Tag Archives: HWISI

Powerful Typhoon Lan Speeds Toward Japan

Powerful Typhoon Lan sped toward Japan on Saturday.  At 11:00 p.m. EDT on Saturday the center of Typhoon Lan was located at latitude 28.9°N and longitude 134.5°E, which put it about 575 miles (925 km) southwest of Tokyo, Japan.  Lan was moving toward the north-northeast at 27 m.p.h. (43 km/h).  The maximum sustained wind speed was 145 m.p.h. (230 km/h) and there were wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 928 mb.

Lan is a large and powerful typhoon.  There is an eye at the center of circulation, but the eye has become less clear during the past few hours.  A ring of strong thunderstorms surrounds the eye and the strongest winds are occurring in that ring of storms.  Additional bands of showers and thunderstorms are revolving around the core of Typhoon Lan.  The outer bands in the western half of the circulation consist primarily of low clouds and showers.  Winds to typhoon force extend out about 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extend out about 335 miles (540 km) from the center.

The Hurricane Intensity Index (HII) for Typhoon Lan was 29.9.  The Hurricane Size Index (HSI) was 20.6 and the Hurricane Wind Intensity Size Index (HWISI) was 50.5.

Typhoon Lan has reached its maximum intensity and it will weaken during the next several days.  Lan is moving over water where the Sea Surface Temperature is near 28°C, but it will move over colder water when it moves farther north.  Westerly winds in the upper levels are starting to increase the vertical wind shear.  Typhoon Lan also appears to be drawing cooler and drier air into the western side of the circulation.  Cooler water, more vertical wind shear and drier air will cause steady weakening of Typhoon Lan.

Typhoon Lan is moving around the western end of a ridge which is steering the typhoon rapidly toward the north-northeast.  Westerly winds in the upper levels will carry Lan quickly toward Japan.  On its anticipated track Typhoon Lan will approach Honshu and the area near Tokyo in 12 to 18 hours.  Lan will still be a strong typhoon when it gets to Japan.  Typhoon will bring strong winds and drop locally heavy rain over the area around Tokyo.  Heavy rain could cause flash floods.

Typhoon Lan Intensifies Into Equivalent of a Major Hurricane

Typhoon Lan intensified into the equivalent of a major hurricane on Friday.  At 11:00 a.m. EDT on Friday the center of Typhoon Lan was located at latitude 20.9°N and longitude 130.3°E which put it about 450 miles (720 km) south-southeast of Okinawa.  Lan was moving toward the north at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (230 km/h).  The minimum surface pressure was 942 mb.

Typhoon Lan has a large and powerful circulation.  There is a large circular eye at the center of circulation.  The eye has a diameter of 60 miles (96 km) and it is surrounded by a ring of strong thunderstorms.  The strongest winds are occurring in that ring of storms.  Multiple bands of showers and thunderstorms are revolving around the core of the circulation.  Typhoon Lan is generating strong upper level divergence which is pumping mass away to the northeast of the typhoon.  Winds to typhoon force extend out about 100 miles (160 km) from the center of circulation.  Winds to tropical storm force extend out about 330 miles (530 km) from the center.

The Hurricane Intensity Index (HII) for Typhoon Lan is 20.6.  The Hurricane Size Index (HSI) is 37.2 and the Hurricane Wind Intensity Size Index (HWISI) is 57.8.  Those indices indicate that Typhoon Lan is capable of causing widespread major damage.

Typhoon Lan will move through an environment that will be favorable for further intensification during the next 24 hours.  Lan will move over water where the Sea Surface Temperature is near 31°C.  An upper level ridge centered east of Lan is producing southerly winds which are blowing toward the top of the circulation.  There are also southerly winds in the lower levels of the atmosphere and thus there is not much vertical wind shear.  The southerly winds in the upper levels are actually enhancing the upper level divergence to the northeast of Typhoon Lan.  Warm water and little vertical wind shear will allow Typhoon Lan to strengthen during the next day or so.  When Lan moves farther north, it will reach the upper level westerly winds in the middle latitudes.  The vertical wind shear will increase at that time, and Typhoon Lan will start to weaken.

