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Winter 2014-2015 Pattern Discussion Thread II


JoshM

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This might be of interest.  Mean NAO by month since 1950:

 

 

The data was gathered from here: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

 

I hope I didn't **** it up in SAS somehow. :lol:

 

 James,

Thanks. So, the NAO averages very slightly negative over the 12 months. I did a similar calc. for the AO a while back and found it to average near -0.3. Therefore, I actually consider a -0.3 AO to be the true neutral number as opposed to 0.     

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I seem to remember a few years back everyone pinning their hopes to a much hyped SSWE to make things better. The event came to fruition only to dump the cold into Europe. Does anyone recall what year that was?

2011-12 and it barely did much there I think it lasted maybe 10 days. I think it was February 2012 to be specific, the EPO ridge did indeed build over Alaska but in about 5-7 days the thing retrograded to Siberia and that was all for that winter.

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2011-12 and it barely did much there I think it lasted maybe 10 days. I think it was February 2012 to be specific, the EPO ridge did indeed build over Alaska but in about 5-7 days the thing retrograded to Siberia and that was all for that winter.

Alaska had their best winter ever that year with the goa trough a stable feature.
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Consider these stats for ATL: For major SN/IP since 1950, whereas there were five that had +NAO/+AO, only a little higher number, seven, had a -NAO/-AO.

For major ZR since 1950: whereas there were five that had +NAO/+AO, only little higher number, six, had a -NAO/-AO.


NAO: median/mean -0.1/-0.1 with range +1.0 to -1.1 for major SN/IP and median/mean -0.2/-0.3 with range +0.8 to -1.9 for major ZR

AO: median/mean -0.2/-0.7 with range +2.3 to -4.8 for major SN/IP and median/mean -0.4/-0.3 with range +3.5 to -2.8 for major ZR

After considering these stats, I'm a bit relieved about +NAO/+AO because they aren't as bad as I had expected. The NAO median/mean for major SN/IP are practically neutral!
 

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Consider these stats for ATL: For major SN/IP since 1950, whereas there were five that had +NAO/+AO, only a little higher number, seven, had a -NAO/-AO.

For major ZR since 1950: whereas there were five that had +NAO/+AO, only little higher number, six, had a -NAO/-AO.

NAO: median/mean -0.1/-0.1 with range +1.0 to -1.1 for major SN/IP and median/mean -0.2/-0.3 with range +0.8 to -1.9 for major ZR

AO: median/mean -0.2/-0.7 with range +2.3 to -4.8 for major SN/IP and median/mean -0.4/-0.3 with range +3.5 to -2.8 for major ZR

After considering these stats, I'm a bit relieved about +NAO/+AO because they aren't as bad as I had expected.

I saw research from someone about 8-10 years ago showing that the SE US in particular tends to see more winter storms during the inactive period of the Atlantic basin hurricane phases, so that would basically be 1969-1994 and I guess 1919-1944 or so since they run 25 year cycles historically..,the reason why was uncertain but there sure did seem to be a downward trend for many of the SE cities in the 1945-1968 period and after 1994

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I saw research from someone about 8-10 years ago showing that the SE US in particular tends to see more winter storms during the inactive period of the Atlantic basin hurricane phases, so that would basically be 1969-1994 and I guess 1919-1944 or so since they run 25 year cycles historically..,the reason why was uncertain but there sure did seem to be a downward trend for many of the SE cities in the 1945-1968 period and after 1994

SG,

ATL, itself, hasn't held to this as it has been a pretty even split since 1919 fwiw:

Major winter storms ATL including ZR

1919-44: 12

1945-68: 11

1969-94: 10

1994-14: 9

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seems the past couple years have been pretty "inactive", but I'm not sure what that term refers to - total 'canes, land-falling storms/canes/t-s/depressions, fish storms, named storms in toto ...?

We are probably coming out of this active phase soon, been in it since 1995 now but yes the last 2 years have been dead.

