Tag Archives: Tropical Storm Ophelia

Latest on Ophelia & Nesat

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Dr. Jeff Masters’ WunderBlog
Ophelia strengthening; Typhoon Nalgae a new threat to the Philippines
Posted by: JeffMasters, 1:51 PM GMT on September 29, 2011 +4
Tropical Storm Ophelia is strengthening as it pulls away from the Lesser Antilles Islands and heads north-northwest. Recentsatellite loops show that Ophelia has developed a Central Dense Overcast (CDO) of high cirrus clouds over its core, which is characteristic of strengthening tropical storms that are nearing hurricane intensity. Dry air and moderate wind shear of 15 – 20 knots are slowing down Ophelia’s intensification, but by Friday morning, wind shear is expected to fall to 10 – 15 knots, and remain below 15 knots through Sunday morning. This should allow Ophelia to intensify into a hurricane on Friday. Most of the models agree that Ophelia will track far enough to the east of Bermuda that the island should see sustained winds below 45 mph, since it will be on the weak (left) side of the storm. We can’t rule out the possibility that Bermuda will receive hurricane force winds yet, but the odds are low–the 5 am wind probability forecast from NHC gave Bermuda just a 3% chance of receiving hurricane force winds. Ophelia’s closest approach to the island will be late Saturday night and early Sunday morning. Ophelia is likely to bring high winds and heavy rains to Southeast Newfoundland Sunday night, as a weakening tropical storm.

In the middle Atlantic, Tropical Storm Philippe is headed west-northwest, and is not expected to trouble and land areas.Satellite loops show Philippe is a small system with little heavy thunderstorm activity. Wind shear is expected to diminish some today over the storm, which should allow the storm to intensify. However, by Saturday, Philippe will be encountering very high wind shear of 30 – 40 knots associated with the upper-level outflow from Ophelia. This shear will probably be high enough to destroy Philippe by Monday. In the event Philippe does survive the shear, the storm could penetrate far enough west that Bermuda might need to be concerned with it.

Elsewhere in the Atlantic, none of the computer models is calling for a new tropical storm to form in the coming seven days. The large-scale environment over the Atlantic currently favors sinking air, due to the current phase of the Madden-Julian Oscillation (MJO). This situation will likely last well into next week, and will discourage formation of new tropical storms. The MJO is a 30-60 day cycle of thunderstorm activity that affects the tropics.


Figure 1. Morning satellite image of Ophelia, showing the large Central Dense Overcast (CDO) that has formed.

Typhoon Nesat battering China
Typhoon Nesat hit China’s Hainan Island today as a Category 1 typhoon with 75 mph winds. While Nesat’s winds and storm surge will not cause major damage, it is a very wet storm, capable of dropping up to 8 inches of rain in 24 hours, according to latest satellite rainfall forecasts. Haikou on Hainan Island recorded a wind gust of 78 mph and 3.23″ of rain as the eyewall passed just to the north. Nesat will hit Vietnam near Hanoi as a tropical storm on Saturday.

Nesat roared across Luzon Island in the Philippines Monday as a powerful Category 3 typhoon with 120 mph winds, leaving35 people dead and 45 missing. The Philippines has a new worry today: Typhoon Nalgae has formed 700 miles to the east of Luzon Island, and is expected to follow a course just to the north of Nesat’s. Nalgae is expected to intensify into a major Category 3 typhoon and hit the northern portion of Luzon on Saturday afternoon, local time. With soils on the island already saturated from the heavy rains Nesat brought, the new typhoon promises to bring heavy flooding to Luzon this weekend.


Figure 2. True-color MODIS image of Typhoon Nesat over the South China Sea taken at 1:35 pm local time September 28, 2011. At the time, Nesat was a Category 1 typhoon with 75 mph winds. Image credit: NASA.