Typhoon Lan is moving around the western end of a subtropical ridge which is steering the typhoon toward the north.  As Typhoon Lan moves farther toward the north, it will begin to move toward the north-northeast.  When Lan reaches the upper level westerlies on Sunday, it will turn more toward the northeast.  On its anticipated track the center of Typhoon Lan will pass east of Okinawa and the Ryuku Islands on Saturday.  Typhoon Lan will approach Honshu in about 48 hours.

Typhoon Lan will still be a large powerful typhoon when it approaches Honshu.  Lan will be capable of producing strong gusty winds and very heavy rainfall.  Flash floods could occur when Typhoon Lan moves across Japan.

Typhoon Lan Heads North and Strengthens

Typhoon Lan headed northward and strengthened on Thursday.  At 11:00 p.m. EDT on Thursday the center of Typhoon Lan was located at latitude 19.2°N and longitude 130.0°E which put it about 550 miles (885 km) south-southeast of Okinawa.  Lan was moving toward the north at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 956 mb.

Lan strengthened into a large powerful typhoon on Thursday.  A big circular eye developed at the core of Typhoon Lan.  The eye was not perfectly clear.  There was a small area of convection at the center of the eye and there was a clear moat around that area.  A ring of thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Multiple bands of showers and thunderstorms were revolving around the typhoon.  Lan is a very large typhoon.  Winds to typhoon force extended out up to 140 miles (225 km) from the center of circulation.  Winds to tropical storm force extended out up to 305 miles (490 km) from the center

The Hurricane Intensity Index (HII) for Typhoon Lan was 16.5.  The Hurricane Size Index (HSI) was 46.8 and the Hurricane Wind Intensity Size Index (HWISI) was 63.3.  The circulation of Typhoon Lan is almost as large as the circulation of Hurricane Sandy was when Sandy hit the U.S. in 2012.

Typhoon Lan will be moving through an environment favorable for further intensification.  Lan will move over water where the Sea Surface Temperature is near 30°C.  It will move through and area where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Lan could intensify into the equivalent of a major hurricane during the next day or two.

Typhoon Lan is moving around the western end of a subtropical ridge which is steering the typhoon toward the north.  Lan is likely to continue to move toward the north on Friday.  The typhoon will be affected by westerly winds when it moves farther north.  Those winds will cause Typhoon Lan to move more toward the north-northeast during the weekend.  On its anticipated track the center of Typhoon Lan could pass southeast of Okinawa in 24 to 36 hours.  Lan could approach Honshu within three days.

Hurricane Nate Speeds Toward Gulf Coast

Strengthening Hurricane Nate sped toward the central Gulf Coast on Saturday.  At 11:00 a.m. EDT on Saturday the center of Hurricane Nate was located at latitude 26.6°N and longitude 88.4°W which put it about 265 miles (425 km) south of Biloxi, Mississippi.  Nate was moving toward the north-northwest at 26 m.p.h. (43 km/h).  The maximum sustained wind speed was 90 m.p.h. (150 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 984 mb.

A Hurricane Warning was in effect for the portion of the coast from Grand Isle, Louisiana to the Alabama/Florida border including New Orleans and Lake Pontchartrain.  A Hurricane Watch was in effect for the portion of the coast from the Alabama/Florida border to the Okaloosa/Walton County line and from Grand Isle to Morgan City, Louisiana.  A Tropical Storm Warning was in effect for the portion of the coast from the Alabama/Florida border to Indian Pass, Florida and from Grand Isle to Morgan City.  A Tropical Storm Watch was in effect for the portion of the coast from Morgan City to Intracoastal City, Louisiana.

Hurricane Nate strengthened on Saturday as it moved over the warm water in the Gulf of Mexico.  An eye with a diameter of 30 miles (50 km) began to form at the center of circulation.  A ring of thunderstorms around the eye was generating strong upper level divergence which pumped mass away from Hurricane Nate.  The strongest winds were occurring in the eastern side of the circulation.  Winds to hurricane force extended out about 35 miles (55 km) east of the center of circulation.  Winds to tropical storm force extend out about 120 miles (195 km) east of the center, but they only extend out about 60 miles (95 km) to the west of the center.

The Hurricane Intensity Index (HII) for Hurricane Nate is 13.9.  The Hurricane Size Index (HSI) is 7.7 and the Hurricane Wind Intensity Size Index (HWISI) is 21.6.

