WunderBlog Archive » Category 6™
Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Julia Clinging to Life; Karl Continues West With Little Change
Tropical Depression Julia continues to cling to life as it spins a few hundred miles off the coast of South Carolina. Satellite images on Saturday morning showed that Julia continued to struggle with high wind shear, with the low-level center of the storm completely exposed to view, and the heaviest thunderstorms all to the east of the center. The top winds observed at any offshore buoys on Saturday morning were 19 mph, gusting to 23 mph, at buoy 41002, 225 nm south of Cape Hatteras, North Carolina, at 7:50 am EDT.
Figure 1. Latest satellite image of Julia.
Forecast for Julia
Julia is embedded in an atmosphere with very dry air (45 - 50% relative humidity at mid-levels of the atmosphere) and wind shear is expected to stay high, 20 - 30 knots, through Sunday evening. These conditions should cause the storm to gradually weaken as it meanders off the coast of South Carolina in an atmosphere with weak steering currents. Two of our top models, the GFS and European, predict that high wind shear and dry air should combine to allow Julia to spin down into a remnant low by Monday. However, the UKMET model disagrees, predicting that Julia will survive the hostile conditions this weekend, and re-intensify into a strong tropical storm early in the week when the wind shear finally relents. The UKMET model keeps Julia wandering off the coast of South Carolina/North Carolina until at least Thursday. At this point, I don't see any reason to disagree with the official NHC forecast of dissipation of Julia by Sunday.
Figure 2. Latest satellite image of Karl.
Tropical Storm Karl continues west with little change
Tropical Storm Karl was headed west at 13 mph in the central tropical Atlantic late Saturday morning, and does not pose a threat to any land areas for at least the next five days. Satellite images on Saturday morning showed much the same picture as on Thursday and Friday: Karl was well-organized, with a large circulation and plenty of low-level spiral bands, but the center was nearly completely exposed to view due to moderate wind shear of 15 - 20 knots, with the storm’s heavy thunderstorms limited to the northeast side of the center. Karl has marginal conditions for development, with relative humidity at mid-levels of the atmosphere near 50% and sea surface temperatures (SSTs) near 27°C (81°F). By Sunday, SSTs will increase to 28°C and wind shear is expected to drop to the low range—less than 10 knots. These conditions favor strengthening. However, the atmosphere surrounding Karl will be quite dry through Tuesday, which should slow development.
The track forecast for Karl for the next five days is fairly straightforward, with the steering currents expected to take the storm slightly south of due west, then west-northwest. Karl should clear the northern Lesser Antilles Islands by several hundred miles at the time of its closest approach on Wednesday. As usual, the picture gets pretty murky more than five days into the future. The most probable track painted by the models for Karl a week or more into the future is for the storm to get caught in the steering flow of a strong trough of low pressure passing to its north late in the week. This would result in a recurving path for Karl to the north and then northeast, with the storm missing the U.S. East Coast. This is the prediction from about 90% of the 50 members of the 00Z Saturday run of the European ensemble forecast, and all 20 members of the 00Z Saturday GFS ensemble forecast. In this situation, Bermuda and the Maritime Provinces of Canada might still be at risk from a direct hit, though. The other possibility is that the trough passing to the north of Karl late in the week will not be able to capture the storm, and a ridge of high pressure will build in over Karl, forcing it the west or northwest, potentially bringing Karl to a landfall along the U.S. East Coast about nine days from now.
96L off the coast of Africa may develop
A large tropical wave with plenty of spin and heavy thunderstorm activity was located between Africa and the Cabo Verde Islands on Saturday morning. This system was designated Invest 96L by NHC on Saturday morning. The tropical wave has favorable conditions for development through Monday as it heads west-northwest at 10 - 15 mph through the Cabo Verde Islands. The latest 00Z Saturday runs of our three top models for forecasting tropical cyclone genesis--the GFS, European and UKMET models—all showed development of the system over the next three days. 96L is headed into a region of ocean where very few storms ever threaten any land areas. In their 8 am EDT Saturday Tropical Weather Outlook, NHC increased their 2-day and 5-day development odds to 40% and 70%, respectively.
Invest 93E off the Pacific coast of Mexico may develop
In the Eastern Pacific, satellite loops show that an area of low pressure about 400 miles south of Manzanillo, Mexico (Invest 93E) is close to tropical depression status. Our top three models for predicting hurricane genesis, the GFS, UKMET and European models, predicted in their 00Z Saturday runs that 93E would develop into a tropical storm or tropical depression, but that this storm would stay well offshore of Mexico’s Baja Peninsula, and not make landfall. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave this system 2-day and 5-day development odds of 80% and 90%, respectively.
Figure 3. Radar image of Typhoon Malakas as it brushed Taiwan at 8:40 am local time on September 17, 2016. Image credit: Taiwan Central Weather Bureau.
Category 3 Malakas brushes Taiwan en route to Japan
Just as Super Typhoon Meranti narrowly avoided a direct landfall on the southern tip of Taiwan, Typhoon Malakas did the same on the island’s northeast corner on Saturday morning. Malakas peaked as a Category 4 storm with 135 mph winds at 18 UTC Friday, and its brush with Taiwan disrupted the storm’s inner core, reducing the typhoon to a low-end Category 3 storm with 115 mph winds by 12 UTC Saturday. Malakas brought up to 283 mm (11.14”) of rain to Taiwan in a 48-hour period. The typhoon will brush Japan’s Yaeyama Islands, then turn to the northeast toward Japan’s main island, Honshu. Malakas could arrive as a Category 1 typhoon, merging with the remnants of Meranti and bringing torrential rain that could easily top 10” in some locations.
