Tag Archives: Iceland

Erin Transitions to Powerful Extratropical Cyclone

Former Hurricane Erin made a transition to a powerful extratropical cyclone over the Atlantic Ocean south of Nova Scotia on Friday.  At 5:00 p.m. EDT on Friday the center of former Hurricane Erin was located at latitude 40.0°N and longitude 59.7°W which put the center about 375 miles (605 km) south-southeast of Halifax, Nova Scotia.  Erin was moving toward the east-northeast at 33 m.p.h. (54 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 957 mb.

Former Hurricane Erin made a transition to a large and powerful extratropical cyclone on Friday.  The structure of Erin’s circulation changed as part of its transition to an extratropical cyclone.  A warm front now extends east of the center of Erin’s circulation.  A cold front extends southwest of the center of former Hurricane Erin.

The size of the circulation around former Hurricane Erin increased as Erin made its transition to an extratropical cyclone.  Winds to hurricane force extend out 125 miles (200 km) from the center of circulation.  Winds to tropical storm force extend out 440 miles (705 km) from the center of former Hurricane Erin.

The Hurricane Intensity Index (HII) for former Hurricane Erin is 13.9.  The Hurricane Size Index (HSI) is 47.3 and the Hurricane Wind Intensity Size Index (HWISI) is 61.2.  Former Hurricane Erin is similar in size and intensity to Hurricane Sandy when Sandy hit the east coast of the U.S. in 2012.

The westerly winds in the middle latitudes will steer former Hurricane Erin quickly toward the east-northeast during the next few days.  On its anticipated track the powerful extratropical cyclone will be south of Iceland by early next week.

Tropical Storm Dexter Passes South of Newfoundland

Tropical Storm Dexter passed south of Newfoundland on Wednesday evening.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Dexter was located at latitude 40.2°N and longitude 54.2°W which put the center about 450 miles (730 km) south of Cape Race, Newfoundland.  Dexter was moving toward the east at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 999 mb.

Tropical Storm Dexter was making a transition to an extratropical cyclone on Wednesday evening.  Dexter was move over water where the Sea Surface Temperatures are near 24°C.  It was moving under the southern part of an upper level trough that is southwest of Greenland.  The upper level trough was producing strong westerly winds that were blowing toward the top of Dexter’s circulation.  Those winds were causing strong vertical wind shear.  The cool Sea Surface Temperatures and the strong vertical wind shear were causing Tropical Storm Dexter to make a transition to an extraropical cyclone.

The transition to an extratropical cyclone was causing changes to the structure of Tropical Storm Dexter.  Thunderstorms were still developing in the eastern side of Dexter’s circulation.  Bands in the other parts of Tropical Storm Dexter consisted primarily of showers and lower clouds.

The size of the circulation around Tropical Storm Dexter increased as Dexter made its transition to an extratropical cyclone.  Winds to tropical storm force extended out 170 miles (275 km) from the center of Dexter’s circulation.

The upper level trough southwest of Greenland will steer Tropical Storm Dexter toward the east-northeast during the next 48 hours.  On its anticipated track, Tropical Storm Dexter will pass south of Greenland and Iceland.

Tropical Storm Dexter will complete the transition to a strong extratropical cyclone on Thursday.  Dexter is likely to strengthen as it completes the transition to an extratropical cyclone.

Subtropical Storm Ernesto Forms West of the Azores

Subtropical Storm Ernesto formed west of the Azores on Wednesday morning.  At 11:00 a.m. EDT on Wednesday the center of Subtropical Storm Ernesto was located at latitude 38.1°N and longitude 46.0°W which put it about 695 miles (1120 km) southeast of Cape Race, Newfoundland.  Ernesto was moving toward the north at 8 m.p.h. (13 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 1008 mb.

More thunderstorms formed closer to the center of a low pressure system west of the Azores on Wednesday morning and the National Hurricane Center designated the system as Subtropical Storm Ernesto.  Several bands of showers and thunderstorms wrapped around the eastern and northern portions of the circulation.  Bands northwest of the center of Ernesto consisted primarily of showers and lower clouds.  The circulation may have been transporting some cooler, drier, more stable air into that part of the circulation.  Showers and thunderstorms around the center of Ernesto were generating upper level divergence which was pumping mass away to the northeast of the subtropical storm.

Subtropical Storm Ernesto will move through an environment that could support some intensification during the next day or so.  Ernesto will move over water where the Sea Surface Temperature is near 26°C.  It will move through a region where the upper level winds are not too strong and there will not be much vertical wind shear.  Subtropical Storm Ernesto could strengthen during the next 12 to 24 hours.  Ernesto will move over cooler water later on Thursday and it will start to weaken.  An upper level trough east of the U.S. will approach Subtropical Storm Ernesto from the west.  Southwesterly winds ahead of the trough will cause more vertical wind shear and Ernesto could make a transition to an extratropical cyclone.

The southwesterly winds ahead of the upper level trough will steer Subtropical Storm Ernesto in a general northeasterly direction.  On its anticipated track Subtropical Ernesto will pass between the Azores and Greenland.

Tropical Depression 19 Strengthens to Tropical Storm Rina

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 Forms East of Bermuda

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.

Tropical Storm Alex Brings Wind and Rain to the Azores

Tropical Storm Alex weakened to just below hurricane intensity as it moved across the Azores on Friday morning.  At 10:00 a.m. EST the center of Hurricane Alex was located at latitude 39.3°N and longitude 27.0°W which put it about 35 miles north of Terceira in the Azores.  Alex was moving toward the north at 28 m.p.h. (44 km/h).  The maximum sustained wind speed was 70 m.p.h. (115 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 986 mb.

It appears that the center of Tropical Storm Alex made landfall on the island of Terceira.  Weather stations on Santa Maria and Sao Miguel have measured tropical storm force winds.  However, it seems like the core of Tropical Storm Alex which contains the strongest winds remained over water.  Higher wind speeds most likely occurred on the windward sides of mountains in the Azores.

In anticipation of the movement of Tropical Storm Alex away from the islands all Hurricane Warnings and Tropical Storm Warnings for the Azores have been discontinued.

Tropical Storm Alex is over water where the Sea Surface Temperature is near 16°C.  It will move over even cooler water and Alex will soon be unable to extract enough energy from the ocean to sustain the structure of a tropical cyclone.  The structure of Alex will gradually change to the structure of a cold core extratropical cyclone during the next several days.  It is likely to maintain much of its intensity as it moves through the extratropical transition.

An upper level trough is steering Tropical Storm Alex toward the north-northwest and a general northwesterly motion is expected to continue for the next two or three days.  Tropical Storm Alex could end up south of Greenland over the weekend as a strong extratropical cyclone.