Hurricane Nate will continue to intensify during the next 12 hours until it makes landfall.  Nate will move over water where the Sea Surface Temperature is near 29°C.  An upper low over the western Gulf of Mexico is producing southerly winds which are blowing toward the top of the circulation.  However, there are also southerly winds in the lower levels of the atmosphere and as a result, there is not much vertical wind shear.  Hurricane Nate is likely to intensify to a Category 2 hurricane on the Saffir-Simpson Scale before it makes landfall.  There is a chance Hurricane Nate could intensify to Category 3 before landfall, if it continues to intensify rapidly.

The upper low and an upper level ridge east of Florida are combining to steer Hurricane Nate quickly toward the north-northwest and that motion is expected to continue for the next few hours.  An upper level trough over the Central U.S. will approach Nate on Saturday night as the hurricane nears the coast.  The trough will turn Hurricane Nate more toward the north as it reaches the coast.  The trough should steer Nate quickly toward the north-northeast after it makes landfall.  On its anticipated track the center of Hurricane Nate will pass near the mouth of the Mississippi River on Saturday evening.  The center of Nate will likely make landfall on the coast of Mississippi or near Mobile on Saturday night.

Hurricane Nate will be capable of causing regional serious damage when it makes landfall.  Nate will produce strong winds, especially in locations east of the track of the hurricane.  Nate will also be capable of producing a storm surge of 10 to 12 feet (3 to 4 meters) along the coast.  The surge will be higher in bays, inlets and mouths of rivers that funnel the water into specific areas.  Nate will also be capable of dropping heavy rain as it moves inland.

Hurricane Maria Strengthens to Cat. 5 Near Leeward Islands

Hurricane Maria quickly strengthened to a Category 5 hurricane on the Saffir-Simpson Scale on Monday.  At 8:00 p.m. EDT on Monday the center of Hurricane Maria was located at latitude 15.3°N and longitude 61.1°W which put it about 15 miles (25 km) east-southeast of Dominica.  Maria was moving toward the west-northwest at 9 m.p.h. (15 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 925 mb.

Hurricane Warnings were in effect for Puerto Rico, Culebra, Vieques, Dominica, Guadeloupe, St. Kitts, Nevis, Martinique, Montserrat, the U.S. Virgin Islands and the British Virgin Islands.  Hurricane Watches were in effect for Saba, St. Eustatius, St. Maarten, Anguilla, St. Martin, St. Barthelemy and the portion of the coast from Isla Saona to Puerto Plata, Dominican Republic.  Tropical Storm Warnings were in effect for Anguilla, St. Lucia, Antigua, Barbuda, Saba, St. Eustatius and St. Maarten.  Tropical Storm Watches were in effect for St. Vincent, the Grenadines and the portion of the coast from Puerto Plata to the Haiti/Dominican Republic border.

Hurricane Maria has a tight compact circulation.  There is a small eye with a diameter of 10 miles (16 km) at the center of circulation.  The eye is surround by a ring of strong thunderstorms and the strongest winds are occurring in that ring of storms.  Additional bands of showers and thunderstorms are revolving around the core of Maria.  The overall circulation of Hurricane Maria is small.  Winds to hurricane force only extend out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force only extend out about 125 miles (200 km) from the center.

The Hurricane Intensity Index (HII) for Hurricane Maria is 35.0.  The Hurricane Size Index (HSI) is 9.1 and the Hurricane Wind Intensity Size Index (HWISI) is 44.1.

Hurricane Maria will continue to move through an environment very favorable for strong hurricanes.  Maria will move over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Hurricane Maria could strengthen further.  Since the eye of Hurricane Maria is so small, it would be easy for a rainband to wrap around the eye.  If that happens, then an eyewall replacement cycle could begin and the cycle could result in a temporary weakening of the hurricane.

Hurricane Maria is being steered to the west-northwest by the subtropical high pressure system over the Atlantic Ocean.  That high is forecast to weaken and Maria is likely to move more toward the northwest during the next several days.  On its anticipate track the center of Hurricane Maria will pass very close to Dominica and Guadeloupe on Monday night.  Maria could pass near Montserrat, St. Kitts and Nevis on Tuesday.  It could be near the U.S. Virgin Islands on Tuesday night and Hurricane Maria will approach Puerto Rico on Wednesday.

