That was quick
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Pattern Dazzling December
- Thread starter Rain Cold
- Start date
Atlantic looks awesome. Pacific, as usual, looks like leaky anus.
L
Logan Is An Idiot 02
Guest
There is nothing stopping that garbage pacific. It’s like clockwork. Every single winter
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That just looks like 33-38 and rain without even looking at other maps
Massive block on the Canadian. Dec 2010 style
That type of block alone can get the job done the deeper you go into December. Much of 2010 from late January on had a neutral to slightly negative PNA and there was some decent storms in that time for parts of the south
How much stock do we put in the Canadian?
That gefs progression with trapping energy under the block is what you want to see as that offers up confluence and acts as a suppressor
Prestige Worldwide
Member
Oh my- this is very interesting
That is an impressive signal for North Atlantic blocking that far out on an ensemble. Now just move that red blob in the Pacific around Alaska and replace with a blue blob around the Aleutians and we might in bidness
That’s sexy 
That’s some 2010 type ----
and it should be noted that there is legit cold air being built up in Canada, this type of blocking can push it south and east
L
Logan Is An Idiot 02
Guest
Mild winter upcoming according to this wooly worm.
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You’ve been saving that worm in a bag for the past 5 years. Be honest.Mild winter upcoming according to this wooly worm.
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What a pleasant surprise seeing this much agreement for some stout blocking to be in place as we head into mid December. This is around the time I believed the models were pin pointing this to take place. I would expect the longer this -NAO stays around the more and more muted that SER gets. This pattern can get quite exciting given the right circumstances. Still I would love for some transient +PNA to show up to be able to nudge some much colder air down our way but we are setting up for some CAD down the line into December with this look. Id expect some icy solutions and potentially wintery to start showing up on long range deterministic runs anywhere from December 5-15 … think this is around when the pattern flips more cold for us in NC at least 
It isn’t a interesting pattern without a nicky saying it’s happening paragraph
??hey you give me a euro ensemble 240+ hours out with a signal of this type of blocking .. you’re going to get a paragraph outta me 10/10 times
handful of gefs members starting to show something around day 11-14 (mostly icy solutions) with the TPV sliding east and cold shallow air
Bleh. Bring on the snowy solutions.
Itryatgolf
Member
Hopefully we can get a few jet extensions, which should help us moving forward
Itryatgolf
Member
This would a good start, maybe.
L
Logan Is An Idiot 02
Guest
I see people comparing this pattern to December of 2010. Was there also a -PNA during that time?
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Itryatgolf
Member
There was Logan. No winters are the same, but very similar to Dec 2010 if it sets up, but imo I don't think the -nao has staying power as was the case in dec 2010-early Feb then it finally broke down.
All but one day had a -PNA that month
Dec 2010 had a stubborn Aleutian ridge and PNW trough and a big -NAO block, which in any other normal circumstance isn’t great for us if you get rid of the -NAO. but it’s different because the deep -AO/-NAO. Here’s how it compares to modeled solutions with and also 2018 which is similar as well. IMHO this is a “handoff” pattern. You feed energy from out west and then it goes under the block, and amplifies, which feeds the Atlantic trough/50-50 low and amplified it. It’s Not a strong -PNA being modeled at all, but one that rather keeps a active pattern going
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and this is the type of a pattern that can and has produced a number a winter storms even with the negative PNA… it’s probably would not work for areas of the Deep South, but could definitely work for places like northern GA, AL, and most of the Carolinas
With a -PNA, it’s always ok to be skeptical, as we have seen with experience, looks like mid December during the strong -NAO it’ll hang around -0.5 to -1 sigma, as long as it stays this weak, it won’t be to much of a PITA and could help with feeding us more activity. Anymore and it starts becoming a problem. Anyways with the TPV lobe and its associating energy getting caught under the block in SE Canada/the NE and the Atlantic and amplifying, typically that favors confluence to be in place
Tarheel1
I TOLD YALL IT WASN’T GOING TO SNOW
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As long as just the tips are coldMild winter upcoming according to this wooly worm.
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Interesting stuff here. Other indices are in the thread beneath
Thanks, that’s me! I meant to post this on here earlier.
The block in Dec 2010 was just absurd (1st image below is Euro forecast from early Dec 2010). A block of that nature can just overwhelm the North America pattern and take control. But that's an extreme outlier. Hopefully we can get something in the ballpark of that one, but it will be tough of course.
The good news is that the lower stratosphere is under attack and in a weakened state. Research from Simon Lee shows that a -NAO is 7 times more likely when the lower stratosphere is in a weak state. 2nd image below shows the forecast (orange line) of near record low zonal wind at the troposphere/stratosphere coupling layer at 100mb, indicating a potential weak lower stratosphere condition upcoming (the blue line is from last winter for comparison).
And in the 3rd image (loop), the GEFS forecast shows the split stratospheric vortex at 50mb, with ridging building into Greenland. This forecast of bottom-up ridge coupling extending from the troposphere into the stratosphere gives the forecast of a healthy -NAO block more credence, and with the idea that it won't be an in-and-out quick hitter.
The good news is that the lower stratosphere is under attack and in a weakened state. Research from Simon Lee shows that a -NAO is 7 times more likely when the lower stratosphere is in a weak state. 2nd image below shows the forecast (orange line) of near record low zonal wind at the troposphere/stratosphere coupling layer at 100mb, indicating a potential weak lower stratosphere condition upcoming (the blue line is from last winter for comparison).
And in the 3rd image (loop), the GEFS forecast shows the split stratospheric vortex at 50mb, with ridging building into Greenland. This forecast of bottom-up ridge coupling extending from the troposphere into the stratosphere gives the forecast of a healthy -NAO block more credence, and with the idea that it won't be an in-and-out quick hitter.
Great analysis here as well from John. December 10-20 still looking good if this all continues.
As for the Pacific side pattern, it's been a bit odd so far this late fall with how the MJO has been more active and moving seemingly faster than I would expect. Based on that, it's a bit difficult to assign how much effect the MJO is having on the pattern. My guess here is that we will continue to see a La Nina-like ridge in the Central-North Pacific, extending into Alaska until there is something significant that comes along to disturb that base state. Probably the thing to look for to do that would be a big episode of Positive East Asian Mtn Torque. At the moment, it doesn't look like one is on the radar for the foreseeable future....mid-Dec may be the next timeframe for something like that to occur, with effects occurring in the weeks after of ridging moving closer to the west coast (just a guess based on the cyclical nature of those events - see red line in image below). Good news is that we aren't currently seeing low pressure setup shop over Alaska, and Canada is getting supplied with cold air.
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Webberweather53
Meteorologist
-PNA/-NAO is a good way to get ice storms in CAD favored areas of the Carolinas & NE GA. The mean storm track will try to cut into the TN/OH Valley & interior NE US, and really the only way we can score a storm in the absence of a neutral to +PNA is with warm/moist air overrunning shallow low-level cold air mass. Really need to build-up some snow cover to our north to enhance low-level cold/dry pushes from the NE, and I don't see something like this becoming established until about Dec 15 at the earliest.
This looks a little better. Way out there and very low skill, though.
Better
Respiratory Distress seems pretty bad, however.
Better
Respiratory Distress seems pretty bad, however.
SnowwxAtl
Member
Atlanta for the 12/11...I guess there is so hope! ???? this will change thousand times.
06z GFS NAO Index
