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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.

Hurricane Erin Passes South of Cape Cod

Hurricane Erin passed south of Cape Cod on Thursday afternoon.  At 5:00 p.m. EDT on Thursday the center of Hurricane Erin was located at latitude 36.4°N and longitude 69.1°W which put the center about 320 miles (520 km) south of Nantucket Island.   Erin was moving toward the northeast at 20 m.p.h. (32 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 952 mb.

A Tropical Storm Warning is in effect for the portion of the coast from Duck, North Carolina to Chincoteague, Virginia.

A Storm Surge Warning is in effect for the portion of the coast from Cape Lookout to Duck, North Carolina.

A Tropical Storm Warning is in effect for Bermuda.

Hurricane Erin started to weaken slowly as it moved over the Atlantic Ocean between Cape Cod and Bermuda on Thursday.  No eye was visible at the center of Erin’s circulation on satellite images.  Bands of showers and thunderstorms were revolving around the center of Hurricane Erin.  Storms near the center of Erin were still generating upper level divergence that pumped mass away from the hurricane.  The removal of mass in the upper levels of the atmosphere almost matched the inflow of mass in the lower levels.  There was slightly more mass flowing into the center of Erin’s circulation.  So, the surface pressure was slowly increasing.

The circulation around Hurricane Erin was very large.  Winds to hurricane force extend out 100 miles (160 km) from the center of Erin’s circulation.  Winds to tropical storm force extend out 320 miles (520 km) from the center of Hurricane Erin.

The Hurricane Intensity Index (HII) for Hurricane Erin is 16.5.  The Hurricane Size Index (HSI) is 36.9 and the Hurricane Wind Intensity Size Index (HWISI) is 53.4.  Hurricane Erin is similar in size and intensity to Hurricane Ike when Ike hit Texas in 2008.  Erin is not quite as strong as Ike was, but Hurricane Erin is bigger than Hurricane Ike was.

Hurricane Erin will move through an environment that will be unfavorable for intensification of a hurricane during the next 24 hours.  Erin will move over water where the Sea Surface Temperatures are near 26°C.  It will move under the eastern side of an upper level trough over the Northeast U.S. and the Great Lakes.  The upper level trough will produce southwesterly winds that will blow toward the top of Erin’s circulation.  Those winds will cause moderate vertical wind shear.  Hurricane Erin will weaken slowly during the next 24 hours.  Erin is likely to make a transition to a strong extratropical cyclone during the weekend.

The upper level trough over the Northeast U.S. and the Great Lakes will steer Hurricane Erin toward the east-northeast during the next 24 hours.  On its anticipated track, the center of Hurricane Erin will pass south of Nova Scotia on Friday.

The large circulation around Hurricane Erin will continue to produce large waves that will move toward the east coast of the U.S.  Erin could continue to cause a storm surge of up to four feet (one meter) along the Outer Banks of North Carolina on Thursday night.  Mandatory evacuations are in effect for Hatteras Island and Ocracoke Island.  Water has already washed over parts of Hatteras Island.  The large waves are likely to cause significant beach erosion.  Conditions along the Outer Banks should start to improve on Friday when Hurricane Erin moves farther away.

The large circulation around Hurricane Erin could also produce tropical storm force winds in Bermuda.

Hurricane Erin Moves Southeast of Cape Hatteras

Hurricane Erin moved southeast of Cape Hatteras on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Erin was located at latitude 32.8°N and longitude 73.1°W which put the center about 215 miles (345 km) southeast of Cape Hatteras, North Carolina.  Erin was moving toward the north-northeast at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 942 mb.

A Tropical Storm Warning is in effect for the portion of the coast from Beaufort Inlet, North Carolina to Chincoteague, Virginia.

A Storm Surge Warning is in effect for the portion of the coast from Cape Lookout to Duck, North Carolina.

A Tropical Storm Watch is in effect for Bermuda.

