MillvilleWx

I was just peeking at the 3H level to see the jet structure. On the last panel, you can see the increased ridging downstream as the upstream trough amplifies. The SLP will nestle right inside the right entrance region of the jet, so the low center in NC would likely move N to NNE for a period, but as the trough axis goes negative and the 5H low cuts SE into WV/VA, that's when you'll see the surface reflection hit the brakes and get pulled back towards the coast. It's something the Euro has outlined pretty well for last few days. GFS was too progressive in nature with the trough, allowing the low to be further out to sea before getting pulled back as trough went negative late. So, if you drew a line from the low center, draw it NNE up off Wallops, then cut west, drift, then slide ENE. That's a favorable motion for this type of setup.

Occlusion is when the cold conveyor belt (CCB) catches up to the warm conveyor belt (WCB), or for a lack of better terms, when the cold front on the base of a low wraps up to the warm frontal boundary. Occlusions are the peak maturity of a baroclinic cyclone. Storms that vertically stack reach occlusion phase and move at a slower pace.

It doesn't read like Tip because it's not a thesis with indexes and a freakin table of contents (I love Typhoon Tip btw. Incredible poster). HM wouldn't troll. Bob is probably sharpening his shovel

This is correct. This actually happens with a lot of the blockbuster events that just "snow themselves out" before slowly trekking east out into the Atlantic. One of the classic cases was Feb 2013 in New England. Once it stacked, the storm slowly pulled due eastward, but it strengthened up until the 5H low tucked under Cape Cod. That's when cyclones reach full maturity. It's also a good time to look for TROWALS that can enhance snowfall on their way out.

I'm thinking it's Neil deGrasse Tyson and we're being punked

How do you go from what you posted a hour ago to this? This is great posting. Am I living in a Twilight Zone? Wtf

Areas within the deformation axis would undoubtedly get heavy snow as the resolution factors in the globals will not pick up such intricate banding structures. Considering the strength and placement of the 850 and 700mb lows, there would be a general enhancement to the north and northwest of the central low positions. Plenty of 850-700mb frontogen within the CCB as well. Efficient for piling up over time, even under light to moderate snowfall.

I was watching the evolution of the 85H, 7H, and 5H lows and I was in awe in the synchronous movement and precise placement that is necessary for a regionwide storm of this caliber. The best was the 7H low maturation as it sunk under us then strengthened as it pivoted over Quantico into the Atlantic. 7H and 85H wind field suggests a deformation type axis along a thermal gradient placed between Baltimore to Philly with 40 miles on either side. You can see with the precip enhancement on the 6hr QPF panels between 21z Monday and 12z Tuesday. It was an absolute thing of beauty. The physical properties of the lift with the temps verbatim would be a dendrite fest for just about everyone Monday night as the CCB pivots and gracefully moves to the NE. It's a textbook case of mid-latitude cyclogenesis and occlusion.

The CAD wedge on the Euro is very impressive. The isobar bags straight down into Upstate SC. The thermal profile with the initial snow is very solid. Boundary layer temps between -6 to -10C for several hours with modest frontogenic forcing. A solid 3-6" for basically everyone on Sunday without much trouble.

Oooof. You are a good man Charlie Brown

I'm out of likes for the time being, so here's a

Sorry to you and @mappy for that. Literally have a great disco going and this dude just comes out the shadows and flings crap all over the thread. My pot shot had to be taken as my back is still sore from the epic hip adjustment I got at the chiro. I apologize to you guys.

Yeah. I actually don't know why it wanted to hold on to the primary for so long. It's even longer than the GFS. Maybe it has trust issues and doesn't want to let go of its spawn? You know how young and maturing kids like to cling to the parents

GFSv16 and NAM 12km look similar at 5H at hour 84 but worlds different at the surface. Then it gets really crazy from there with the handling of the primary and its obvious convective feedback errors with surface low placements on the coast. It was doing well until about 72, then it went haywire when looking at the Model Comparison trends on Pivotal. I'll chalk that run into the trash unless something remotely agrees with it.

I actually have to head to a chiropractor appointment, so hopefully one of the other mets can answer. I'll be back soon. Sorry for not being able to answer atm

This was EXACTLY what WPC mentioned in their Day 3-7 disco and why they were not using the GFS.

That run was so close to something bigger for part of the sub-forum. This storm has so much potential, but the question is how far north does the CCB core end up. GFS was very close to a banner event for everyone north of I-70.

The GFS took a small step toward the other models with regards to the 5H reflection, but it's still the most progressive and aggressive with the primary into OH. In fact, you can look at how it's struggling to pinpoint the surface reflection on the coast with the low parked over a broad area of convection in the Atlantic. It's way different than every model. It's not even in the same zip code as the GFSv16 either. It's either seeing something, or it's got some serious biases to shake. It was doing better up until the 5H depiction went into IL. Then it reverted back. Still a nice WAA push on Sunday, so I do like seeing that regardless of the outcome later on.

Thru Hr 57, the 5H shift is apparent from last nights 00z run. It is not as progressive and the vort is holding together over MO and not opening up as has been the case last several runs. It's taking another baby step to the rest of guidance. Still have to wait and see what it does once it reaches the OH Valley.

It's one of those times where I hope the NAM is on to the right idea for y'alls sake!

RGEM once again holding ground with the cold powder idea for the WAA snow on Sunday. Thermal profile is frigid through the whole front end, just like the NAM. Modest 850-700mb frontogen over NoVA and the 270 corridor.

WAA is a translation to greater moisture feed. When you have warmer, less dense air riding into colder airmasses, you get a period of ascent that generates precip once it enters the colder thermal profile. Snowfall is physical mechanism generated by cooled water and enhanced through ascent (lifting mechanisms). WAA over a cold environment will lead to enhanced areas of lift within the boundary layer responsible for a majority of crystal growth in snow. You might have seen the term "Frontogenesis or Frontogen" mentioned in the forum at times. Those are favored areas of lift within certain boundary layers in the atmosphere. WAA regimes are typically located within the 850mb to 600mb layer aloft, which is favored with moisture transport. The better the lift between certain temperature profiles tends to generate better snow crystal structure (Dendrites) that accumulate more efficiently and are lighter in nature due to less water vapor condensing to make the snowflake.

Man. I know it's the NAM, but that front end from the WAA is cold powder for a majority of the snowfall. The thermal profile is perfect and slowly starts to degrade at 850mb half way through. It would be beautiful

Right now a transfer is off the NC coast. I know its the NAM at range, but you can see it starting down near ILM on the final panel.

.