Jan 6/7 "Event" and obs

[Interstate]

2 minutes ago, osfan24 said:

Eh, it's fine I guess, at least for those of us just west of Baltimore. But not great for everyone else. Certainly looked better just looking at the animation. Would have expected some totals around half a foot with what looked like very heavy rates for a few hours.

Yeah me too... but remember us west and north of Baltimore missed out on Monday... so there is that.

[Wetbulbs88]

 

1 minute ago, EastCoast NPZ said:

Looks perfectly reasonable 

I'd wager it's too generous. 

[WinterWxLuvr]

2 minutes ago, nj2va said:

15z HRRR looks great for Davis/Deep Creek.  12"+....great for the ski resorts.  Fozz will have good time.

Lol I have decided I will only look at the hrrr out to one hour. That means it will have already happened 

[MN Transplant]

16z HRRR will be the first run that has the entire storm within the 18 hours.  The 15z is a minor improvement on the 12z, taking the <0.10" QPF amounts off the table.

[aldie 22]

1 minute ago, MN Transplant said:

16z HRRR will be the first run that has the entire storm within the 18 hours.  The 15z is a minor improvement on the 12z, taking the >0.10" QPF amounts off the table.

> or <

[RevWarReenactor]

4 minutes ago, Wetbulbs88 said:

Obvious but true, and we tend to forget it. I hate to be a debbie downer but in situations like these, we tend to underperform. Not saying that will happen, but I'm looking for 1-3" here. You never know--either the WAA can remain stronger for longer, or the coastal can develop earlier than expected. But when you're trying to thread that needle, you're trying to thread that needle. Then you're trying to catch a decent band either way.   

 

On the HRRR the WAA is angled in a way where it snows in NH before it snows in DC. Not a great sign. See that before and it doesn't end well.  By the time its in the I-95 corridor, its weak, and the coastal has taken over giving Coastal southern Del and Coastal NJ the snow leaving a hole. Its very plausible.

I'm thinking 1-2 for I-95, anything else would be a bonus.

[Warm Nose]

O/U remains 3" it seems like. Shifts between now and then but we'll just have to nowcast.

[jayyy]

2 minutes ago, SnowGolfBro said:

That’s really the unicorn solution for us right now. Get the precip to come in from SW to NE and hold on a couple extra hours before the coastal takes over.

Indeed. How many times have we said “the initial slug of precip came in faster / heavier than modeled” or “we were a few degrees colder than modeled due to heavier precip than expected at the onset” after a marginal event was over?
 

It certainly happens. Will it happen here? Maybe. Hard to know. We should get an idea pretty early on regarding how much of that precip is getting eaten up as it crosses the Apps. But it’s DC to Baltimore’s (central MD) best shot at seeing the higher end totals being depicted by the Canadian and GFS - as the likelihood the coastal gets going early enough to throw Atlantic moisture into the CWA is very low (models see that happening in southern New England - not anywhere near our latitude)

The 4-5” being depicted near Baltimore could just be the obvious shortcomings of using global models this close to an event with this type of setup, but it’s still possible if the initial energy manages to hold together for a few extra hours.

That’s why it’s best that we blend models at this juncture, which is why I think NWS’s 2-4” with 5-6” lollies area-wide is a very reasonable forecast for most. 

[MN Transplant]

14 minutes ago, leesburg 04 said:

> or <

edited!

[Ravens94]

HRRR shows a NE wind for quite awhile when the snow is along the apps you would think it would be saturated enough east to snow vs a NW component 

[jayyy]

One thing is for sure - some places will get 1-2”, while others relatively nearby see 3-4-5”. Nature of the beast when you’re banking on banding and WAA.  Could very well see dc metro at 1-2” with Baltimore hitting 3-4” in this setup. Or both see 1-2” with 3-6” totals to the NW and NE of both metros. That line is very fine in these setups and often comes down to very minute differences in timing, track, thermals, etc. 

If you stick with 2-4” as the general forecast, it’ll likely verify for 90% of the CWA. Nowcasting is when we’ll be able to verify where the lollies / jackpot zones setup. Somebody expecting 6” will see 1-2” and somebody expecting 1-2” will see 6”. That's how these setups almost always pan out. We use previous setups to make our best educated guess on where that occurs leading up to the event, but we won’t know until it happens. 

