A Tropical Plume

The big news story lately has of course been Hurricane Ike. However there was also an interesting situation further to the west, before the landfall of Ike. From northern Mexico up into West Texas and Oklahoma, there was a persistent swath of cloud cover and rain. In spite of some analyses, this was not primarily due to interaction with a frontal zone. Instead, it was due to a plume of mid-level tropical moisture being blown northeastwards from Tropical Storm Lowell in the Pacific. In terms of winds or direct impacts, Lowell was never much of a storm. But its remote impacts through this plume of moisture were fairly significant. To some extent this pattern simply extended the influence of the North American Monsoon System further east into the Plains than usual. Because of the relatively wet ground in northern Mexico, it was feared that there could have been particularly bad flash flooding if Ike had tracked to the west over the region. The area of East Texas that was traversed by Ike was actually somewhat in need of rain, although they obviously could have done without the high winds.