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Pattern Magnificent March
- Thread starter GaWx
- Start date
Kylo
Member
This would be a heck of way start off March.
Kylo
Member
This is CPC MRF model which not sure what that contains or is based on.
pcbjr
Member
What is weathermodels.com showing as far as surface temps are concerned at the same time?
Webberweather53
Meteorologist
It's fun to watch all the planetary waves in the Western Hemisphere and North Pacific retrograde as this high latitude block initially over Scandinavia goes to Greenland and eventually northern Canada. The trough over the west coast and ridging in the NE Pacific retrograde in the longer term and every cyclone over the North Atlantic occludes west of its predecessor, eventually we are gonna get a big cyclone near the eastern seaboard. This means the PNA will eventually go to neutral of even positive as the entire height field retrogrades west in response to this block
In no way, shape, or form is this negative NAO within 1 sigma of normal as that image shows when both the high latitude blocking high over Greenland and corresponding trough south of Atlantic Canada have height anomalies >1-1.5 sigma. Coarse ensemble mean guidance will dampen extreme blocking regimes like this that's why both the Euro and GFS op are off the charts negative
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Jon
Member
It’s because of how those are generated,
“The indices are standardized by standard deviation of the observed monthly NAO index from 1950-2000 interpolated to the day in question. A 3-day running mean is applied to the forecast time series.”
That’s likely causing the anomalies not to be as negative/strong. Probably because of the 3-day running mean if anything, but also due to the years I’m sure, as the imagine I posted above uses 1985-2012. I assume weatherbell uses something similar.
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Jon
Member
Yeah it truly is amazing to watch and it’s crazy how similar it is to 1962 and how the -NAO disrupted the pattern in the same fashion.
Hold on to your butts.
Grr...gif is too big to display, lol.
Code:
https://m.imgur.com/a/bn3lASent from my iPhone using Tapatalk
Kylo
Member
It doesn't have a 5 day mean on that site. Temps don't flip until day 12+ but then get colder as the run extends.
pcbjr
Member
That is the GEFS mean based NAO 14 day forecast, which is the one we follow the most closely and jibes with the daily NAO index that we all follow. Since 1950, the most negative single day NAO has only been down to -3.254 (10/21/2002). There have been only 5 days since 1950 with the NAO below -3:
-3.254 10/21/2002
-3.095 7/14/1962
-3.048 10/20/2002
-3.022 10/22/2002
-3.004 7/13/1962
I'm not at all saying there's not a good possibility of a very strong -NAO coming up. I think there is. But let's be realistic. A very strong -NAO is somewhere in the -2 to low -3 range. The posted GFS charts' prediction of several days of -4 to -5 is what I'm not at all buying, especially when taking into account what I posted, which is what we always follow, the daily NCEP GEFS based forecast out 14 days. No single member even gets below -2 on any one day. So, do you really think we're going to have several days of sub -4 NAO?
So, here is my prediction: there will be a strong -NAO event that may or may not lead to a cold SE. (I'm leaning toward a cold period in early March but that's not what I'm currently debating.) But the daily index that has been followed for many years on wx boards will not get anywhere near as negative as -4 to -5. I predict it won't get below -2.5. I'll follow this closely and follow up with the verification after the NAO peaks. This is what has always been used and what I'll use for verification:
ftp://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii
Does anyone want to bet on the NAO peaking more negative than -3.5, which would be a record breaker? If so, please reply to this and let me know. Don't be afraid. Better yet, if anyone wants to bet it will be -4 to -5, please indicate that here. I say strong -NAO but not below -2.5.
Kylo
Member
Sounds good.
If weatherbell or weathermodels use a different method to calculate it doesn’t matter. Like you stated a strong -NAO on CPC site is -2 or -3 or lower seems reasonable. It’s all pointing to a strong -NAO.
Jon
Member
The weatherbell -4 isn’t the same as your -4, it’s probably closer to your -2. Again, it all depends on methodology in generating the anomalies and there seems to me multi day means and “smoothing” to the method you choose to follow, which makes it not as anomalous. The fact that -3 is that anomalous in the method you follow shows that. Either way, we’re talking about the same thing here.
A deeply negative NAO is coming, no matter what you use
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Excellent post! You made my point better/more succinctly than I did. That's what I think is going on. For whatever reason, the posted alternative sources to the traditional NCEP GEFS graphs that have been followed forever on wx forums are not an apples to apples to comparison. We're not about to get a -4 to -5 NAO based on the index we all have followed for many years.
The weatherbell -4 isn’t the same as your -4, it’s probably closer to your -2. Again, it all depends on methodology in generating the anomalies and there seems to me multi day means and “smoothing” to the method you choose to follow, which makes it not as anomalous. The fact that -3 is that anomalous in the method you follow shows that. Either way, we’re talking about the same thing here.
A deeply negative NAO is coming, no matter what you use
Excellent post. It appears we're all on the same page more or less though I do still wonder about WxBell. Remember those WxBell graphs that predicted the near alltime record -EPO around Xmas of sub -400 to nearly -500 that I got so excited about and kept posting about? It never got anywhere close. It ended up just a run of the mill -EPO with a dip down only to -183.83 on 12/22/17:
ftp://ftp.cdc.noaa.gov/Public/gbates/teleconn/epo.reanalysis.t10trunc.1948-present.txt
I learned from that to be way more cautious about WxBell and other alternative sources. Much of that miss was due to the models way overdoing that -EPO (the Alaskan ridge never got even close to what the models showed for then), but I still have to wonder about WxBell's methodology.
Webberweather53
Meteorologist
The smoothing plus using a base period with more frequent +NAO regimes after the late 1970s (& is honestly more relevant to our bgd climate state) is somewhat to blame although the shorter base period wxbell and NOAA ESRL uses implies larger standard deviations which makes it more difficult to attain larger standardized anomaliesThe weatherbell -4 isn’t the same as your -4, it’s probably closer to your -2. Again, it all depends on methodology in generating the anomalies and there seems to me multi day means and “smoothing” to the method you choose to follow, which makes it not as anomalous. The fact that -3 is that anomalous in the method you follow shows that. Either way, we’re talking about the same thing here.
A deeply negative NAO is coming, no matter what you use
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ForsythSnow
Moderator
Happy hour doesn't disappoint.
pcbjr
Member
GOOOO Larry!Happy hour doesn't disappoint.
Fantasy land, but so was his 1st this year ... Damn if he could only score twice this year ... who more deserves it?
After all, he's rooted everyone else on ...
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Doesn’t dissapoint if you live in NYC or BOS!Happy hour doesn't disappoint.
I’ll take that bet! And roll with this guy....
Webberweather53
Meteorologist
