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 , 3:47 PM GMT on September 10, 2011
Tropical Storm Nate in Mexico's Bay of Campeche continues to have trouble intensifying. Latest visible satellite loops show that Nate has a large, cloud-filled center, and the storm is probably pulling in dry air to its north into its center. Nate is also likely having trouble with all the cool waters it has stirred to the surface. Assuming Nate is able to close off its center from the dry air, it would take the storm at least a day to tighten up its rather large center, form a solid eyewall, and reach hurricane intensity. Nate doesn't have enough time before landfall for that to happen, and it is unlikely Nate will ever become a hurricane. The latest wind probability forecast form NHC gives Nate a 13% chance of reaching hurricane strength on Sunday. Latest radar imagery from Alvarado, Mexico shows heavy rains from Nate are affecting the coast near Veracruz, and heavy rains of 4 - 6 inches will be the main threat from Nate.
Figure 1. True-color MODIS image of Tropical Storm Nate taken at 12:45 pm EDT Friday, September 9, 2011. At the time, Nate was a tropical storm with 50 mph winds. Image credit: NASA.
Nate is a small storm, and is not likely to bring significant rains to Texas; only extreme South Texas near Brownsville could see an inch or so of rain on Sunday from an outer spiral band of Nate. Our latest wundermap wind forecast map from the European Center model, with the fire layer turned on, shows that Nate's wind field on Saturday and Sunday will not be large enough to fan the fires burning in Texas.
Tropical Storm Maria
Tropical Storm Maria doesn't look much like a tropical storm--on the latest satellite imagery it looks like a squashed question mark instead of a spiral. The surface circulation center is very poorly defined, and moderate wind shear of 15 - 20 knots has really done the Lesser Antilles Islands a big favor by ripping up Maria. It is doubtful this storm will generate any sustained winds of tropical storm force in the islands, and it is a 50/50 proposition that Maria will degenerate into a tropical disturbance and become ex-Tropical Storm Maria later today. Martinique radar shows heavy rains from Maria are mostly east of the islands, and the thunderstorms are not well-organized into spiral bands. The wind shear affecting Maria will probably last through Sunday. By Monday, wind shear is predicted to fall enough so that Maria could potentially organize again. However, the storm is expected to be far from land when that occurs. Bermuda could see a few rain showers from Maria on Wednesday, and Maria may be a threat to southeast Newfoundland late next week.
Figure 2. Morning satellite image of Tropical Storm Maria shows the the storm looks like a squashed question mark?
Hurricane Katia brushed by Newfoundland, Canada this morning, and is now racing east-northeast at 52 mph into the open Atlantic. With water temperatures 19°C (66°F) underneath it, Katia has lost its tropical characteristics, and has transitioned to a powerful extratropical storm. Extratropical Storm Katia will continue east-northeastward towards Europe, and on Monday, the storm will pass very close to northern British Isles. The offshore waters of Northern Ireland and Western Scotland can expect storm-force winds of 50 - 60 mph on Monday as Katia roars past to the north. The storm will bring 2 - 4 inches of rain to the coast, and likely cause significant tree damage and power failures.
Figure 3. Image of Hurricane Katia taken from the International Space Station at 15 GMT September 9, 2011, by astronaut Ron Garan. At the time, Katia was a Category 1 hurricane with 85 mph winds. Long Island, New York is visible at the lower left.
Elsewhere in the tropics
The NOGAPS and UKMET models predict the possible development of a tropical wave 6 - 7 days from now off the coast of Africa.
I'll have an update by early Sunday afternoon.
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