Jan 4th Coastal

[NorthArlington101]

 
 
Judging on what i see for that map... My city in Magnolia DE gets almost a foot of snow and even more down south?

Watch out, that map is in millimeters.

[WeathermanB]

2 minutes ago, showmethesnow said:

Just had a chance to look at the surface on the 12K NAM and this is why I take what it shows there with some skepticism and focus solely on the 500's. The surface seems some what fine all the way until we see it to just off of OBX. When this storm is located there we see it stacked all the way from 500 mb on down to the surface. Now this is where the surface goes somewhat wonky. We see the 500mb sliding up the coast and yet we see all the levels underneath including the surface taking a turn out to sea. While I expect a little tilt to the vertical stacking this is beyond that as it looks as if they are trying to escape. While possible I suppose, I do find this unlikely. The more likely outcome is that we see the 500mbs dragging the lower levels and the surface low along with it up the coast. 

 

Where along the coast? Mid-atlantic or just off the coast by like 50-100 miles?

[cae]

5 minutes ago, WeathermanB said:

Judging on what i see for that map... My city in Magnolia DE gets almost a foot of snow and even more down south?

If nothing else, this storm is making me learn geography east of the bay!  But nobody around here gets a foot of snow on that map, unless ratios are crazy high.  The scale is in mm of water equivalent, so 25 mm is about 1" qpf which is about 1' of snow.  You're probably closer to 3-4".

[WeathermanB]

Just now, cae said:

If nothing else, this storm is making me learn geography east of the bay!  But nobody around here gets a foot of snow on that map, unless ratios are crazy high.  The scale is in mm of water equivalent, so 25 mm is about 1" qpf which is about 1' of snow.  You're probably closer to 3-4".

 

Oh whoops i got overhyped and didn't read that carefully  

[mitchnick]

5 minutes ago, psuhoffman said:

It's closer I'll give it that but the fatal problem I still see and why even given the early phase and bomb on the nam it still misses is the northern stream (piece C) is diving down right on top of us. It phases later but that takes some time so for our purposes it acts as a kicker. It has too. The phase isn't going to stop time so that it can happen simultaneously and everything is progressing as this process is taking place. So if the trough is digging right over us...I don't see how this ends up tucked in like we need it. I guess why I've been so disengaged in this is that I see that as the most important thing. I want to see that dive down west of us. At least into Ohio if not Indiana. Not into PA. And while some of the changes with the stj wave and the first northern stream system have been favorable, I've seen no improvement in that final part. And absent that my fear is there is only so much this can go. We're seeing those other improvements with parts A & B help the Carolinas for sure and the Delmarva. But for west of the bay if that last northern stream piece keeps diving down on top of us it's going to hit a brick wall and turn east. It may or may not hook back in time for New England. Might even screw then. 

It would take an extremely rare almost perfectly clean immediate phase to tuck in tight enough given that trough axis or a sudden shift in that feature.  

If I see something start to change that last part of the equation I will immediately jump in. I want this. I'm just not feeling it as long as I keep seeing the trough diving in on top of us. 

I don't understand the need for folks to say they're in or out. It doesn't matter.  Nobody is keeping score because it's not a competition. If you're here you're a weenie.

[psuhoffman]

12 minutes ago, mitchnick said:

3k Nam much more impressive.  988 slp further south and west at 60 hrs versus 993 on 12k. Precip much further inland too.

I hadn't looked at the 3k before writing my last bit. It's "interesting."  Get a global to look like that and I will be way more vested in this. Looking at the h5 at the end the northern stream trough is slightly sharper with a tiny bit more room to get something up the coast east of it.  It's still tighter then I want but I can see a path from there on that prog at least.  Shift that trough axis just another 50 miles west and it's really game on. It's close enough to have me interested. But I want to see it from something more reliable to get sucked in. 

[showmethesnow]

8 minutes ago, psuhoffman said:

It's closer I'll give it that but the fatal problem I still see and why even given the early phase and bomb on the nam it still misses is the northern stream (piece C) is diving down right on top of us. It phases later but that takes some time so for our purposes it acts as a kicker. It has too. The phase isn't going to stop time so that it can happen simultaneously and everything is progressing as this process is taking place. So if the trough is digging right over us...I don't see how this ends up tucked in like we need it. I guess why I've been so disengaged in this is that I see that as the most important thing. I want to see that dive down west of us. At least into Ohio if not Indiana. Not into PA. And while some of the changes with the stj wave and the first northern stream system have been favorable, I've seen no improvement in that final part. And absent that my fear is there is only so much this can go. We're seeing those other improvements with parts A & B help the Carolinas for sure and the Delmarva. But for west of the bay if that last northern stream piece keeps diving down on top of us it's going to hit a brick wall and turn east. It may or may not hook back in time for New England. Might even screw then. 

