The Return of the 12/5 Snowstorm

[bncho]

5 minutes ago, baltosquid said:

Bad RGEM run, drier DC and north. Hopefully just a blip.

Bad is hyperbole IMO. It's only a slight tick downward.

[winter_warlock]

Ahhh ok.i stand corrected..

 

Oops..

 I didn't have the chance to check the ensemble members.. my mistake lol

[Jebman]

20 minutes ago, SnowenOutThere said:

700mb frontgen is entering the southern parts of our region were now at Nowcasting time!

Also some weird line of 850 frontgen over NOVA that has been strengthening over the past couple hours. Anyone know whats up with that?

That's the HoCo/MoCo super deathband.

[Solution Man]

9 minutes ago, BristowWx said:

Damn locked and loaded.  Looks like NoVA DC bullseye.  We are ready 

Looks good for us, we are gonna be in a good spot for this one. Imagine that

[wawarriors4]

2 minutes ago, Solution Man said:

Looks good for us, we are gonna be in a good spot for this one. Imagine that

Certainly not bad being in Stafford for this one.

[Scraff]

2 minutes ago, Jebman said:

That's the HoCo/MoCo super deathband.

I’m not feeling anything but a car-topper here in Hoco, but damn I love your energy. Always have! My kids who are grown ass adults now tell me they still like to go on Jebwalks in the snow. 

[MillvilleWx]

20 minutes ago, SnowenOutThere said:

700mb frontgen is entering the southern parts of our region were now at Nowcasting time!

Also some weird line of 850 frontgen over NOVA that has been strengthening over the past couple hours. Anyone know whats up with that?

 

18 minutes ago, Eskimo Joe said:

850 frontogenesis might be the cold front pressing down. Check out the wind barbs over MD and WV panhandle compared to central VA. Watch this area closely for a deathbed to set up.

As EJ eluded too, take a look at the 850mb temps. and also take a look at 925mb while you are at it too because the layer of greatest importance lies within the 925-700mb zone for this setup. Winds within 850mb are convergent across the Mid Atlantic, especially along and east of the BR. There's a nice 160+ kt jet max just off to our north with RER dynamics positioned over the Central and Southern Mid Atlantic. This is important in terms of ascent being maximized within the DGZ, allowing for better dendritic growth regimes to materialize with banding structures likely situated within the stronger 850mb FGEN and up around 700-500mb FGEN maxima due to the stronger mid-level vorticity advection passing to the south of the M/D. Where these two areas intersect will be the stripe of the higher totals, mainly southwest VA through true Central VA, perhaps sneaking into far SoMD. Further north, the 850mb FGEN will be the main show and where that sets up will likely spur some 1-2" totals which looks to be along and south of Rt50, and maybe as far north as I-70, although it will be close! 

Fun little setup here! Wish we had a little more amplitude in the mid-level pattern, but beggars can't be choosers! 

[Maestrobjwa]

59 minutes ago, TSSN+ said:

Haven’t been seeing very much in the past few years up here. So many southern sliders in these Nina’s. Hopefully can pull something out soon cause the legit storm drought up here is wild. I haven’t seen a storm over 7” since 2016. 

Wait seriously? Wow...It's crazy how your yard and mine have suffered the same thing since 2016 despite you being way north of me! Just a frustratingly weird 10 years of this.

[WxWatcher007]

29 minutes ago, Eskimo Joe said:

850 frontogenesis might be the cold front pressing down. Check out the wind barbs over MD and WV panhandle compared to central VA. Watch this area closely for a deathbed to set up.

It’ll be a deathbed for some if they get fringed.

KIDDING, KIDDING!

[T. August]

31/15 dry af

[nw baltimore wx]

I said it a couple of months ago, but I still think the Reaper will make a few appearances this season.

