Former Subtropical Storm Ernesto made a transition to a tropical storm on Thursday afternoon. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Ernesto was located at latitude 43.0°N and longitude 41.0°W which put it about 645 miles (1035 km) east-southeast of Cape Race, Newfoundland. Ernesto was moving toward the northeast at 18 m.p.h. (30 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1007 mb.
Even though now Tropical Storm Ernesto moved over water where the Sea Surface Temperature was between 24°C and 25°C, there was enough energy in the upper ocean to cause more thunderstorms to develop. In addition, many of the thunderstorms developed close to the center of circulation. The inner bands of showers and thunderstorms became stronger and the bands in the outer parts of the circulation weakened. Ernesto exhibited a structure like a tropical cyclone and the National Hurricane Center classified the system as a tropical storm in the 5:00 p.m. EDT advisory.
Tropical Storm Ernesto will move over much cooler water during the next 24 hours. It is likely to make a transition to an extratropical cyclone when it moves over the cooler water. Ernesto could strengthen when colder air is pulled into the western half of the circulation and a cold front forms south of the center. The development of the cold front and upper level divergence could strengthen the pressure gradient force which would give the air a stronger push. An upper level trough east of the U.S. is forecast to steer Ernesto in the general direction of Ireland and the United Kingdom.
Tropical Depression Nineteen strengthened into Tropical Storm Rina on Monday night. At 10:00 p.m. EST on Monday the center of Tropical Storm Rina was located at latitude 30.4°N and longitude 49.9°W which put it about 890 miles (1430 km) east of Bermuda. Rina was moving toward the north at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1010 mb.
Although an upper level low northwest of Tropical Depression Nineteen continued to produce westerly winds which caused moderate vertical wind shear, stronger thunderstorms developed east of the center of circulation. Downdrafts in those storms were able to transport stronger winds to the surface and winds to tropical storm force were occurring at the surface. The National Hurricane Center upgraded Tropical Depression Nineteen to Tropical Storm Rina on Monday night.
The circulation of Tropical Storm Rina is asymmetrical. The stronger storms are occurring east of the center of circulation. The winds to tropical storm force are occurring northeast of the center. Winds to tropical storm force extend out about 60 miles to the northeast of the center of circulation. The bands west of the center consist primarily of lower clouds and showers. The upper level westerly winds are tilting the circulation toward the east with height.
The moderate vertical wind shear will continue to inhibit the intensification of Tropical Storm Rina. Rina will move over water where the Sea Surface Temperature is near 25°C. Although the water is cooler than it is in the tropical, colder air in the upper levels will make the atmosphere unstable enough to allow thunderstorms to continue to develop. The vertical wind shear could decrease during the next 24 to 36 hours and some intensification is possible. When Tropical Storm Rina moves farther north, it will move over colder water.
The upper level low to the northwest of Tropical Storm Rina and a ridge to the east of Rina are steering the tropical storm toward the north. A general motion is expected to continue for another day or two. On its anticipated track Tropical Storm Rina will pass between Labrador and the Azores.
Tropical Depression Nineteen formed east of Bermuda on Monday. At 10:00 a.m. EST on Monday the center of Tropical Depression Nineteen was located at latitude 29.5°N and longitude 50.4°W which put it about 875 miles east of Bermuda. It was moving toward the north-northeast at 3 m.p.h. (5 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1013 mb.
A small low pressure system has been meandering over the Atlantic Ocean between Bermuda and the Azores. More showers and thunderstorms formed near the center of the the low and the circulation became more circular. Because the low pressure system developed the characteristics of a tropical cyclone, the National Hurricane Center designated the system as Tropical Depression Nineteen on Monday morning.
The circulation of Tropical Depression Nineteen is being affected by vertical wind shear. An upper level low located to the northwest of the system is producing easterly winds which are blowing across the top of the depression. Those winds are producing moderate vertical wind shear shear which is tilting the upper portion of the circulation to the east. The surface center of circulation was exposed on visible satellite images. Most of the showers and thunderstorms were occurring to the east of the center.
Tropical Depression Nineteen is forecast to intensify into a tropical storm. The depression will move over water where the Sea Surface Temperature is near 25.5°C, which is marginally warm enough to support intensification. The upper level low will continue to produce vertical wind shear which will inhibit intensification during the next 12 to 24 hours. The shear is forecast to decrease on Tuesday and Tropical Depression Nineteen could strengthen into a tropical storm before it moves over colder water.
