December 16-17, 2020 Winter Storm Obs/Nowcasting

[Weather Will]

3 minutes ago, WinterWxLuvr said:

Thank you

Sure.  Should show the surface temps too.  I’m afraid anywhere DC proper SE is literally toast.  I’m sorry.  

[BristowWx]

27/19...not bad

[Warm Nose]

[Negnao]

5 minutes ago, psuhoffman said:

Ok I think some are over analyzing a run where the low tracks OVER BALTIMORE!!!!  Hopefully it’s wrong. But come on. If the low actually tracks from Richmond to Baltimore to Wilmington anyone from 81 east and south of York PA is screwed. We know that. This isn’t that complicated. Just hope that track is wrong. If you get the 12k NAM or GFS track with the euro storm presentation we get a big storm 95 NW.  unfortunately the best guidance at this range we have looks like poo. No one mentioned both the RGEM and HRDRPS look awful and had their worst runs at 18z. I am rooting for the gfs but...it’s the GFS lol. Other then the GFS and 12k NAM everything else I saw continued to degrade at 18z. 

A low tracking to Baltimore is not the kind of track that produces snow in philly or NYC. Interesting that no matter how bad the track is they seem to score from this storm. 

[DDweatherman]

1 minute ago, Negnao said:

A low tracking to Baltimore is not the kind of track that produces snow in philly or NYC. Interesting that no matter how bad the track is they seem to score from this storm. 

Well from a high level it scoots out east from our latitude. You've seen on some models it crashes the column even for us, along with the mid-levels closing off. If the low trekked up over NYC, you wouldn't see the same results there. 

[Fozz]

5 minutes ago, Negnao said:

A low tracking to Baltimore is not the kind of track that produces snow in philly or NYC. Interesting that no matter how bad the track is they seem to score from this storm. 

That's because the low redevelops off the southern Jersey shore, crashing the heights in time for Philly and NYC, and then tracks east towards the benchmark, which is a classic track for the northeast cities.

[psuhoffman]

13 minutes ago, WinterWxLuvr said:

I have a question. At what pressure level are snowflakes formed?

Usually around 500mb or a little under that. 

[DDweatherman]

Well PSU, we're down to the HRRR then huh? 

[WinterWxLuvr]

16 minutes ago, Eskimo Joe said:

http://stream1.cmatc.cn/pub/comet/WinterWeather/oceansnowcase/comet/norlat/snow/micro_ice/1.5.natural_cloud_seeding.htm

Thanks. Very interesting 

[PhineasC]

3 minutes ago, Fozz said:

That's because the low redevelops off the southern Jersey shore, crashing the heights in time for Philly and NYC, and then tracks east towards the benchmark, which is a classic track for the northeast cities.

So basically this is the atmosphere going well out of its way to screw the MA to the greatest extent possible? Kinda impressive, really.

[WinterWxLuvr]

4 minutes ago, psuhoffman said:

Usually around 500mb or a little under that. 

That is really surprising to me. I thought it would be much lower except in very high elevation snow.

[Fozz]

1 minute ago, PhineasC said:

So basically this is the atmosphere going well out of its way to screw the MA to the greatest extent possible? Kinda impressive, really.

Seems like it, and it's happened over and over again throughout the years. I think Boxing Day 2010 was the most vile example, but there've been so many others.

[psuhoffman]

10 minutes ago, Negnao said:

A low tracking to Baltimore is not the kind of track that produces snow in philly or NYC. Interesting that no matter how bad the track is they seem to score from this storm. 

If that track verifies I guarantee you Philly doesn’t get that much. Maybe a few inches. NYC won’t get prolific #s but their saved a reasonable storm because it does eventually hit the brick wall and turn due east. There is a block. But it exerted its influence ~100 miles too late for DC to get a big snow.  CAPE pointed out, and was right, that the block is centered a little north of ideal for us. Still it was good enough to work if other things went right. We don’t need PERFECT. But the trough digs too far west and pumps ridging ahead of it and the 50/50 is just a little too far NE to prevent it. NYC is far enough north that it barely saves them. At least to an extent. The big totals will be in central PA and North of them. 

[IronTy]

22 minutes ago, Weather Will said:

Sure.  Should show the surface temps too.  I’m afraid anywhere DC proper SE is literally toast.  I’m sorry.  

Wtf am I literally going to be 50 degrees on Thursday!?  Burn it all down, can't we just permanently shift to  warm climate at this point?  At least I could BBQ comfortably then. 

[SnowGolfBro]

I’m under a WWA and a flood watch. What a country!

[psuhoffman]

At least I’m not worried about ground temps. I still have snowcover. 

[medmax]

18z Euro is awful for I-95'ers...and a step down for many inlanders too

Post a money shot

[CAPE]

3 minutes ago, Fozz said:

Seems like it, and it's happened over and over again throughout the years. I think Boxing Day 2010 was the most vile example, but there've been so many others.

