MillvilleWx

Evening everyone. I know this storm is basically getting on everyone's last nerve in terms of tracking, so I'll keep this short and sweet. My current thoughts have not changed since my 12z post model analysis earlier this afternoon. This is a classic fall line storm with areas NW of the cities seeing incrementally more snow the further you are away from the urban corridor. Below is a copy of the Deterministic Heavy Snow and Icing Discussion from WPC. They produce these twice a day and will give you the scoop on what WPC is seeing since they ingest and dissect guidance on the daily, then collab with local offices, which then decisions in terms of Watches/Warnings/Advisories are made, as well as coordination with surrounding offices for precip totals on both QPF and snow, when applicable. Here's the discussion from this afternoon below. I cut off part of the discussion to omit the parts we don't care about..... The NAM Nest this evening was basically my thoughts amplified with the core of 85H and 7H frontogen packing a punch on the initial thump as WAA screams north ahead of the trough, and under formidable diffluent flow will allow for a "hot and heavy" start to the precip for much of the sub-forum beginning Wednesday morning and carrying into the afternoon. The issue calls between 18z-21z as boundary layer easterlies become more aggressive and we see a lift of the R/S line to the north on the lead of the 50-60kt LLJ at 850mb. Expect cold temps at the surface to hold for much of the area north if I-70, but the I-95 corridor and low land areas below 500' will likely bump to at or above freezing for a time due to the depth of the WAA aloft mixing more efficiently to the surface, as well as physical latent heat release from precip falling through the column. Mix line will protrude west towards the Rt15 corridor, and perhaps even sneak past for a time towards the Catoctin front, but will likely hit a impass there as mountains shield the 81 corridor from the low level intrusion, which is classic for these types of setups. By 01z Thu, guidance is consistent showing the deepest extension of the boundary layer warmth, and we begin to see the 5H and 7H troughs pivot overhead and potentially close off for a time, allowing the SLP along the Delmarva coast to become stacked and meander to the east. This will allow for a shifting dynamic from WAA to the generation of a CCB axis that will bisect much of PA into NNJ, and maybe extend down to the northern reaches of the sub-forum as shown by 7H Frontogenic progs on the 3km NAM Nest and the European. This will allow for cold air to rush in on the backside and we see a sharp response in 850mb temps and the lower boundary layer as temps go from as high as +2C to as low as -7C within just a few hrs. This is typical for a maturing deformation zone and anyone within the band will see the best ratios of the entire storm where snowfall can rack up quickly. Considering the mean SLP position, blend of Euro/NAM Nest/GFS 7H and 85H frontogenic forcing, the best chance for max snow will lie along the 81 corridor from the NE slopes of the BR in WV for areas like Paw Paw, up through HGR into C PA, pivoting back NE into NNJ. There's a secondary max that might be found from HGR east to Northern Baltimore Co, but the eastward extent is only if the deformation axis is a bit further east in development. More likely is HGR to Northern Carroll, but GFS keeps the door open on further eastward extent. Here's my projected totals for snow/sleet: East of I-95 near Baltimore: 2-4" with max to 6" if everything breaks right and boundary layer stays colder on initial WAA thump East of I-95 near DC: 1-3" DCA: 1-3" IAD: 4-8" BWI: 2-5" Eastern HoCo: 4-8" Western HoCo: 6-10" Southern MoCo: 2-5" Northern MoCo: 4-9" Loudon: 4-8" with local 10" in West Loudon NoVA south of DC: T-2" Southern Carroll: 6-10" Northern Carroll (Westminster and north): 8-14" with local to 17" Southern Frederick County: 6-10" Northern Frederick: 10-16" with local to 20" Winchester: 10-16" with local to 18" WV Panhandle: 10-16" with local to 18" Southern Harford County: 5-10" Northern Harford County: 7-12" Southern Baltimore County: 3-7" Northern Baltimore County: 6-12" with local to 15" Southern PA from Chambersburg to Gettysburg: 12-18" with local to 22" Gettysburg to York: 11-17" with local to 20" Bullseye: Northern York County to Harrisburg to Eastern PA Coal Country: 16-24" with local to 28" Ji's House: -7" (I'm gonna pay @leesburg 04 to steal his snow)

I was driving to work during the Browns TD then Ravens FG. I almost lost control on Business 20. Totally worth it. I missed 90% of that game. I'm glad I caught/heard the last 10%. Incredible

Hey Losetoa! Just woke up not too long ago and haven’t looked at anything in depth. I think this will be a pretty formidable qpf bomb and those that stick over 1” of qpf as snow will be in the double digits. I’m keeping an eye on projected deform for this storm cuz it has potential to get some in this sub a bug hit for the final 6-8 hrs. I still like the Rt15 to 81 corridor as the winners in the sub, but you guys along the Mason Dixon to Mappy have outside shot to really cash too. Your area and PSU have the best chance of anyone outside that aforementioned corridor to go over 12”. The Nam Nest showed the potential at 18z and Euro has been starting to signal the CCB into MD last few runs. Watch the 7H frontogen closely where that bend back is located. That’s a good signal .

