ILMRoss

1 hour ago, BullCityWx said:

You're the pro so you're seeing things I'm not I am sure. I'm concerned that the flow looked so progressive on the euro. If we can slow it down like we had yesterday at 12z then I think we've got a pretty good signal. 

This is what I saw: 

I really like to compare ensembles on if their "seeing" the S/W. GFS ENS did- check the indent over the Missouri Valley on 6z:

Euro ENS on same timeframe had a ridge in basically the same place:

We hem and haw about how "oh yeah its 7 days away the models dont know anything" but i generally believe the wheat separates from the chaff in the 7-9 day timeframe. If Euro got on board and showed a weaker ridge and stronger S/W signal, that was when I'd start salivating. Unfortunately, 12z models are bending towards the Euro. Hopefully the Euro produces better news in an hour.

Euro being a stick in the mud should give everyone great pause. There's pretty stark differences in its ensembles too. Temper your expectations in case the models slide into a Euro-ish direction today. That being said, if the euro and ensembles hop on board, we have a great (dare I say elite) long term signal.

Keep a lazy eye on next weekend. Euro was close to something. 

I think that DT is generally pretty smart and a good forecaster. I may be biased, I think that my first "rodeo" following these things on models and online and in social media was the Boxing Day 2010 storm, where he was issuing those wild probability maps. I still get an adrenaline rush when I see that *ALEET* on my Facebook feed! That being said I do think he inflates numbers a little to get some more social media exposure. Take 30% off his forecast and I think you have a solid call. 

Overall, I think the dye has been cast; There's going to be a front-end push of precip that could start as snow, and if it's heavy/quick enough it may surprise some folks/forecasters. It wouldn't be the first time I've seen that front-end overperform. Now when I say overperform, I mean "maybe an inch before flipping over", not "all snow event that will break forecasts". After a quick dry spell, the comma head will come in Friday night and drag through the northern 2/3s of the state and drop a half inch to an inch of accumulation, maybe a little more if you're lucky and you're sitting in a nice band. It will hopefully be enough to make things look pretty; great weather for sipping scotch. The place to be, I would say, is likely the NC/VA border, specifically near the mountains where elevation will help BL temps. If I were chasing, I would probably find a nice cabin in Fancy Gap. 

Some thoughts:

- I would not rely on the 12km NAM precip shield depiction. Something I first noticed tracking that early Jan 2018 coastal is that it is pretty terrible and inconsistent at rendering these things, with a lot of features that aren't supported by synoptics/surface features. I think they're fun to look at but I don't take them very seriously. I trust the 3km depiction more.

- Flipside: I think somebody is going to get dry-slotted and shafted. Don't know who, but it's just the nature of these transfers of lows from inland to the coast. 

- 3km NAM is showing the "splotchy" nature of the precip shield really well- that's how it will turn out! It will be feast or famine! One lucky locale may even see a little thundersnow, not out of the question! Don't know who. 

Fun fact- The elephant in the room is that BL temps are pretty terrible for this event - the main difference with the RGEM is that it's totally colder; not really much else going on. 

Just now, griteater said:

Euro Ens Mean looks about perfect to me for western areas for a week away...solid looking storm that is tracking south of you...32 deg line on the mean thru CLT....of course, this is one model

Thanks for the images yall, and completely agreed; for a week out it's a pretty lovely signal. I've been around long enough to bake a NW trend into any long range projection, so I like where we are sitting at now. 

Euro with a bit of a monkey's paw run - oh, i hear you don't want suppression, how about this! Shout out to the folks that really get it good on that run but let's hope future runs settle down; a big sharp trough like that is begging to see a NW trend. 

keep the euro ens images coming if you got em, should be a pretty enlightening run.

35 minutes ago, BullCityWx said:

Yeah, anything I get on Friday I consider a bonus. Sometimes scraping out 2-3" from an event like that can transition a winter from good to great so fingers crossed. Would you think if we do get 2-3" down and keep it around until Sunday, it helps us on Monday?

Anything helps - whether it's snow here that helps depress the surface temps some, or snow in S VA to keep the upstream airmass fresher for us, anything helps. 