[Scraff]

So how’s our dusting shaping up? 

[jayyy]

2 minutes ago, Scraff said:

So how’s our dusting shaping up? 

Relatively clueless on whether or not the DC to BAL corridor will see 1” or 6” within 12 hours of a storms onset. You know… the usual. 

[psuhoffman]

1 hour ago, WinterWxLuvr said:

Same here. GFS showed a better northern edge that turned out to be pure fantasy.

Gfs doesn’t have the resolution or the physics to resolve fine details like banding and sharp edges due to subsidence around banding. It smoothed everything which gives a too expansive representation of precip along sharp edges. 

43 minutes ago, WxUSAF said:

RGEM in camp 2

It’s very subtle, one of those things where we’re right near a critical mass switch flip and models can’t decide which side we end on, but the deciding factor seems to be how much energy transfers to the coastal v simply amplifying the primary associated with the SW. 

Runs that key on a quicker transfer and amp the coastal more v the primary less, cause 2 effects. It interferes with the south and easterly flow around the primary cutting off better moisture transport. And it develops a more intense deform band along the coastal front sooner which puts a subsidence zone over our area. 
 

The models that amplify the primary more and coastal less delay that process, or in the case of the Gfs simply never really develop the secondary and just have the primary amplify and merge with the secondary, so the initial band intensifies after the mountains as it crosses our area aided by a nice southeast moisture influx from the primary.  

35 minutes ago, Bob Chill said:

Globals are too broad brush for narrowly defined sensible wx in the short range. Euro has the resolution but it's still a global. OTOH- mesos try to be "too accurate" with exact placement of subtle variations of qpf/bands etc. I know you know this but just reminding everyone that all decent models are useful in the short range but no one model is deadly. Just blend and apply climo. Rarely fails. 

I tend to like to use the euro for Synoptics like where to expect a feature then the higher resolution models for what the exact details of said feature will look like. That’s not 100% and I definitely factor the Gfs and other data into it and can nudge the euro representation one way or the other but that method has served me pretty well as a “starting point” from which to build on in the past. 

[NorthArlington101]

UKIE is (a bad model and cannot be trusted) but is on the team of having the screw zone being closer to PHI.

 

[psuhoffman]

9 minutes ago, jayyy said:

One thing is for sure - some places will get 1-2”, while others relatively nearby see 3-4-5”. Nature of the beast when you’re banking on banding and WAA.  Could very well see dc metro at 1-2” with Baltimore hitting 3-4” in this setup. Or both see 1-2” with 3-6” totals to the NW and NE of both metros. That line is very fine in these setups and often comes down to very minute differences in timing, track, thermals, etc. 

If you stick with 2-4” as the general forecast, it’ll likely verify for 90% of the CWA. Nowcasting is when we’ll be able to verify where the lollies / jackpot zones setup. Somebody expecting 6” will see 1-2” and somebody expecting 1-2” will see 6”. That's how these setups almost always pan out. We use previous setups to make our best educated guess on where that occurs leading up to the event, but we won’t know until it happens. 

If you want to look smart say 2-5 everywhere.  90% will verify. When in reality we know there is likely to be a zone of 3-6 with a zone of 1-3 but placing those exact bands is risky and really just an educated guess. 

[Scraff]

5 minutes ago, jayyy said:

Relatively clueless on whether or not the DC to BAL corridor will see 1” or 6” within 12 hours of a storms onset. You know… the usual. 

Of course! Well, I have to actually go sell some beers in MoCo now, so see you  all at happy hour GFS!
 

Side note-I’ll be at Downtown Crown at 4:00 if anyone wants to drink beer and talk snow.  

[Wetbulbs88]

46 minutes ago, WinterWxLuvr said:

Lol I have decided I will only look at the hrrr out to one hour. That means it will have already happened 

I'll only look an hour after, only to remind myself never to look. 

[jayyy]

18 minutes ago, psuhoffman said:

If you want to look smart say 2-5 everywhere.  90% will verify. When in reality we know there is likely to be a zone of 3-6 with a zone of 1-3 but placing those exact bands is risky and really just an educated guess. 

