December 22-23, 2022: Warm Rain to Arctic Chill

[Interstate]

The NAM is starting to show the line of snow showers behind the front

[H2O]

VDOT already beet juice spraying. WTF

[Eskimo Joe]

Both the NAM and GFS have some insane frontogenetic forcing with this fropa tomorrow. Probably going to see a few snow squall warnings as this thing rips through.

[Ravens94]

[Ravens94]

Definitely a coastal low signature trying to form in NC

[AlexD1990]

4 minutes ago, Ravens94 said:

Definitely a coastal low signature trying to form in NC

I would laugh so hard if we somehow still get a coastal out of this...talk about a Christmas miracle...

[Interstate]

GFS is stubborn that is for sure.

[Kmlwx]

12 minutes ago, H2O said:

VDOT already beet juice spraying. WTF

Gotta ensure they keep their budget up somehow.  

[WxUSAF]

2 minutes ago, Interstate said:

GFS is stubborn that is for sure.

It is. Not sure I’m going to believe it until the snow is falling though. 
 

p.s. if you look though, gfs may be slowly backing down on the amount of precipitation behind the front over the last 4-5 runs.

[NorthArlington101]

6 minutes ago, Ravens94 said:

Definitely a coastal low signature trying to form in NC

Don't think that would solve the temperature issues for most of us but kinda cool to watch.

Upped the ante for those who were already likely to see snow, though.

[Baltimorewx]

Doesnt the GFS have the tendency to leave too much precipitation behind arctic fronts and also be a little too strong with cold pushes? Its being consistent but I find it hard to believe we'll be 19 degrees at 1PM. I buy a quick burst of snow for the N&W elevation areas but Im pretty skeptical a bout the metros and low lands cashing in on much of a changeover

[NorthArlington101]

I'm not sure its ever been a useful tool but it's nice to see the FV3 hi-res kind of agree with the GFS. It doesn't always do that, e.g., it looks nothing like it's parent(?) for the Thursday morning part of the system.

 

[Kleimax]

22 minutes ago, Ravens94 said:

Definitely a coastal low signature trying to form in NC

It's the Tony Pann coastal low

[mattie g]

16 minutes ago, Ravens94 said:

Definitely a coastal low signature trying to form in NC

17 minutes ago, alexderiemer said:

I would laugh so hard if we somehow still get a coastal out of this...talk about a Christmas miracle...

It's been there for a while, but the problem is that we get relatively flooded with warmth from southerly flow ahead of the vort in the Midwest.

What the GFS did all those days ago was to have confluence keep that vort from cutting, then eventually getting below us and giving us a double dip from the southern energy and that northern stream vort. With the confluence no longer coming into play, that vort cuts and floods us with warmth, then the precip from the southern energy falls into a warmer column. It's not until the front comes through that temps support the possibility of frozen.

[Kmlwx]

13 minutes ago, NorthArlington101 said:

I'm not sure its ever been a useful tool but it's nice to see the FV3 hi-res kind of agree with the GFS. It doesn't always do that, e.g., it looks nothing like it's parent(?) for the Thursday morning part of the system.

IIRC the GFS is based on an FV3 core. So it sort of makes some sense that they'd agree. Believe the FV3 is slated to replace the various hi-res/regional models. 

[MN Transplant]

This is as the front is coming through my area of the DC burbs.

[Eskimo Joe]

 

[SomeguyfromTakomaPark]

Friday night probably gonna need a wind chill advisory even for the metros.  Teens with 30mph gusting winds would put us below zero wind chills,

[mappy]

48 minutes ago, Baltimorewx said:

Doesnt the GFS have the tendency to leave too much precipitation behind arctic fronts and also be a little too strong with cold pushes? Its being consistent but I find it hard to believe we'll be 19 degrees at 1PM. I buy a quick burst of snow for the N&W elevation areas but Im pretty skeptical a bout the metros and low lands cashing in on much of a changeover

good point. and we don't often score when cold rushes as precip moves out sooner than modeled. 

[MN Transplant]

Here's further proof that some of the snow maps we are seeing from the GFS are simply processing artifacts.  Check out the following examples from Dupage and Pivotal.  The snow accumulation products are clearly not able to handle the fast-moving front and are incorrectly partitioning the precipitation between rain and snow.  However, the snow depth products do not have the same problem.  The GFS may still be wrong about 0.5-1.0" on the backside of the front, but that is the actual projection.

 

[IUsedToHateCold]

If I get 0.8 inches new snow depth then I’ll take it and run.

