Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 1:51 PM GMT on September 23, 2005
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.
Figure 1. Heat potential of the waters beneath Rita show that she will soon be passing to an area of lower available heat (dark blue area). This should put an end to any intensification cycle she may be starting on.
Although Rita should be a Category 3 or 4 hurricane at landfall, she will still carry to the coast a storm surge characteristic of a much stronger hurricane. A Category 4 or 5 level storm surge is likely along a 40 - 60 miles stretch of coast near and to the right of where the storm makes landfall on Saturday. Storm surge heights will peak at 15 - 20 feet in some bays, and bring the ocean inland up to 50 miles from the coast. This surge will be lower and cover less length of coastline than Katrina's surge, but will still cause widespread destruction in the cities of Port Arthur, Orange, and Cameron.
We can track Rita now from the Lake Charles radar. This radar will probably get knocked out by Rita sometime Saturday.
Where will Rita go?
The latest computer models are tightly clustered around a landfall point just west of the Texas/Louisiana border. Confidence is high in this forecast. Houston and Galveston should escape major wind and storm surge damage, and only experience maximum sustained winds of 60 mph with gusts to 85 mph. It is still too early to tell what will happen after landfall, as the models all take Rita different ways. A major rainwater flooding problem will ensue after Rita's landfall, with 10 - 30 inches of rain falling over a large area of Texas and Louisiana.
Elsewhere in the tropics
Tropical Storm Philippe is a minimal tropical storm that may bring 30 mph winds to Bermuda, but is expected to die by Saturday. A strong tropical disturbance near 11N 30W, off the coast of Africa, has acquired a circulation and some deep convection. This system has the potential for development the next few days as it moves west to west-northwest over the Atlantic. Another area of disturbed weather 500 miles south of Bermuda also needs to be watched. Long range computer models do not show a threat to land from either of these systems in the next five days.
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