Reply #12: Good explanation from Wundergound [View All]

[Oreo]

http://www.wunderground.com/blog/JeffMasters/show.html

Rita completed an eyewall replacement cycle this morning. The inner eyewall completely collapsed, and an outer eyewall 35 miles in diameter took its place. During the time, the pressure rose to 927 mb, and remained constant at that level between 4:30 am and 8 am EDT. The hurricane hunters noted no increase in surface winds, which remained at about 140 mph. They did note that the eyewall was beginning to contract again, which may signal the beginning of an intensification cycle. Rita is over warm waters (30C) which are warm to a great depth. Thus, the amount of heat available for intensification is high (see plot below). By this afternoon, Rita will be passing over waters that are still warm, but are shallow, so the amount of heat available to draw energy from is much lower. This should end any intensification. In addition, 10 - 15 knots of shear is impacting Rita's south side, and one can see from satellite images the lack of high cirrus clouds on her south side that results from this shear. This shear is expected to increase to 25 knots by Saturday morning, and the combined effect of the shear and the lower heat content of the ocean beneath her should prevent her from making landfall any stronger than she is now (Category 4), and may act to weaken her to a Category 3 hurricane.