Hurricane Maria is a small but very dangerous hurricane.  The winds in the core of Hurricane Maria are capable of causing extensive damage.  In addition, heavy rain falling over steep terrain will likely produce flash floods.  Hurricane Maria will affect some of the same islands that were severely damaged by Hurricane Irma.  Maria will significantly hamper efforts in some places to recover from the effects of Hurricane Irma.

Elsewhere over the Atlantic Ocean, Hurricane Jose has begun the transition to an extratropical cyclone as it moves northward off the east coast of the U.S.  At 5:00 p.m. EDT on Monday the center of Hurricane Jose was located at latitude 34.8°N and longitude 71.1°W which put it about 445 miles (720 km) south of Nantucket, Massachusetts.  Jose was moving toward the north at 10 m.p.h. (16 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 977 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Watch Hill, Rhode Island to Hull, Massachusetts including Block Island, Martha’s Vineyard and Nantucket.  Tropical Storm Watches were in effect for the portion of the coast of Long Island from Fire Island Inlet to Port Jefferson and from New Haven, Connecticut to Watch Hill, Rhode Island.

The structure of Hurricane Jose began to change on Monday from the more circular shape of a purely tropical hurricane to an asymmetrical shape seen more commonly in extratropical cyclones.  Drier air wrapped around the western and southern sides of the circulation.  Most of the strong thunderstorms and heavy rain were occurring in the northern half of Jose.  Winds to hurricane force extended out about 60 miles (95 km) north of the center, but there were few if any winds to hurricane force south of the center.  The circulation of Hurricane Jose is much larger than the circulation of Hurricane Maria.  Winds to tropical storm force extend out about 320 miles (515 km) from the center of Jose.

The Hurricane Intensity Index for Hurricane Jose was 10.4.  The Hurricane Size Index for Jose was 15.6 and the Hurricane Wind Intensity Size Index was 26.0.

Hurricane Jose will move into an environment that is unfavorable for hurricanes on Tuesday.  Jose will stay over warm Sea Surface Temperatures until it moves north of the Gulf Stream.  Once Jose moves north of latitude 38°N, it will start to move over cooler water.  An upper level trough over the eastern U.S. is producing southerly winds which are causing moderate vertical wind shear over Jose.  Cooler water and moderate shear would normally cause a hurricane to weaken.  However, as Hurricane Jose makes the transition to an extratropical cyclone, it will start to be powered by the temperature difference between warm and cold air.  The transition to an extratropical cyclone can sometimes produce a stronger storm when it occurs.

Hurricane Jose is moving around the western end of the subtropical high.  Another surface high pressure system is forecast to move north of Jose when the hurricane approaches the northeastern U.S.  The second high will block the northward motion and it will force Hurricane Jose to move toward the east.  Some models are forecasting that Jose could make a clockwise loop southeast of Cape Cod.  Hurricane Jose could bring gusty winds and high waves to sections of the coast in the northeastern U.S. during the next few days.

Hurricane Irma Batters Florida Keys

Hurricane Irma battered the Florida Keys on Sunday morning.  At 9:00 a.m. EDT on Sunday morning the center of Hurricane Irma was located at latitude 24.5°N and longitude 81.5°W which put it about 30 miles (50 km) east-northeast of Key West, Florida.  Irma was moving toward the north-northwest at 8 m.p.h.  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  Hurricane Irma was a Category 4 hurricane on the Saffir-Simpson Scale.  The minimum surface pressure was 929 mb.

A Hurricane Warning was in effect for the portion of the coast from Fernandina Beach to Indian Pass, Florida including the Florida Keys and Lake Okeechobee.   A Hurricane Watch was in effect for the portion of the coast from Fernandina Beach, Florida to Edisto Beach, South Carolina.  A Tropical Storm Warning is in effect for the portion of the coast from Fernandina Beach to South Santee River, South Carolina and from Indian Pass to the Okaloosa/Walton County line.

A Hurricane Warning is in effect for the Cuban provinces of La Habana and Matanzas.  A Tropical Storm Watch is in effect for Bimini and Grand Bahama Island.

An outer eyewall started to wrap around the original eye of Hurricane Irma, but Irma did not go through an eyewall repacement cycle.  The original eyewall remained intact and the strongest winds were occurring in that eyewall.  The uncompleted formation of an outer eyewall did result in an increase in the size of Hurricane Irma.  Winds to hurricane force extend out about 80 miles (130 km) from the center of circulation.  Winds to tropical storm force extend out over 200 miles (320 km) from the center.

