I dont care anymore....I am starting a storm thread for March 20-21. Got nothing to lose.

[WxUSAF]

1 minute ago, Maestrobjwa said:

Would you or somebody mind defining what exactly the WAA is? (Forgive the novice question, but I'm still learning, lol)

WAA stands for warm air advection. With a storm like this, it basically means the “frontside” precip where the low is still to the west and precip is running out ahead of the storm and overrunning the warm front aloft. This is opposed to the cold air advection precip, which we often term the CCB (cold conveyor belt), which is the precip on the backside when the low is to our east.

[H2O]

4 minutes ago, MillvilleWx said:

That H5 progression was closer to a major hit than a dud on the 12z GFS. Broad area of diffluent flow with the upper low passing just south of the area. Jet couplet off the eastern seaboard with low development and tuck near the coast. There was even a reinvigoration of the jet max off New England that helped pop another low and keep it snowing into Wednesday night. That wasn’t a bad run at all imo. It’s going to take a lot for areas outside the favored climo spots to stay snow or mostly snow with the initial WAA thump. We should maintain attention to the second round of the storm as Bob and others have mentioned. That’s the main show for here. I’m curious to see how the Euro pans out. If it holds steady, then you have to wonder if GFS is just coming in too amplified. ICON is way too jumpy to give much merit at this point.


.

[Bob Chill]

7 minutes ago, Maestrobjwa said:

Would you or somebody mind defining what exactly the WAA is? (Forgive the novice question, but I'm still learning, lol)

Let me help you (and probably a lot of people) out with our common acronyms. 

 

WAA= warm air advection. Think about how a low pressure spins (counter clockwise). When the low is west of us it's drawing warm moist air up from the south (hence the term WAA). There is always a warm front in front of a low pressure that divides colder antecedent air in place and warm air advecting from the south. That boundary produces lift and precipitation. It is usually lower ratio snowfall because of the way the temperatures contrast up through the column. It can be very heavy snow but not big pretty light weight dendrites. That's CCB

 

CCB = cold conveyor belt. Again, think about cyclonic flow. When a low pressure is to the east of us we are on the "cold side". Cold air is wrapping in at the surface and mid levels. Since there is plenty of moisture available because of WAA wrapping around, CCB snow can be very high ratio and big fluffy flakes. CCB snow is king of big storms. There is nothing else like it. 

[ers-wxman1]

CMC shows another possible solution but same general idea. Colder overall with the WAA front end thump and juiced up 500 trough, though not as impressive as the GFS. Either gets the job done. Still a lot  to be figured out and things will evolve. Did listen to a detailed periscope by Rayno last night and he thought the second piece was the one to watch with a slowing trend. Good call. 

[AdamHLG]

Over 200 posts here in last hour is all I need to know. Bring it on!

Sent from my SM-N950U using Tapatalk

[psuhoffman]

17 minutes ago, Bob Chill said:

Exactly. @ers-wxman1 posted a few minutes ago. The "show" doesn't start until after that stuff moves through. It really is that simple. Can we fail? Yea, no doubt it can all come together wrong. But seeing heights/thicknesses tick north with the front runner doesn't mean jack S. The upper level stuff was a bit close for comfort but still totally workable on the gfs. CMC looks totally good. Icon is good enough. Euro will probably lose a little ground too at the onset but our ONLY show is what happens after the low gets east of us AND the trailing upper level energy catches up to it. We're absolutely in the game for that across ALL guidance. 

Yea if your above about 750 feet maybe the WAA stuff works but we're just a bit late for that to have much chance at low elevation at our latitude. Almost all our post March 20th snows come from dynamic systems east of us where we get into good deform/ccb banding on the back side. If the euro is right and we get dumped from WAA and ccb this is a 1/100 year event. I'd be happy with a 1/25 year event and get the second wave to work. 

[WestminsterSnowCapitalMA]

We need the front end to be snow or i wont make 24 inches and i wont be happy at all

[Bob Chill]

@Maestrobjwa

One last thing, you hear us talking about bowling balls and ULLs and such. They are also king of big storms because of what is happening way upstairs. When a low closes off at 500mb there is a big, cold, unstable, pool of air spinning around at 18k+/- feet. When it closes off all the energy consolidates inside of the closed low. Not all closed upper level lows are created equal but they can be VERY fun. With high altitude unstable air combines with precipitation and lift (you'll see us use the term VV's at 700mb or vertical velocities) then things can be very dynamic. That's one of the ways thundersnow can happen. Plenty of lift and unstable air combine and get's wrung out inside of the closed low. Think of tall cumulus towers spinning around a closed low. That type of snowfall is VERY high ratio because it's really cold upstairs and the lift happens in the best dendritic growth zone (DGZ acronym). Bursts of heavy snow happen similar to convection in the summer. 

 

All this stuff make sense?