Concentric eyewalls formed again in Hurricane Erin on Wednesday.  The inner eyewall had a radius of 17 miles (28 km).  The outer eyewall had a radius of 75 miles (120 km).  The strongest winds were occurring in the outer eyewall.  Bands of showers and thunderstorms were revolving around the concentric eyewalls.  Storms near the center of Erin generated strong upper level divergence that pumped mass away from the hurricane.  The removal of large quantities of mass caused the surface pressure to decrease on Wednesday.

The circulation around Hurricane Erin was very large.  Winds to hurricane force extend out 90 miles (145 km) from the center of Erin’s circulation.  Winds to tropical storm force extend out 265 miles (425 km) from the center of Hurricane Erin.

The Hurricane Intensity Index (HII) for Hurricane Erin is 19.2.  The Hurricane Size Index (HSI) is 33.0 and the Hurricane Wind Intensity Size Index (HWISI) is 52.2.  Hurricane Erin is similar in size and intensity to Hurricane Ike when Ike hit Texas in 2008.

Hurricane Erin will move through an environment that will become unfavorable for intensification during the next 24 hours.  Erin will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the eastern side of an upper level trough over the Northeast U.S. and the Great Lakes.  The upper level trough will produce southeasterly winds that will blow toward the top of Erin’s circulation.  Those winds will cause the vertical wind shear to increase on Thursday.  Hurricane Erin will start to weaken when the vertical wind shear increases.

The upper level trough over the Northeast U.S. and the Great Lakes will steer Hurricane Erin toward the northeast during the next 24 hours.  On its anticipated track, the center of Hurricane Erin will be move away from Cape Hatteras on Thursday.  Erin will pass far to the south of Long Island on Thursday.

The large circulation around Hurricane Erin will produce large waves that will move toward the east coast of the U.S.  Erin could cause a storm surge of up to four feet (one meter) along the Outer Banks of North Carolina.  Mandatory evacuations have been ordered for Hatteras Island and Ocracoke Island.  Water is already washing over parts of Hatteras Island.  The large waves are likely to cause significant beach erosion.  The large circulation around Hurricane Erin could also bring tropical storm force winds to the Outer Banks.  Conditions along the Outer Banks should start to improve on Friday when Hurricane Erin moves farther away.

Tropical Storm and Storm Surge Warnings Issued for Outer Banks

A Tropical Storm Warning and a Storm Surge Warning were issued for the North Carolina Outer Banks on Tuesday because of the threat posed by Hurricane Erin.  At 2:00 p.m. EDT on Tuesday the center of Hurricane Erin was located at latitude 26.1°N and longitude 72.5°W which put the center about 655 miles (1050 km) south-southeast of Cape Hatteras, North Carolina.  Erin was moving toward the north-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 958 mb.

A Tropical Storm Warning is in effect for the portion of the coast from Beaufort Inlet to Duck, North Carolina.

A Storm Surge Warning is in effect for the portion of the coast from Cape Lookout to Duck, North Carolina.

A Tropical Storm Watch is in effect for the portion of the coast from Duck, North Carolina to Cape Charles Light, Virginia.

After weakening on Monday night, Hurricane Erin was exhibiting signs of strengthening on Tuesday afternoon.  The inner end of a rainband was wrapping around the northern side of the center of Erin’s circulation.  There was some evidence on satellite images to indicate that a new eye could be forming at the center of Hurricane Erin.  Bands of showers and thunderstorms were revolving around the core of Erin’s circulation.  Storms near the core of Erin started to generate more upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to start to decrease again.

The circulation around Hurricane Erin is large.  Winds to hurricane force extend out 80 miles (130 km) from the center of Erin’s circulation.  Winds to tropical storm force extend out 205 miles (330 km) from the center of Hurricane Erin.

The Hurricane Intensity Index (HII) for Hurricane Erin is 17.8.  The Hurricane Size Index (HSI) is 24.8 and the Hurricane Wind Intensity Size Index (HWISI) is 42.6.  Hurricane Erin is similar in size and intensity to Hurricane Gustav in 2008.