Regular ol GFS showed the potential really nicely- play your cards right and you get a legit, bona fide Miller A here. 

Really excited to see what the Euro and it's ensembles show... If it shows a similar set up to the GFS this board is going to have an aneurism. I think suppression is still obviously on the table, there's a lot of shortwaves flying around and it wouldn't take much to smush this. 

In terms of "potential" I am much more excited and anticipatory on the 12z suite for the *Monday event* rather than the *Friday event* , much higher ceiling for a much larger swath of people.

21 minutes ago, BornAgain13 said:

Some of you experts can weigh in on this , but does it seem like the GFS is on to something, by not being as wide spread event and just scattered? Or would you lean more toward the EURO/EPS , with it being more widespread?

I don't know if it's "on to something" per se; this is the nature of a lot of these ULLs that roll through. There are going to be competing forces within the feature that promote both rising air (more precip) and sinking air (less precip) which is the reason for the "splotchy" look on snow maps. As for the Euro, the more consistent snow map strikes me as just a difference in how the snow map is calculated and not the nature of the precip. Lastly, as a general rule, EPS will always have that smoothed-out look because it's an average of 51 different members. Those members themselves may be splotchy... but together they're look very uniform.

Please- don't worry about how a Euro run only gives table scraps to the triangle. These are fun things to gawk at but right now I would focus on what the globals are good at (synoptic track and larger scale features). Overall, some nice trends today with the ULL continuing to nudge south. I will say, you don't want the vort to pass too far south, or else the best dynamics (and heaviest precip) stay to our south as well. Let's get a few hi-res cycles closer to the event under our belt before we start a pity party for the triangle.

This is fun. Any trough this strong and sharp is worthy of scrutiny! That being said, the globals are starting to converge on an axis extending from Nashville-ish northward to have the best shot of noteworthy snow. If you're east of the apps, its about time to see some ensemble members show big hits to think that you're in the mix for a noteworthy event. If the trough wants to tilt negative as the trends today pointed to- I don't think the trough orientation is quite in our favor, and likely favors an inland low track. 

Some optimism- It's a ton of energy- I wouldn't shut the door on a weak clipper system or some flurries as the base of the trough passes. 

Really happy for PA.

Had a lunch with Tim Buckley (Greensboro met) right before I started on my real short broadcast career. He told me that the state college area is usually 1. Too inland for the coastals and 2. Too far east for the lake effect stuff. So a lot of what they see is nickel and dime stuff. Nice to see that region reel in a big one!

5 minutes ago, griteater said:

But on Pivotal, the QPF (liquid) and ZR QPF are essentially the same amounts...so, they are just showing you how much precip will fall as freezing rain as opposed to how much ice accretion will occur.  I'd go with something like a 50% reduction for this storm given temperatures, warmth pre-storm, etc.  0.4 inches of liquid = 0.2 ice accretion.

Pivotal has added ice accumulation maps using the FRAM estimate with a paid subscription (I don't have one) - https://vlab.ncep.noaa.gov/documents/10157/137122/FRAM_VLAB_Presentation.pdf/50ff7877-c52d-80f4-1413-b294db7710e9

Yeah, I should of been more specific. "ZR qpfs" was a pre-coffee phrase. Meant calculated ZR totals... there's a variety of reasons it always happens, its not just a 'models have no idea how to handle this!' situation. It's always a dash of precip coming in an hour or two later than forecast, dews being a smidge higher than forecast, more sleet than ZR, things like that that can combine to eat in what forecasts say.

Two things to keep in mind:

-There is some scientific backing behind "hi-res models do better with CADs", which at face value can scan as a weenie-ism sometimes. Hi-res models will have a  much more detailed rendering of the apps and topography in general- as it turns out when forecasting a topographically-induced weather event, having the topography rendered as accurately as possible is important!

-I have never, in 9 winters of lurking and posting through this board, seen ZR qpfs be accurate. They are almost always inflated. The only legitimate ice storms I can really remember that mildly panned out were all in 2014.

