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 , 2:57 PM GMT on September 19, 2012
Tropical Storm Nadine continues to churn towards the Azores Islands at 4 mph, where tropical storm warnings are up. Nadine brought sustained winds of 32 mph, gusting to 46 mph to Horta Castelo Branco in the Azores at 1:30 pm local time, and occasional heavy rain showers have affected most of the islands today. Nadine is a very large storm, as seen on visible satellite loops, and will affect the islands for at least three more days as it treks slowly to the southeast of the islands. On Thursday, Nadine will become tangled up with an upper-level low pressure system, and will convert to an extratropical storm. The final fate of Nadine is very uncertain; most of models predict that the two systems will merge, and the extratropical version of Nadine will move back to the west-southwest next week, where it could potentially become a tropical storm again. However, the GFS model predicts that Nadine and the upper-level low will remain separate, and extratropical storm Nadine will go on to hit Portugal and bring much-needed rain to the region on Monday. Much of Portugal and Spain are in moderate to severe drought, according to the Global Drought Monitor from the University College London.
Figure 1. Morning satellite image of Tropical Storm Nadine brushing the Azores (at right of image) and of an extratropical storm with a 10% chance of becoming a subtropical or extratropical cyclone by Friday (center of image.)
Extratropical storm east of Bermuda may acquire tropical characteristics
A large, cold-cored extratropical storm has formed about 800 hundred miles east of Bermuda, and has the potential to develop heavy thunderstorms that will enable it to become a warm-cored subtropical or tropical storm. Wind shear is a moderate to high 10 - 25 knots, and the low has plenty of cold, dry air aloft that will slow down any transition to a tropical storm. None of the reliable models develop this system into a tropical storm, though the latest runs of the GFS model and NOGAPS model predict that the system will begin to develop a warm core at low levels over the next few days. The storm is moving west at 10 mph, and should turn to the north by this weekend and potentially affect the Canadian Maritime Provinces. In their 8 am EDT Tropical Weather Outlook, NHC gave the storm a 10% chance of becoming a subtropical or tropical cyclone by Friday morning.
Elsewhere in the tropical Atlantic, none of the reliable computer models is predicting tropical cyclone development through September 25.
One interesting note on Typhoon Sanba, which hit Korea on Monday as a Category 1 storm with 90 mph winds. Sanba brought heavy rains to the coast of Russia, causing street flooding in Vladivostok. The city recorded 4.37" of rain (111 mm) over a 2-day period, causing a mudslide in the city that temporarily disrupted a train connection between two local stations. As pointed out to me by Maximiliano Herrera, significant typhoons impacts are uncommon in Russia, and Sanba was the 2nd typhoon to impact Vladivostok this year. On August 29, Typhoon Bolaven brought wind gusts of up to 73 mph to Vladivostok, and the rains from the storm helped put out wildfires burning in eastern Russia.
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