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shield your eyes, it's hideous https://www.mdpi.com/2225-1154/13/12/246

Congratulations!! The birth of a future weather weenie

interesting. the 12z EPS has as far as I can tell, completely evacuated the mid month Rosby rollout/warm up. This mean centered on the 17th ( for ex) bears no signature of that any longer

Yes it's 50 now Iol

Dewpoints actual vs HRRR at 3 pm: GSO -10 CLT -1 RAH -9 ROA -0 This tells me the warm front to the south has not advanced as far north as modeled. If this continues I would expect the rain/snow line as well as the heavier rates to shift south, although too early too have any confidence in this scenario based on OBS

I was about to say...this looks like cold and dry to me since it may be harder for anything to amplify and ya get more interference.

Had a brief dusting with the first round of snow showers about 45 minutes ago. Enough to log a "trace" for the day but not measurable. But it did lower the temp from 40F to 31F very quickly. Sun is back out now but perhaps a more legitimate squall appears to be approaching from the west.

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

You're in a good spot - I seriously hope you overperform. My Dad (Midlothian outside of Richmond) is too. I doubt I'll see much more than conversation flakes, but boy it's been cold here. Parts of Broadford Lake (poor man's Deep Creek near my house) are starting to ice over even. Hi of 26 yesterday and currently sitting at 23 with a thick overcast.

I myself would be happy to see my children go berserk over snow TV this early in the season. Win/Win. I just hope it doesn't end until evening.

Don't forget your selfie stick!

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.

18z 3km NAM total QPF

I agree with you in general. However, there is a timeframe that I think has more potential for a negative tilt, digging trough late next week into next weekend (Dec 11-14). This is the timeframe that both operational models and ensembles show the blocking retrograding from western Greenland to near Baffin Island and then into central Canada, and possibly linking up with western US ridging. The period when blocks retrograde and decay into Central Canada and then link up with western US ridging is the one when significant snowstorms are most likely in the coastal parts of the NE US. Now to clarify, I don't see the potential for a significant (6"+ snowstorm) for the I-95 corridor from NYC to BOS. But my point is that the pattern does match periods which are more favorable for significant coastal storms along with sufficient cold air for snow. Given the northern stream/clipper dominated pattern and the troughs turning negative tilt relatively late, snowfall would be most favored across far northern NY and northern New England, but eastern Long Island to SE New England also climatologically can do well in these types of events if they dig far enough south. The ECMWF and (to a degree) the GEM both show the above-mentioned blocking and negative tilt/digging trough trends late next week into next weekend.

Yep. Moore, OK called and want their storm back

Ripping +SHSN

Should be WInter Storm Warming stuff

Randall my good man. Please get him back. OT should not get him kicked from here-just OT only Matthew Baratta Niktu

Any chance for high ratios? LOL! Get every bit out of it we can squeeze!

Bumped up again, now 65% chance at 4", a 38% chance at 6" and a 10% chance at 8". NWS bumped forecast to 3-6 total.

This system will probably do more than Monday night Tennessee north of I-40. Not everywhere, but more places esp northeast Tenn. More I mean snow. Fortunately the ice looks trace again. Regrettably I don't have time to write more. Good luck up there!

He got banned over some nonsense in that moronic OT thread. So ludicrous. Supposed adults acting like children.

Extreme snow squall in progress. Captured this image from my neighbor's webcam. Right now vis is 1/16th of a mile. When I can't see the other side of my pasture we know that heavy rates are happening.

I did not know he was deliberately away what happened?

yeah has a nice little axis of precipitation from E CT on east