There is still no word from the Philippines island of Itbayat, four days after it received a direct hit from Super Typhoon Meranti at Category 5 strength with 185 mph winds.
Jeff Masters
Figure 1. Latest satellite image of Julia.
Forecast for Julia
Julia is embedded in an atmosphere with very dry air (45 - 50% relative humidity at mid-levels of the atmosphere) and wind shear is expected to stay high, 20 - 30 knots, through Sunday evening. These conditions should cause the storm to gradually weaken as it meanders off the coast of South Carolina in an atmosphere with weak steering currents. Two of our top models, the GFS and European, predict that high wind shear and dry air should combine to allow Julia to spin down into a remnant low by Monday. However, the UKMET model disagrees, predicting that Julia will survive the hostile conditions this weekend, and re-intensify into a strong tropical storm early in the week when the wind shear finally relents. The UKMET model keeps Julia wandering off the coast of South Carolina/North Carolina until at least Thursday. At this point, I don't see any reason to disagree with the official NHC forecast of dissipation of Julia by Sunday.
Figure 2. Latest satellite image of Karl.
Tropical Storm Karl continues west with little change
Tropical Storm Karl was headed west at 13 mph in the central tropical Atlantic late Saturday morning, and does not pose a threat to any land areas for at least the next five days. Satellite images on Saturday morning showed much the same picture as on Thursday and Friday: Karl was well-organized, with a large circulation and plenty of low-level spiral bands, but the center was nearly completely exposed to view due to moderate wind shear of 15 - 20 knots, with the storm’s heavy thunderstorms limited to the northeast side of the center. Karl has marginal conditions for development, with relative humidity at mid-levels of the atmosphere near 50% and sea surface temperatures (SSTs) near 27°C (81°F). By Sunday, SSTs will increase to 28°C and wind shear is expected to drop to the low range—less than 10 knots. These conditions favor strengthening. However, the atmosphere surrounding Karl will be quite dry through Tuesday, which should slow development.
The track forecast for Karl for the next five days is fairly straightforward, with the steering currents expected to take the storm slightly south of due west, then west-northwest. Karl should clear the northern Lesser Antilles Islands by several hundred miles at the time of its closest approach on Wednesday. As usual, the picture gets pretty murky more than five days into the future. The most probable track painted by the models for Karl a week or more into the future is for the storm to get caught in the steering flow of a strong trough of low pressure passing to its north late in the week. This would result in a recurving path for Karl to the north and then northeast, with the storm missing the U.S. East Coast. This is the prediction from about 90% of the 50 members of the 00Z Saturday run of the European ensemble forecast, and all 20 members of the 00Z Saturday GFS ensemble forecast. In this situation, Bermuda and the Maritime Provinces of Canada might still be at risk from a direct hit, though. The other possibility is that the trough passing to the north of Karl late in the week will not be able to capture the storm, and a ridge of high pressure will build in over Karl, forcing it the west or northwest, potentially bringing Karl to a landfall along the U.S. East Coast about nine days from now.
96L off the coast of Africa may develop
A large tropical wave with plenty of spin and heavy thunderstorm activity was located between Africa and the Cabo Verde Islands on Saturday morning. This system was designated Invest 96L by NHC on Saturday morning. The tropical wave has favorable conditions for development through Monday as it heads west-northwest at 10 - 15 mph through the Cabo Verde Islands. The latest 00Z Saturday runs of our three top models for forecasting tropical cyclone genesis--the GFS, European and UKMET models—all showed development of the system over the next three days. 96L is headed into a region of ocean where very few storms ever threaten any land areas. In their 8 am EDT Saturday Tropical Weather Outlook, NHC increased their 2-day and 5-day development odds to 40% and 70%, respectively.
Invest 93E off the Pacific coast of Mexico may develop
In the Eastern Pacific, satellite loops show that an area of low pressure about 400 miles south of Manzanillo, Mexico (Invest 93E) is close to tropical depression status. Our top three models for predicting hurricane genesis, the GFS, UKMET and European models, predicted in their 00Z Saturday runs that 93E would develop into a tropical storm or tropical depression, but that this storm would stay well offshore of Mexico’s Baja Peninsula, and not make landfall. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave this system 2-day and 5-day development odds of 80% and 90%, respectively.
Figure 3. Radar image of Typhoon Malakas as it brushed Taiwan at 8:40 am local time on September 17, 2016. Image credit: Taiwan Central Weather Bureau.
Category 3 Malakas brushes Taiwan en route to Japan
Just as Super Typhoon Meranti narrowly avoided a direct landfall on the southern tip of Taiwan, Typhoon Malakas did the same on the island’s northeast corner on Saturday morning. Malakas peaked as a Category 4 storm with 135 mph winds at 18 UTC Friday, and its brush with Taiwan disrupted the storm’s inner core, reducing the typhoon to a low-end Category 3 storm with 115 mph winds by 12 UTC Saturday. Malakas brought up to 283 mm (11.14”) of rain to Taiwan in a 48-hour period. The typhoon will brush Japan’s Yaeyama Islands, then turn to the northeast toward Japan’s main island, Honshu. Malakas could arrive as a Category 1 typhoon, merging with the remnants of Meranti and bringing torrential rain that could easily top 10” in some locations.
There is still no word from the Philippines island of Itbayat, four days after it received a direct hit from Super Typhoon Meranti at Category 5 strength with 185 mph winds.
Jeff Masters
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