The Typhoon Did It

When Hurricane Isaac was moving toward the United States, several individuals emailed and asked if it would have any impact on us locally. Historically, it has been rare for the remnants of a hurricane or tropical system to bring rainfall into this area.  Instead of getting rain from a tropical system, a hurricane may help alter the upper level wind flow to temporarily adjust the pattern that would influence our weather in that manner.

That is particularly true with western Pacific typhoons.  Powerful typhoons in particular often help form a large ridge of high pressure to their east, which induces the formation of an area of low pressure and a corresponding trough east of that ridge in the Aleutian Islands.  That storm in turn tends to advect warmer Pacific air into Alaska.   The colder air over Alaska is then forced south into the lower 48 states impacting areas east of the Rocky Mountains in particular.

In some ways, typhoons in the Pacific can alter our weather more than their hurricane cousins in the Atlantic.