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Pattern Fab-February 2020 The dark age

Jon said:
Interesting. Everything I'm finding is contradicting which state is better. I see a majority of evidence supporting -AAM during the winter for cold. Do you have the research that shows -AAM leads to a strong SER? I'm seeing that a +AAM is bad because storms can't slow down and amplify, as in, the CONUS pattern is too progressive to lead to digging to put it in our terms. I'd be interested to learn the other side, as I just thought I was figuring it out until I saw your post. lol. I also saw that a -AAM could vary over the CONUS (Warm/cold over the SE) based on the IO state. Yet another 3 letter word that could mean different things at different times.
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For the SE US? For the upper Midwest and westward, for example, the -AAM/La Nina tends to be colder. All that I learned is directly from Maxar pro mets. As I said, look at January and see what period was colder. Jan 1-16 at KATL was +11 but Jan 17-31 was -2. Tat being said, it is just one index and no one index is totally in control. We need the +AO to go away to allow us to have a good shot at a +PNA. That could pose a problem.

I just googled it for an internet link,. From here:

https://business.weather.com/blog/a...mechanism-and-future-implications-this-summer

"During low AAM states, the atmosphere is often in a La Nina driven pattern, where upper-level cold troughs impact the West and a ridge builds over the southeastern U.S. "

"Low" AAM = -AAM
 
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Just went to walk around watching cars go down this slushy road lol the traffic map is definitely not as bad as I thought it would be

I would say about 2-3 inches here is a good bet so far

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GaWx said:
For the SE US? For the upper Midwest and westward, for example, the -AAM/La Nina tends to be colder. All that I learned is directly from Maxar pro mets. As I said, look at January and see what period was colder. Jan 1-16 at KATL was +11 but Jan 17-31 was -2. Tat being said, it is just one index and no one index is totally in control. We need the +AO to go away to allow us to have a good shot at a +PNA. That could pose a problem.

I just googled it for an internet link,. From here:

https://business.weather.com/blog/a...mechanism-and-future-implications-this-summer

"During low AAM states, the atmosphere is often in a La Nina driven pattern, where upper-level cold troughs impact the West and a ridge builds over the southeastern U.S. "

"Low" AAM = -AAM
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This may be season specific so his post above is really summer based and doesn’t hold up in winter?

It seems Mets agree that a -AAM would lead to blocking in winter, which is what we have been without all season...so it makes sense to me to try to root for that. I agree it’s not a catch all index, since it’s only part of the puzzle, but a -AAM makes more sense to me than a strongly +AAM persisting.

There’s not a lot of research on wintry impacts. I’ve found a lot on tornado and severe frequency and that’s what has the most interest from researchers.

Other than random blog posts I’m not finding much concrete data relating to wintry patterns.

I found this (not sure I can trust the composites, maybe I can find time to do them myself) https://longrangesnowcenter.net/aam-composites/

And this post (he’s a consulting meteorologist)

LRT: The Complex Influences of AAM and GWO – NY NJ PA Weather

nynjpaweather.com nynjpaweather.com

And this one (he’s a NWS met)
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@Jon @KyloG @WEATHERBOYROY and others:

For February (January very similar), here are some correlations that illustrate well what I've been saying about -AAM and La Nina:

- AAM (aka -GLAAM)(1st image) and -MEI (La Nina)(2nd image) correlation to 500 mb hts:

Cold is far away (upper Midwest/Plains/Rockies) and warm is right here in the SE due to SER, which is what we've been experiencing most of the winter with the -AAM. The opposite is true of the +AAM/El Nino....BN hts SE...no SER. +AAM and El Nino are more desirable unless you want a SER/warnth.

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GaWx said:
@Jon @KyloG @WEATHERBOYROY and others:

For February (January very similar), here are some correlations that illustrate well what I've been saying about -AAM and La Nina:

- AAM (aka -GLAAM)(1st image) and -MEI (La Nina)(2nd image) correlation to 500 mb hts:

Cold is far away (upper Midwest/Plains/Rockies) and warm is right here in the SE due to SER, which is what we've been experiencing most of the winter with the -AAM. The opposite is true of the +AAM/El Nino....BN hts SE...no SER. +AAM and El Nino are more desirable unless you want a SER/warnth.

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The AAM is a small piece of what went wrong with this winter. The arctic and tropics were far bigger drivers at went wrong.
 
Bastardi finally threw in the towel on his forecast this morning. With the MJO headed back to 5/6, he realizes it is what is driving the EPO and the pattern and does not feel it will flip the other way. Most of us here held out hope that the pattern would flip by the 15th of Feb but it looks unlikely now. Look for a cool and very wet spring for the bulk of the SE and a small severe season
 
KyloG said:
The AAM is a small piece of what went wrong with this winter. The arctic and tropics were far bigger drivers at went wrong.
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I agree especially about the Arctic though I don't know exactly which driver had more influence.. But I was addressing -AAM and La Nina, alone, in that post, which both correlate with a SER as the maps clearly show. We all know no one index has anywhere near a 100% correlation.
 
Sister in law says ground temps have hindered accumulations in OKC. She said they’ve been stuck at 3-4 inches most of the afternoon
 
NAM completely whiffed with the energy Digging, hopefully not a sign
 
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