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Old 05-21-2016, 11:35 AM
 
Location: Near the Coast SWCT
83,275 posts, read 74,492,361 times
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Quote:
Originally Posted by chicagogeorge View Post
I'm just regurgitating what I've been reading in the studies done on the AMO/PDO. The more research I do, the more I'm convinced that the AMO is a bigger driver than the PDO for the eastern US. Of course they work together to produce varying effects on climate.


You're posting too many I haven't even had a chance to read the one from last week. LOL


When the pattern is blocked in the U.S like a Rex Block, 100% I agree that is the Atlantic's fault.


But notice the important word... "Blocked".. Things move West to East... AKA ... Starts in the West & Pacific but the Atlantic can either slow things down, speed things up, or block things up.. but doesn't set the overall pattern.
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Old 05-25-2016, 11:25 AM
 
Location: Near the Coast SWCT
83,275 posts, read 74,492,361 times
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Steve D: Ignore the forecast aspect of it and grab the knowledge from it instead. Obviously this past winter is a poor result but Nothing is ever guaranteed so using only this past winter is foolish versus the average. but hopefully this helps in one way or another.


Quote:
The Pacific:


There will be three fundamental drivers in the weather pattern this winter. The first is the obvious, Sea Surface Temperatures in the Pacific. Note I did not just say El Nino, but the entire Pacific. The second is the Sea Surface Temperature Anomalies in the northern and western Atlantic. The third is the state of the stratosphere which will influence the development of the Arctic Oscillation and high latitude blocking over the northern Hemisphere.


The pattern in the Pacific is going to be a dominant influence on the winter’s weather pattern. Obviously we have El Nino to consider which is a very warm body of water between 170E and 80W. However, there is also the positive Pacific Decadal Oscillation (PDO) which is a very warm body of water in the Gulf of Alaska down the West coast.


Meanwhile, in the northern Pacific we continue to feature a strong signal for a positive PDO. Note the above normal temperature anomalies throughout the northern Pacific, the below normal SSTA over the central Pacific and then the above normal SSTA between 10N and 40N and 150W and 100W. These features are certainly rather unique this Fall and have a significant influence on how the Pacific Polar and Sub Tropical jet streams influence the North American patterns.


Much like around the Tropical Pacific, thermal gradients provide us with an important clue on the future of the 500 MB pattern. Remember, the atmosphere is driven by one key rule, the conservation of mass and energy. Mass and energy are in the form of temperatures. That’s why we have weather as the Earth attempts to balance out the cold and warm anomalies.


Now that you understand this factor, we have a powerful gradient surrounding that cold pool in the central Pacific. The thermal gradient along and east of the date line to the north of 30N supports the development of a trough to the south of the Aleutian islands and a ridge to develop along the West coast and over western North America. This is a text book signature of a positive PDO


As you can see above, when a positive PDO is in place, below normal heights are found to the south of the Aleutian Islands, above normal anomalies around found over western North America and around the Arctic Circle, and finally a trough is found over the eastern two-thirds of the nation. This pattern, in theory, would support a cross Polar wind pattern at 500 MB from the Arctic circle toward the Gulf Coast and East coast of North America




The Atlantic:


While the Pacific is a very important factor in seasonal forecasting, the Atlantic can not be ignored either. One of the most important factors is the development of the North Atlantic Oscillation. The North Atlantic Oscillation is a measure of pressure anomalies in the northern Atlantic. When there are above normal heights over Greenland and below normal heights to the south of Greenland to around Iceland, this is called a negative NAO. The pattern leads to enhancement of a trough over the eastern United States and typically supports a storm track over the coastal waters of the northern Mid Atlantic.

A positive phase of the North Atlantic Oscillation (NAO) features the exact opposite features and a jet stream that quickly moves west to east. The Eastern United States can still become cold, however the weather pattern is what we call progressive which means low pressure development can exit out into the Atlantic very quickly.

So now, lets look at these Sea Surface Temperature Anomalies! Clearly what stands out is the cold pool in the northern Atlantic and the very warm water over the western Atlantic. Both of these features are extremely important for this forecast
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Old 05-25-2016, 12:13 PM
 
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Looked at all summers on record that had strong +PDO

Very strange. Below average west?





Using a long term base period West coast above average, interior mountains average, Plains/Upper Midwest cool, I'm around normal, southern Midwest above, New England cool, Southeast above? Makes no sense unless we factor in AMO and other teleconnections.