It would take an extremely rare almost perfectly clean immediate phase to tuck in tight enough given that trough axis or a sudden shift in that feature.  

If I see something start to change that last part of the equation I will immediately jump in. I want this. I'm just not feeling it as long as I keep seeing the trough diving in on top of us. 

That trailing piece of energy has been depicted (timing, location, etc...) in so many different ways by all the models it probably isn't even worth considering at this point because that will probably not be nailed down until 24 hours out or even a little less. What I have been focusing on is getting that first initial clean phase to get the ball rolling otherwise we are SOL even before this begins. I will let the cards fall as they may after we see that.

[usedtobe]

I'm still having a hard time getting excited by the storm even with the Euro and CMC now giving me some snow,  about an inch from last night's Euro.  I more or less agree with PSUHoffman, we need the northern stream shortwave to dig in a little farther east so the best height falls are not to our east when the southern stream system really gets the low cranking.  If the Euro comes west with its low, then I may change my tune.  I noticed that last night's Euro ensembles gave around a 31% chance of DCA seeing snow but only around a 8 % chance of seeing over an inch.  THat's still not great odds.  I'm happy that the 06Z Canadian came west but don't trust the model nor do I trust the 09Z SREF which gets such a high QPF mean from 3 very wet and unrealistic members unless somehow the upper low closes off and lifts over VA just to our south and east.   That seems unlikely.  Hope I'm wrong.  I'd love to get my inch from the Euro.

[showmethesnow]

8 minutes ago, WeathermanB said:

 

Where along the coast? Mid-atlantic or just off the coast by like 50-100 miles?

No, the 500's pull up to roughly off of OC by 200 miles or so before it then starts tracking NE.

[WeathermanB]

The ECMWF still has time to shift back to the original spot, like it was at thursday 12z. I still think that is pretty possible. Sometimes the ECMWF will show something for the east coast, cave to the GFS 4-6 days out, and then shift back to it's original location proving to be right. We'll see.

[showmethesnow]

Nam was an interesting run to look at. But until I start seeing these type of solutions on the globals it probably isn't worth the effort to get worked up over this.

[AfewUniversesBelowNormal]

This is one of the strongest storms on record and H5 is completely disorganized... 

[psuhoffman]

9 minutes ago, mitchnick said:

I don't understand the need for folks to say they're in or out. It doesn't matter.  Nobody is keeping score because it's not a competition. If you're here you're a weenie.

I've just been giving my thoughts. Others kept asking "are you out" so I answered and went with it. I guess people like to keep score and compartmentalise.  I'm just rolling with it. You can call it whatever you want. But the bottom line is I've been pessimistic this can become a significant snow for 95 and west. Im rooting for my forecast to fail miserably. I was way off on my thoughts this past week. Hopefully I am just as wrong now. 

[BristowWx]

Just now, showmethesnow said:

Nam was an interesting run to look at. But until I start seeing these type of solutions on the globals it probably isn't worth the effort to get worked up over this.

I assume the NAM injests the same upper air data as the GFS?  So it’s really how they handle that data is the key?  

[AfewUniversesBelowNormal]

Can a nontropical low not be closed off at 500mb and be in the 960smb/950smb as far south as Virginia? Has it happened? 

[csnavywx]

Couple of issues:

The NW/W cutoff is likely to be extremely sharp. Very dry air will be in place in the boundary layer (Td <0F), which will take significant lift and precip from above to overcome.

Relatively strong and widespread conditional instability in the warm sector will result in a lot of convection near the developing low. Not only will this affect where the low develops, but moisture transport as well. The extreme deepening rates on the models is partially due to all of the convection and low static stability of the warm sector, hence the high spread and dprog/dt of the low location. It is best to use upper level features this far out.

 

That said, very strong 850-700mb frontogenesis does favor a nice, intense band on the west side of the circulation. I think it'll just be an all-or-nothing deal for those close to the edge.

