North Pacific Ridging Of Uncommonly Long Duration - Spring 2014

[IbrChris]

CFSv2 runs averaged over the last 30 days (120 runs) seem to be set on keeping the anomalous ridging near the Aleutians through March, perhaps into April. In talking with several met friends of mine including a met at NWS' Portland office it appears this persistent of a ridge in the North Pacific during winter is unprecedented, at least in the 1948-present reanalysis period.

[Dan the Weatherman]

There has been a bullseye of SST anomalies of 3+ C in the north Pacific around 145W-155W, 40N-50N, according to the latest CPC ENSO discussion. The time period shown on the map was 12/29/13 to 1/25/14. I am wondering if this warm water pool may be the culprit behind this long lasting ridge, or did the water warm to this extent once the ridge had been in place for a while?

[westiztehbest]

There has been a bullseye of SST anomalies of 3+ C in the north Pacific around 145W-155W, 40N-50N, according to the latest CPC ENSO discussion. The time period shown on the map was 12/29/13 to 1/25/14. I am wondering if this warm water pool may be the culprit behind this long lasting ridge, or did the water warm to this extent once the ridge had been in place for a while?

Pretty remarkable.  I'd think that the ridge causes the warm SSTs...not the other way around.

[snow_wizard]

Those Feb and March anomalies strongly suggest below normal temps for the NW.

[Phil]

Pretty remarkable. I'd think that the ridge causes the warm SSTs...not the other way around.

Exactly. If anything, warm SSTs will induce more vigorous rising motion/overturning as the warmer parcels expand.

 

The persistent ridge is mainly a result of a very stable stratospheric wind/eddy field associated with the +QBO, various tropical forcings in a heavy playing field given the lack of a stable ENSO circulation, and a healthy Brewer-Dobson circulation pumping O^3 poleward in the stratosphere over the NPAC/Polar domain.

 

The idea that tropical SSTs vary on their own and single-handedly run the system is a fairytale that captivates many when they see the pretty colors on their computer screens.

[richard mann]

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What's caused, the ridge. ? -Or the larger patterning connected and adjacent to it where looking at things more broadly. ?
 
— More basically, that is. These are the main questions for me.
 
SSTs are certainly a contribution. And on the other side of the Jet, both the degree, looked at along together with vicinity of main cold stores. 
 
My view is, start with these two main ideas if you want to try to figure why the formation, and why the persistence. 
 
.. But then you'll need to answer the questions further, of why, along with what (or which), main colder air mass has been caused to move and spread more south—into the mid-latitudes, down and out from its main higher latitude source regions to the north—when it has, where. And with this, then, why that colder air is caused to move either whether more assertively, or otherwise more slowly, from west to east, when it is.
 
With this, and pointed to more generally where looking at the idea of any more persistent ridge formation, my own feeling is that the concept of "blocking" is, for one, far too simplistic. Two, far over-rated as a main focus (or "cause") connected.  And ultimately, wrong, as it's presented.

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[IbrChris]

I see the warm SSTs as symptomatic of the pattern, not causal. Simply put the area has been underneath general ridging since fall and the lack of cloud cover plus lack of an active storm track to churn up the cooler water lying just under the surface layer is part of it. That surface layer perhaps 30-50' deep still contains a lot of heat stored from last summer/fall.

 

There have been other examples of stubborn EPO ridging in other winters, most often those which are cold across the central and eastern US.

[Dan the Weatherman]

I see the warm SSTs as symptomatic of the pattern, not causal. Simply put the area has been underneath general ridging since fall and the lack of cloud cover plus lack of an active storm track to churn up the cooler water lying just under the surface layer is part of it. That surface layer perhaps 30-50' deep still contains a lot of heat stored from last summer/fall.

 

There have been other examples of stubborn EPO ridging in other winters, most often those which are cold across the central and eastern US.

 

Thanks for answering my question about the warm SSTs. It makes perfect sense that the water has grown warmer as a result of being under the ridge due to the lack of upwelling and lack of cloud cover associated with passing storms.

 

Has this pattern broken down completely now, or has it simply weakened and shifted for the time being, and ready to bounce back again later this month? I am just wondering when southern California is going to receive meaningful precipitation this season. This has been the driest winter I have ever seen to date so far, and I have lived in Orange County my entire life.

[IbrChris]

Thanks for answering my question about the warm SSTs. It makes perfect sense that the water has grown warmer as a result of being under the ridge due to the lack of upwelling and lack of cloud cover associated with passing storms.

 

Has this pattern broken down completely now, or has it simply weakened and shifted for the time being, and ready to bounce back again later this month? I am just wondering when southern California is going to receive meaningful precipitation this season. This has been the driest winter I have ever seen to date so far, and I have lived in Orange County my entire life.

That's a good question. CFSv2 suggested continued EPO ridging into March/April but it does seem to have switched patterns recently. Remains to be seen if it's temporary or if a decent Aleutian low has finally taken up residence.

[Dan the Weatherman]

That's a good question. CFSv2 suggested continued EPO ridging into March/April but it does seem to have switched patterns recently. Remains to be seen if it's temporary or if a decent Aleutian low has finally taken up residence.

 

Hopefully the pattern has changed so that we have a chance at some beneficial rains before this season is over.