Weather extremes provoked by trapping of giant waves

[calm_days]

This topic was originally titled along with this news release;

Weather extremes provoked by trapping of giant waves

 

Could a moderator restore the topic title? 

bluewave is still an active member so i'm not sure what happened here.

 

Wave behavior does partially seem to continue resemble being trapped, and an increase in what are apparently called retrograding lows has been noticed this summer. 

[Sickman]

Not sure why bluewave scratched out the title/post, but members do have the ability to do so using Full Editor.

 

Anyhoo, I split off your post to start a new thread.

[calm_days]

Ok!  Thank you!  I will try asking bluewave what happened, though i don't know them directly. 

 

Here is the original topic from 2013 of which this is an extension.  This one will be used for continuation of observation and extrapolation of this changing set of climactic phenomena. 

 

http://www.americanwx.com/bb/index.php/topic/39540--/

 

[blizzard1024]

My theory is that when the baroclinicity is higher than normal in winter especially in the NH, NOT lower than normal, you obviously have colder air over the continents which can contrast more with the slower responding seasonal temperature changes of the oceans. This increases baroclinicity which leads to larger and much deeper oceanic storms which in turn eventually advects warmer air northward and eventually builds upper level high  pressure to the north and forces much colder air well south to the mid latitudes and lower heights to the south. This is when you get blocking. So when there is excess cold air in the NH high latitudes, that is when you get blocking patterns as the atmosphere forces this colder air south and warmer air north due to increased storminess. The blockiness is an enhanced wave train.

 

Weaker baroclinicity leads to weaker storms which will reduce the massive warm advections into the Arctic. But the Arctic in these situations already is NOT as cold as it would be due to a warmer season. Also in these patterns you get more zonal flow and the mid latitudes get flooded with milder oceanic air versus polar air. This makes sense because in these less baroclinic environments the wave amplitudes are weaker, which makes sense because there is less energy. The baroclinicity drives how amplified the wavetrain becomes.

 

The 1960s and 70s showed major blocking episodes and that was globally a cooler period. All this research about global warming leading to more blocking is very suspect in my opinion.

[blizzard1024]

I was thinking about this a little more. There is a way that waves could become "trapped" or slowed in their progression. I am not certain how the role of a warming climate from increasing GHGs would factor into this.

 

Here goes. When the static stability of the atmosphere is lower but still stable in a baroclinic environment, the ageostrophic motions required to try to restore geostrophic balance are stronger and act over a shorter distance than for a more statically stable baroclinic atmosphere. In this way, the wave can develop faster and be of a smaller scale and eventually separate from the mean current. The wave would move slower or stall and because the ageostrophic flow is stronger you get more acceleration from the equations of  motion and hence a more intense slower moving storm is the result. In this way, you could see more extreme weather events. In fact, as the atmosphere becomes less statically stable from warming from winter to spring you often see this. How often do we get more closed lows in March/April and even May?  How often do we see our biggest snowstorms in March? All this is related to the Rossby  radius of deformation.

 

Anyway, in a warming climate based on increasing Greenhouse gases, I believe the warming is supposed to stronger in the upper troposphere so static stability will then increase. I don't quite see how warming could lead to this from increasing GHGs. However, it certainly could be something to look into.