Comparing this to boxing day is apples and oranges. literally. Throughout the years there are many different atmospheric scenarios and outcomes, most of which favor NE for obvious reasons.

[BristowWx]

6 minutes ago, SnowGolfBro said:

I’m under a WWA and a flood watch. What a country!

I’d like to see an ice storm warning someday.  Not very common.  Or heavy freezing spray.  Not seen to often. 

[PivotPoint]

34 minutes ago, Weather Will said:

I picked the worst panel for each level.  Between 7-10pm.  WB

That’s not horrible for Leesburg if that’s the warmest panel, surface might be a bit above freezing but banding would take care of that. Not as bad as I thought.

29 minutes ago, Weather Will said:

Sure.  Should show the surface temps too.  I’m afraid anywhere DC proper SE is literally toast.  I’m sorry.  

I call bs. Basically top corner of dc is 47 and ffx county at 32. That’s like maybe 30 miles in a straight line. No way it’s a 17 degree difference. No way

[clskinsfan]

What is the GFS v16?

[jayyy]

Late to the party. Just got off work. Euro is out to lunch, IMO. How does it keep moving the low farther and farther west while barely changing snowfall totals? Something seems wrong. 

[jayyy]

Come on MESOs... 

[mappy]

7 minutes ago, psuhoffman said:

At least I’m not worried about ground temps. I still have snowcover. 

I’m in Shrewsbury and there’s still snow on the ground too from yesterday. 

[BristowWx]

Just now, jayyy said:

Come on MESOs... 

Apparently you have not seen WRF-ARW...that’s a beaut!

[Negnao]

13 minutes ago, psuhoffman said:

If that track verifies I guarantee you Philly doesn’t get that much. Maybe a few inches. NYC won’t get prolific #s but their saved a reasonable storm because it does eventually hit the brick wall and turn due east. There is a block. But it exerted its influence ~100 miles too late for DC to get a big snow.  CAPE pointed out, and was right, that the block is centered a little north of ideal for us. Still it was good enough to work if other things went right. We don’t need PERFECT. But the trough digs too far west and pumps ridging ahead of it and the 50/50 is just a little too far NE to prevent it. NYC is far enough north that it barely saves them. At least to an extent. The big totals will be in central PA and North of them. 

Thanks for the feedback and agree with all of the above. 

[psuhoffman]

5 minutes ago, CAPE said:

Comparing this to boxing day is apples and oranges. literally. Throughout the years there are many different atmospheric scenarios and outcomes, most of which favor NE for obvious reasons.

Agree. The spacing was just a little off. Even with the SW that dug the trough that was pointed out had that 50/50 been a little slower to vacate, but a huge gap opened up and this storm is taking advantage of the ridge to cut inside. It happens. It’s December. But I’ll say this...and I’ve been too busy to track this and post in long range so I took a break but the -AO NAO does not look like a transient think. I think we finally are getting our winter where blocking will be a significant feature. If we get a -AO winter and the pac isn’t a disaster (so far it’s meh but not awful) and still manage some awful single digit snowfall then the “somethings” wrong argument has more legitimacy. Blocking won’t guarantee we get great results but it should (absent a dumpster fire Pac) get us some snow events. If it doesn’t it’s gonna get ugly in here. 

[nesussxwx]

0z HRRR looks like 3-5" of sleet/snow b4 rain for DC proper based on my untrained eye.

sharp cutoff to the SE 

 

 

 

[nj2va]

1 hour ago, DDweatherman said:

Is it a nicer experience out there for the snow? I haven’t been up there in years and never experienced a snow there. 

It’s beautiful in the snow.  And so many good hiking trails to enjoy in the days after or if you cross country ski, you can do that too.  Models are keying in some upslope snow showers to take on an extra inch or two Thursday/Friday.  

[CAPE]

2 minutes ago, psuhoffman said:

Agree. The spacing was just a little off. Even with the SW that dug the trough that was pointed out had that 50/50 been a little slower to vacate, but a huge gap opened up and this storm is taking advantage of the ridge to cut inside. It happens. It’s December. But I’ll say this...and I’ve been too busy to track this and post in long range so I took a break but the -AO NAO does not look like a transient think. I think we finally are getting our winter where blocking will be a significant feature. If we get a -AO winter and the pac isn’t a disaster (so far it’s meh but not awful) and still manage some awful single digit snowfall then the “somethings” wrong argument has more legitimacy. Blocking won’t guarantee we get great results but it should (absent a dumpster fire Pac) get us some snow events. If it doesn’t it’s gonna get ugly in here. 

WRT to this event, even though there is ridging up over GL, its not what I would consider an "effective" block for this area. If it were, the 50-50 low wouldn't be hauling ass up into the NA. So in this case we really needed to thread the needle- to time everything perfectly, because that low and the associated confluence (and surface HP) are on the move. We really aren't getting the necessary compressed flow/suppression, which would have inhibited height rises out in front and forced the low track further south.