MillvilleWx

January 12th, 1996 showing up high on the list of analogs for this storm now. I've seen it on the CIPS list for the past few days. Has a pretty decent look for areas north and west of the fall line. Almost in line with my current thinking. Not as dynamic with the 5H pattern, but similar positions of the mean tough and 850mb flow pattern expected. Interesting

That front end thump on both the GFS and Euro are something else. This is giving me very 2/2014 vibes right now. That precip will come in like a wall. With the mid-level ascent depicted, 1-2"/hr wouldn't just be a possibility, it would be a certainty. Would certainly be fun to watch come down in the first part of the storm.

There's a bit of a trowal signature on the Euro when looking at the 850-700mb frontogen pattern. I would say right now it's just barely in MD and more into PA, but watch for that backend stuff. That will not be something resolved game time.

Current National Blend of Models 50th percentile for the region through 00z Tuesday next week. This displays a pretty idea of what the current thinking should be given everything we've seen so far. Meso-banding and other parts will of course change localized amounts, but this is solid for a smoothed mean.

Parsing through some of the details, this run is very similar to the current NBM result from this AM, and it also jives with the CIPS run from last night in terms of impacts and evolution of the precip field. There's differences in the strength of the low compared to a blended mean and analog pattern, which lends credence to a pretty sizeable thump off a significant 700mb frontogen depiction, then a flip to sleet/rain for areas east of Rt 15. I-81 corridor is going to be close, but some sleet likely gets west of the BR, but could easily change back to snow on the back end of system. It's overall not a terrible run for west of the bay and certainly better than last nights 06z run.

00z runs last night shed a bit more light on what to expect for certain areas, but there's still some question marks to be answered in the overall evolution. Looking at the GFS and ECMWF, there's a distinct period at the end of the storm that bares watching for trends that could save some areas that experience a quicker changeover during the storms height. As of now, the GFS does not have as pronounced a comma head to the precip and any that does develop is off to the NW into PA and perhaps towards the Alleghany front. The ECMWF otoh has a pretty significant back play of the deformation zone that sweeps back east as the low occludes to the north and drifts NE. This is a period where snow can pile up quickly due to increased forcing on the backside of the low within the deformation zone. The DZ often has the best ratios for snowfall due to the prevailing dynamics at play with a robust mid-level frontogen signature and funneling CCB classic with a prevailing SLP in the development stage. This is partly why the snowfall is pretty solid on the ECMWF despite the proposed changeover. Two factors here are important for this to occur: 1) The SLP has to be away from the BR as backside flow from the W/NW would induce down-sloping off the Apps and create a cull in the precip on the underside of the low. A low further east towards the bay has more room to alleviate those concerns, which we have seen in the past. 2) The low needs to continue on a development phase into at least SoPA for this to become a possibility. An occlusion early would incur a persistent warm fetch off strong SE flow. This is less likely to occur as model guidance has now, but something to monitor. A passage of the ULL to the south is what we want. A passage overhead may provide a period of ascent locally under the attendant ULL, allowing for a switch from liquid/IP to snow before the snow shuts completely off. The path of least resistance to scoring would be for the low to pass to the south. Any pass south of Rt 50 would likely yield a fruit of at least 2 hrs of solid snowfall as heights crash and we get a top-down shift in the ptype. Think what happened in 1/26/11...This storm will have a similar ULL strength, so the prospects are there, but the evo right now as progged is off. ULL's are tricky. They can change their paths on a moments notice depending on a multitude of variables, but most notably the proxy of other s/w features that could aid/hinder the height pattern near and downstream of the prevailing longwave trough. Moral to the story, there is a lot we still don't know, some we have a general consensus on, and some mesoscale details that will be fine tuned in the future. NAM 3km will actually be VERY useful this storm. It did a great job on the transition zone in a myriad of events with the most notable being March 2017. Remember, with the HP to the NE, the u-vector component of the wind field will be very robust, so the intrusion of warm air could be tough to overcome, especially east of the fall line. As for areas that can hold off the climo factor of screaming easterlies, that is our I-81 gang. That's why I would wager, for the time being, they will be the benefactors for snow, but high impacts along the transition zone to the fall line are still likely. Temperatures will struggle at the surface for elevations above 500'. Same song and dance, so keep the faith and know a meteorological marvel will probably unfold before our eyes on Sun-Mon. As a meteorologist with absolutely no skin in this game, I will be watching satellite and wishing I was back home. Synoptic meteorology has a special place in my heart.

Guys, it's a deterministic at Day 6. Yes, as it shows, it would be an I-81 special and people east of Rt 15 would get a driving sleet/rain before changing back. There's too many variables on the table to decipher before pegging any particular solution. There could even be a piece that's not even modeled that could throw another variable into the mix. Welcome to the world of chaos with a dynamic fluid that is the atmosphere.

