WxMan1

This is an excellent opportunity to consider the 'self-development process'. True, the upper levels (amplification) dictate what goes on at lower levels. Cyclogenesis, frontogenesis, etc. However whenever you can get an overabundance of sensible and diabatic heating into the system (i.e. over the Atlantic Gulf Stream), you can actually get the low-level dynamics to reform what happens aloft. In other words, accelerated amplification in the upper trough that isn't solely from exit region upper forcing upstream (i.e. DPVA). It's all about what the Atlantic can do for us. The Gulf Stream as well as those shelf waters. This would be a good time actually for positive SST anomalies.

Not to mention the cooling affect (diabatic cooling) whenever there is any melting. Guaranteed with 4-8+ inches of snow, depending on your location, along with a thick layer of glaciating sleet, many areas east of I-95 expected to flirt with 30-32F per the guidance won't unless we get a substantial E-SE surface wind.

That was me in Crofton. Between 5.75 and just under 6" before the sleet.

Just a hair over 5" in Crofton MD, no pingers yet, but probably within the hour based on the CC trends.

Probably a hair under that here in Crofton (It was around 3" last time I measured a little while ago). Hopping for 6" before the pingers, though I wouldn't be shocked if we were just under that.

Typically the degree of the warm air (MaxT aloft) will be proportional to the depth. In other words, the highest the MaxT aloft, the deeper the warm or >0C air. In many studies I've seen though, no matter how deep or shallow the warm air is, when you hit 3C or 37F, you're completely melting the hydrometeor. Once that happens, there's no going back to sleet or anything "pellety" unless the air somewhere within the subfreezing layer can get down to -13C/8F or lower. Unless that happens, the rain drop does not refreeze. When we see sleet, it's typically associated with an elevated warm layer temp between 0.5C and just below 3.0C. When it's closer to 0.5C, it's probably more of a sleety & rimed snow mix. When the MaxT aloft is closer to 2.5C, it's more like a sleet ball, with little if any evidence of a mangled snowflake.

And with at least a 12-1 during the period of snow (reasonable), that's at least a 6" floor for all of us. Which I think is safe. 6-8" would be good forecast for those of us in the metro area along/east of 95.

I honestly don't see us getting that much sleet or freezing drizzle (yes I think it would be more drizzle than FZRA, given the lack of ice nuclei) -- I see us here east of I-95 going over to a mainly light mix by Sunday afternoon. Maybe not a dry slot, but not a lot of accumulating sleet and/or ice either. Certainly not enough to compact 6-10+ inches of snow. I live in Crofton (central AA County) and have always expected areas N-W doing better with amped up systems. It happens...it's climo. Feb 12 2014, Jan 24-25 2016, etc. Honestly, we folks south and east have gotten the bullseye more often than not the last few years--we've been long overdue for a climo distribution. Not a kick in the gut at all, believe me. Certainly not when I'm shoveling -- I'm not gonna regret not getting more at that point!

I mean, I try to think of events that gave us 11-12+ inches of snow followed by the crust. I can't think of any, lol. Seems to be we tend to get 6-8" in those situations, maybe 9-10" at most. Meh, still significant no matter how you look at it. Plus, the crust should inhibit the melting.

I guess Amped is saying you don't want it too amped.

Like the CMC, Ukie begins to change to sleet around midday over DCA, but not much precip after that. Almost like ending as a period of sleet that lightens up quickly by mid/late afternoon. Still a nice front end THUMP before that. Considering how intense that front end WAA snow is...I'll take it. Notice the low in WV by 18Z Sun. Yeah, not the kind of Miller B you want, but again, this would be one hell of an acceptable front-end thump.

Very Miller B-ish

Absolutely. With 96 or so hours to go, absolutely. But that high to the north though, no GL low, lots of in-situ CAD potential. Again though, low-layers (sfc-850mb) are not the issue. Areas east of 95 but not on the Eastern Shore would be lucky to hit 30F for a high Sunday. It's the warm nose above 750mb that would either rime the hell out of the snow or give us a crusty layer of sleet. Personally I'll gladly take 10-12" with a nice encapsulating sleet crust.

I just got done with wanting the N-NW trends to stop and all of a sudden a few minutes later the CMC comes out with a sleet bomb. Lol, that was quick. The shifting, more amplified orientation of the heavy snow axis (more SW-NE vs. W-E) makes me think of the Feb 12, 2014 event. Here in the Crofton area we got a solid 7+ inches of cold smoke before a sleet fest, then another 3-5" of wrap around later the next day. That was more of a true Miller A though.

Well, with the north trends (more of a SW-NE oriented heavy snow axis, closer to climo), we know that means the MIX area gets close. This is a pretty picture now, but we're still 96+ hours away from the onset of the precip. LOVE the northern trends, yes, but for the metro area now would be a good time for the trends to STOP. I don't think they will though, lol. Oh, don't get me wrong, surface temps will stay in the 20s. But those 750-700 mb temps may flirt with 0C with a mix or period of sleet all the way up to Southern MD...maybe even Rte 50 for a little bit. Wouldn't surprise me. Still a hit, oh boy a big hit, but I don't think the northern trends are done either.