[Buddy1987]

I feel like looking at the various 12z model runs we shouldn't overlook some of the total freezing rain qpf output. Half of some of those totals would create problems. This go around as well temps have been well below freezing. 

[WinterWxLuvr]

We will be cold enough here tomorrow morning so the question comes down to the same old thing … how much precip?

[Stormfly]

The last time it was this cold on Christmas for this area was 1983.  And too, back then the wind chill numbers were different due to the scale changing.
And the last time we had real cold with wind was end of Jan 2019?
So many people are not used to this, Jack Frost is definitely going to be nipping for sure!

For the "storm of a lifetime" [sic] we may get a wind and wind chill advisories?

At least the bitter cold is relatively short lived!  Still, it doesn't take long to get logs stuck to the ground like they've been gorilla glued!

[NorthArlington101]

Unfortunately for our I-81 comrades the 12z EURO is putting out a icier solution than earlier runs. Cut back snow totals a decent bit.

[high risk]

1 hour ago, MN Transplant said:

Here's further proof that some of the snow maps we are seeing from the GFS are simply processing artifacts.  Check out the following examples from Dupage and Pivotal.  The snow accumulation products are clearly not able to handle the fast-moving front and are incorrectly partitioning the precipitation between rain and snow.  However, the snow depth products do not have the same problem.  The GFS may still be wrong about 0.5-1.0" on the backside of the front, but that is the actual projection.

 

         Here is how it works.     Inside the GFS, there is a bucket for snow accumulation.   Anything from the direct model integration of the microphysics scheme that reaches the ground as snow or sleet goes into the snow accumulation bucket as a liquid equivalent.   This liquid equivalent is output as a snowfall product.

          The snow (+ sleet) is also passed into the land-surface part of the model where an SLR is applied.   This determines how much snow is on the ground in the model.

           The disconnect has 2 sources:      1)  users apply their own ratios.  Most use 10:1, but some use the generous Kuchera.   Kuchera for this case will love the crashing temps and put some weenie ratios and end up with big accumulations     2)  the snow depth is instantaneous, and some melting (not in the Friday example) or compacting may occur by the time shown

            The model is absolutely "handling the fast-moving front".   Right or wrong, it has snow falling on the cold side of the front.   The products showing "snowfall" do have an element of post-processing artifacts, especially the Kuchera.

[Chris78]

6 minutes ago, NorthArlington101 said:

Unfortunately for our I-81 comrades the 12z EURO is putting out a icier solution than earlier runs. Cut back snow totals a decent bit.

Quite the difference compared to the gfs for the I - 81 crew. (Mby included)

I wonder which one will be correct lol

[IceCAPS]

15 hours ago, Ji said:

15 hours ago, Terpeast said:

Not sure when NAM gets into its range, but it seems to be trending colder at precip onset. Only checked 850 temps, not ptype

Frustrated that 850 is below 0 but still rain. So Frustrating. Worst winter ever

You're too funny Ji!  "Worst Winter ever" on the first day of said Winter.... Let's just delay our collective call on THIS being the worst of all time just yet.  Although, you may be proven correct, I'm going to hold out hope for a middle of the road Winter myself with three months of it to go. Heck March around these parts can be interesting! 

[MN Transplant]

9 minutes ago, high risk said:

         Here is how it works.     Inside the GFS, there is a bucket for snow accumulation.   Anything from the direct model integration of the microphysics scheme that reaches the ground as snow or sleet goes into the snow accumulation bucket as a liquid equivalent.   This liquid equivalent is output as a snowfall product.

          The snow (+ sleet) is also passed into the land-surface part of the model where an SLR is applied.   This determines how much snow is on the ground in the model.

           The disconnect has 2 sources:      1)  users apply their own ratios.  Most use 10:1, but some use the generous Kuchera.   Kuchera for this case will love the crashing temps and put some weenie ratios and end up with big accumulations     2)  the snow depth is instantaneous, and some melting (not in the Friday example) or compacting may occur by the time shown

            The model is absolutely "handling the fast-moving front".   Right or wrong, it has snow falling on the cold side of the front.   The products showing "snowfall" do have an element of post-processing artifacts, especially the Kuchera.

Yes, I didn’t mean to imply that the model was handling it incorrectly, only that the accumulation maps were not showing the entire picture due to processing choices. There is no physical/meteorological reason why there is a hole in the accumulation product NW of Philly, for example.

[Terpeast]

Looked at the models and trends today. I’m not buying into the anafront, but it wouldn’t surprise me to see a brief snow shower or two (no accumulation) just as precip shuts off on fropa. I’ll take that.