SnowenOutThere

Do you have a link to this for other airports (CHO in my case)?

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.

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.

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?

Looks like its the band hits Charlottesville a couple hours earlier (4am sounding for refence). Will be a fun Jebwalk! (sorry to my poor roommate who has to deal with that though). But what a thing of beauty compared to the HRRR runs we were looking at earlier.

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

I don't particularly like that hole of sub 2 inches near where I am but I will have faith that the HRRR is onto nothing (though honestly it sorta makes sense two have two maxes).

Generally seems wetter than the HRRR depiction which helps us all out even south id think. I’m just praying I don’t get stuck between bands!

I am interested in how the lift profile throughout the atmosphere impacts snow rates if you got any resources on that. Ik that sometimes it causes our events to underperform but I have no idea how to read if that’ll happen

A halo in folk meteorology means a storms coming but yk close enough

Mine has a halo around it which can only mean one thing…

Are we allowed to panic if the snow falling isn’t good ratio stuff because of misaligned DGZ and lift?

Should mention "hot and heavy" is still in the context of this storm's version of it. Though it will definitely be pretty as it falls.

For posterity heres all of that condensed into a snowfall map for my friends (sorry MD crew).

Alright let's do this one last time. One final real analysis post before it becomes nowcasting time. Firstly, lets go over the whole progression that got us to this point. Feel free to skip past this part if you just want updates! 5 days ago I made my first post where I lamented over the low out west getting stuck leading to thermal issues over us. It's important to note that initially we were relying on the shortwave after our current storm to induce cyclogenesis. I will give myself some credit as I correctly identified we needed to get our low out of the Southwest ASAP (though admittedly, I was still thinking of the second shortwave). By Monday the guidance was split over if wave 1 or wave 2 would be the trigger for the storm. Last Monday's 12z Euro this quite well as it had our wave get shredded to pieces before wave 2 tried to help out. Notice how this is for Saturday 0z, hence why this storm was initially progged as a Friday-Saturday storm. At this juncture it was pretty clear we had to get wave 1 to be dominant over wave 2 (or run out ahead of it) to get a storm. Luckily, over the next few days that is exactly what happened. We got the double positive of wave 1 speeding up and the mess of energy entering the west slowing down. Another thing we needed (identified Tuesday) was to have the incoming velocity be both more negatively tilted and further south (as it would encourage our wave to gain latitude). The difference between the 18z Nam 12k on Tuesday and its 12z run today shows just how positively almost everything trended! We have a further east wave 1, generally slower wave 2, more N/S orientation of wave 2, and more energy displaced south for wave 2! Look at how our shortwave responds by actually gaining a tilt instead of flattening out! Tracking the evolution of this storm has been a reward by itself as it really shows just how many things we need to go right to get snow. Of course, the real reward is the snow itself. So with the history out of the way what is left to forecast? Well, at this point the synoptics are in place and we have our last real useful runs before this fully transitions to nowcasting. That said, lets draw some attention to the start of this event. Another piece that has trended better overtime is how quickly we can fully saturate the column with moisture (namely as a stronger storm means better wind direction and speed to advect moisture into our area), as the initial atmosphere is extremely dry (see sounding at 7pm tonight) Luckily as mentioned above we have strong winds from around 850mb up to bring in moisture from the Gulf! However, this alone would not really get us anywhere. This is where the real exciting part of this post comes in! 700mb temp advection and frontogenesis! I'll be honest this part is extremely exciting to me. Take this Nam snapshot at 1am tonight of temperature advection in the 700mb layer. Look at that strong temp advection in the 700mb layer! That's how you bring in moist air! As a note, this is better than its 12z run hence the improvement in snowfall totals. What this then means is this storm looks to come in hot and heavy with a good thump of snow via 700mb frontogenesis (once the column fully saturates ofc). This is shown with the NAM sounding at 1am as you can really see the lift this provides for 850mb up past 500mb (which includes the DGZ btw)! One other thing I want to note is a maximum that shows up with 850mb forcing right over the NOVA area at 9z on the Nam (and to a less extent the HRRR) I do wonder if this holds true that someone in that zone could have a mini jackpot. (A counterpoint to that is that the DGZ is still above 600mb but honestly I don't know how that interacts with lift in the 850mb layer). From here on out I'll be looking at the NWS analysis page to see where the best frontgen ends up occurring! It has truly been a joy tracking this event with all of you. Being honest, University wasn't all it was cracked up to be (in some regards I still like it overall!) so your kind words were appreciated. I also want to thank everyone who's posted meteorology analysis before as those contributions are what got me to make this thread (even if years removed from the advice given). My advice for any poster who wants to learn analysis is just look at the 500mb maps and try to figure out the connections of vorticity for what makes a "good" and "bad" run as that should get you started thinking more upper-air based. Thank you all again (especially @Terpeast @WxUSAF @psuhoffman @CAPE @Eskimo Joe and the posters I'm forgetting from this list (sorry!)) for helping. Hope for snow.

