means a lot of things, but it means that the atmosphere, water, land-surface, and sea ice will all "talk" to each other.

1 minute ago, WxUSAF said:

Definitely not dismissing it for us. I’m mentally assuming a changeover somewhere between the times the NAM and euro suggest. Maybe 15-16z for us?

      I would love if it takes that long, but I'm mentally prepared for 13-14z.  

7 minutes ago, MN Transplant said:

 

I have just enough knowledge of this to be dangerous, but high risk can correct me.  Models have a dynamical core and various physics packages.  About a decade ago NOAA/NWS decided to try to align all of the operational models with a single dynamical core.  The FV3 was chosen but there have been some problems with it when it is run at finer convection-allowing resolution.  So, the alternative was MPAS (model for prediction across scales) from NCAR.  I know that NSSL has been testing out MPAS a lot and that one may end up being the dynamical core.  One of the problems with MPAS, though, is that it is computing-hungry compared to FV3.  So, NOAA is weighing pros and cons.

              You are spot on.   MPAS is going to replace FV3 in RRFS Version 2, and it will probably be used across the board eventually in the NWS models.

Just now, DDweatherman said:

I thought the fv3 was the next gen gfs? And I had heard here it wasn’t going to make it to the big game for a while still if it did

        The GFS does use the FV3 core now.     That has been the case since 2019.

4 minutes ago, DDweatherman said:

that actually made me laugh out loud. Serious question for a sec, why did the FV3 GFS replacement never game big time? 
 

on this storm, it has been consistently colder and snowier for most than the other suites, but not all that different than the OP GFS. Does it have a published cold bias that just can’t be corrected? 

     With apologies, what do you mean by the "FV3 GFS replacement"?   

6 minutes ago, stormtracker said:

maybe @high risk can explain.  Maybe lends to NAM being too dry.   Weenie hope

        It's pretty clear that the NAM is slow with the leading edge of the precip.    It definitely has a bias of being too slow to advance precipitation into very dry air.     The 18Z cycle doesn't bring snow into DC until 6Z, and I doubt it will take that long.   It's probably good reason to ignore its QPF for the front end thump and go with wetter models.    That said, none of that means that it must be off with the timing of the transition to sleet.    It might very well be too fast with that, but I wouldn't base that off of not getting snow to the ground quickly enough at the leading edge.

2 minutes ago, DDweatherman said:

Just like HighRisk reminded us that the short term US models do know thermals, do need we to remind you the Euro’s resolution is better than that of all models outside the 3k NAM?

       Not true:   HRRR and the three HiResWindows are all 3km.    That said, I don't trust any of those for thermal profiles.

3 minutes ago, DDweatherman said:

I agree it’s had value before, but that doesn’t diminish the horrible accuracy of the NCEP short term model suite. The blanket NAM sucks might be silly, but it’s also the anomaly on precipitation amounts vs the other suites. There’s a reason they’re all being decommissioned, and SOME of them don’t even make it to commissioning at all. 

            The reason that the NAM and Hires Windows are being retired is because it's impossible to maintain a model suite with so many different cores.     That said, I need to figure out why I'm spending time defending the NAM....   

1 minute ago, TSSN+ said:

Thermals could be right, but also doesn't matter if it is not modeling the storm correctly or qpf. It is significantly drier than all the other models and the other ones are getting wetter each run. 

    The fact that it's one of the driest solutions is absolutely odd, and I don't mind treating it as a massive outlier.    But I'm not sure that missing how significant the initial thump is will matter with how quickly we changeover, and I also don't think that it makes sense to compare radar to model forecast 400 miles away to determine what will happen here.    Anyhow, you'll change over way later than we will no matter what......

The blanket "the NAM sucks" stuff is wild to me when the strength of the NAM Nest is nailing thermal profiles inside of Day 2.   Maybe it's going to be too fast with the changeover, but complete dismissing of it makes no sense.

4 minutes ago, LordBaltimore said:

This will literally be the most difficult thing to shovel most people have seen in years. God help anyone who doesn't put up their wiper blades

    Agree fully.    The wet content of what's on the ground followed by the deep freeze means that it will take a long time to get sidewalks and side streets back in order

14 minutes ago, WxUSAF said:

@high risk how much can I hug the HREF to toss the nams? 6-8” of snow and little ZR for the metros, so presumably sleet on there.

https://www.spc.noaa.gov/exper/href/?model=href&product=frzrfram_024h_mean&sector=conus  (Toggle other winter parameters)

      So, the problem is that the NAM Nest is part of the HREF.......     That means, though, that the other members (HRRR and HiRes Windows) are much snowier.     They're all less icy than the RRFS and ECMWF.

