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 , 3:44 PM GMT on September 22, 2005
We continue to live history as this incredible Hurricane Season of 2005 unfolds more stunning surprises. Rita has peaked in intensity as the third strongest hurricane of all time, with a pressure of 897 mb and 175 mph winds. She is on the decline now, as the 11am hurricane hunter mission found a pressure of 913 mb, and increase of 5 mb in just 3 hours. The hurricane hunters also found concentric eyewalls of 17 and 55 nautical miles in diameter. All these signs indicate that Rita will continue to weaken today as her inner eyewall collapses and an eyewall replacement cycle begins. Rita is about to leave the vicinity of a warm eddy of Gulf water called the Loop Current that has been aiding her intensification. In addition, 10 knots of shear has developed on her south side, thanks to the fact that the upper-level high pressure system that was providing such excellent outflow for Rita has now shifted to the southeast of the storm. All these signs point to a substantial weakening trend for Rita that will continue through Friday and probably reduce her to a Category 4 hurricane. The GFDL forecast model and NHC predict that this weakening trend will continue until landfall Saturday, when Rita will be a Category 3 hurricane. Lower heat content water and continued shear are expected to cause this weakening.
While this is cause for some relief, Rita, like Katrina did, will still bring to the coast a storm surge characteristic of a much stronger hurricane. A Category 4 or 5 level storm surge is likely along a 60 - 80 miles stretch of coast 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. Large sections of I-10 between Houston and Beaumont could be inundated, and the flood waters may reach the cities of Beaumont, Orange, and Lake Charles. Wind damage will be severe, and Houston can expect a hazardous rain of glass from its high rise building like was experienced during Hurricane Alica in 1983. If the eye passes just west of Galveston Bay, the storm surge will push 1 - 3 of water into some of Houston's eastern suburbs, such as Deer Park.
Figure 1. Expected inland penetration of a Category 5 level hurricane storm surge. Only areas along and to the right of Rita's landfall point may get a Category 5 storm surge. If Rita makes landfall east of Galveston, Houston and Galveston will not see the storm surge flooding shown here.
Current buoy measurements
NOAA buoy 42001 measured sustained winds of 58 mph, gusting to 78 mph, and 34 foot waves at 10am CDT. At the time, the buoy was located 75 miles WNW of Rita. This evening at 5pm CDT, Rita should make a very close pass by this buoy. I expect waves of 50 - 70 feet will impact the buoy, and huge swells from Rita are already starting to pound the Gulf Coast. A time series plot of the wind and pressure from buoy 42001 is worth checking out.
Where will Rita go?
The computer models made a modest shift eastwards this morning, calling for a landfall between Galveston and the Texas/Louisiana border. The Hurricane Center shifted their landfall point as well, and now go with the model consensus. The models have been flip-flopping frequently, and it is not unreasonable to suppose that they will shift the landfall point 50 or so miles further west again this tonight. However, a landfall within 100 miles of Galveston seems to be the the best call. Landfall will still occur sometime Saturday, but this may be afternoon instead of morning, as the storm is moving slower than before.
Most of the models now indicate that steering currents will weaken and Rita will stall and sit in place for several days once it moves inland. This will result in severe flooding problems for wherever Rita stalls, as 10 - 30 inches of rain could fall in the affected region. As is usually the case when steering current get weak, the model forecasts of Rita's motion are highly unreliable. Rita may stall over the Dallas area, or central Louisiana, or Oklahoma or Arkansas. It's too early to tell. Finally, on Tuesday, Rita's remnants are forecast to lift out to the north.
Elsewhere in the tropics
Tropical Storm Philippe is a minimal tropical storm heading out to sea, and is not a threat to any land areas. An area of disturbed weather off of the coast of Honduras is being sheared by the strong upper-level winds flowing south from Hurricane Rita. If this disturbed area still exists on Sunday, it has some potential for development. Development off of the coast of Africa is also possible beginning on Sunday.
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