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Pattern Dazzling December

RainlessSnowless & Grumpy said:
Yeah I'd definitely rather block up a modified Canadian airmass that a Pacific airmass. History shows a -NAO that strong leads to good things. It's definitely going to slow the flow and push the storm track south. Can we get it cold enough is the big question.
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Just imagine if the PNA goes positive or close to positive. Will be interesting.


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Myfrotho704_ said:
I wouldn’t worry about that to much atm, thats a look that would sneak cold down, but we’re probably gonna see a -EPO event in a couple weeks when tropical forcing returns back in that favor (WPAC). having that TPV on our side is gonna be our supply for the time being. Only thing I would worry about is before the -EPO event we end up getting a +EPO like what yesterdays CMCE/GFS runs showed, do not want to do that otherwise we block pacific air like 2021
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Agree, the biggest thing we don't want to see is a large trough develop over Alaska = chinook winds downsloping off the Canadian Rockies and warming Canada. In addition, if we were to see a major cold Arctic outbreak into the central U.S., that would lead to an episode of positive mountain torque along the Rocky Mtns which would speed up the jet over the North Atlantic. This would tend to break down the -NAO regime as a weak N Atlantic jet fosters cyclonic wave breaking which helps to reinforce the blocking Greenland ridge. As always, it's a delicate balance.
 
griteater said:
Agree, the biggest thing we don't want to see is a large trough develop over Alaska = chinook winds downsloping off the Canadian Rockies and warming Canada. In addition, if we were to see a major cold Arctic outbreak into the central U.S., that would lead to an episode of positive mountain torque along the Rocky Mtns which would speed up the jet over the North Atlantic. This would tend to break down the -NAO regime as a weak N Atlantic jet fosters cyclonic wave breaking which helps to reinforce the blocking Greenland ridge. As always, it's a delicate balance.
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I am currently taking Biochemistry so everything I am learning is about cycles and what promotes and what inhibits one cycle over the other. I cant imagine the indices being to different in the sense that one may inhibit the other etc. You mentioned for example a a major cold outbreak being an "inhbitor" of a -NAO. We typically see those under -EPO/+PNA regimes for example. I just want to understand the relationship between all the indices a little better.
 
Lickwx said:
I am currently taking Biochemistry so everything I am learning is about cycles and what promotes and what inhibits one cycle over the other. I cant imagine the indices being to different in the sense that one may inhibit the other etc. You mentioned for example a a major cold outbreak being an "inhbitor" of a -NAO. We typically see those under -EPO/+PNA regimes for example. I just want to understand the relationship between all the indices a little better.
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Yeah, -NAO is actually more common during -PNA than it is during +PNA....but yeah, it all interrelates in the atmosphere so to speak
 
RainlessSnowless & Grumpy said:
Like I said in my previous post it's too far out but assuming something like that happens where does Canada get it's cold air supply? Wouldn't that allow Canada to moderate and rain on our parade later in the month? I know no one is expecting extreme cold the first half of the month but we need Canada to remain cold. The blues over the SE are pretty and all but I'm looking ahead to the latter half of the month when we may have a real shot. Maybe someone with more knowledge can explain how that's a great look.View attachment 124388
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I think what you gotta remember is that this map is showing temperature anamolies at 500mb, not what is actually at the surface. If you look at the 500mb temps for any extended cold period into the south that is caused by strong blocking over Canada and Greenland you’ll likely see similar temperatures at 500mb up there. The key is that you never a flow that floods Canada with warm temperatures and high dewpoints like we saw in December 2000. There still very cold air and deepening snow pack at the surface
 
RainlessSnowless & Grumpy said:
Yeah I'd definitely rather block up a modified Canadian airmass that a Pacific airmass. History shows a -NAO that strong leads to good things. It's definitely going to slow the flow and push the storm track south. Can we get it cold enough is the big question.
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Another big help is we will likely get help on this side of the Apps with strong CAD pushes. That is a serious 50/50 low with anchored HP in Greenland to lock it in place. Very easily could get a better setup than even last January where that featured a strong CAD but didn't have the NAO block to really lock it in place like we would this time. I think we are sitting pretty on this side of the mountains to get something next month and through the first of January, but it's going to be tough to tell whether that's ice or snow.
 
Loganelliott99 said:
Just imagine if the PNA goes positive or close to positive. Will be interesting.


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You want to watch out though with that because if we get a PNA that too high in the positive range, say like late last January, you end up with a flow that either squashes all the energy to far south and we end up vodka cold and dry. That’s why I’ve been saying that a neutral to slightly negative PNA is probably best with this strong of blocking setting up.
 
