Bob Chill

Very good explanation. I found this skew diagram while reading through the links that trix posted. I don't think there could be a better visual to go along with your explanation.

I only recently started understanding the vertically stacked evolution of cyclones so I'm pretty sure I'm missing some important details. I do understand that when a noreaster becomes vertically stacked is has basically stopped strengthening and has become fully mature. What stands out in my mind is the final evolution of an east coast storm becoming vertically stacked. Isn't the period when the ull is becoming stacked over the surface low when the most intense snows occur to the n & w of the storm? Does the pivot that we often see during strong winter storms have to do with the final evolution before becoming vertically stacked or is this unrelated?

Honestly, I'm not positive either. It's just what I've gleaned through years of reading and thinking and I'm probably off in my explanation. Great thread to be corrected in though because I don't know where else I can post this kind of stuff and discuss it. We're only as good as what we know and if what we know is wrong it doesn't help much. There is a significance of where a noreaster becomes vertically stacked and how it impacts our area but I don't know the finer details. This is a pretty good loop of the 12/19 storm. Maybe a met can chime in and explain it in more detail?

Another term that gets tossed around with the big storms or noreasters around here is vertically stacked. I only had a rough idea of what this meant but it totally hit home in 09-10. Generally speaking, most of our winter storms are tilted. Meaning the surface low (850) and upper level low (500) are not in the same place. This past weekend was a good example. The upper level low tracked though tn/ky/wv and the surface low tracked through ga, sc, and off the nc coast. This is probably the more common setup for us in the ma. Even though "energy transferred to the coast" it was not a miller B because the energy to our west was in the upper levels and not the surface. We get our biggest storms with Miller A's when the ull (500mb) stacks directly above the surface (850mb) just south of our latitude (obx is generally the best spot I think). A vertically stacked low passing through our latitude can be distinguished by the classsic "eye" look of a noreaster. It's kinda the same principal of a hurricane but it's a cold core vs warm core system so there are sig differences. However, vertically stacked lows are spinning from the surface all the the way through the upper levels in the same place so the center is "hollow" for lack of a better term. Miller B's are not the same irt to what happened this weekend so it's important not to confuse the 2. Miller B's have 2 surface lows. Primary will move west of us and then transfer it's energy to the "newer" surface low developing along the coast. Long story short, I see too many people confusing a miller B with a miller A when the ull tracks to the west and the surface tracks to the se of us. Miller B's can have a trailing upper level low too. We can totally whiff in the MA with the 850 transfer but still score a little something if the upper level low takes a favorable track. With a little know how of what you're looking at on the model runs, it's very easy to distinguish between the two and set your back yard expectations accordingly. Miller A = single surface (850) low tracking across the gulf and SE. Upper level low can track to the west into KY/TN but it is still a Miller A. Best case scenario is when the upper level low stacks over the suface low near or a bit south of our latitude. When this happens the amwx server melts down. Miller B = 2 surface lows. One tracking into the oh valley and one tracking to our se. The initial stronger surface low will go to our west and then hand over all the goods to the newer low to our se and then that becomes dominent. NE loves these and the MA cries more often than not. Miller B's putting down good snow in our backyard is a function of latitude during the transfer. We want the secondary 850 well to our SE as the primary hands over the goods. Models have a really tough time with this as do our nerves. If we're near the southern fringe on the models, more often than not we will be dissappointed in this area. The Feb 10th 2010 was an excellent example of what needs to happen for us to score. Folks down in central VA weren't too happy though. Let's not even talk about 12/26/10. Clicking through 850/slp maps on the models is the easiest way to understand whether we are going to have a Miller A or Miller B evolution. You don't even need to ask questions about Miller A vs Miller B if you can understand this simpleton explanation. Met's, I may be screwing up the vertically stacked definition. I didn't really address anything @ 700mb because I don't really know enough about it other than RH. I know you can also have closed 700 lows but I generally only concentrate on the surface and 500 when looking at a coastal. Please correct any and all mistakes. I was trying to explain it in simpleton terms so anyone could understand. I know the regular MA folks know alot of this stuff but I hope the "storm drop in" weenies read this post because they often don't get it.

Coastal, I probably do know decent definitions of both of those terms but I doubt I could explain them properly. Could you (or any met) give a brief laymens explanation for both? These are very important terms to understand, what features cause them, and what the sensible weather is below them. Maybe toss in how they can be identified on a radar image or loop too.

Don't think anyone answered you. Yes. For anyone who didn't see the same thing, the red temp line @ 500 is just below the light grey -30C line in the grid.

