Friday, September 14, 2012

Super Typhoon Sanba In Western Pacific

This week marks the traditional midway point and peak of hurricane activity in the Atlantic. From here on out a slow decline in potential for tropical systems will take place through the duration of Fall. Nadine still spins in the Central Atlantic, not a threat to America.

On the other side of the globe, the equivalent of a hurricane is known as a typhoon...and in the Western Pacific, typhoons can be classified as "super" if their maximum winds are over 150 mph, which is just shy of Category 5 status on the Saffir-Simpson scale. The Western Pacific, with its warm oceans and large amounts of open water, produce a few super typhoons annually. One is now firing through the Western Pacific on a northward course towards Okinawa.  Super Typhoon Sanba has 170 mph maximum winds as of this morning and is moving northwards, far to the east of Taiwan.  It's a large storm with a well-defined eye, likely around its peak intensity based on satellite taken this morning (below).  As it lifts north in the coming days, it will begin to gradually weaken as it reaches progressively less favorable conditions.  However, because it is a such a strong storm now it will pack a wallop as it crosses Okinawa and then makes a path for the Korean peninsula next week.

This would be the fourth tropical system to impact -- either directly or indirectly -- the Korean peninsula this year, with the last impact just a couple of weeks ago from Typhoon Bolaven.

Why post about weather in the Western Pacific?  Well, typhoons that develop and push north and then northeast through the Far East do provide an indirect impact on our weather.   The "recurve rule" for the Western Pacific suggests that typhoons that make the turn north and northeast help create an mid atmospheric trough near Alaska, a ridge off of the US West Coast, and then a downstream trough along the East Coast a few days after they begin their northeast trek through the middle latitudes.

That downstream trough -- and cooler weather for the eastern half of the country -- has been hinted at in various modeling for the end of next weekend and beginning of the week of the 24th.