Looking at the latest Water Vapor images from NRL Monterey, a non-tropical cyclone well to the north of Igor extends a cool front southward to about 30N creating a weakness in the ridge and therefore a decrease in steering currents. This weak front is pulling out to the northeast. Although this weakness has slowed Igor down, this trough appears too far to the north to pull Igor into a more northwesterly movement. A center of high pressure near 28N 60W is moving eastward â€“ and at a much faster rate than Igor is crawling westward. A second trough extends south and southwestward to about 27N 70W. This trough is moving to the east northeast with the southern portion of the trough weakening as it aligns west-east. A large strong anticyclone is over Louisiana and has extended a strong ridge well to the east over the western Atlantic.

Although the trough to its north did slow Igor down, it did not alter the direction of motion and that trough is now slipping off to the east as the high pressure between the two troughs pushes eastward and should soon give a nudge to Igor and start him off again on a westward track that should become more west northwest as the high slips by to the north of Igor. So far, this has generally been what has been anticipated. The weakening of the base of the second trough and the development of the ridge to the east from the Louisiana high pressure center become the future factors that will determine the ultimate movement of Igor. Iâ€™d anticipate that the second trough would at least enable the west northwest track to continue into Tuesday and Wednesday â€“ perhaps even northwest on Wednesday â€“ but if the ridge continues to build to the east, on Thursday and Friday the track could again resume more of a movement to the west northwest.

Its worth noting that currently, with the exception of Julia which has a west northwest motion, every system and wave within a couple of degrees of 15N from Mexico and Central America to West Africa is moving to the west.
ED