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.

...aaand with 96 hours to go before the first flakes fly (for some of us), I wouldn't be surprised this time Friday evening we're looking at the heaviest snow axis progged W-NW-N-NE of DCA. Hello climo. We'll still get hammered for those of us in the greater DC metro region, but I do expect the northerly trends to continue, with the gradient tightening a bit and considerably lower totals farther south toward central-southern VA as the snow mixes with/changes over to sleet.

Exactly. This storm does have some similarities to PDII in February 2003. I was working at the AKQ WFO at the time and at one point we had 12-18" for RIC and counties north. Problem is LWX had the same totals for their CWA in northern VA. We were like, hmmm, not *everyone* will get that...there has to be a mix somewhere, likely in the heavier QPF area farther south. Sure enough, RIC got 3-5" of sleet. Still a WSW, but yeah, in the mid Atlantic it's quite rare to get a 100-150 mile north-south swath of jackpot snow. Just doesn't happen. Climo, climo, climo! I know where the heaviest QPF is still progged (south), but I bet you the best ratios, and thus heaviest snow, will be north of Rte 50, maybe even north of I-70.

Nice to see the 06Z ECMWF look like what the AIFS was showing yesterday. A couple things come to mind for this veteran meteorologist (ugh, I can't believe I said that, but I am in my mid 50s now ). 1) I used to live in Central and Southern VA. As much as I would be excited about those snow totals, it would be difficult to believe given the op model trends towards the EC AIFS. Meaning a high likelihood of a transition at some point. That would put the max snow farther north, maybe even north of me (Crofton) and in the traditional max climo areas N and W of DCA when all is said and done. 2) I wouldn't get hung up on SLR just yet. It is VERY difficult for this region to vastly exceed 10 or 11 to 1 with abundant moisture and intense WAA within 850-700mb. While 850mb temps should remain plenty cold, it's the warm nose between 750-700mb that could eventually cut down on the flake size. Remember, you want to have your temps below -10°C (between -12 and -18°C) within the layer of deepest ascent, otherwise known as the dendritic growth zone or DGZ. Based on climo given that surface low track, I would suspect the best SLRs to be closer to 12-14 to 1, and more likely N and W of DCA, i.e. Dulles to Westminster.

The good news, and we've seen it before ... Snow on th ground, fresh snowpack, will definitely help with radiational cooling and enhance the risk for sub-zero min temps assuming we can decouple. BUT, it can also provide a nice layer of insulation to prevent the intense cold from seeping in the subflooring. Let's hope so anyway!

Ugh...kiss of death bro!

Yeah, 00Z GEM looks more like those AI solutions up to this point. Where you go from "damn, are we gonna get fringed with cold smoke" to "uh oh, how close is that mix zone?" I would be more worried if I were in central-southern VA if wanting an all snow event. I do think the northerly trends will continue. ...but hopefully end at some point. Anxious to see the 00Z op ECMWF (aren't we all), but also the GFS/EC AI runs.

What irks me about all of this is here we are, 2025, and the global models still struggle consistently locking in with a system for 5+ days out during the winter. At least, one that's going to involve snow for the DMV. Rain storms April through November? No problem. It always seems that the models are generally in better agreement. Whether It's split flow, northern and southern stream contributions, amplified waves or not. Same sampling issues, or lack thereof, that we have with winter storm tracks here in the East. Can't figure it out, unless it's just anecdotal on my part. This is where I thought AI would help, and maybe to some extent it is. But even the EC AIFS has bounced around with solutions between days 4-7.

Remember that well. It was on the heels of the Thursday, January 22 1987 storm. It was also Super Bowl Sunday, Sunday, Jan 26th. Broncos vs the Giants, SB21. Started snowing late in the AM and was heaviest during the evening.

While there's no doubt reason to doubt, just remember what so many of you said, including PSU Hoffman... In terms of the pattern, in terms of the teleconnections, it was all about Feb 20th-ish for a long time now. Nothing has changed. That was talked about even before this past snow event. THIS was potentially the bigger prize because of the phasing and tucked in low track off the coast. Nothing has changed in that regard. Enjoy the ride!

Not sure if anyone has seen this yet. Tomer's got an experimental site going, which includes p-type for the EC AIFS. Pretty cool! https://polarwx.com/models/?model=aifs&base=ptype_estimate&background=plain&state=states_brown&country=countries_brown&proj=conus&archive=false&run=2025020818