[Ji]

14 minutes ago, Bob Chill said:

The CMC was inches from a PD2 long duration multi-foot shellacking. It was a great run. 

yea man.....wowza.....

[ErinInTheSky]

1 minute ago, WestminsterSnowCapitalMA said:

We need the front end to be snow or i wont make 24 inches and i wont be happy at all

I think my "happy mark" is 6". It would be the biggest snowfall I've ever seen in my life. I'll be elated if it's anything more than that. Those Euro 20" maps just make me go bug eyed.

[Jandurin]

1 minute ago, Bob Chill said:

@Maestrobjwa

One last thing, you hear us talking about bowling balls and ULLs and such. They are also king of big storms because of what is happening way upstairs. When a low closes off at 500mb there is a big, cold, unstable, pool of air spinning around at 18k+/- feet. When it closes off all the energy consolidates inside of the closed low. Not all closed upper level lows are created equal but they can be VERY fun. With high altitude unstable air combines with precipitation and lift (you'll see us use the term VV's at 700mb or vertical velocities) then things can be very dynamic. That's one of the ways thundersnow can happen. Plenty of lift and unstable air combine and get's wrung out inside of the closed low. Think of tall cumulus towers spinning around a closed low. That type of snowfall is VERY high ratio because it's really cold upstairs and the lift happens in the best dendritic growth zone (DGZ acronym). Bursts of heavy snow happen similar to convection in the summer. 

 

All this stuff make sense?

Helpful to me, thanks.

[WestminsterSnowCapitalMA]

more winter anyone?

[Wxdavis5784]

1 minute ago, supernovasky said:

I think my "happy mark" is 6". It would be the biggest snowfall I've ever seen in my life. I'll be elated if it's anything more than that. Those Euro 20" maps just make me go bug eyed.

Hang around here long enough and you will see plenty of 6”+ storms. Last year and this year have been awful...

[aldie 22]

So when you log on and look at the page and see a certain name as the last person who posted in a thread....do certain posters give you an idea what was said before you even open the thread? My answer is yes

[pasnownut]

10 minutes ago, Bob Chill said:

Here's my final post on the 12z gfs. I'm totally good with how this ball gets where it gets. It was a good run.

This....

Thanks for keeping hold of the wheel bud.  Its been a bad year, but if anyone looks at that and has a problem, they need to lurk....not post.

[clskinsfan]

2 minutes ago, WestminsterSnowCapitalMA said:

We need the front end to be snow or i wont make 24 inches and i wont be happy at all

Staying all snow is not out of the question for those of us in the favorable spots. Just remember the majority of the subforum lives in the cities. Hence the majority of the discussion is for those areas. I like where we sit with this one which is different from every event since the 2016 blizzard. The GFS is getting the first precip in here at a pretty good time for the usually colder elevated areas. And we have no idea what the actual temps will be at that time. 

[psuhoffman]

22 minutes ago, WxUSAF said:

GGEM is all snow with the WAA for DC and points north. And then misses the tail end to the south. But still gives an acceptable 12” or so.

Fringed

[H2O]

5 minutes ago, Bob Chill said:

@Maestrobjwa

One last thing, you hear us talking about bowling balls and ULLs and such. They are also king of big storms because of what is happening way upstairs. When a low closes off at 500mb there is a big, cold, unstable, pool of air spinning around at 18k+/- feet. When it closes off all the energy consolidates inside of the closed low. Not all closed upper level lows are created equal but they can be VERY fun. With high altitude unstable air combines with precipitation and lift (you'll see us use the term VV's at 700mb or vertical velocities) then things can be very dynamic. That's one of the ways thundersnow can happen. Plenty of lift and unstable air combine and get's wrung out inside of the closed low. Think of tall cumulus towers spinning around a closed low. That type of snowfall is VERY high ratio because it's really cold upstairs and the lift happens in the best dendritic growth zone (DGZ acronym). Bursts of heavy snow happen similar to convection in the summer. 

 

All this stuff make sense?

blah blah snow blah blah blah how much for dover blah blah blah were's mine blah blah blah ICON

thats what I read

[WestminsterSnowCapitalMA]

Just now, clskinsfan said:

Staying all snow is not out of the question for those of us in the favorable spots. Just remember the majority of the subforum lives in the cities. Hence the majority of the discussion is for those areas. I like where we sit with this one which is different from every event since the 2016 blizzard. The GFS is getting the first precip in here at a pretty good time for the usually colder elevated areas. And we have no idea what the actual temps will be at that time. 

Yeah, We definitely make out well in these times traditionally. I made out well last March too i think. 

[Bob Chill]

And one final post on the mechanics of all this stuff....