The dress looks nice so far

For the most part, yup. The GFS and CMC both had a bizarre back end of the storm with it petering to nothing almost. There is no way that happens with a bomb like this. That comma head would be a thing of beauty, which is exactly what the Euro depicted. I still think we are far from being able to parse the nitty gritty on the setup, but the trends are favorable for a sizeable system.....for now. Hopefully it can stay locked in. It's going to be a wild ride until Friday me thinks.

This does have a lot of similarities, although the kicker here is it's showing a more powerful setup. These models are gonna underestimate the 500mb prowess up until game time. Euro I think has the closest idea to what I would expect with that evo

I was there for that and remember it well. An incredible storm in so many ways. The thundersnow occurred when we were all hanging out sledding that evening. Crazy Very much the 500mb evolution for that one. Super dynamic ULL, which for the time being this storm also has. There's a pretty good chance of thundersnow somewhere in the sub-forum and NC/VA if this holds. That was on one of the lists outside the top 10, but it was there!

Sooooooo. The 12z CIPS analogs are out...... The top two analogs with regards to the 500mb height pattern at 132 hrs out are: 1/26/2011 2/13/2014 Lead up at 120 hrs out number one analog...... 2/10/1983 This doesn't mean we can expect those exact results, but it does show what type of pattern and setup we are heading into these next 5-7 days. Remarkable swing these last 18 hrs.

The Euro would be an incredible storm for all the sub-forum west of the bay. There is going to be a huge thump of snow before any changeover if the current 5H and SLP setup hold. A jog further east with the SLP and you'll be looking at an all-timer around these parts. Still so many details to go through. A storm is very much on the table now.

He's already looking at the one behind this one

Correct. Also, the GFS is not a good model with handling a sharp transition zone with storms like this. It erodes the PBL too easy, then goes way off the rails near the surface. The antecedent airmass leading in is fresh and very cold. That's another reason why a setup like this would yield a thump of snow before a transition. This is a dynamic system if it evolves as depicted.

Absolutely agree with this assessment. The 5H look SCREAMS a huge thump of snow before any switch over. There is one part to keep an eye on and its the positioning of the high pressure to the north. A spot like the CMC would allow for u-vector winds to be off the charts and usher in maritime air within the 850-925mb layer of the PBL. That would change things to sleet EASY, but not before a nuking occurs with snow. The further NW you are, the better in this setup. This is actually a great system for an area like Hagerstown/Martinsburg/Winchester crew.

Short Pump forecasts go here

Not strength, but track!!! haha This ain't even in the same zip code in terms of strength. I do like Chaos though

SLP was super jumpy too. The 5H progression was actually pretty solid, but the SLP was west of where it should be. You can see the jumpiness of the low when you walk through from 00z Monday, onward. Should take a 1993 Superstorm track, not a track over DC. Split hairs with a track over even CAPE's hood would be a big difference.

Looking at soundings, I would see this more of an IP than a rain situation outside of south of Rt 50 and east of the Bay. GFS scouring the airmass so fast in the lowest confines of the boundary. Also, the wet bulb aspect of the forecast is bizarre. GFS brings the dew point up to the temperature with no drop in the temp within a 3 hr window. Would call complete BS on that as well. That track has yielded IP plenty of times. ULL is also cold as hell with it dropping to 528dm over Wakefield and 525dm over Dover. Color me skeptical of the reach of pure liquid. 850mb jet is screaming, so a transition would be all but probable, but the pure change to rain probably wouldn't be as likely west of the fall line.

Obviously a track like that from the SLP would yield a transition period from snow to IP/ZR, but it was still a very good 5H setup for a front end crush job prior to any changeover. This was a classic I-81 storm track where deformation axis would ride from RNK to HBG. The western side of the LP on the precip field was a little wonky for such a dynamic system. I would see it more defined than what the GFS had. Regardless, the prospects of some snow are definitely on the table. Favored areas probably west of I-95 with most favorable west of Rt 15. Long way to go. No where near settled and big swings are certainly possible.

Man, the GEFS and EPS are absolutely all in on extended winter for these parts. GFS deterministic showed a textbook cold outbreak signature for much of the CONUS. GEFS supports a long lasting cold signature. Winter is coming guys, buckle up!

Good morning y'all. Looking at guidance this morning, it's pretty prudent to lead with this potential setup is riddled with fine details and the probability that we are at the final solution is extremely low. In order for the sub-forum to get what the GFS just advertised, you need everything right in terms of 5H spacing, phasing timing, and thermodynamic structure to yield a scenario like that. Absolutely in no way am I saying it can't happen like that. The major storms, especially the historic storms all have that occur, but this isn't a split phased bomb where a southern jet gets merged with a NS vort. This is very much a deep digger, translating into a Miller B bomb that could climb the coast due to increased spacing between the TPV over Quebec and the second s/w progressing through the northern plains at the same time our storm is going off. Timing timing timing. It is everything with this setup, but there is absolutely an environment available for something truly special. We haven't even gotten into the fine details of frontogenic forcing, jet stream dynamics, complexities of LLJ structure and positioning. The big ones are special for a reason, so keep a level head and don't swing hard on each run. That's Ji's job

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