For sure. I agree fully. As far as nws is concerned, their forecast makes sense. General 2-4” with lollies up to 6”. 

[jayyy]

All we need to do is will the initial shortwave into holding together and eventually merging with the coastal… instead of seeing it fade out as it approaches our area and transferring its energy to the coast 

 Come on guys, we’ve got this. 

[Interstate]

Well at least now with the model runs we know our fate within the first 10 minutes of the run.

[WinterWxLuvr]

32 minutes ago, NorthArlington101 said:

UKIE is (a bad model and cannot be trusted) but is on the team of having the screw zone being closer to PHI.

 

I do not feel comfortable when the UKIE is one of the better looking models for my area. 

And how did you do that smaller script lol

[Bob Chill]

31 minutes ago, psuhoffman said:

  I tend to like to use the euro for Synoptics like where to expect a feature then the higher resolution models for what the exact details of said feature will look like. That’s not 100% and I definitely factor the Gfs and other data into it and can nudge the euro representation one way or the other but that method has served me pretty well as a “starting point” from which to build on in the past. 

Exactly. Expectations for models are at an all time high but we're still many years away from the level of detail and accuracy that many want put faith in today. Like you, I just create a data equation in my head with weighting on what I think makes the most sense, then double check previous similar events to get a handle on boom/bust for my specific yard. Even doing this for what... 25 years (15 intensely for me), the element of surprise in any direction is always present. I suppose that's what makes it so fun... and maddening... and evil... all at the same time 

[DDweatherman]

If anyone wants to start posting obs, made a thread for us 

 

[mappy]

can't we just keep obs and stuff here? 

[Chris78]

2 minutes ago, Bob Chill said:

Exactly. Expectations for models are at an all time high but we're still many years away from the level of detail and accuracy that many want put faith in today. Like you, I just create a data equation in my head with weighting on what I think makes the most sense, then double check previous similar events to get a handle on boom/bust for my specific yard. Even doing this for what... 25 years (15 intensely for me), the element of surprise in any direction is always present. I suppose that's what makes it so fun... and maddening... and evil... all at the same time 

Models have been locked in for a couple days now. Were talking .05 to .15 wobbles in precip for the most part.

Pretty darn good in my opinion.

I think a general 2 to 5 has been a consensus on models for the last few days.

I know you've been preaching this for days now but it's hard to expect a model to nail down that minute amount of precip to the acre someone lives on.

[Kmlwx]

3 minutes ago, mappy said:

can't we just keep obs and stuff here? 

Yeah agreed. It's already a storm specific thread. 

[Bob Chill]

5 minutes ago, Chris78 said:

Models have been locked in for a couple days now. Were talking .05 to .15 wobbles in precip for the most part.

Pretty darn good in my opinion.

I think a general 2 to 5 has been a consensus on models for the last few days.

I know you've been preaching this for days now but it's hard to expect a model to nail down that minute amount of precip to the acre someone lives on.

The only thing I really care about is not having to deal with the ragged jagged precip shield and never getting any good lift overhead. The one thing that's keeping my confidence in a couple inches at least is the shortwave isn't dry. It's loaded up with pac moisture streaming from the jet from the pac nw thru the central rockies and into the TN Valley. Often these shortwaves have only moisture from Canada and can't tap anything. Those are tough on the nerves. I may end up in a relative min but I don't think it will be less than 2" (famous last words)

[Ji]

2 minutes ago, Kmlwx said:

Yeah agreed. It's already a storm specific thread. 

so many posts for a 3 inch snowstorm. no wonder Bob quit the weather board

[ravensrule]

1 minute ago, Bob Chill said:

The only thing I really care about is not having to deal with the ragged jagged precip shield and never getting any good lift overhead. The one thing that's keeping my confidence in a couple inches at least is the shortwave isn't dry. It's loaded up with pac moisture streaming from the jet from the pac nw thru the central rockies and into the TN Valley. Often these shortwaves have only moisture from Canada and can't tap anything. Those are tough on the nerves. I may end up in a relative min but I don't thing it will be less than 2" (famous last words)

Those are only famous last words in the Chill household.