18 minutes ago, baltosquid said:

I sure hope the RRFS MPAS core is wrong. Gets crazy amounts of freezing rain all up the beltway. It's an 06z run as it is delayed but that would be devastating.

        The FV3 RRFS is also going bonkers with the freezing rain.   I *think* it's way, way overdone and favor the sleet bomb idea of the NAM, but this will have to watched closely tomorrow.

13 minutes ago, TSSN+ said:

How anyone can even talk about the Nam seriously is hilarious. Just in comparison here’s the last 3 runs of Rgem and Nam for current 6hrs Rgem pretty steady, nam not so much 

 

        There are plenty of valid arguments against the NAM, but making that point by showing changes across cycles of an forecast of what the lowest level radar reflectivity will look like at one particular moment, and then comparing that to a 6h-averaged precip rate from a different model doesn't make your case.

5 minutes ago, Eskimo Joe said:

IMO, it's rimmed snow, but that's snow.

                  God, I really hope you meant "rimed". 

24 minutes ago, Weather Will said:

WB 12Z NBM para

  Love that you showed the para!   Friendly reminder that the NBM winter fields update at 01, 07, 13, and 19Z, so instead of showing the 12Z, it's best to wait one hour and use a version that incorporates more recent guidance.

2 minutes ago, TSSN+ said:

Where is the cold air btw? Temps are running +5 to +10 over modeled currently around our region.

   The arctic front doesn't come through until Friday evening, but when it does, the freeze is on.    Multiple models show upper 30s at 4pm falling to low teens by 1am.

2 minutes ago, wxmeddler said:

I was aware that the FV3 based RRFS got absolutely shellacked in testing with offices and centers. It originally also supposed to go to 72hrs only and there was outcry of loosing the extra 12 hrs the NAM provided. They *points vaguely* folded on both thankfully 

        Yes, but we're still going to get 2 years of the FV3-based RRFS in operations.

2 minutes ago, wxdude64 said:

Temps at a first glance, but I have a hard time thinking it would be off that much ?

    Big warm layers can easily reside in between those two levels.   Some of the forecast soundings I have seen for this event show that exact scenario.    The NAM precip type code is rock solid, based on the forecasted temperature profile.

Just now, wxdude64 said:

Somehow the column between ground/850/700 is -2 to -8 and it is showing sleet?? Right. 

    Are you looking at the actual sounding, or just the temperatures at those levels??

17 minutes ago, Terpeast said:

Thanks for pointing that out. The 12k and 3k might as well be two different models. May sound like a weenie, but I’d lean more on the 3k within 48 hours of onset. 

        They differ in more than just resolution, so they effectively are two different models (even though they have obvious commonalities).    As you said, though, the 3 km is a far superior model, except for when it deepens hurricanes down to 850 mb.

3 minutes ago, wasnow215 said:

Sorry off the topic here High Risk but since you're a met maybe you can help.

Why do you think Wakefield is using such strong verbiage about concern with an ice storm for Richmond then?

Are they basing it solely on the Euro?

In this area many businesses and obviously hospitals etc. etc. are making some difficult decisions, grocery stores have been ransacked with everything bought off the shelves in cases, because we keep being told that we are going to have a massive ice storm, and that it's not possible but actually probable most of the area loses power.

Because let's face a few inches of snow here and then sleet that is not a big deal at all.

       The Euro and its ensemble contribute heavily to the NBM, which is the starting point for these forecasts.   And I disagree with you:  several inches of snow followed by a ton of sleet would be a very big deal at these temperatures.

2 minutes ago, Ralph Wiggum said:

Exactly. @high risk already mentioned this would be ran on Saturday 1/24

   No, no, sorry.   I clearly wasn't nearly as clever as I thought with that post.   I am expecting that the happy hour NAM Nest cycle right before the storm will go bonkers.   

5 minutes ago, bncho said:

To straighten things up.
There are only two versions of the NAM Nest. The regular 'ol 12k NAM and the hi-res 3k NAM. There is no such thing as a 1.33k NAM (that I know of).

The 3k NAM should start to get into range for this storm by 0z tomorrow night, where it starts to enter its useful range.

Hoped that helped.

        Apologies for bursting your bubble, but @wxmeddler is correct.    There is a 1.33 km relocatable NAM Nest used for fire weather purposes that can be used for other types of events during non-fire-weather season.    There used to be graphics online, but I don't think that there are anymore.    And I think they've stopped running it for events like these. 

6 minutes ago, T. August said:

Not only that, but the individual panels are eerily uniform. Almost no variation in track or strength. I wonder how useful they truly are for precipitation.

   The AI ensembles tend to me under dispersive even in the medium range, so it's really no surprise that you're seeing very little spread as we enter the short range.