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Former Hurricane Ophelia Brings Strong Winds to Ireland

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).

Ophelia Strengthens to Major Hurricane South of the Azores

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 Moves Closer to the Azores

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.

Ophelia Strengthens Into a Hurricane Southwest of the Azores

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.

Tropical Storm Ophelia Forms Over Eastern Atlantic

The busy 2017 Atlantic hurricane season continued when Tropical Storm Ophelia formed over the eastern Atlantic Ocean on Monday.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Ophelia was located at latitude 31.5°N and longitude 39.6°W which put it about 845 miles (1355 km) west-southwest of the Azores.  Ophelia was moving toward the northeast at 3 m.p.h. (5 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 1005 mb.

Thunderstorms formed on Monday near the center of a low pressure system which had been lingering over the eastern Atlantic Ocean and the National Hurricane Center designated the system as Tropical Storm Ophelia.  The thunderstorms formed near the eastern side of the center and several bands of showers and thunderstorms formed in the rest of the eastern half of the circulation.  There were fewer thunderstorms in the western half of Ophelia.  The thunderstorms near the center of circulation were generating upper level divergence which was pumping mass away to the east of the tropical storm.

Tropical Storm Ophelia is an environment that is somewhat favorable to intensification.  Ophelia is moving over water where the Sea Surface Temperature (SST) is near 27°C.  It is near the axis of an upper level trough which is oriented east to west over the Atlantic Ocean.  The trough is producing westerly winds which are blowing toward the top of the circulation and those winds are causing some vertical wind shear.  However, since Ophelia is over water where the SST is 27°C, the clouds are not rising as far into the atmosphere as they would if the water was warmer and some of the upper level winds are blowing completely over the top of the circulation of the tropical storm.  So, the vertical wind shear is not as significant as it could be if the top of Ophelia was higher in the atmosphere.  Tropical Storm Ophelia is likely to strengthen during the next several days and it could eventually become a hurricane.

Since Tropical Storm Ophelia is near the axis of the upper level trough, the steering winds are weaker.  The westerly flow is pushing Ophelia slowly toward the northeast.  The orientation of the trough is forecast to change during the next day or two and Ophelia is expected to move more toward the east-southeast.  On its anticipated track Tropical Storm Ophelia is expected to meander over the eastern Atlantic Ocean for several more days.