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I saw research from someone about 8-10 years ago showing that the SE US in particular tends to see more winter storms during the inactive period of the Atlantic basin hurricane phases, so that would basically be 1969-1994 and I guess 1919-1944 or so since they run 25 year cycles historically..,the reason why was uncertain but there sure did seem to be a downward trend for many of the SE cities in the 1945-1968 period and after 1994

Yep, by 1940 RDU's 30 yr avg was almost 9" and same by 1990. Our up to date 30 year avg is roughly 6", so there is something cyclical about our seasonal snowfall. Was thinking it would be turning around about now or the next couple of years.

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Yep, by 1940 RDU's 30 yr avg was almost 9" and same by 1990. Our up to date 30 year avg is roughly 6", so there is something cyclical about our seasonal snowfall. Was thinking it would be turning around about now or the next couple of years.

Pack,

Don 't forget major ZR 's. You may have had more big ZR's & big IP 's during the slower SN periods. So, just looking at # of inches may possibly be deceiving. In ATL, that has tended to be the case and vice versa.

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Nothing to like about last nights runs in the LR at all. Ugly, ugly ugly. 6z PARA was close to something big for the Carolinas in the 240 range. Other than that yuck.  :yikes:

Plenty of cold air lurking around closeby in the long range (late next week and beyond)..... 6z GFS downright cold for the Carolinas next Thursday-ish. 

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Plenty of cold air lurking around closeby in the long range (late next week and beyond)..... 6z GFS downright cold for the Carolinas next Thursday-ish. 

 

It is indeed there but the 00z GFS and Euro runs looked bad in the LR for how the cold air will get here (or not get here). Good news is it was one set of runs and it's in the LR which recently has been like shaking a magic eight ball in a dice game on a roulette table to figure out whats going on.

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It is indeed there but the 00z GFS and Euro runs looked bad in the LR for how the cold air will get here (or not get here). Good news is it was one set of runs and it's in the LR which recently has been like shaking a magic eight ball in a dice game on a roulette table to figure out whats going on.

 

I was going to say anything past 5 days on the models is constantly changing. They are not reliable at all past that point.

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Still watching 1/8 through 1/11 time frame. Key is movement of PV into eastern Can. This trend has been weaker in latest GFS runs.


 



Watching 1/15-1/20 as potential time for colder possibly more stable pattern to develop. Big -EPO ridge on latest GEFS/GGEM ENS D15-16.


 



However ECMWF ENS not as excited yet, although could be going there by late in its 00z run. We shall see!


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Interesting double top at +3 for the AO being modeled. If this was a stock this would be a good sign for a AO about take a steep dive.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

Around the 5th/6th the OP has gone from negative to neutral several times for the last 10 runs...I'm kinda interested in this because a good amount of the members (roughly 14/21) dip at least neutral to negative during this time...however it does appear transient and the next chance to develop one would be around the 13th so mid-month as you can see with the lastest ensemble members. But we don't necessarily need an -AO for snow that's why the period before the 10th interests me.

 

 

Still watching 1/8 through 1/11 time frame. Key is movement of PV into eastern Can. This trend has been weaker in latest GFS runs.

 

Watching 1/15-1/20 as potential time for colder possibly more stable pattern to develop. Big -EPO ridge on latest GEFS/GGEM ENS D15-16.

 

However ECMWF ENS not as excited yet, although could be going there by late in its 00z run. We shall see!

 

Yeah, time around the 10th or so has been on the radar for a while...the GFS sucks. What I'm paying attention to is the Euro in the LR, which is the bottom tweet by Allan. Just comparing the Euro vs the GFS at 216 I believe it was shows how crappy the GFS is in the LR and why any "trend" whether positive or negative, in this case, should be ignored.

post-785-0-02184600-1419948356_thumb.png

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As I've stated before I think our best chance for wintery precip will be the end of January into the first two weeks of February. The only reason I can give (other than gut feeling) is from past readings about how the pattern usually flips to an opposite configuration(from the dominate winter pattern) during mid winter. Either this is a mid winter thaw or a mid winter cold snap.

 

I think 1999-2000 was a similar winter where it was warm up until the last part of January. The pattern got cold and we ended up with this:

 

http://www4.ncsu.edu/~nwsfo/storage/cases/20000125/

 

Not saying we'll get a major storm but  think this will be the most favorable time period.    

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