The Hurricane Intensity Index (HII) for Hurricane Irma was 25.1.  The Hurricane Size Index (HSI) was 24.2 and the Hurricane Wind Intensity Size Index (HWISI) was 49.3.  Hurricane Irma is not quite as strong as Hurricane Charley was when Charley hit southwest Florida.  However, Hurricane Irma is much bigger than Charley was.  Hurricane Irma is stronger than Hurricane Wilma was when Wilma hit south Florida in 2005.  Irma is a little smaller than Wilma was.

Carysfort Reef Light near Key Largo reported a wind gust of 93 m.p.h. (150 km/h).  Hurricane Irma is causing winds to hurricane force over much of the Florida Keys.  Winds to tropical storm force are occurring in areas around Miami, Florida.

Hurricane Irma has turned toward the north.  The core of Hurricane Irma could make a landfall on the southwest coast of Florida between Everglades City and Naples, Florida later this afternoon.  Hurricane Irma could move northward near the west coast of Florida.  The center of Hurricane Irma could reach the Tampa/St. Petersburg area and Central Florida on Sunday night.

Hurricane Irma is large and dangerous hurricane.  It is capable of causing widespread extensive damage.  There are likely to be widespread power outages.  Irma will also generate a storm surge of 15 feet (5 meters) in some locations.  Irma will drop locally heavy rain and flooding could occur in some places.

Hurricane Irma Grinds Along Cuba’s North Coast

Hurricane Irma ground its way along the northern coast of Cuba on Saturday morning.  At 2:00 p.m. EDT on Saturday the center of Hurricane Irma was located at latitude 23.1°N and longitude 80.2°W which put it about 145 miles (235 km) southeast of Key West, Florida.  Irma was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 125 m.p.h. (205 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 941 mb.

A Hurricane Warning is in effect for the portion of the coast from Aucilla River to Fernandina Beach, Florida including the Florida Keys and Lake Okeechobee.  Hurricane Watches are in effect for the portions of the coast from Auculla River to Indian Pass, Florida and from Fernandina Beach, Florida to Edisto Beach, South Carolina.  Tropical Storm Watches are in effect for the portions of the coast from Indian Pass to the Okaloosa/Walton County line and from Edisto Beach to South Santee River, South Carolina.

A Hurricane Warning is in effect for the Cuban provinces of Camaguey, Ciego de Avila, Sancti Spiritus, Villa Clara, Matanzas, La Habana.  A Hurricane Warning was in effect for Andros Island, Bimini and Grand Bahama Island.  A Hurricane Watch and a Tropical Storm Warning was in effect for the Cuban provinces of Holguin and Las Tunas.

Hurricane Irma weakened on Saturday morning as the center moved along the northern coast of Cuba.  However, the core of Hurricane Irma remained intact.  There was an eye at the center of circulation.  A ring of strong thunderstorms surrounded the eye.  Numerous spiral bands were revolving around the core of Hurricane Irma.  Thunderstorms in the core of Irma were generating upper level divergence which was pumping mass away from the center of the hurricane.

Hurricane Irma is a large hurricane.  Winds to hurricane force extend out about 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extend out about 185 miles (295 km) from the center.  The Hurricane Intensity Index (HII) for Irma was 23.6.  The Hurricane Size Index (HSI) was 23.6 and the Hurricane Wind Intensity Size Index (HWISI) was 47.2.  Those indices indicate Hurricane Irma is capable of causing widespread major damage.

Hurricane Irma will move through an environment favorable for intensification for another 12 to 18 hours.  Irma will over water where the Sea Surface Temperature is near 31°C.  The upper level winds are relatively weak and there will be little vertical wind shear.  Hurricane Irma is likely to intensify back to Category 4 on the Saffir-Simpson Scale and it could reach Category 5.  Hurricane Irma will move closer to an upper level trough over the eastern U.S. on Sunday.  Southerly winds on the eastern side of the trough will increase the vertical wind shear and Hurricane Irma will start to weaken.