Chazwin said:
You want to watch out though with that because if we get a PNA that too high in the positive range, say like late last January, you end up with a flow that either squashes all the energy to far south and we end up vodka cold and dry. That’s why I’ve been saying that a neutral to slightly negative PNA is probably best with this strong of blocking setting up.
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Neutral PNA would almost certainly get the job down this way with that strong of a -NAO. We want the perfect combination of fresh cold over snowpack that will keep us in the mid 20's throughout the atmosphere. You start dropping the whole TPV from a strong PNA which a decent chunk of it appears to be on our side of the planet, you're definitely going to end up with nothing but single digit lows, highs in the teens and 20's and plentiful sunshine.
 
Myfrotho704_ said:
I wouldn’t worry about that to much atm, thats a look that would sneak cold down, but we’re probably gonna see a -EPO event in a couple weeks when tropical forcing returns back in that favor (WPAC). having that TPV on our side is gonna be our supply for the time being. Only thing I would worry about is before the -EPO event we end up getting a +EPO like what yesterdays CMCE/GFS runs showed, do not want to do that otherwise we block pacific air like 2021
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Temps are always a concern for me. Even if we have an -EPO, with no western ridge I think the location of the TPV and CAD is going to be key in order to get anything frozen, I have my doubts in December for MBY but great to see a huge blocking pattern. Very interested to see what it can do.
 
smast16 said:
Maybe i'm just a grumpy grinch, but that doesn't look that cold to me. I agree, the blocking is about perfect, but the first batch of cold air comes from the Pac NW after coming over the mountains and sits in the central US before sliding east. The 2nd batch comes from a nuked Canada.


I know it's all 10+ days away and probably won't even happen this way.
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and that's fine. i generally don't think your airmasses need to be that cold to generate decent southern snowfall chances. obviously they still need to be supportive of snow but i don't think they need to be record-breaking per se. i think what you're purchasing with NAO blocking is a drunken storm track that gets easy to amplify, and by virtue of where that storm track ends up, it's easier to push colder air in as well.

the example i'll cite is the feb 12 2010 storm, which is, to this day, the most classic, no stress, southern slider i've ever seen. it happened on a friday night- that friday was cloudy with a high in the upper 30s in wilmington, cold for sure but nothing frigid. we got 4 inches of snow that night, arguably should of been more given the synoptics (jacksonville got 8). I think the night after radiational cooling brought it down to, say, 25? 23? Point is that one of the most slam dunk snow events that was working with a -nao i can remember was going into an airmass that was nothing to write home about. just my take.
 
GFS looks much better. Blocks are connecting over the pole. Really interested to see if we start seeing some serious noise out in the LR of a storm starting to show up. We've had a couple runs here and there showing different storms at different times, but obviously it's still way out there. I still think probably the last 10 days is when we really start cooking, but There's pulses all along the southern jet and we are setting our selves up with some type of CAD coming here in the medium range so who know where it goes at this point.
 
iGRXY said:
GFS looks much better. Blocks are connecting over the pole. Really interested to see if we start seeing some serious noise out in the LR of a storm starting to show up. We've had a couple runs here and there showing different storms at different times, but obviously it's still way out there. I still think probably the last 10 days is when we really start cooking, but There's pulses all along the southern jet and we are setting our selves up with some type of CAD coming here in the medium range so who know where it goes at this point.
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Hopefully over the next week we can see some snowpack build over interior New England and Mid-Atlantic… will definitely help with CAD
 
ILMRoss said:
and that's fine. i generally don't think your airmasses need to be that cold to generate decent southern snowfall chances. obviously they still need to be supportive of snow but i don't think they need to be record-breaking per se. i think what you're purchasing with NAO blocking is a drunken storm track that gets easy to amplify, and by virtue of where that storm track ends up, it's easier to push colder air in as well.

the example i'll cite is the feb 12 2010 storm, which is, to this day, the most classic, no stress, southern slider i've ever seen. it happened on a friday night- that friday was cloudy with a high in the upper 30s in wilmington, cold for sure but nothing frigid. we got 4 inches of snow that night, arguably should of been more given the synoptics (jacksonville got 8). I think the night after radiational cooling brought it down to, say, 25? 23? Point is that one of the most slam dunk snow events that was working with a -nao i can remember was going into an airmass that was nothing to write home about. just my take.
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That was the big event in Columbia. I didn’t see before nor have I seen after that event a slam dunk like that for cola.
 
BullCityWx said:
That was the big event in Columbia. I didn’t see before nor have I seen after that event a slam dunk like that for cola.
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The jackpot was literally at CAE (The airport in Columbia). Solid harmless 7-8 hour snowstorm that dumped 1 inch per hour rates. Lot of memories in that one.
 
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