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Pattern December, Make analogs relevant again

NorthGaWinter4 said:
Eps!
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You talking about this:D

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SD said:
Now that's interesting

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You got to figure, if we atleast get the NE, and SE Canada cold, we could easily score a good CAD event, at the least!
 
The 12 EPS as others mentioned, continues to look good. One thing that stands out is -NAO appears to weaken post D10, but this is a mean over 10 days out. However, the ridge is nice and tall out West through D15, keeping us colder through the run.
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StoneMtnWx said:
The 12 EPS as others mentioned, continues to look good. One thing that stands out is -NAO appears to weaken post D10, but this is a mean over 10 days out. However, the ridge is nice and tall out West through D15, keeping us colder through the run.
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How can you tell if NAO weakens post day 10?? Is the NAO the ridge in greenland
 
Storm5 said:
To hell with the nao...ill take a tall western ridge and a fast flow any day of the week
Scored many times over the last 6 years . Can work out great for my area
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If one likes it cold in winter in the SE, it is never a bad thing to see all 3 major ensemble runs have H5 lines dip deeply down from well up in W Canada to the SE US each and every day from day 10 through day 15 and with then still no end in sight. How often has this happened in recent years? Enjoy it while you got it! Enjoy the wx as it is the only wx you've got.

Edit: PS: Many major SE winter storms have occurred with a +PNA and no -NAO . It is so far from being a requirement. It isn't even close to that being the case.
 
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Meteorologist1999 said:
How can you tell if NAO weakens post day 10?? Is the NAO the ridge in greenland
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Just saying less height anomalies over Greenland post D10, but it is a Day15 euro ensembles mean, and the -NAO signal is still there post D10.

I agree with you Storm, I like seeing the tall ridge out West, and with the trough centered over the E US. We keep that feature in place over a good period of time and there is a good chance some will score later in December into January.
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1. Further to the above about a -NAO not even being close to being required for major SE snow chances. here is the NAO for the 21 Raleigh 6"+ SN/IP storms since 1950. (I'm calling neutral NAO to be from +0.25 to -0.25):


-1/19/1955: -NAO

- 12/11/1958: neutral NAO

- 3/2-3/1960: neutral NAO

- 3/9/1960: neutral NAO

- 2/26/1963: neutral NAO

- 1/25-7/1966: -NAO

- 2/9/1967: +NAO

- 3/1/1969: -NAO

- 1/7-8/1973: -NAO

- 2/18-9/1979: neutral NAO

- 3/1-2/1980: +NAO

- 1/13-14/1982: neutral NAO

- 3/24/1983: neutral NAO

- 2/6/1984: +NAO

- 1/7-8/1988: +NAO

- 2/17-8/1989: +NAO

- 1/24-5/2000: -NAO

- 1/2-3/2002: -NAO

- 2/26-7/2004: -NAO

- 12/25-6/2010: -NAO

- 2/24-6/2015: +NAO


Tally:

-NAO: 8

Neutral NAO: 7

+NAO: 6

Honorable mention since Raleigh didn't get heavy snow from it but many others did: 3/12-3/1993 Storm of the Century: +NAO

Conclusion: Although most of us including myself would rather have a -NAO than +NAO and I love seeing the solid -NAO on the models, results like this on a pretty nice sized sample tell me that any correlation of -NAO with heavy SE US SN/IP is not all that large.


2. I did a similar tally for PNA for the 21 individual 6"+ SN/IP storms at Raleigh since 1950 (I'm calling +0.25 to -0.25 neutral PNA):


+PNA: 10 (48%)

Neutral PNA: 8 (38%)

-PNA: 3 (14%)


Not included in the above tally but an honorable mention since Raleigh didn't get heavy snow from it but many others did: 3/12-3/1993 Storm of the Century: neutral PNA


Conclusion: There's a good chance that there is a stronger correlation between a +PNA and a heavy SE snowstorm than a -NAO and the same. At the minimum, I'd much rather have either a +PNA or neutral PNA than a -PNA for heavy SE snow chances since 18 of the 21 (19 of 22 if include 3/1993) had either of those.


The only 3 -PNA big RAH SN/IP were the two in March of 1960 and 2/24-26/2015, and the 2/24-6/2015 storm was only borderline -PNA. So, RAH went nearly 55 years between getting -PNA big snowstorms!


+PNA storms: 1958, 1963, 1967, 1969, 1973, 1983, 1984, 1988, 2000, 2002

Neutral PNA storms: 1955, 1966, 1979, 1980, 1982, 1989, 2004, 2010

-PNA storms: both in 1960, 2015

Edit: PS: Although results for a place like ATL, GSP, or Birm should be similar, I'm not as sure about the rare immediate Gulf/SE coast snows. I'd have to check those.

 
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Larry, it would be interesting to know what the AO and EPO were during those storms as well. We were saved by the EPO in 2015 I believe.
 
