Not A Typical November -PDO Pattern So Far

[bluewave]

So far November is not starting out with a typical -PDO pattern. Usually during a -PDO pattern in November the blocking

on the Atlantic side is the dominant 500 mb height anomaly in the Northern Hemisphere. The early part of the month

forecasts continue with a strong ridge north of Hawaii and a trough southeast of Greenland. In the North Atlantic

a trough southeast of Greenland with a Scandinavian Ridge is more typical of what you would see during a +PDO

pattern. We are only in the early part of the month so we'll have to wait and see what the second half brings. But

I thought that this first half pattern was a little different than what you might expect.

November -PDO composite

November +PDO composite

Forecasts for the next ten days

[SnowGoose69]

There is no question it is not looking good early on here, but the key words there are early on. The models are definitely showing a very classic La Nina SE Ridge type thing going on and the NAO is very positive though a few GFS runs have shown indications of a -NAO late.

[usedtobe]

I think if you look at the MJO you might see some of the reason why the pattern is not looking that much like a neg pdo pattern.

[Rainshadow]

I think if you look at the MJO you might see some of the reason why the pattern is not looking that much like a neg pdo pattern.

We snuck out on the warm side.

[usedtobe]

We snuck out on the warm side.

Yep, we're in phases 3 and 4 which also would sort of explain the low going across the south. Below is the typical temp anomlies for 3 and 4 during Oct-Dec.

[Isotherm]

Yep, we're in phases 3 and 4 which also would sort of explain the low going across the south. Below is the typical temp anomlies for 3 and 4 during Oct-Dec.

Agree Wes. MJO wave should circulate into more favorable phases for Eastern cold and the development of a -NAO after November 15th. Most models try to bring it into phase 7-8 a couple weeks from now.

[Glacier Point]

The MJO wave with a strong phase 1-2 projection in late October was very interesting, not least because it possibly accentuates the pattern that was already there with the atmosphere seemingly in a state with falling inertia typified by the GWO / MJO in phases 1-2.

Composites for strong MJO wave amplitude in October and November are an excellent match hemispherically..

Rolled forward into Dec....

[tacoman25]

I'm not sure I agree with the premise of the OP. The PDO, of course, is a Pacific state (though it can have correlations to blocking patterns elsewhere). The Pacific pattern right now very much resembles a typical -PDO pattern. The Atlantic side doesn't match your composite for November so far, but since the PDO is a Pacific signal, it would be weirder if the Pacific side resembled a +PDO pattern.

[Mallow]

I'm not sure I agree with the premise of the OP. The PDO, of course, is a Pacific state (though it can have correlations to blocking patterns elsewhere). The Pacific pattern right now very much resembles a typical -PDO pattern. The Atlantic side doesn't match your composite for November so far, but since the PDO is a Pacific signal, it would be weirder if the Pacific side resembled a +PDO pattern.

Agreed, for the most part.

Though the Atlantic side might look more like a typical +PDO pattern, the Pacific side looks almost exactly like a -PDO pattern. And though the OP made a good point that the strongest PDO anomalies this time of year are actually generally focused on the Atlantic (based on his November composite), that doesn't mean the Pacific anomalies aren't important. I'd guess that the pattern showing up in the models generally projects onto a -PDO-like pattern, with the glaring exception of the NAO region.

[tacoman25]

Agreed, for the most part.

Though the Atlantic side might look more like a typical +PDO pattern, the Pacific side looks almost exactly like a -PDO pattern. And though the OP made a good point that the strongest PDO anomalies this time of year are actually generally focused on the Atlantic (based on his November composite), that doesn't mean the Pacific anomalies aren't important. I'd guess that the pattern showing up in the models generally projects onto a -PDO-like pattern, with the glaring exception of the NAO region.

Yeah, and as far as I know there isn't a strong correlation between -PDO and -NAO.

[BethesdaWX]

Yeah, and as far as I know there isn't a strong correlation between -PDO and -NAO.

Yes there is a correlation but I don't believe the PDO and NAO are linked to eachother but instead the weak correlation is due to another forcing agent, called the sun. It influences ENSO so it'd do the same to the PDO naturally, while also forcing the NAO though a whole different process.

[tacoman25]

I realize that greater periods of blocking coincide, both Pacific/Atlantic side, but as far as individual shorter periods (days/weeks/months), I don't believe there is a strong independent correlation between PDO and NAO.

[SoCoWx]

While it has yet to be seen if we'll have favorable blocking again this Winter, I gotta say..seems the usual paranoia about Winter being a dud similar to last Winter (understandable because of the strong Nina) is sinking in again. And last year, it was about now when folks started worrying. Another interesting thing would be the Euro now also hinting at a pattern change to cold close to thanksgiving. If I recall correctly, it remained pretty seasonable...here in the southern Mid-Atl anyway until about Black Friday. Then it all changed. Repeat performance maybe?

[bluewave]

I'm not sure I agree with the premise of the OP. The PDO, of course, is a Pacific state (though it can have correlations to blocking patterns elsewhere). The Pacific pattern right now very much resembles a typical -PDO pattern. The Atlantic side doesn't match your composite for November so far, but since the PDO is a Pacific signal, it would be weirder if the Pacific side resembled a +PDO pattern.

Agreed, for the most part.

Though the Atlantic side might look more like a typical +PDO pattern, the Pacific side looks almost exactly like a -PDO pattern. And though the OP made a good point that the strongest PDO anomalies this time of year are actually generally focused on the Atlantic (based on his November composite), that doesn't mean the Pacific anomalies aren't important. I'd guess that the pattern showing up in the models generally projects onto a -PDO-like pattern, with the glaring exception of the NAO region.

The pacific side is closer but the stronger positive height anomaly north of Hawaii is allowing for colder temperatures to make it into the southwest than you would expect.

November -PDO temperature composite