Hurricane Erin will move through an environment that will be  favorable for intensification during the next 24 hours.  Erin will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Erin will intensify during the next 24 hours.  Erin could strengthen back to a major hurricane.

Hurricane Erin will move around the western side of a high pressure system over the Atlantic Ocean. The high pressure system will steer Erin toward the north during the next 24 hours.  On its anticipated track, the center of Hurricane Storm Erin will be southeast of Cape Hatteras on Wednesday night.

The large circulation around Hurricane Erin will produce large waves that will move toward the east coast of the U.S.  Erin could cause a storm surge of up to four feet (one meter) along the Outer Banks of North Carolina.  Mandatory evacuations have been ordered for Hatteras Island and Ocracoke Island.  The large waves are likely to cause significant beach erosion.  The large circulation around Hurricane Erin could also bring tropical storm force winds to the Outer Banks.

Hurricane Erin Prompts Watches for Outer Banks

The potential risks posed by Hurricane Erin prompted the issuance of a Tropical Storm Watch and a Storm Surge Watch for the North Carolina Outer Banks on Monday afternoon.  At 5:00 p.m. EDT on Monday the center of Hurricane Erin was located at latitude 24.0°N and longitude 71.3°W which put the center about 815 miles (1310 km) south-southeast of Cape Hatteras, North Carolina.  Erin was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (265 km/h).  The minimum surface pressure was 937 mb.

A Tropical Storm Watch is in effect for the portion of the coast from Beaufort Inlet to Duck, North Carolina.  The Tropical Storm Watch includes Pamlico Sound.

A Storm Surge Watch is in effect for the portion of the coast from Cape Lookout to Duck, North Carolina.

A Tropical Storm Warning is in effect for the Turks and Caicos.  A Tropical Storm Warning is in effect for the Southeast Bahamas.

A Tropical Storm Watch is in effect for the Central Bahamas.

Hurricane Erin was maintaining its intensity on Monday afternoon.  A circular eye with a diameter of 45 miles (75 km) was at the center of Erin’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Erin’s circulation.  Storms near the core of Erin were generating strong upper level divergence that was pumping mass away from the hurricane.  The removal of mass in the upper levels was approximately equal to the inflow of mass in the lower levels of the atmosphere/  The balance of outflow and inflow of mass caused the surface pressure to remain nearly constant.

An earlier eyewall replacement cycle increased the size of the circulation around Hurricane Erin.  Winds to hurricane force extended out 80 miles (130 km) from the center of Erin’s circulation.  Winds to tropical storm force extended out 230 miles (370 km) from the center of Hurricane Erin.

The Hurricane Intensity Index (HII) for Hurricane Erin is 28.3.  The Hurricane Size Index (HSI) is 24.4 and the Hurricane Wind Intensity Size Index (HWISI) is 52.7.  Hurricane Erin is similar in size and intensity to Hurricane Helene in 2024.

Hurricane Erin will move through an environment that will become less favorable for intensification during the next 24 hours.  Erin will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  However, Erin will move into a region of drier air on Tuesday.  The drier air is likely to cause Hurricane Erin to start to weaken slowly.

Hurricane Erin will move around the southwestern side of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Erin toward the northwest during the next 24 hours.  On its anticipated track, the center of Hurricane Storm Erin will pass of the Bahamas on Tuesday.

The large circulation around Hurricane Erin will produce large waves that will move toward the east coast of the U.S.  Erin could cause a storm surge of up to four feet (one meter)  along the Outer Banks of North Carolina.  Mandatory evacuations have been ordered for Hatteras Island and Ocracoke Island.  The large waves could also cause significant beach erosion.  The large circulation around Hurricane Erin could also bring tropical storm force winds to the Outer Banks.

Bands in the western side of Hurricane Erin will continue to bring gusty winds and heavy rain to the Turks and Caicos and to the Southeast Bahamas until Erin moves farther away. The gusty winds and heavy rain could spread over the Central Bahamas on Tuesday.  Heavy rain could cause floods in some locations.