As big storms develop there are areas of low pressure at different altitudes. You have surface low pressure, 850mb low pressure, 700mb low pressure, and 500mb low pressure. During the intense development stage all the different low pressures are in different places. Think of the atmosphere as being "tilted". SLP is in front, then the 850 low, then 700mb, and finally 500mb. A mature storm is "vertically stacked" or having the lowest pressure at all levels of the atmosphere being lined up vertically. Once a storm gets vertically stacks it starts to die or "spin itself out". This often called "occluded". Once a low is occluded it's boring and showery. Windy yes, big precip no. The sweet spot is being in the path of a storm as it evolves towards becoming vertically stacked. You get the warm air advection piece, then the cold conveyor belt piece, and then finally the upper level low pass. Sometimes the ULL trails like Feb 2014 or Jan 2011. Other times it's all one big long duration event like Dec and Feb 2010. 

[RichmondTarHeel]

Let me rephrase:  I'm tossing the GFS snow maps until it shows 2'+ for mby.

[psuhoffman]

25 minutes ago, Bob Chill said:

Here's my final post on the 12z gfs. I'm totally good with how this ball gets where it gets. It was a good run.

Wiggum is out of his mind if he is debbing this run. Ggem still south with wave 2. This is fine so far. He is in some kind of bizarro world, he was positive last week when the ship was sinking and now he is "bailing water" with an imaginary bucket from a dry deck. 

[WxUSAF]

Trying to figure out how this fails and I think I have it. Front running wave goes north and rains on us and then tail end low develops too far south and then loops around to crush Boston. Lock it up folks.

[Maestrobjwa]

3 minutes ago, Bob Chill said:

And one final post on the mechanics of all this stuff....

As big storms develop there are areas of low pressure at different altitudes. You have surface low pressure, 850mb low pressure, 700mb low pressure, and 500mb low pressure. During the intense development stage all the different low pressures are in different places. Thing of the atmosphere as being "tilted". SLP is in front, then the 850 low, then 700mb, and finally 500mb. A mature storm is "vertically stacked" or having the lowest pressure at all levels of the atmosphere being lined up vertically. Once a storm gets vertically stacks it starts to die or "spin itself out". This often called "occluded". Once a low is occluded it's boring at showery. Windy yes, big precip no. The sweet spot is being in the path of a storm as it evolves towards becoming vertically stacked. You get the warm air advection piece, then the cold conveyor belt piece, and then finally the upper level low pass. Sometimes the ULL trails like Feb 2014 or Jan 2011. Other times it's all one big long duration event like Dec and Feb 2010. 

Ah, so that's why Jan 2011 looked the way it did (I distinctly remember the transition from rain to thick, wet flakes!) So you're saying that where the models have us now...we'd be in that sweet spot?

[Cobalt]

1 minute ago, Maestrobjwa said:

Ah, so that's why Jan 2011 looked the way it did (I distinctly remember the transition from rain to thick, wet flakes!) So you're saying that where the models have us now...we'd be in that sweet spot?

IIRC it was snow in the morning, rain, and then the ULL pass was the main event. Is this correct?

[nj2va]

Just now, Cobalt said:

IIRC it was snow in the morning, rain, and then the ULL pass was the main event. Is this correct?

It was the “commutaggedon” storm.  Started off in the early afternoon as rain, transitioned to sleet in my neighborhood around 3-4pm (had thunder sleet too!) then quickly to heavy, wet snow.  Rates were incredible.  People got stuck on major highways and had to abandon their cars as everyone bailed work in the early to mid afternoon so people just sat in bumper to bumper traffic as snow piled up.  

[Interstate]

You people are crazy... One extreme to the other...  This run sucks... then this run is great.  I am starting a new group therapy.

 

WA=  Weather Anonymous... We meet every Tuesday at 6 PM in the church's basement.

 

 

[Bob Chill]

2 minutes ago, Maestrobjwa said:

Ah, so that's why Jan 2011 looked the way it did (I distinctly remember the transition from rain to thick, wet flakes!) So you're saying that where the models have us now...we'd be in that sweet spot?

No, not in this case. There are 2 discrete pieces of energy in the upper levels. Jan 2011 was one very strong closed upper level low to the SW. It pushed a bunch of WAA precip out in front (mostly rain in my yard but snow to the north) and it was still warmish when the closed low approached so it was rain to snow for the big show.  
 

If it was only the first piece then this has fail written all over it. Rain during the WAA and temps never recovering after a flip to snow (assuming the track doesn't go too far north). In this case there is a second (and very vigorous) piece of upper level energy hot on the heels. How the 2 different pieces play together is very hard to get right. Too much lead time. All we know is there are 2 pieces and potential for one or both to work in our favor. The first piece "should" pop a low to our east and cool the column prior to the second piece either combining with the first piece or being a completely separate event on its own. There is no way to know how things are going to break yet. 

[osfan24]

19 minutes ago, supernovasky said:

I think my "happy mark" is 6". It would be the biggest snowfall I've ever seen in my life. I'll be elated if it's anything more than that. Those Euro 20" maps just make me go bug eyed.

You missed 2016?

[ErinInTheSky]

3 minutes ago, osfan24 said:

You missed 2016?

Got here late December 2016.