Typhoon & Tropical Storm Update fr/Dr. Masters

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Typhoon Roke batters Japan; Ophelia forms in the Central Atlantic
Posted by: JeffMasters, 1:28 PM GMT on September 21, 2011 +9
Typhoon Roke hit Japan near Hamamatsu at 14:00 JST Wednesday as a Category 1 typhoon with 80 mph winds. Roke brought sustained winds of 62 mph, gusting to 83 mph to the Tokyo airport at 5:25 pm local time, and a wind gust of 89 mph was reported at Shizuhama Airbase. Roke has dumped heavy rains of 155 mm (6.20″) at Hamamatsu and 125 mm (4.86″) at Tokyo. Damage due to flooding from Roke’s heavy rains will likely be the main problem from Roke, as the soils over much of Japan are saturated from the passage of Tropical Storm Talas during the first week of September. Talas was a very slow moving storm, and brought extreme rainfall amounts of over six feet to some portions of Japan. Roke brought winds less than 25 mph to the damaged Fukishima-Dai-Iche nuclear plant northeast of Tokyo, and heavy rains of 189 mm (7.50″) toHirono, located 8 miles south of the plant.


Figure 1. Radar image of Typhoon Roke as it made landfall at 14:00 JST on September 21, 2011. The typhoon brought a large area of rainfall of 50 mm/hr (2″/hr) to Japan. Image credit: Japan Meteorological Agency.


Figure 2. MODIS image of Typhoon Roke taken at 3:55 UTC on Wednesday, September 21, 2011. At the time, Roke was a Category 1 storm with 80 mph winds. Image credit: NASA.

Tropical Storm Ophelia forms in the Atlantic
Tropical Storm Ophelia formed last night in the Central Atlantic from the tropical wave (Invest 98L) we’ve been tracking this week. Satellite imagery shows that Ophelia is suffering the classic symptoms of high wind shear, with the low level center of circulation exposed to view, and the storm’s heavy thunderstorms pushed to the northeast side of the center of circulation. An analysis of wind shear from the University of Wisconsin CIMMS group shows a high 20 – 30 knots of wind shear due to strong upper level west-southwesterly winds affecting Ophelia. We don’t have any ship, buoy, or hurricane hunter observations of Ophelia’s winds, but an ASCAT pass from 7:27 pm EDT last night found top winds of 45 mph in the northeast quadrant of the storm. Ophelia will be passing south of buoy 41041 late tonight. Water vapor satellite imagesshow dry air to the the west of Ophelia, and the strong upper level west-southwesterly winds bringing high wind shear to the storm are also injecting dry air into the storm’s core, interfering with development.


Figure 3. Morning satellite image of Ophelia showing the low-level center exposed to view, with all the storm’s heavy thunderstorms pushed to the northeast side.

Forecast for Ophelia
The latest SHIPS model forecast predicts that Ophelia will experience moderate to high wind shear of 10 – 25 knots over the next five days, and will move into a region with drier air. The combination of shear and dry air should keep Ophelia from strengthening, and could dissipate the storm, as predicted by the ECMWF and HWRF models. The Northern Lesser Antilles could see some wind gusts of 30 – 40 mph and heavy rain squalls from Ophelia on Saturday and Sunday, but right now it looks unlikely that the islands would see sustained tropical storm force winds of 39+ mph, since they are likely to be on Ophelia’s weaker (dry) side. At longer ranges, Bermuda will have to keep an eye on Ophelia, since a large cut-off low pressure system over the Eastern U.S. should turn Ophelia to the northwest and then north early next week. Ophelia may eventually be a threat to Canada, but it is too early to assess the odds of this happening.

Ophelia is the 15th named storm this year, putting 2011 in 10th place for the most number of named storms in a year. Ophelia’s formation date of September 21 puts 2011 in 4th place for earliest date of arrival of the season’s 15th storm. Only2005, 1936, and 1933 had an earlier 15th storm. With only three of this year’s fifteen storms reaching hurricane strength, though, this year has been near average for destructive potential. Atlantic hurricane records go back to 1851.

Jeff Masters