[PWC Split]

33/21 at 10:30 (Haymarket)

[SnowenOutThere]

10 minutes ago, MillvilleWx said:

 

As EJ eluded too, take a look at the 850mb temps. and also take a look at 925mb while you are at it too because the layer of greatest importance lies within the 925-700mb zone for this setup. Winds within 850mb are convergent across the Mid Atlantic, especially along and east of the BR. There's a nice 160+ kt jet max just off to our north with RER dynamics positioned over the Central and Southern Mid Atlantic. This is important in terms of ascent being maximized within the DGZ, allowing for better dendritic growth regimes to materialize with banding structures likely situated within the stronger 850mb FGEN and up around 700-500mb FGEN maxima due to the stronger mid-level vorticity advection passing to the south of the M/D. Where these two areas intersect will be the stripe of the higher totals, mainly southwest VA through true Central VA, perhaps sneaking into far SoMD. Further north, the 850mb FGEN will be the main show and where that sets up will likely spur some 1-2" totals which looks to be along and south of Rt50, and maybe as far north as I-70, although it will be close! 

Fun little setup here! Wish we had a little more amplitude in the mid-level pattern, but beggars can't be choosers! 

Yeah, this is where I can admit that this is way beyond my pay grade and that real mets are on a whole nother level thats basically magic. Though from trying to piece together what I can understand and the SPC analysis page you're basically saying that the primary max stripe is driven by the 700-500mb FGEN (as it overlaps with DGZ better) and strong 850mb FGEN and this setups somewhere in Central VA. Meanwhile NOVA and the like are displaced from the higher level FGEN and will use the 850mb instead. While I don't understand the math or physics behind it should I generally assume the 700-500 FGEN will just progress along with the wind barbs (which does seem to place it oddly northward to even fringe me?)

Oh, and while I'm annoying you I'm targeting around 3:30 start of my Jebwalk lmk if that checks out.

[WesternFringe]

2 hours ago, SnowenOutThere said:

UVA delayed start till 10am so I get out of my Chem group exam at 8:30am!

When I was an undergraduate there in the mid 90s, they canceled classes for the second time ever in the history of UVA from 1819. I wonder how many times they have canceled since then?

[Interstate]

29.5/17.3 here in 21057

[WEATHER53]

1 hour ago, stormtracker said:

Looks like about 1 to 2 from EZF north...3 down there and like 2" up to the DC metro and an inch to the Federick County southern border

 

I mean, yeah, relative to yesterday's runs, I'd buy and not look back

And it will improve a tad more come Go Time!

[WxWatcher007]

1 minute ago, WesternFringe said:

When I was an undergraduate there in the mid 90s, they canceled classes for the second time ever in the history of UVA from 1819. I wonder how many times they have canceled since then?

Canceled for the superstorm? 

[PrinceFrederickWx]

36/24 mostly cloudy

[MillvilleWx]

1 minute ago, SnowenOutThere said:

Yeah, this is where I can admit that this is way beyond my pay grade and that real mets are on a whole nother level thats basically magic. Though from trying to piece together what I can understand and the SPC analysis page you're basically saying that the primary max stripe is driven by the 700-500mb FGEN (as it overlaps with DGZ better) and strong 850mb FGEN and this setups somewhere in Central VA. Meanwhile NOVA and the like are displaced from the higher level FGEN and will use the 850mb instead. While I don't understand the math or physics behind it should I generally assume the 700-500 FGEN will just progress along with the wind barbs (which does seem to place it oddly northward to even fringe me?)

Very close, yes! There can be shifts in the latitudinal alignment of the 700-500mb FGEN and you can tell positioning potential based on advection regime by assessing the wind field and height contours. Notice across MD/NoVA, the winds are parallel to the height field with a touch more perpendicular trait further south. This is a relatively zonal scheme, however the passage of the mid-level disturbance allows for a bit of amplitude downstream of the mean trough as it migrates eastward. That's why as the storm materializes and move east-northeast, there's a bit of a southwest to northeast slope of the QPF field as we head into morning with a bit more latitudinal gain in the FGEN placement. It comes down to that minor downstream amplification still positioned within the RER of the retreating upper jet over the Northeast. The static image you provided would make it SEEM like that would be the case, but the evolution of the synoptic pattern will allow for just enough general amplitude to have things shift up into our hoods to give us some fun. Fluid dynamics is a treat, isn't it?  

[stormtracker]

GFS looks about an inch or two along and north of EZF up to along and south of 50

[stormtracker]

Don't do it Ravens.  Seriously.  Low hanging fruit.

Anyway, decent

[BristowWx]

23 minutes ago, wawarriors4 said:

Certainly not bad being in Stafford for this one.

