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Sunday, June 30, 2013

Alberta Floods and Arctic Amplification : Is There A Correlation?

The theory of Arctic Amplification, simply stated, suggests that as sea ice melts, more moisture is available for precipitation and that as the far northern latitudes warm, the jet stream's oscillation patterns tend to elongate, creating larger ridges and troughs that have the net effect of decreasing the rate of storm movement from west to east.  This essentially slows the storms down causing them to linger in place longer.  As storms linger longer and have more precipitation available to them, it follows that severe weather impact, such as flooding events, droughts, snowfall, or other consequences of strong weather related events could be more likely to occur.

As Alberta sets about learning how we could have improved our ability to forecast the recent flooding event, the one certainty we have is that more time would have been beneficial as outlined in this article in the Calgary Herald.  Also, here is an excellent primer video on Arctic Amplification and Rossby Wave elongation.

Rossby waves move storms from west to east, as they move slower due to elongation, it's evident that storms tend to persist.  In addition,the elongation of Rossby waves tend to create larger ridges and troughs which have the effect of shifting weather patterns further to the north and to the south.  As it turns out, when the storms were forming that caused the recent flood events in Alberta, I happened to be at latitude 60 experiencing hot sunny days with high temperatures in excess of 100 degrees farenheigt in the region while latitude 50 - 52 running through southeast BC and southwest AB were experiencing a jet stream ridge that may have caused precipitation to linger in the eastern range of the rocky mountains, washing away snow pack and distributing large amount of precipitation into the headwaters of the river systems that later generated large scale flooding events.

Without a doubt, this is not certain... and there are a lot of other circumstances involved to be sure.  But at the very least, this may be a like a red flag for scientists that the theory of Arctic Amplification affecting Rossby waves may be worth a hard look.  From a layman's perspective, it appears that elongation of the Rossby waves in the jet stream from 17-19 June, followed by a return to a more normal Rossby wave, may have contributed to the flooding events.

Heavy rain in the mountains, no doubt, exacerbated melt rates of high snow pack and these forces combined with rain moved into the watershed and were sufficient to create the flooding events.  If the Rossby wave elongation did contribute to the overall impact, it is certain that nothing could have been done to prevent the flooding, but perhaps a meteorological integration of the understanding of Rossby wave pattern elongation combined with precipitation analysis from satellite imagery may be enough to extend predictive capability.  Any additional amount of forewarning may have proven valuable to those responsible for emergency planning.  It is important, however, to keep in mind these theories are only now getting widespread attention.

Still, if there is anything this story should tell us it's that there should be attention paid to changing jet stream patterns and alteration of the Rossby waves.  That science has been gaining momentum over the last couple of years.  One of the more interesting videos I've seen on this was a lecture given by Dr. Francis of Rutgers University.  She explains the elongation of the Rossby waves and then goes on to analyze large storm events over the last couple of years and checked to see if there was a Rossby wave elongation over those areas.  In the storms she analyzed, Rossby wave patterns were elongated... much like the pattern we saw in Alberta.

A more extensive video on extreme weather events by Dr. Francis may be viewed here:

What do you think?

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