GaWx said:
1. Further to the above about a -NAO not even being close to being required for major SE snow chances. here is the NAO for the 21 Raleigh 6"+ SN/IP storms since 1950. (I'm calling neutral NAO to be from +0.25 to -0.25):


-1/19/1955: -NAO

- 12/11/1958: neutral NAO

- 3/2-3/1960: neutral NAO

- 3/9/1960: neutral NAO

- 2/26/1963: neutral NAO

- 1/25-7/1966: -NAO

- 2/9/1967: +NAO

- 3/1/1969: -NAO

- 1/7-8/1973: -NAO

- 2/18-9/1979: neutral NAO

- 3/1-2/1980: +NAO

- 1/13-14/1982: neutral NAO

- 3/24/1983: neutral NAO

- 2/6/1984: +NAO

- 1/7-8/1988: +NAO

- 2/17-8/1989: +NAO

- 1/24-5/2000: -NAO

- 1/2-3/2002: -NAO

- 2/26-7/2004: -NAO

- 12/25-6/2010: -NAO

- 2/24-6/2015: +NAO


Tally:

-NAO: 8

Neutral NAO: 7

+NAO: 6

Honorable mention since Raleigh didn't get heavy snow from it but many others did: 3/12-3/1993 Storm of the Century: +NAO

Conclusion: Although most of us including myself would rather have a -NAO than +NAO and I love seeing the solid -NAO on the models, results like this on a pretty nice sized sample tell me that any correlation of -NAO with heavy SE US SN/IP is not all that large.


2. I did a similar tally for PNA for the 21 individual 6"+ SN/IP storms at Raleigh since 1950 (I'm calling +0.25 to -0.25 neutral PNA):


+PNA: 10 (48%)

Neutral PNA: 8 (38%)

-PNA: 3 (14%)


Not included in the above tally but an honorable mention since Raleigh didn't get heavy snow from it but many others did: 3/12-3/1993 Storm of the Century: neutral PNA


Conclusion: There's a good chance that there is a stronger correlation between a +PNA and a heavy SE snowstorm than a -NAO and the same. At the minimum, I'd much rather have either a +PNA or neutral PNA than a -PNA for heavy SE snow chances since 18 of the 21 (19 of 22 if include 3/1993) had either of those.


The only 3 -PNA big RAH SN/IP were the two in March of 1960 and 2/24-26/2015, and the 2/24-6/2015 storm was only borderline -PNA. So, RAH went nearly 55 years between getting -PNA big snowstorms!


+PNA storms: 1958, 1963, 1967, 1969, 1973, 1983, 1984, 1988, 2000, 2002

Neutral PNA storms: 1955, 1966, 1979, 1980, 1982, 1989, 2004, 2010

-PNA storms: both in 1960, 2015

Edit: PS: Although results for a place like ATL, GSP, or Birm should be similar, I'm not as sure about the rare immediate Gulf/SE coast snows. I'd have to check those.
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Nice stats as usual! I see my all time favorite in there! W/ a +NAO, nonetheless!! :)
 
GaStorm said:
Larry, it would be interesting to know what the AO and EPO were during those storms as well. We were saved by the EPO in 2015 I believe.
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indeed, I think you're correct about 2015 being saved by the -EPO since it had +NAO/+AO./-PNA. But normally it is far from being required (see below).


1. AO For Raleigh 6"+ SN/IP since 1950: (assuming neutral AO to be +0.5 to -0.5)

6 –AO (3/9/60, 1966, 1969, 1983, 2004, 2010)
8 neutral AO
7 +AO (1963, 1967, 1979, 1982, 1984, 1989. 2015)

3/1993 Storm of Century had +AO


So, no strong signal from AO, not too dissimilar to NAO.


NAO/AO combo: Out of 21, 4 were -NAO/-AO and 4 were +NAO/+AO...so, no strong signal from the NAO/AO combo


EPO: (assuming neutral EPO +50 to -50)

Out of 21, 7 –EPO (3/2-3/1960, 1966, 1973, 1988, 1989, 2002, 2015), 8 neutral, 6 +EPO (1955, 1963, 1967, 1979, 1984, 2010)

3/1993 Storm of Century had -EPO


So, little signal from EPO.


My conclusion: though I'd prefer -AO/-NAO/-EPO/+PNA, PNA is probably the #1 best indicator of PNA, NAO, AO, and EPO for major SE US snowstorms

Storm of the Century 3/1993: neutral PNA, +NAO, +AO, -EPO

AO/-NAO (I think -AO moreso) are certainly pretty strongly correlated to SE cold, regardless. To some extent the -EPO is, too, especially up in NC/TN. The two largest correlations to SE cold overall (not just NC/TN) are -AO and +PNA from research I've seen recently. For FL and S GA, the +PNA is #1 for cold.
 
Thanks Larry. Makes sense that more weight should be given to the -AO and +PNA. Either way the time is up on the crap pattern of the last 2 years and usually when we flip those type patterns something good tends to happen.
 
Storm5 said:
To hell with the nao...ill take a tall western ridge and a fast flow any day of the week
Scored many times over the last 6 years . Can work out great for my area
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That's where my concern is. This may be more of an issue for us folks east of the mountains in the Carolinas (in the CAD regions), but all too often, I watch as the High pressure to my north scoots off the east coast and takes my cold with it leaving my winter storm a cold, cold rain. Or, if we do get a winter storm, the high still is not entrenched deep enough to get all snow, thus the sleet fests we've been having the last several years in CLT. However with a good solid -NAO, we get good confluence from the Northeast and the highs stay more locked in. Yes we can get fortunate with good timing without it, but I'd love to be able to slow everything down to make it more likely my peanut butter (cold) meets up with my jelly (moisture).
 
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