Yep.  You are in the sweet spot. Stafford County FTW.  In early December..  unbelievable

[ravensrule]

Just now, stormtracker said:

Don't do it Ravens

What an impressive distribution. What’s your prediction for inches?. 

[wxdude64]

Looking at traffic cams, snowing in Blacksburg and Beckley WV, draw a line between the two for forward progress of the snow. Currently 32.0.26.7 here and waiting.

[BristowWx]

1 minute ago, ravensrule said:

What an impressive distribution. What’s your prediction for inches?. 

Prediction? PAIN

[BristowWx]

2 minutes ago, wxdude64 said:

Looking at traffic cams, snowing in Blacksburg and Beckley WV, draw a line between the two for forward progress of the snow. Currently 32.0.26.7 here and waiting.

My son is at Radford.  It’s coming down.  He’s drunk at a frat party.  Bastard. 

[cbmclean]

4 minutes ago, stormtracker said:

Don't do it Ravens.  Seriously.  Low hanging fruit.

Anyway, decent

Wait are you referring to the bird-like shape, or something dirty, because I al a little confused.

[WesternFringe]

10 minutes ago, WxWatcher007 said:

Canceled for the superstorm? 

Yes!

[SnowenOutThere]

16 minutes ago, MillvilleWx said:

Very close, yes! There can be shifts in the latitudinal alignment of the 700-500mb FGEN and you can tell positioning potential based on advection regime by assessing the wind field and height contours. Notice across MD/NoVA, the winds are parallel to the height field with a touch more perpendicular trait further south. This is a relatively zonal scheme, however the passage of the mid-level disturbance allows for a bit of amplitude downstream of the mean trough as it migrates eastward. That's why as the storm materializes and move east-northeast, there's a bit of a southwest to northeast slope of the QPF field as we head into morning with a bit more latitudinal gain in the FGEN placement. It comes down to that minor downstream amplification still positioned within the RER of the retreating upper jet over the Northeast. The static image you provided would make it SEEM like that would be the case, but the evolution of the synoptic pattern will allow for just enough general amplitude to have things shift up into our hoods to give us some fun. Fluid dynamics is a treat, isn't it?  

Thank you for these posts as I think I get what you’re saying now. If I’m understanding you’re saying that the FGEN takes on a more titled angle of SW to NE because the mid lat low amplifies and pumps up the height lines ahead of it just a tiny bit (alongside some jet dynamic sorcery). In practical effects this tilting would cause the eastern bit of the FGEN to be lifted north relative to the screenshot expected trajectory by wind barbs (as they change with the mid-lat cyclone deepening), while the western FGEN would tilt south some. I do worry a little bit that my new location (no longer NOVA as I’ve progressed to UVA) may end up between the 850mb FGEN focus in NoVa and the higher level FGEN further south but honestly from what you’ve said it looks like I’m pretty good to at least catch the western (if tilted south) half of the 700-500mb FGEN! Oh also am NOT looking forward to knowing the equations behind this stuff because damn lapse rate and first law of thermodynamics stuff already almost took me out.

[MillvilleWx]

1 minute ago, SnowenOutThere said:

Thank you for these posts as I think I get what you’re saying now. If I’m understanding you’re saying that the FGEN takes on a more titled angle of SW to NE because the mid lat low amplifies and pumps up the height lines ahead of it just a tiny bit (alongside some jet dynamic sorcery). In practical effects this tilting would cause the eastern bit of the FGEN to be lifted north relative to the screenshot expected trajectory by wind barbs (as they change with the mid-lat cyclone deepening), while the western FGEN would tilt south some. I do worry a little bit that my new location (no longer NOVA as I’ve progressed to UVA) may end up between the 850mb FGEN focus in NoVa and the higher level FGEN further south but honestly from what you’ve said it looks like I’m pretty good to at least catch the western (if tilted south) half of the 700-500mb FGEN!

You're getting it!! Static presentations tell some of the story, but how the whole evolution materializes, or is expected to materialize paints the full picture. You'll learn a lot more about jet dynamics as you work through classes. The derivations will help give you an understanding of the "why", even though they can be a bear to tackle (Math portion). Contextual models will also help as well, which I know they'll go through. You are doing great and really find interest in this, so keep up the great work and never stop asking questions