Hurricane Irma is moving around the western end of a subtropical high pressure system over the Atlantic Ocean.  The subtropical high is steering Hurricane Irma toward the west-northwest.  Hurricane Irma will turn more toward the north-northwest when it reaches the western end of the high.  On its anticipated track the core of Hurricane Irma will move away from Cuba.  The center of Hurricane Irma will be near the Florida Keys by early Sunday morning.  Hurricane Irma could be near the southwest coast of Florida by Sunday afternoon.

Hurricane Irma will be capable of causing widespread extensive damage.  Winds blowing water toward the coast will generate significant storms surges.  Hurricane force winds will cause widespread damage as the Hurricane Irma moves near the west coast of Florida.

Elsewhere over the Atlantic Ocean Hurricane Jose was moving near the northern Leeward Islands.  At 2:00 p.m. EDT the center of Hurricane Jose was located at latitude 18.8°N and longitude 61.9°W which put it about 95 miles (155 km) east-northeast of the northern Leeward Islands.  Jose was moving toward the northwest at 14 m.p.h. (23 km/h).  The maximum sustained wind speed was 145 m.p.h. (230 km/h) and there were wind gusts to 175 m.p.h. (285 km/h).  The minimum surface pressure was 945 mb.

A Tropical Storm Warning was in effect for Barbuda, Anguilla, Sint Maarten, St. Martin and St. Barthelemy.

The core of Hurricane Jose and the strongest winds will move northeast of the northern Leeward Islands.  The southern part of the circulation will bring gusty winds which will hamper recovery efforts after Hurricane Irma.  Jose is forecast to stall over the Atlantic and there is much uncertainty about the ultimate long term track.

The remnants of Hurricane Katia were raining themselves out over eastern Mexico.  At 11:00 a.m. EDT on Saturday the center of Tropical Depression Katia was located at latitude 20.0°N and longitude 97.9°W which put it about 125 miles (200 km) west-northwest of Veracruz, Mexico.  Katia was moving toward the west-southwest at 5 m.p.h. (8 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 1004 mb.

Hurricane Irma Batters Bahamas, Jose Threatens Leewards, Katia Nears Mexico

The tropical Atlantic Ocean continued to be very active on Friday.  Destructive Hurricane Irma battered the Southeastern Bahamas and Turks and Caicos.  Powerful Hurricane Jose threatened the northern Leeward Islands only 48 hours after Hurricane Irma caused significant damage to them.  Hurricane Katia neared a landfall on the coast of Mexico between Tampico and Veracruz.

At 5:00 p.m. EDT on Friday the center of Hurricane Irma was located at latitude 22.1°N and longitude 76.5°W which put it about 345 miles (555 km) southeast of Miami, Florida.  Irma was moving toward the west at 12 m.p.h.  The maximum sustained wind speed was 155 m.p.h. (250 km/h) and there were wind gusts to 180 m.p.h. (290 km/h).  The minimum surface pressure was 925 mb.

A Hurricane Warning was in effect for the portion of the coast from Anna Maria Island to Sebastian Inlet, Florida including the Florida Keys and Lake Okeechobee.  Hurricane Watches were in effect for the portions of the coast from Anna Maria Island to the Suwannee River and from Sebastian Inlet to the Flagler/Volusia Count line.  A Hurricane Warning was in effect for the Cuban provinces of Camaguey, Ciego de Avila, Sancti Spiritus and Villa Clara.  Hurricane Warnings were in effect for the northwestern Bahamas including the Abacos, Andros island, Berry Island, Bimini, Eleuthera, Grand Bahama Island and New Providence.  Hurricane Warnings were in effect for the central Bahamas including Cat Island, the Exumas, Long Island, Rum Cay and San Salvador.  Hurricane Warnings were in effect for the southeastern Bahamas including the Acklins, Long Cay, Crooked Island, the Inaguas, Mayaguana and the Ragged Islands.

Hurricane Watches were in effect for the Cuba provinces of Matanzas, Holguin, Las Tunas and Guantanamo.  Tropical Storm Warnings were in effect for the Cuban provinces of Holguin, Las Tunas and Guantamo.

Hurricane Irma completed an eyewall replacement cycle on Friday morning.  After the inner eyewall dissipated the circulation rapidly concentrated on the outer eyewall.  The eyewall replacement cycle caused some weakening of Hurricane Irma but it remained a powerful Category 4 hurricane on the Saffir-Simpson Scale.  The eyewall replacement cycle resulted in an increase in the size of the circulation of Hurricane Irma.  Winds to hurricane force now extend out about 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extend out almost 185 miles (295 km) from the center.