I think both you and dtk have really provided some valuable insight to mechanics of models and I find it dissappointing that so many posters feel the need to say "models are terrible...blah blah blah" all the time. It is extremely unrealistic to think the physics of the atmosphere can be perfectly replicated in a computer model (especially past a few days in many cases). What the models are able to do already is astounding imo. I think sometimes we forget (or don't even consider) the fact that the surface of the earth is almost 200 million square miles and the volume of our effective atmoshpere is something close to 1 billion cubic miles. Saying a model is god awful because the snow missed you by even 200 miles is a ridiculous statement in alot of ways. Before criticizing a model, one should be able to thoroughly read the model runs and understand why it is likely wrong. If you only interpret a model absolutely verbatim, there is no room to criticize anything. dtk- your technical model insight here is invaluable. Please continue to share as much as possible.

I wasn't really trying to re-invent the wheel here. There are alot of folks in subforums who either don't want to or are scared to post in the main forum. Plus, we can get into mby stuff here because (just like every other area) the ma has it's own nuances with its climo and we can really get into detail with both winter storms and severe in our specific regions. Mets, appreciate the answers to winterymix's model questions. I've slowly learned over time to better understand what the models are doing with specific setups. The nam is definitely superior with CAD events. I always put more stock in the nam's handling of the surface and 850 temps when flow is from the n & ne in the lower levels. Euro struggles a bit in the lr with split flow. Especially with vorts in the southern stream. It catches up and outperforms the other globals once we are at the day 5 range but beyond that it's important to understand that it likes to move things out of the sw slower and that has a large effect on the evolution down the line. These obs of the nam and euro are just what I've seen over the least 5 years or so. Please correct me if I'm posting bad info here.

Excellent. Just excellent. I'm pretty good with temp and p levels but I really had no idea what the curved lines meant and I was a bit afraid to ask until today. Thank you for the simple and straightforward definition of the lines.

You see, this is exactly what I'm talking about. My question is answered. Thanks gals, excellent stuff. I will thoroughly read everything as I find the time. E-woods post is an excellent starting point for anybody interested in learning this stuff.

I think this is a good idea for a thread. I think some folks are afraid to ask basic questions about models and weather for fear of getting ridiculed. There are alot of finer details that I really want to understand better but it never seems appropriate to ask during storm threads. Here are some guidelines I would like to have in the thread: 1. Let's try not to flood the thread with too many active questions at a time. It shouldn't take too long to resolve each one before moving on. 2. No banter please. Just Q&A and teaching/learning here. 3. No questions are too stupid to ask. More knowledge improves post content across the board. 4. All topics are fine. Not just winter. Severe, topical, teleconnections, ENSO, anything is welcome. 5. If someone posts a link in response to a question, read the link before asking anymore questions. Don't be lazy. 6. Do not reply to a question or be on the teaching side of a discussion if you don't have a clear understanding of the question at hand. Bad information is at the root of alot of bad posts here. Ok, since it's my thread, I'm asking the first question. Below is a common sounding post and I don't know how to read it correctly at all. To narrow down my question, I know what the wind axis, hpa axis, and temp axis are. I do not know how to property interpret the colored lines and I don't understand what the light grey grid represents.

This is one of my favorite loops. I have a larger 5.7mb high res file but it is too big to post. The propagating bands are too cool. It might be a little while but I can't wait to see another one like this.

Multiple earthquakes and a big azz hurricane rolling our way. I guess this is all a prelude to the end of the world in Dec 2012.

It caused more commotion than anything else. We have almost no seismic along the east coast. A 7.0 would level buildings because our codes don't require buildings to be earthquake resistant. Saying we can't handle it isn't really a fair statement. Atlanta can't handle a heavy snowfall and Chicago can't handle a serious heatwave. But they have no problem the other way around.

Any reports of tsunamis on Lake Anna?

I like earthquakes at lot better than snowstorms and hurricanes. I didn't have to agonize over 50 models runs just to be worn out and disappointed. Earthquakes just happen. That shizzle is cool.

Alexandria here. In the basement of my friends 4 story house. Holy F! Scared the hell out of me. I ran out the damn front door. Rocking and a rolling. The one we had some months back was nothing like this one. Damn!

Most memorable storm of my life because one of my best friends was getting married and couldn't cancel. I ended up having to drive him and a packed truckload of crap from Rockville to Columbia. Started the drive @ noon and got to the hotel @ 3. I have never in my life driven in such bad conditions. My suburban handled it like an absolute champ. 495 and 95 were a complete free for all. It snowed its eyeballs out the entire trip and there was 12-18 of snow on the interstate by the time I got on 95. I weaved around so many stranded people that it was ridiculous. There were so many cars stuck that it was surreal. I plowed through every obstacle and got the groom there with enough time to relax before his big day. Honestly, I had a blast driving and loved every minute of it. Then I was treated like a celebrity the whole night at the wedding. Great storm!

This was grabbed on Wed the 3rd. It shows the moisture connection all the way past HI. I remember really getting excited that this storm is going to be BIG.