CoastalWx

I still can't believe how the fook that storm created what it did...lol. I mean yeah I get it, but man that was a big bag of WTF.

That is awesome. Wow, so cool....another example of a WTF moment from this storm....and there were many.

No way. I got smoked the 19-20. I had about 3" in that storm there, but the two days prior targeted this area. In fact where I am now probably jackpotted on those days.

I also read that ZDR that high in combo with low CC might point to a melting layer. That's unbelievable. What a beast.

I actually remember this one. I got into a pretty sweet band, but just north near MQE was an awesome meso band as you can see.

What a little nuke of mash potatoes this was, although I missed it. This gave PVC a mini inflow jet.

For Halloween gale

LOL they were pics of pics. I know...but I was excited to find them.

Bump.

To be fair, your placement of "stupid" could be argued for #1....if you wanted to be unbiased.

There also was a weak diffuse boundary in the area. That combined with low level CAPE probably added to this brief spin up. Of note, the cell also briefly turned to the right and migrated more easterly once it began to develop rotation. 

We got about 18-20" in Somerville where I was. A little less than I hoped, but not bad.

If I knew we would break up 3 months later, I would have stayed home for that. Of course when I went down, it was scheduled to whiff us.

I apologize for the crappy quality. I'll scan them when I get a chance, but wanted to quickly throw them up. I came home down that after being away in NJ for that storm and snapped a few picks. It was close to 2' OTG. Might have been more if I measured every 6 hrs or so.

Found some old PDII pics. That's my old car on the right. That lump. It's a pic of a pic, sorry about the quality.

It's October. You should expect a shaft.

I stumbled upon this link for archived radar imagery. It's a little cumbersome to navigate, but it has some nice imagery. Only goes back to 2008 though. http://nmq.ou.edu/

I think you are thinking of the Jan 11-12 storm perhaps?

Well, I could spend all morning..lol, but I'll try my best. Frontogenesis simply means the genesis or formation of a front. It's an important process for precipitation to form. This basically means you have something separating different airmass or temperatures within an airmass. So, deformation....we all love it as winter weenies. What deformation does, is to actually help cause frontogenesis. Deformation helps pack the isotherms tighter together. Packing isotherms tighter together leads to frontogenesis. You see this many times both and the cold and warm seasons..but mostly the cold season. Here is a textbook image of what the thermal field would look like. Instead of air flowing parallel to the isotherms, the wind is acting to deform the temp field and pack the isotherms together. Now in real life, it's not as pretty as that image. It's a little less obvious sometimes, but the idea is there. Even winds the aren't in a 90degree angle...as long as winds are at an angle and helping to converge or pack the isotherms together, you'll deform the thermal field and lead to frontogenesis. Here is an image from the SPC meso analysis site. This is from 12/26/10. Notice the closed 700mb low with a frontal looking feature cutting through SNE (in black). Now look at the winds to the east of the low. 70kts or so from the south, pumping up warmer air. Now, lets look north of the front in NNE. Notice the winds are more NE. You can even see some winds in se Canada that are more NNE and helping to bring down colder air at that level. While this image is not as classic as the image above, you can see how warmer air is rapidly moving north and converging with the colder air and associated ne winds over NNE. What you are doing, is stretching and deforming this thermal field, and helping to pack the isotherms closer together with time. Indeed you can see in purple, that we have frontogenesis over SNE..meaning the thermal field is becoming sharper and sharper over a smaller horizontal distance, with time. So that's all fine and dandy, but why is this important? Well when you have isotherms packed together over a smaller horizontal distance, you have a much sharper frontal slope in the atmosphere. So, the air will rise faster along this sharper slope, than it would normally with a weaker slope. Also, the atmosphere is always wanting to stay in balance. It hates being out of balance. During times of strong frontogenesis, you disturb the thermal wind balance. A fancy way of saying...the temperature is changing to quickly over a small distance. So what happens is that you get this circulation that develops where you have rising air over the warmer, or southern side of the gradient and sinking air over the colder or northern side of this gradient. This is why many times you have that narrow, but enhanced band of snow or rain on the nw side of a storm. It's also a reason for sucker holes or subsidence in the region of sinking air. So if you think about it..it's a pretty cool way of balancing the atmosphere. What happens when air rises? It cools. So you have rising air helping to combat all the warming on the warm side of the gradient. What about sinking air? Sinking air warms, so you have that also trying to fight against the colder air moving in on the north or colder side of the gradient. Hope that helps.

It can get complicated real quick, so I'll try my best. You are right in that the strength of the low is in part, due to how strong the vortmax is, embedded in the shortwave trough. This is one of several factors in determining storm strength and position, but it's the most important one. 500mb is an important height level because in general this separates the atmosphere where about half the airmass lies below it and half above it..more or less. It's this level where features drive the surface pattern in terms of low and high pressure. If you want a low to form, you want convergence of air below this level, and the air to diverge or evacuate at that level and above. After all, in order to get low pressure to form, air must continuously be evacuated away from the area, so that more air rises in its place. This is a broad brushed idea, but I hope you understand what I mean. So getting back to the original question, a strong vortmax embedded in the shortwave trough will really help kick things off. The basic idea, is that these features move at a certain phase speed....we'll say 40kts or so. Now the air moving through it, may be 60-80 kts. So, the air moving through this feature is moving faster than the actual feature itself. As the air leaves this area of spin, it begins to slow down and like a skater moving their arms away from their body...begins to diverge. So, if the air is diverging in the mid and upper levels, buy definition..air must converge below in order to help fill this void of air. So the tighter and stronger the vortmax..usually the stronger a storm will be. Now there are other feedback factors that start to come into play, but I'm just focusing on 500mb right now. Here is an example of a powerful shortwave trough and associated strong vorticity maxima. Lets look at the Jan 26-27 2011 storm. Here is the 500mb prog for 06z on the 27th. Here is the surface low depiction. Notice that it's very close, if not under the 500mb vortmax. This is an indication of a mature low that is getting ready to occlude. Now remember we talked about rising air out ahead of the vorticity maxima? Look at this water vapor animation. Notice the higher cloud tops over SNE spiraling out ahead of the vortmax well to the south of SNE. This is an indication of rapidly rising air, and indeed there were 5" per hour snows in CT and we all know about your TSSN that you had in the evening.

It's good to also break down technical terms that we throw around here, into simpler terms. Sometimes I'm guilty of that myself, but it's good to let the enthusiasts know what we mean by deformation or frontogenesis...you know, things like that. All these words sound cool and all, but I'm sure some people have no idea what we mean, other than the fact that it sounds good for heavy snow..lol. People shouldn't be afraid to ask, heck even I'm still learning about various things in meteorology. The day you stop learning and don't care anymore, is the day you should probably hang it up.

Like I said with the gambler analogy...with certain models...gotta know when to hold them....know when to fold them. I actually like the NAM for things like identifying heavy rain, CAD, and also rapid cyclogenesis as a strong PV interacts with the Gulf Stream. However, I don't really take seriously what the NAM shows until within 48 hrs and even then...it is met with questioning unless other guidance agrees.

I think we talked about it on the board, but I remember thinking that GC was going to get buried. I just said to myself "those motherf*ckers are going to get smoked." That day you could see the banding setting up in PA and it was developing northeast towards western mass. I didn't want to make them too happy, but I was like..."they are gonna get whacked again." LOL.