Thursday, September 27, 2012

Typhoons and Potential Connections to Alaska

Source: Joint Typhoon Warning Center
That's super typhoon Jelewat, which presently has maximum sustained winds of 135 mph, with gusts to 165 mph.  The maximum significant wave height is 48 feet.  That will get your attention.

The current track forecast has it turning clockwise, brushing by Taiwan and then moving across Okinawa.  Little wonder why the US Navy and Pacific Air Forces are so concerned about typhoons.
Source: Joint Typhoon Warning Center
I've been looking at the long-range forecasts produced by the GFS and after undergoing what is known as extratropical transition, the remnants of Jelewat move over Nome, Alaska by October 4th.  The weak low center over western Alaska in the image below is it.

It is pretty common for tropical cyclone remnants to move across the North Pacific and undergo reintensification (a process known as extratropical transition).  Many move into the high latitudes.  What role do these events play in the climate of Alaska and the Arctic?  This strikes me as a potentially interesting avenue of research.  Some relevant discussion of major events from weather historian Christopher Burt is available here.  


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  2. Interesting thought, you would think that if you had a string of strong ETs in the western Pacific (or even the Atlantic to some degree), that the Arctic would warm due to the constant injection of a warm tropical airmasses. However, the bigger question which I think you are are getting at is what kind of temporal scale are we talking about for such a warming? I.E are we talking warming for a few days, or weeks or even months!... Perhaps doing a correlation between the number of strong ETs in a season and the arctic sea ice extent (or 500-hPa height anomalies, 850-temp. ect ect..) for the following months would reveal this answer! Granted, there are probably other processes that can be attributed to a decline in the arctic sea ice extent as well so conclusions would have to be made carefully...

    Another potential side effect is that there could be additional fluxes of warmer tropical air from the downstream development or wave amplification that is often cause by such systems (I.E you will have stronger meridional flow from a more amplified wave pattern).