Thanks! I've been trying to look at everything closely. I'm interested in the mesoscale aspect this storm. It's going to be interesting between 21z Wed and 09z Thu. NAM Nest was a bit overamped I feel, but it's got the general idea right. Once the storm gets to DE lat, it could be an all out beatdown for some in the sub.

The Nest has a closed 5H depiction for several hrs compared to every other model. It amps up and moves north, well west of other guidance. Something to monitor as that would screw a lot of people over. Still at range and can have those tendencies to be over amped beyond 36 hrs, at least from my experience.

Hey y'all! Before I head back to bed, since I'm in the middle of a stretch of mid shifts, I want to say thank you for all the great comments. You guys were my first home in the forum when I lived at Millersville. My roots are in Baltimore area and the Mid Atlantic in general, but my posting didn't truly begin until I was at school. I miss you all and I am working hard at the NWS to try and set myself up to move back east to either Sterling, State College, or Mount Holly (And perhaps Boston if the opportunity arises). I think PA is the winner for this one and several of you in the forum will see 10-20" with lolli's to 2' in the sub. I wouldn't even rule out a 24-28" for some lucky SOB lol. I still love the US15 to 81 corridor with a max generally positioned over the York Hills in the northern tier of the county up to central PA for areas south of State College. That's where I think the best 7H frontogen will be located for an extended period when the deformation axis develops Wednesday night into Thursday AM. Look for the pivot! I'll check in every now and then during the storm. Hope everyone is healthy and ready for some snow xMDxSon is my twitter handle. It's also my XBL gamertag since I first created the account years and years ago for gaming news. If anyone wants to play some COD sometime, send me a PM!

I just laughed wicked hard at this for some reason

After about 4.5 hrs of sleep, I decided to be a human at 1230 PM CST and get up for a bit to look at models. After gleaning over the runs, here's my quick thoughts. I mentioned overnight how I thought the NAM12km had overamp bias with the surface and had height rises too high out ahead of the s/w trough along the Atlantic coast. All the while, the GFS still had a flat bias and the storm was escaping to the east too quickly with focus on the eastern LP instead of the western tuck of the double barrel structure. The guidance is coming into alignment now with majority showing a coastal SC to mouth of Chesapeake to a coastal hug of the Delmarva before stacking near Cape May as the 5H trough axis pivots overhead and briefly closes off. Today was the day where we can officially bring the Nam Nest into picture since it's finally at range. I mentioned before the Nest is a great tool for mesoscale and short term synoptic trends as it handles the UL pattern much better than the parent with a limited overamp bias inside 36 hrs. One of the positives in comparing the 12z suite was there was a good deal of agreement on the placement of the SLP center at Wed 18z at the mouth of the bay, about 25-50 miles near ORF. Traditionally, this is where the western crew would benefit as it throws moisture plume would be aimed up the 81 corridor with expansion NE as we see a better low-level convergence signature towards the low center with 85H frontogenesis increasing intensity up the 95 corridor. There will be a quick shift from nothing to moderate precip for pretty much everyone and there won't be a wasted QPF time frame as dew point depressions remain within reasoning of column moistening, unlike what we see with a pure arctic airmass. Between 18-00z Thu is where there are some differences in guidance. The GFS has come on board with western low developing and becoming the principle SLP component of the double barrel structure, along with the rest of guidance. They all have similar SLP placement near Lewes, DE at 00z Thu, although CMC/RGEM combo is still the most progressive of the bunch with the primary SLP NE of the remainder of guidance, so I would hesitate using verbatim output on the model due to it's progressive bias. In any case, one of the issues we are seeing is the delay in closing off 85H and 7H until somewhere overhead, which leads to a persistent SE fetch off the Atlantic. This would allow for a protrusion of warmer boundary layer air to advect west of the Piedmont and shift ptype from snow at onset, to sleet/rain, especially those east of the fall line. This has been one of the reasons I was hesitant to give higher totals on prediction for the I-95 corridor until you are farther away with elevation as mixing potential was much greater within that area east of Rt15. Rt15 to I-81 has been consistently the sweet spot for this due to multiple facets of the forecast. One is of course further away from the screaming easterlies within the boundary layer, so the warm nose is limited. There's also a benefit of consistent 7H frontogen extension back to I-81 where lift can be maximized for longer periods of time, leading to a QPF max centered in a triangle from Front Royal to Hagerstown to the Pars Ridge line in NW MoCo. There's a secondary QPF max likely within the strongest, most persistent corridor of 85H frontogenesis to the east along the I-95 coastal plain, so when the low finally begins to stack and 850mb temps crash, there will likely be a secondary snow max (Albeit not as hefty as further west due to snow longevity) along and west of the frontogenic forcing. This places an area like Pars Ridge in Carroll and northern Baltimore Co at play for another tick in snow compared to the rest of the sub. The alignment and strength of the frontogenic forcing is still up in the air, but so far the consistent placement on the Euro and now NAM Nest lead me to believe we are starting to see those fine details coming into the picture. The strongest mid-level frontogen will lift into PA, but there is a curve back towards the NW tier of the sub as the 5H and 7H trough axis pivots and closes north of our lat. That will be when the deformation axis begins to develop and we see more SW/NE banding alignment take shape. All guidance has a bulk of the CCB into PA now due to the northern close off, so the max snow potential will reside into PA with the central PA corridor as the best spot for lolli's to 2'. I still think a general 8-14" with local to 16" is possible from Emmitsburg to Mappy with the highest totals further west. 10-16" with local to 20" is possible along the 81 corridor out into WV and SoPA from the Rt99 to US15 extension (Ala @Ellinwood map). The I-95 coastal plain will unfortunately take the brunt of this shift with lowest totals around 1-3" to the east of the corridor, but incremental increases further to the NW, especially once west of the fall line. From there, 3-6" at the beginning of the fall line, with 5-10" 20 miles after that down thru western HoCo, western MoCo, and Loudon in VA. The Catoctins are probably the odd ball in the bunch given elevation, so I would place them in the 10-16" range for this one. Precip should come to an end between 06-12z everywhere with snow lasting the longest over the northern tier of the sub. It sucks not being able to be back home to enjoy it, but I love forecasting and this was fun to track and look at the meteorology unfolding from afar with no skin in the game. I hope it trends a bit further SE and everyone can cash a bit more. There's still time for a small tick, but I think the markings are set right now.