WWA hoisted to include both metros. Lets reel this one in!

What ratio would you advise using instead of Kuchera for this event

Congrats and good luck! My sister was born during the 2002-2003 winter (or the "one where it snowed a lot" as they call it) and my parents have similar stories. I'll try to be the intern filling in for your absence posting wise!

Wonder if that mini supercell alley is a direct result of the gap in the mountains I-64 takes impacting the flow. As for pictures I already have my d850 charging and ready to go. I think I plan to get the class Rotunda Pic, Dell pictures, and various Garden pictures. If you have any other pretty snow picture spots on Grounds please let me know!

Do you know any resources I could use to see and possibly anticipate how much down sloping to expect (besides annoying my resident professor on microclimates which I plan to do)?

What would you expect for Charlottesville? I'm thinking that at least an inch is a safe bet with a max of 3 (1.5-2 is my target). Only worry is down sloping or a further slip south (though with the H5 that would be quite a change to skunk me) but generally I think I'm pretty locked in for a pretty Friday morning on Grounds.

One last post before I call it a night. Something that I thought was a fun demonstration of how moistening the atmosphere truly works was this snapshot of the HRRR at 2am Friday. I really love how you can see the actual snowfall hitting the ground earliest along the spine of Shenandoah because the couple 1000 feet elevation they have compared to the surrounding areas means that there is less dry air between the clouds and the ground. It's fun to then see this reflected by it showing snow hitting the ground instead of sublimating. Dewpoint depression shows how the higher up you go the more moisture is making it to the surface as the lower values are found almost identically to an elevation map. None of this actually has a sensible impact on our weather or forecasts (though it does explain that the Shenandoah maximum in this storm is less the result of orthographic lift but instead this dry air quirk) but instead just a fun exercise to show how moistening the column works from the top down elevation wise. I will be sure to this run to show my mountain meteorology/climate near the ground professor as I feel that they'd appreciate it.

FWIW the RAP is pretty juiced

The one thing that annoys me about the HRRR is how the best forcing arrives with the precip (which makes sense I suppose). However, according to the soundings we have an entrenched layer of dry air (someone pointed this out earlier) which would sublimate before it could be saturated. HRRR shows this taking a couple hours which would be painful (though another actually smart met will need to chime in on how much that matters in relation to its molded snowfall output or if its factored into it). The good news to my eyes is once the column does saturate its game on with a saturated DGZ and good lift aligned with it! I know @psuhoffman mentioned that strong winds in the DGZ can break apart crystals but from my (admittedly chatgpt) understanding this soundings seems fine in that regard.

To illustrate the 0z run has the higher heights in front (notice how there is less confluence in Maine compared to 18z) which helps the storm amplify. Secondly, the shortwave itself is a bit stronger and less stretched out as the NS "kicker" is further south which almost seems to help spike development in our shortwave (while having the benefit of kicking it east slower) 0z 18z