On 12/10/2020 at 10:15 AM, ILMRoss said:

Whatever next week is fits neatly into the same category of the Monday system. It has upside, may be worth some token stuff, but a lot of things need to break in the right direction for it to be anything more than that. I would pay attention to how much the associated S/W digs/cuts off and if it keeps the integrity of that cut-off through the SE on today's model runs- some positive developments there would be cool. 

Generally anything progged to put snow down in Oklahoma and moving laterally warrants at least a lazy eye for our Carolina folks.

^ here's a take that aged like milk in a hot car. it happens.

For next Wednesday, don't really think it's our storm unless you're above 2k feet (even then, apps may have moisture issues). That CAD high will need to get stronger or drop south some for this storm to be relevant to non-mountain folks. 

Whatever next week is fits neatly into the same category of the Monday system. It has upside, may be worth some token stuff, but a lot of things need to break in the right direction for it to be anything more than that. I would pay attention to how much the associated S/W digs/cuts off and if it keeps the integrity of that cut-off through the SE on today's model runs- some positive developments there would be cool. 

Generally anything progged to put snow down in Oklahoma and moving laterally warrants at least a lazy eye for our Carolina folks.

I guess no one has looked at the Euro?

Euro has had first snow shower potential for two runs in a row now for much of the southern/western piedmont coming up on Tuesday. 

Had a friend that said Birmingham got some flakes today. MPING has the Atlanta suburbs seeing some flakes. Wouldn’t be surprised some pretty widespread token flake action in the Carolinas tonight but if you want to see it time to get that coffee brewing.

Tbh probably the first time in a while I’m rooting for a warm winter

If we’re going to be in lockdown 2 at least let me get some more golf in.

I would be cautious in interpreting these soundings from tropical tidbits.  Strictly speaking, one should compare the virtual temperature of a lifted parcel to the virtual temperature of the background environment to assess lifted parcel buoyancy and CAPE, but their soundings use actual temperature.  So this plot is misleading - the dashed line is probably a bit more to the right than indicated on here.  Note that there is no MLCIN.  This is actually a pretty good looking thermodynamic profile.

Attached is a similar sounding from the same approximate location and time, plotted correctly from dupage.  You can see that there is actually quite a bit of low-level buoyancy for a lifted parcel.
 
 

We really don’t know if the high ceiling will be realized until this time tomorrow. Every CAM has a different technique on how they render boundary layer mixing, which dictates how warm it gets at the surface. 3km NAM still displays a “mild” solution, in this case meh surface temperatures never get past the mid 70s and rising parcels don’t really have a ton of difference between their temp and the background temp until they rise to about 700 MB, according to this sounding I pulled. If the 3km is right, expect to see a lot of shallow, ‘baby’ supercells that struggle to stay alive amongst the strong low level shear. This solution would keep the SPC from slapping a high risk onto things.

Once again, all about boundary layer with this limiter, and other models (looking at you HRRR) will scare a lot of people because they have a tendency to overdue temps and therefore, CAPE.

Couple of thoughts;

-A weird wildcard to keep in mind is that model accuracy has gone down because of the COVID-19 outbreak. Why? Commercial planes are equipped with sensors that collect data that is fed into models. We're not talking hurricane hunters grade stuff here, but enough to increase our sampling to improve model outputs. Model verification has dipped significantly since the onset of the outbreak, and less air traffic is probably the reason why. Now- obviously models are still robust and should be trusted, but they may swing a little more/have a bit less consistency than usual.

Some NC specific things: 

850MB winds will be whipping- the default to expect is a squall line with some embedded spin-ups. There are two ways this becomes something fiercer:

-The model trend has been ticking this thing slower and slower. The slower this goes, the more juiced the atmosphere can get ahead of the storms, and put far east places (New Bern, Edenton, E-City) in range for stronger storms/stronger tornado risk. 

-The flip side to the above is Sunday's storms evolving into an MCS that rockets past guidance, and is offshore the NC Coast by midmorning Monday, allowing the atmosphere over Eastern NC to recover. 

I think that the ceiling for NC on Monday is an enhanced risk; but keep an eye on things. Not a good idea to take your eye off the ball in high-ceiling events like this.