Hurricane Erin Strengthens

Hurricane Erin strengthened again on Monday morning as it moved north of the Turks and Caicos.  At 11:00 a.m. EDT on Monday the center of Hurricane Erin was located at latitude 23.1°N and longitude 70.8°W which put the center about 110 miles (175 km) north of Grand Turk Island.   Erin was moving toward the west-northwest at 10 m.p.h. (16 km/h).   The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (265 km/h).  The minimum surface pressure was 935 mb.

A Tropical Storm Warning is in effect for the Turks and Caicos.  A Tropical Storm Warning is in effect for the Southeast Bahamas.

A Tropical Storm Watch is in effect for the Central Bahamas.

Hurricane Erin began to strengthen again on Monday morning after it completed an eyewall replacement cycle.  A circular eye with a diameter of 37 miles (60 km) was at the center of Erin’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Erin’s circulation. Storms near the core of Erin were generating strong upper level divergence that was pumping mass away from the hurricane.

The eyewall replacement cycle increased the size of the circulation around Hurricane Erin. Winds to hurricane force extended out 80 miles (130 km) from the center of Erin’s circulation. Winds to tropical storm force extended out 230 miles (370 km) from the center of Hurricane Erin.

The Hurricane Intensity Index (HII) for Hurricane Erin is 28.3.  The Hurricane Size Index (HSI) is 24.4 and the Hurricane Wind Intensity Size Index (HWISI) is 52.7.  Hurricane Erin is similar in size and intensity to Hurricane Helene in 2024.

Hurricane Erin will move through an environment that will be favorable for intensification during the next 12 hours. Erin will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Erin could intensify during the next 12 hours.  Erin could move into a region of drier air on Tuesday.  The drier air would cause Hurricane Erin to start to weaken.

Hurricane Erin will move around the southwestern side of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Erin toward the northwest during the next 24 hours.  On its anticipated track, the center of Hurricane Storm Erin will move east of the Bahamas on Tuesday.

Bands in the western side of Hurricane Erin is bring gusty winds and heavy rain to the Turks and Caicos and to the Southeast Bahamas.  The gusty winds and heavy rain could spread over the Central Bahamas on Tuesday.  Heavy rain could cause floods in some locations.

Hurricane Erin Moves North of Dominican Republic

Hurricane Erin moved north of the Dominican Republic on Sunday.  At 5:00 p.m. EDT on Sunday the center of Hurricane Erin was located at latitude 21.7°N and longitude 68.5°W which put the center about 200 miles (320 km) east of Grand Turk Island.  Erin was moving toward the west-northwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 946 mb.

A Tropical Storm Warning is in effect for the Turks and Caicos.  A Tropical Storm Warning is in effect for the Southeast Bahamas.

The inner end of a rainband wrapped around an existing eye and eyewall in the core of Hurricane Erin.  Concentric eyewalls formed.  Hurricane Erin weakened as the inflow became concentrated in the outer eyewall and the inner eyewall started to weaken.  The inner eyewall was still visible in satellite and radar images.  The presence of concentric eyewalls means that Hurricane Erin is still in an eyewall replacement cycle.

The outer eyewall in Hurricane Erin has a diameter of 45 miles (75 km).  Bands of showers and thunderstorms are revolving around the core of Erin’s circulation.  Storms near the core of Erin are generating strong upper level divergence that is pumping mass away from the hurricane.

The formation of concentric eyewalls increased the size of the circulation around Hurricane Erin.  Winds to hurricane force extended out 50 miles (80 km) from the center of Erin’s circulation.  Winds to tropical storm force extended out 200 miles (320 km) from the center of Hurricane Erin.

The Hurricane Intensity Index (HII) for Hurricane Erin is 23.6.  The Hurricane Size Index (HSI) is 14.6 and the Hurricane Wind Intensity Size Index (HWISI) is 38.2.  Hurricane Erin is similar in size and intensity to Hurricane Harvey in 2017.