What I told you the Jets should be relegated? How does that fair on expectations?

He doesn't. That's why the Euro/GFS combo is still my top choice for outside 36 hrs in forecasting. They each have their biases, but GFS has numerically performed very well over the past 6 months.

Hey NBZ. Just woke up a little bit ago and haven't looked too closely at things yet at 12z, but I have been barking at the US15 to I-81 corridor for a while on the max potential for the storm. I love the area from Front Royal to Hagerstown to Emittsburg and connect the triangle. I think, for the sub-forum, that's the best area for heavy snowfall. I've been thinking 12-18" for that corridor for a while. Pending the mesoscale aspects and whether the tongue of 7H frontogen can wrap back into the area prior to pull away, there's an outside shot at 2' along the MD line. If you wanted to trek outside the sub-forum, the best place imo is up near HBG over the northern hills of York Co. That's got elevation and likely nestled into the heart of the 7H frontgenic forcing with a small shot at some TROWAL development (Although I haven't seen anything yet today, so it's possible the TROWAL doesn't fully materialize). Good luck with chasing and stay safe!

For sure. This has Fall Line special written all over it. Massive increases the further north and west you go with this one. Then pinning down the CCB will be another fun task. That's where the real fun totals will come out.

I never move from the Euro since it's got a great resolution and is good with large scale forcing mechanisms. The mesoscale is definitely not good for it, but that's where our short term guidance will come in play. It gets mixed more with other guidance for decision making and review for trends. GFS is in the same boat as the Euro since it has fairly similar properties for large scale ascent depictions.

06z ECMWF was a Fall Line special. Ever wanted to know where that was, look at that Clown snow map. There it is! Pretty textbook actually.

I don't think that's too much of a worry here. The bigger concern would be 7H fronto too far to the north, but nothing shows that right now. GFS stacks a little further south than other models, so there's a more uniform eastward motion of the comma head. Euro and CMC are bit further north, so the drier air undercuts the backside like it normally does and the back edge is further north a bit.

The 06z Euro wasn't a NAM carbon copy at all. It was a slightly further west extension of the SLP once it gets to ORF lat. The dynamics between 00-09z on Thursday are ridiculous. It would be puking fatties for northern neck of VA, C MD, and into PA. Verbatim, the I-81 crew get raked on this run with the northern tier also firmly in 12+".

SO IT WAS YOU!

Omg. That sounds DEVINE. You'll have to share how it tastes. I like those types of beers. I'm not a beer expert by any means like some in here, but I love wheats, sours, and pale ales. I'll try any.

Man, might have to take the wife there when we come home later next year. There's like 3 breweries we want to try that popped up since we left. We will now have 4 breweries to try! I'll make sure to give you a holler when we are in the area

That Raspberry Wheat sounds like one or five on a spring afternoon

It's gonna be a fun storm to watch. Wish I was back home for it, but I'll get mine in due time. I'm working on getting back to the homeland in time. I just need to convince someone gullible enough at Sterling to accept me

You mean mid 2010's? Mid 2000's I was in HS still being a weenie and learning everything while I stalked Accuweather Forums lol. If I had to pick a spot, right now in PA, I'd head to York county in the hills between HBG and THV. There's routes over to I-81 area too. Someone there will clean up

I'm trying!

If anyone is interested, I wrote a book earlier this evening on my thoughts. Feel free to critique. Thanks!

To be honest, I'm not sure. I was a little surprised on the time frame posted. I would've thought they would have something at least starting at 3PM like guidance has. And southern stream moisture tends to arrive faster than modeled. They might have just wanted to cover the period where they think snow is gonna become heaviest. Ahhhhhhh. Okay, that makes more sense. They are breaking up into 6 hr increments. That forecast literally matches mine, so I'm good with it. Thanks for the clarification. I had no idea if there were more maps since I didn't check. I didn't know they made more maps haha. Didn't check the grids for LWX this morning. Been trying to stay awake tonight by listening to heavy metal