January 5-6 Thing II: STORM MODE

[Ravens94]

[Ji]

I'd be cautiously optimistic with the NAM.  It's exciting to look at, but we know the NAM has burned us plenty of times.   If the GFS/Euro combo confirms, then yeah...I can believe over 6 for us

Totally get it. We used to joke that Nam becomes useful 6 hours after the storm starts

This is for the Nam 12k that’s getting retired

Encouraged that the nam3k is on board because it’s usually a dr no model

[TSG]

4 minutes ago, Ji said:

Don’t know. I have seen the Nam make wild swings before close to game time. I predicted this would happen today

have we all forgotten the NAM is basically worthless outside of 36 hours? and really only is worth serious consideration under 24? I feel like I'm going crazy over here. I thought that was an unwavering truth known to this board. Especially older heads

[T. August]

Just looking at sfc 0z icon pretty much identical to 18z

[jayyy]

GFS HRRR RAP NAM3K/12K WRF all on board for a forum wide warning event. Let’s reel in the CMC ICON and Euro tonight. Many of the models on our side are inferior to the varsity models outside of the GFS.

[MN Transplant]

4 minutes ago, Interstate said:

JV done. Varsity is up

Not quite.  The JV ICON is still south, not that we will put any weight on that.

[clskinsfan]

Just now, MN Transplant said:

Not quite.  The JV ICON is still south, not that we will put any weight on that.

Yep. Not gonna make many friends with that run. 

[nj2va]

RGEM still looks to remain in the southern camp too, through H36.

[Amped]

RGEM still just wants to give us virga and pixie dust.

[MN Transplant]

1 minute ago, clskinsfan said:

Yep. Not gonna make many friends with that run. 

And yet, it is still 0.5” precip all frozen in DC.  I’ll take that as the floor.

[Deck Pic]

6 minutes ago, TSG said:

have we all forgotten the NAM is basically worthless outside of 36 hours? and really only is worth serious consideration under 24? I feel like I'm going crazy over here. I thought that was an unwavering truth known to this board. Especially older heads

The problem with the NAM is it will sometimes score a coup and catch on to some feature first.   And so you forget how bad its batting average is at the end of its range.  Plus it runs at really sexy times when the globals are resting.  The public should probably have never been allowed to have access to models.  Models are nice things.

 

[goodwidp]

Sterling's latest maps (as of 9:16 pm):

https://www.weather.gov/lwx/winter

 

Expected:

 

High end:

[nj2va]

RGEM gives RIC 10”+ of snow vs 3k NAM 2”.

[MillvilleWx]

7 minutes ago, wxmvpete said:

The 3kmNAM cross-section early Monday morning is a textbook FGEN/isentropic ascent setup. Also depicts the warm nose very well.

This is pretty much textbook for a cross-section of a WAA thump around here. Very strong FGEN signature during a deep moist layer as well. Verbatim, this is how you get 1-2"/hr for several hrs over a large area. Considering the strength of the LLJ at 85H and the RER dynamics at play with the jet streak to our north, there should be a good amount of moisture being advected northeastward ahead of the mean trough. A small window of lighter precip between the primary WAA pattern and the falling heights under the trough traversing eastward out of KY is likely, but that's the $1 million question what will transpire in the 5H progression as they moves south of us. If that can remain closed or at least move through at a slight neutral to negative tilt....then all bets are off on the potential within a maturing CCB. Jury still out there, but beginning to see some convergence on the initial stage of the event. I'm sure the mix line will be a bit north progged, but you never know. The NAM Nest outcome was fairly reasonable in my eyes given the variables at hand. The northern edge will likely sharpen and there will be a 100 mile swath of some significant snowfall across our area. It's just a matter of the latitudinal "goal posts" of where that will be. Fun times!! 

[high risk]

When looking at 3k NAM output, it's worth looking at the Ferrier snow accumulation product.    This one is connected directly to the model microphysics, so it knows exactly what the model is doing with the falling precipitation.    It can actually run a bit low for areas that stay all snow, but it's terrific at sorting out where the model thinks that the sleet will be mixing or other interference to pure snow accumulation.   

 

[Deck Pic]

Just now, goodwidp said:

Sterling's latest maps (as of 9:16 pm):

https://www.weather.gov/lwx/winter

 

Expected:

 

High end:

Seems like our local forecast office in Sterling is handling this event really well.  The AFD was pretty sweet.  

Get the ruler ready out there at the office.  No slantsticking.  