Hurricane Erin will move through an environment that will be favorable for intensification during the next 24 hours.  Erin will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  The eyewall replacement cycle is likely to prevent Hurricane Erin from intensifying quickly.  However, once the inner eyewall dissipates and the outer eyewall starts to contract, Erin could strengthen rapidly.

Hurricane Erin will move around the southwestern side of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Erin toward the west-northwest during the next 24 hours. On its anticipated track, the center of Hurricane Storm Erin will pass northeast of the Turks and Caicos and the Southeast Bahamas on Monday.

Bands in the western side of Hurricane Erin could bring gusty winds and heavy rain to the Turks and Caicos and to the Southeast Bahamas.  Bands in the southern side of Erin’s circulation could drop heavy rain on parts of Haiti and the Dominican Republic.  Heavy rain could cause flash floods in some locations.

Hurricane Erin Rapidly Intensifies to Cat. 5

Hurricane Erin rapidly intensified to Category 5 on the Saffir-Simpson Scale on Saturday morning.   At 11:00 a.m. EDT on Saturday the center of Hurricane Erin was located at latitude 19.7°N and longitude 62.8°W which put the center about 105 miles (165 km) north of Anguilla.    Erin was moving toward the west at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 190 m.p.h. (305 km/h).  The minimum surface pressure was 917 mb.

Tropical Storm Watches are in effect for  St. Martin, St. Barthelemy, and Sint Maarten.

Hurricane Erin rapidly intensified to a Category 5 hurricane on the Saffir-Simpson Scale on Saturday morning.  A small circular eye with a diameter of 6 miles (10 km) was at the center of Erin’s circulation.  A ring of thunderstorms surrounded the eye and the strongest winds winds occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Hurricane Erin.  Storms near the center of Erin generated strong upper level divergence that pumped large quantities of mass away from the hurricane.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Hurricane Erin is small.  Winds to hurricane force extend out 30 miles (50 km) from the center of Erin’s circulation.  Winds to tropical storm force extend out 140 miles (220 km) in the northern side of Hurricane Erin.  Winds to tropical storm force extend out 60 miles in the southern half of Erin’s circulation.

The Hurricane Intensity Index (HII) is 35.0. The Hurricane Size Index (HSI) is 9.2 and the Hurricane Wind Intensity Size Index (HWISI) is 44.2. Hurricane Erin is similar in intensity to Hurricane Michael in 2018.  Erin is smaller than Michael was.

Hurricane Erin will move through an environment that will be favorable for intensification during the next 24 hours.  Erin will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Erin is likely to continue to intensify during the next few hours.  However, it is likely that the inner end of a rainband will wrap around the existing eye and eyewall.  That would create concentric eyewalls.  It would also start an eyewall replacement cycle.  An eyewall replacement cycle would cause Hurricane Erin to weaken, at least temporarily.

Hurricane Erin will move around the southern side of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Erin toward the west-northwest during the next 24 hours.  On its anticipated track, the center of Hurricane Storm Erin will pass north of the Puerto Rico on Saturday night.

Bands in the southern side of Hurricane Erin are likely to bring gusty winds and locally heavy rain to the Northern Leeward Islands and to the Virgin Islands.  Heavy rain could cause flash floods in some locations.  Bands feeding into the southern side of Hurricane Erin could also drop heavy rain on Puerto Rico.

A Flood Watch is in effect for Puerto Rico.

Hurricane Erin Rapidly Intensifies to Cat. 4

Hurricane Erin rapidly intensified to Category 4 on the Saffir-Simpson Scale on Saturday morning.  At 8:00 a.m. EDT on Saturday the center of Hurricane Erin was located at latitude 19.6°N and longitude 62.0°W which put the center about 120 miles (195 km) northeast of Anguilla.   Erin was moving toward the west-northwest at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 175 m.p.h. (280 km/h).  The minimum surface pressure was 935 mb.

Tropical Storm Watches are in effect for  St. Martin, St. Barthelemy, and Sint Maarten.