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Old 05-27-2016, 09:14 AM
 
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July years with +PDO of 0.5 or greater




and more recent years (since 1980) using the 1981-2010 base period





What I am missing here?
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Old 05-27-2016, 09:40 AM
 
Location: Near the Coast SWCT
83,275 posts, read 74,492,361 times
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Quote:
Originally Posted by chicagogeorge View Post
What I am missing here?
The fact that there is lag time? The fact that you used 1989 as an example while September 1988 to April 1989 PDO was negative not positive.

And that was the only one I checked too. Lol

Upper level pattern is slower than surface plus to get an average it would have to have that pattern more than once which means the PDO would need to be constantly above 0.50 to see the results from it.
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Old 05-27-2016, 10:12 AM
 
29,370 posts, read 19,459,081 times
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Quote:
Originally Posted by Cambium View Post
The fact that there is lag time? The fact that you used 1989 as an example while September 1988 to April 1989 PDO was negative not positive.

And that was the only one I checked too. Lol

Upper level pattern is slower than surface plus to get an average it would have to have that pattern more than once which means the PDO would need to be constantly above 0.50 to see the results from it.


Wait a I minute, I used these years and if you go back and look, the PDO was positive through the spring and the winter prior to that July. Not enough lag time?


1913 positive from Feb
1915 positive from April
1924
1926
1928
1929
1934
1935
1936
1940
1941
1942
1947 positive from March
1958
1977
1981
1983
1984
1985
1986
1987
1988
1992
1993
2003
2005
2006
2014
2015
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Old 05-27-2016, 10:36 AM
 
Location: Near the Coast SWCT
83,275 posts, read 74,492,361 times
Reputation: 16504
Quote:
Originally Posted by chicagogeorge View Post
Wait a I minute, I used these years and if you go back and look, the PDO was positive through the spring and the winter prior to that July. Not enough lag time?
Just having May and June in positive territory is not enough IMO and it's not even strong at that.

But again... why are you trying to make it seem like the PDO is the only thing to look at? Try filtering out the El Nino years, or adding a positive PNA to it. How about the AO with the +PDO? And how about winter instead of Summer. Like you said (& I agree) it affects the pattern much more in Spring, Fall and Winter.






http://research.jisao.washington.edu/pdo/PDO.latest
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Old 05-27-2016, 10:40 AM
 
Location: Near the Coast SWCT
83,275 posts, read 74,492,361 times
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Gee look... PDO affects the Southeast U.S. Are you going to argue with researchers and science?


Global Patterns - Pacific Decadal Oscillation (PDO) | State Climate Office of North Carolina


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Old 05-27-2016, 10:50 AM
 
29,370 posts, read 19,459,081 times
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Quote:
Originally Posted by Cambium View Post
Just having May and June in positive territory is not enough IMO and it's not even strong at that.

But again... why are you trying to make it seem like the PDO is the only thing to look at? Try filtering out the El Nino years, or adding a positive PNA to it. How about the AO with the +PDO? And how about winter instead of Summer. Like you said (& I agree) it affects the pattern much more in Spring, Fall and Winter.
I am not. I'm aiming this towards Tom who thinks that the PDO is the be all end all to his cold winter and cooler than normal summers, which it is not.



That was just one year that had a mostly negative PDO of all the years I chose which had multiple months of +PDO prior and including that July. Come on.


Quote:
Originally Posted by Cambium View Post
Gee look... PDO affects the Southeast U.S. Are you going to argue with researchers and science?


Global Patterns - Pacific Decadal Oscillation (PDO) | State Climate Office of North Carolina


Are you reading your own source? It's when the PDO is in phase with ENSO that it can effect the Southeast. Yes, I know this Cambium. Isn't that what your source says?
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Old 06-02-2016, 11:32 AM
 
Location: Near the Coast SWCT
83,275 posts, read 74,492,361 times
Reputation: 16504
Paul Pastelok video. Good video. Shows a bunch of stuff in the Pacific and Atlantic relating it to the Hurricane season. Watch that cold Atlantic Blob, might drop south which would affect tropical storms coming off Africa.


Shows how the PDO was very warm end of March, then got cooler end of April and could lead to a negative PDO come fall. Check it out.


Link will go bad soon so check it out
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