[AtlanticWx]

rgem goes south with 10" in richmond. what is up with this model lol

[mitchnick]

Fv3 a win

https://www.pivotalweather.com/model.php?m=hrwfv3&p=snku_acc-imp&rh=2025010500&fh=60&r=us_ma&dpdt=&mc=&pwplus=1

[MillvilleWx]

1 minute ago, high risk said:

When looking at 3k NAM output, it's worth looking at the Ferrier snow accumulation product.    This one is connected directly to the model microphysics, so it knows exactly what the model is doing with the falling precipitation.    It can actually run a bit low for areas that stay all snow, but it's terrific at sorting out where the model thinks that the sleet will be mixing or other interference to pure snow accumulation.   

 

I like the Ferrier for marginal events because it does what you mentioned really well. Wish the SLR wasn't capped at 10:1 since that is for certain going to be too low for the northern crew and even much of the area in the initial bout of precip and with any CCB action. My only gripe! Otherwise, it's great for highlighting areas that could see sleet/ZR. As is, that is very nice for many in here. 

[nj2va]

RGEM is basically a carbon copy of 18z but increased totals in the RIC area.

[Eskimo Joe]

5 minutes ago, high risk said:

When looking at 3k NAM output, it's worth looking at the Ferrier snow accumulation product.    This one is connected directly to the model microphysics, so it knows exactly what the model is doing with the falling precipitation.    It can actually run a bit low for areas that stay all snow, but it's terrific at sorting out where the model thinks that the sleet will be mixing or other interference to pure snow accumulation.   

 

Always love the Ferrier output. Would rather underforecast snow than overforecast.

[high risk]

2 minutes ago, MillvilleWx said:

I like the Ferrier for marginal events because it does what you mentioned really well. Wish the SLR wasn't capped at 10:1 since that is for certain going to be too low for the northern crew and even much of the area in the initial bout of precip and with any CCB action. My only gripe! Otherwise, it's great for highlighting areas that could see sleet/ZR. As is, that is very nice for many in here. 

       Agreed.   In areas that stay all snow, a blend of the Ferrier product and the Kuchera product might work pretty well.

[notvirga!]

Bernie Rayno isn’t buying the NAM/HRR. Thinks heaviest snow is DC south. 

[mitchnick]

3 minutes ago, notvirga! said:

Bernie Rayno isn’t buying the NAM/HRR. Thinks heaviest snow is DC south. 

And he'd change it if the globals came north in a second.

[TowsonTownT]

34 minutes ago, Scarlet Pimpernel said:

That was an over-performer for sure in the metro DC area...though I don't think it was as good for areas up toward BWI and north, whereas this one looks better relatively speaking.  I also recall LWX went 8-12" in the metro DC area which at first seemed really aggressive but ended up spot-on.

Bonus question - does anyone remember if this one went north of the consensus 48 hours out? Don't these always go north?

[Jmister]

As we get closer to the event, tracking observations becomes more crucial to see how models are performing. This tool compares HRRR sim radar to the observed radar. As you can see, there are some noticible differences already in placement and intensity of precip.

http://www.jmmweather.com/radar_comparison.html

Please message me with any suggestions as this is a work in progress.

[clskinsfan]

Not that I am sweating the ICON. But its ensemble members are pretty evenly split between north/south SLP positions. 

[mitchnick]

2 minutes ago, Jmister said:

As we get closer to the event, tracking observations becomes more crucial to see how models are performing. This tool compares HRRR sim radar to the observed radar. As you can see, there are some noticible differences already in placement and intensity of precip.

http://www.jmmweather.com/radar_comparison.html

Please message me with any suggestions as this is a work in progress.

Looks like Hrrr is not north enough if I'm understanding it correctly. 

[MillvilleWx]

3 minutes ago, Jmister said:

As we get closer to the event, tracking observations becomes more crucial to see how models are performing. This tool compares HRRR sim radar to the observed radar. As you can see, there are some noticible differences already in placement and intensity of precip.

http://www.jmmweather.com/radar_comparison.html

Please message me with any suggestions as this is a work in progress.

Pretty awesome tool @Jmister I might actually have to bookmark this one for future reference during convective season. Might be helpful in gauging ERO updates during the warm season. Been a minute, but hope you’re doing well!! I remember you went to PSU, correct? 

[clskinsfan]

Just now, MillvilleWx said:

Pretty awesome tool @Jmister I might actually have to bookmark this one for future reference during convective season. Might be helpful in gauging ERO updates during the warm season. Been a minute, but hope you’re doing well!! I remember you went to PSU, correct? 

I did bookmark it. The difference feature is awesome.