Hurricane Erin rapidly intensified to a Category 4 hurricane on the Saffir-Simpson Scale early on Saturday morning.  A circular eye with a diameter of 12 miles (19 km) was at the center of Erin’s circulation.  A ring of thunderstorms surrounded the eye and the strongest winds winds occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Hurricane Erin.  Storms near the center of Erin generated strong upper level divergence that pumped large quantities of mass away from the hurricane.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Hurricane Erin is small.  Winds to hurricane force extend out 30 miles (50 km) from the center of Erin’s circulation.  Winds to tropical storm force extend out 130 miles (210 km) in the northern side of Hurricane Erin.  Winds to tropical storm force extend out 60 miles in the southern half of Erin’s circulation.

The Hurricane Intensity Index (HII) is 29.9.  The Hurricane Size Index (HSI) is 8.4 and the Hurricane Wind Intensity Size Index (HWISI) is 38.3.  Hurricane Erin is similar in size and intensity to Hurricane Charley in 2004.

Hurricane Erin will move through an environment that will be very favorable for intensification during the next 24 hours.  Erin will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Erin will intensity during the next 24 hours.  Erin could strengthen to Category 5 on the Saffir-Simpson Scale.

Hurricane Erin will move around the southern side of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Erin toward the west-northwest during the next 24 hours.  On its anticipated track, the center of Hurricane Storm Erin will pass north of the Puerto Rico on Sunday.

Bands in the southern side of Hurricane Erin are likely to bring gusty winds and locally heavy rain to the Northern Leeward Islands.  Heavy rain could cause flash floods in some locations.  Bands feeding into the southern side of Hurricane Erin could also drop heavy rain on Puerto Rico.

A Flood Watch is in effect for Puerto Rico.

Erin Strengthens to a Hurricane

Former Tropical Storm Erin strengthened to a hurricane east of the Northern Leeward Islands on Friday.  At 11:00 a.m. EDT on Friday the center of Hurricane Erin was located at latitude 18.2°N and longitude 56.1°W which put the center about 460 miles (740 km) east of the Northern Leeward Islands.  Erin was moving toward the west-northwest at 18 m.p.h. (30 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 996 mb.

Tropical Storm Watches are in effect for Anguilla, Barbuda, St. Martin, St. Barthelemy, Saba, St. Eustatius, and Sint Maarten.

Former Tropical Storm Erin strengthened to a hurricane east of the Northern Leeward Islands on Friday.  The inner end of a rainband wrapped around the center of Erin’s circulation.  A small eye with a diameter of 12 miles (19 km) formed at the center of Hurricane Erin.  Bands of showers and thunderstorms were revolving around the center of Erin’s circulation.  Storms near the center generated upper level divergence that was pumping mass away from the hurricane.

The strongest winds were occurring in the northeastern part of Hurricane Erin.  Winds to hurricane force extended out 25 miles (40 km) in the northeastern quadrant of Erin’s circulation.  Winds to tropical storm force extended out 115 miles (185 km) from the center of Hurricane Erin.

Hurricane Erin will move through an environment favorable for intensification during the next 24 hours.  Erin will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the southern part of an upper level ridge over the eastern Atlantic Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Erin’s circulation. The winds in the lower levels of the atmosphere will also blow from the east, but winds will be stronger in the upper troposphere.  So, there will be some vertical wind shear.  The vertical wind shear will slightly inhibit intensification, but the shear will not be enough to prevent intensification. Hurricane Erin will intensity during the next 24 hours.  Erin is likely to strengthen to a major hurricane during the weekend.

Hurricane Erin will move around the southern side of a high pressure system over the Atlantic Ocean.  The high pressure system will steer Erin toward the west-northwest during the next 24 hours.  On its anticipated track, the center of Hurricane Storm Erin will pass north of the Northern Leeward Islands on Saturday.

Bands in the southern side of Hurricane Erin are likely to bring gusty winds and locally heavy rain to the Northern Leeward Islands.  Heavy rain could cause flash floods in some locations.  Bands feeding into the southern side of Hurricane Erin could also drop heavy rain on Puerto Rico.

A Flood Watch is in effect for Puerto Rico.