Tropical Depression Nineteen is currently in an area where the steering currents are weak. The circulation around the upper level low to the northwest of the Tropical Depression is being deflected around an upper level ridge to the east of the depression. Some of the flow is turning northward and the rest of the flow is turning toward the south. The orientation of the upper low and ridge is forecast to change and the two systems are forecast to steer the depression toward the northeast later this week. However, if the wind shear stays strong enough to prevent the circulation of the depression from growing vertically, then the winds in the lower level could steer the depression more toward the west.
Former Hurricane Ophelia brought strong winds to Ireland and parts of the United Kingdom on Monday. Although former Hurricane Ophelia had made a transition to an extratropical cyclone before it reached Ireland, it was still a very powerful storm when it moved across that region. There were reports of several fatalities, damage and power outages across Ireland. Met Eireann (the Irish meteorological agency) reported the following wind gusts during the passage of former Hurricane Ophelia.
At the Fastnet Lighthouse (anemometer at 200 feet [61 meters] ) there was a gust of 191 km/h (118 m.p.h.). Sherkin Island reported a wind gust of 135 km/h (84 m.p.h.) before the power went out. Cork airport reported a wind gust of 126 km/h (78 m.p.h.) before the power went out. Shannon airport reported a wind gust of 122 km/h (76 m.p.h.). Roches Point reported a wind gust of 156 km/h (97 m.p.h.). The Kinsale Platform reported a wind gust of 141 km/h (87 m.p.h.) and the Dublin airport reported a wind gust of 104 km/h (65 km/h).
Hurricane Ophelia strengthened into a Category 3 hurricane on the Saffir-Simpson Scale on Saturday morning as it moved south of the Azores. That made Ophelia a major hurricane. At 11:00 a.m. EDT on Saturday the center of Hurricane Ophelia was located at latitude 34.8°N and longitude 26.6°W which put it about 220 miles (355 km) south of the Azores. Ophelia was moving toward the northeast at 25 m.p.h. (40 km/h). The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 135 m.p.h. (220 km/h). The minimum surface pressure was 960 mb.
It is very unusual to have such a strong hurricane near the Azores, but Ophelia contains all of the elements of a major hurricane. There is a circular eye at the center of circulation. The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring of storms. Well formed rainbands exists in the outer portions of the circulation. Storms in the core of Ophelia are generating upper level divergence which is pumping mass away to the northeast of the hurricane. Winds to hurricane force extend out about 40 miles (65 km) from the center of circulation. Winds to tropical storm force extend out about 125 miles (205 km) from the center.
Hurricane Ophelia is moving over water where the Sea Surface Temperature is near 25°C. Normally, water at that temperature would be considered to be too cool to support the development of a major hurricane. However, the temperature of the air in the upper troposphere is also cool and so the atmosphere is unstable enough to allow for the development of deep convection. An upper level trough west of Ophelia is producing southwesterly winds which are blowing toward the top of the circulation. There are also southwesterly winds in the lower and middle levels of the atmosphere and so the vertical wind shear is not strong enough to inhibit intensification
Hurricane Ophelia will be moving over cooler water and it is likely to weaken gradually during the next several days. When Ophelia moves over the cooler water it will make a transition to an extratropical cyclone. The size of the circulation will increase during the transition. Hurricane Ophelia will evolve into a large very powerful extratropical cyclone during the next several days.
The trough west of Ophelia is steering the hurricane toward the northeast. Hurricane Ophelia is expected to turn more toward the north during the next two or three days. On its anticipated track Hurricane Ophelia will pass east of the Azores later today. The strong extratropical cyclone that Ophelia will transition into could approach Ireland and the United Kingdom by Monday morning. That cyclone will bring very strong winds and heavy rain to that region.
Hurricane Ophelia moved closer to the Azores on Friday. At 5:00 p.m. EDT on Friday the center of Hurricane Ophelia was located at latitude 32.3°N and longitude 31.8°W which put it about 480 miles (770 km) southwest of the Azores. Ophelia was moving toward the east-northeast at 13 m.p.h. (20 km/h). The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h). The minimum surface pressure was 971 mb.
Despite moving over slightly cooler water, Hurricane Ophelia maintained its structure and intensity on Friday. There was a small circular eye at the center of circulation, although there appeared to be a break on the northwest side of the ring of thunderstorms around the eye. Thunderstorms in the core of Ophelia were generating upper level divergence which was pumping away mass. Bands of showers and thunderstorms were revolving around the core of Hurricane Ophelia. The stronger rainbands were in the eastern half of the circulation. Winds to hurricane force extended out about 25 miles (40 km) from the center of circulation. Winds to tropical storm force extended out about 100 miles (160 km) from the center.