[yoda]

Looks like 12z RGEM precip field is more inland, yes?  At the end of its run when you compare 12z at 48 with 06z at 54

And 12z RGEM precip looks better than 12z NAM precip - both at hour 48

[SnowGoose69]

2 minutes ago, yoda said:

Looks like 12z RGEM precip field is more inland, yes?  At the end of its run when you compare 12z at 48 with 06z at 54

The UL differences are not exactly tremendous though.  The RGEM may be more effective with dynamics leading to the precip breaking out.  Its earlier than the NAM overall on that.

[Wonderdog]

3 minutes ago, yoda said:

Looks like 12z RGEM precip field is more inland, yes?  At the end of its run when you compare 12z at 48 with 06z at 54

And 12z RGEM precip looks better than 12z NAM precip - both at hour 48

yep. A little more north aand west into GA.

[showmethesnow]

9 minutes ago, BristowWx said:

I assume the NAM injests the same upper air data as the GFS?  So it’s really how they handle that data is the key?  

I am pretty sure it ingests the same data. Maybe someone else knows that for fact. As far as handling the data differently the NAM focuses more on meso scale features to the best of my knowledge but again someone else can probably give you a better answer then me.

[psuhoffman]

14 minutes ago, showmethesnow said:

That trailing piece of energy has been depicted (timing, location, etc...) in so many different ways by all the models it probably isn't even worth considering at this point because that will probably not be nailed down until 24 hours out or even a little less. What I have been focusing on is getting that first initial clean phase to get the ball rolling otherwise we are SOL even before this begins. I will let the cards fall as they may after we see that.

The vort itself has been all over with timing but the models have  been fairly consistent with the location and depth of where the trough as a whole digs. Looking back over the last few days now there was a bit more improvement there then I thought. It's been so incremental as to be unnoticeable run to run but it's marginally there over days. A bit more and maybe...

The problem is the random outlier runs that nailed us (the 2 ggem runs then the 2 euro and 1 ukmet) did it by diving that last northern stream piece down to our west and phasing in. It required almost a due south dig for gold by that vort. I've not seen any guidance doing that lately and the only runs that were snowy had that. So I'm not saying parts A/B aren't important but absent getting back to a better presentation from part C I don't think this can work for us. The 3k nam was closer but even that was probably going to be a close miss extrapolated.  The northern stream was leaving a bit more room but it still wasn't showing signs of digging in behind and phasing in time for us.  Especially for us up here. Might have clipped D.C. proper. 

[George BM]

[BristowWx]

Just now, showmethesnow said:

I am pretty sure it ingests the same data. Maybe someone else knows that for fact. As far as handling the data differently the NAM focuses more on meso scale features to the best of my knowledge but again someone else can probably give you a better answer then me.

Thanks.  Just curious.  Not worth pouring over.  

[MillvilleWx]

Couple of issues:
The NW/W cutoff is likely to be extremely sharp. Very dry air will be in place in the boundary layer (Td Relatively strong and widespread conditional instability in the warm sector will result in a lot of convection near the developing low. Not only will this affect where the low develops, but moisture transport as well. The extreme deepening rates on the models is partially due to all of the convection and low static stability of the warm sector, hence the high spread and dprog/dt of the low location. It is best to use upper level features this far out.
 
That said, very strong 850-700mb frontogenesis does favor a nice, intense band on the west side of the circulation. I think it'll just be an all-or-nothing deal for those close to the edge.

If we can maintain this H5 presentation, this has Beach mauler written all over it. I’m still thinking this is an Eastern shore deal. We really need to see that last piece dive in from OH Valley or we’ll be left with passing flurries while OCMD uses Beach shovels to get out of their foot of wind swept powder. Fun fact: OCMD has 2 plows on the barrier island. TWO!! Learned that when I went down there for a storm years ago. Father in Millville, DE said last years January storm had 1 plow make a run at Rt 26 the whole storm. Might need some extra help if this comes to fruition.


.

[yoda]

Fwiw, 12z JMA gets 0.2" QPF to I-95 corridor 

[yoda]

Western ridge is better on 12z GFS...

[Stormman96]

Comparing. 12z gfs to 06z gfs.  If anything it look a but further east

[SnowGolfBro]

Would love to see even a baby step from the GFS.

[showmethesnow]

500mb's on the 12z GFS say No.

[cae]

12z GGEM.