Hurricane Ophelia will move through an environment that is capable of supporting a strong cyclone. Ophelia will move over water where the Sea Surface Temperature is near 25°C. Normally, that water would be too cool to support a strong hurricane. However, the temperature in the upper levels of the atmosphere is also cool and that is keeping the atmosphere unstable enough to allow for thunderstorms to develop. The speed of the winds in Hurricane Ophelia is likely to decrease gradually during the next several days.
When Hurricane Ophelia moves farther north, it will move into a cooler environment with stronger westerly winds in the upper levels. A cooler environment with more vertical wind shear will cause the structure of Hurricane Ophelia change into the structure of an extratropical cyclone. The area of stronger winds will expand and the cyclone will become much larger.
Hurricane Ophelia is being steered toward the east-northeast by westerly winds in the middle levels. A trough will approach Hurricane Ophelia from the west. Southwesterly winds ahead of the trough will carry Ophelia more toward the north in about 36 hours. On its anticipated track the center of Hurricane Ophelia will move south of the Azores on Saturday. Ophelia could bring gusty winds and rain to the Azores when it moves by those islands. The strong extratropical cyclone that evolves from Hurricane Ophelia could approach Ireland and the United Kingdom on Monday. That cyclone could bring very strong winds and heavy rain to that region.
Tropical Storm Ophelia strengthened into a hurricane southwest of the Azores on Wednesday. At 11:00 p.m. EDT on Wednesday the center of Hurricane Ophelia was located at latitude 30.0°N and longitude 35.7°W which put it about 745 miles (1195 km) southwest of the Azores. Ophelia was moving toward the northeast at 3 m.p.h. The maximum sustained wind speed was 85 m.p.h. (140 km/h) and there were wind gusts to 100 m.p.h. (160 km/h). The minimum surface pressure was 986 mb.
The circulation of Hurricane Ophelia became more circular and symmetrical on Wednesday. A circular eye developed at the center of circulation. Thunderstorms in the ring around the eye became taller. Additional bands of showers and thunderstorms were revolving around the core of Hurricane Ophelia. Thunderstorms in the core were producing upper level divergence which was pumping mass away to the east of the hurricane. Winds to hurricane force extended out about 25 miles (40 km) from the center of circulation. Winds to tropical storm force extended out about 70 miles (110 km) from the center.
Hurricane Ophelia will be moving through an environment that could support further intensification on Thursday. Ophelia will move over water where the Sea Surface Temperature is near 26.5°C. Ophelia is in an area of weaker upper level winds. It is north of the subtropical jet stream and it is south of the stronger westerly winds in the middle latitudes. As a result the vertical wind shear is minimal. The combination of warm water and little shear allowed Ophelia to intensify into a hurricane and it could strengthen further on Thursday.
Hurricane Ophelia is in an area of weak westerly winds which are steering the hurricane slowly toward the east. An upper level trough will approach Ophelia from the west and the trough will start to pull the hurricane toward the northeast more quickly later this week. On its anticipated track Hurricane Ophelia could approach the Azores in two or three days.
Kate intensified into the fourth Atlantic hurricane of 2015 as it raced northeastward. At 10:00 a.m. EST on Wednesday the center of Hurricane Kate was located at latitude 36.8°N and longitude 60.5°W which put it about 395 miles (635 km) northeast of Bermuda and about 780 miles (1160 km) south-southwest of Cape Race, Newfoundland. Kate was moving toward the northeast at 45 m.p.h. (72 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 985 mb.
The organization of Hurricane Kate improved on Wednesday when a partial eyewall wrapped around the northern and western sides of the center of circulation. The structure of Kate is somewhat tilted toward the northeast by stronger southwesterly wind in the upper levels of the atmosphere. However, Kate currently has a warm core and it is still a tropical cyclone. Kate is moving over water where the Sea Surface Temperature (SST) is near 25°C. In a day or so the effects of strong vertical wind shear and cooler SSTs will cause Hurricane Kate to begin a transition to an extratropical cyclone.
Strong westerly winds are steering Kate rapidly toward the northeast and that general motion is expected to continue during the next few days. Kate could approach the United Kingdom as a strong extratropical cyclone during the weekend.