The Hurricane Intensity Index (HII) for Hurricane Irma is 33.3.  The Hurricane Size Index is 23.0 and the Hurricane Wind Intensity Size Index is 56.3.  Hurricane Irma is stronger, but a little smaller than Hurricane Wilma was when Wilma made landfall in south Florida in 2005.

Hurricane Irma is moving through a very favorable environment.  Irma is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is little vertical wind shear.  Part of the southern side of the circulation is passing over Cuba, but the core of Hurricane Wilma is remaining over water.  Hurricane Irma should remain a very powerful hurricane during the next 36 hours.

Hurricane Irma is moving near the western end of a large subtropical high that has been steering the hurricane toward the west.  Irma started to move a little more slowly on Friday afternoon as it approached the end of the high.  Hurricane Irma is forecast to continue to move west-northwest for another 12 to 24 hours.  When Hurricane Irma reaches the end of the high, it will start moving toward the north.  On its anticipated track the core of Hurricane Irma will pass north of the north coast of Cuba on Saturday.  Hurricane Irma is forecast to reach the Florida Keys on Saturday night.

Hurricane Irma is a large and dangerous hurricane.  Irma is capable of causing widespread extensive damage.  Hurricane Irma’s winds will be very destructive and they could cause widespread power outages in Florida.  There will be a significant storm surge in the Florida Keys and on both the east and west coast of Florida.

Hurricane Jose intensified rapidly on Friday to Category 4 on the Saffir-Simpson Scale.  Jose now threatens to bring very strong winds to places devastated by Hurricane Irma earlier this week.  At 5:00 p.m. EDT on Friday the center of Hurricane Jose was located at latitude 16.6°N and longitude 58.3°W which put it about 335 miles (540 km) east of the Leeward Islands.  Jose was moving toward the west-northwest at 17 m.p.h.  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 180 m.p.h. (290 km/h).  The minimum surface pressure was 940 mb.

Hurricane Warnings are in effect for Barbuda, Anguilla, St. Barthelemy, Sint Maarten and St. Martin.  A Hurricane Watch is in effect for Antigua.  Tropical Storm Warnings are in effect for Antigua, Saba and St. Eustatius.  Tropical Storm Watches are in effect for Montserrat, St. Kitts, Nevis, the British Virgin Islands, St. Thomas and St. John.

Hurricane Jose has a small, well organized circulation.  There is a clear eye at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strong winds are occurring in that ring of storms.  Hurricane Jose is much smaller than Hurricane Irma.  Winds to hurricane force extend out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extend out about 140 miles (225 km) from the center.

Upper level divergence from Hurricane Irma is causing some vertical wind shear over Hurricane Jose, but the shear did not prevent Jose from intensifying into a major hurricane.  Hurricane Jose is forecast to remain a major hurricane for several more days.  The same subtropical high steering Hurricane Irma is also steering Jose toward the west north-west.  On its anticipated track Hurricane Jose could reach the northern Leeward Islands late on Saturday.  Some of those islands suffered widespread extensive damage from Hurricane Irma and a direct hit by Jose would be devastating.  Even if the core of Hurricane Jose moves just north of those islands, the strong winds will serious affect efforts to recover from Hurricane Irma.

After being nearly stationary over the southwestern Gulf of Mexico for several days, Hurricane Katia began to move toward the coast of Mexico on Friday.  At 5:00 p.m. EDT on Friday the center of Hurricane Katia was located near latitude 21.0°N and longitude 96.5°W which put it about 125 miles (225 km) north of Veracruz, Mexico.  Katia was moving toward the west-southwest at 7 m.p.h.  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 972 mb.

A Hurricane Warning was in effect for the portion of the coast from Cabo Rojo to Laguna Verde, Mexico.

Hurricane Katia is a small hurricane.  Winds to hurricane force only extend out about 25 miles (40 km) from the center.  Winds to tropical storm force only extend out about 70 miles (110 km) from the center.

A mid-level ridge over the western Gulf of Mexico is steering Hurricane Katia toward the west-southwest.  On its anticipated track Hurricane Katia will make landfall on the coast of Mexico between Tampico and Veracruz on Friday night.  The center is likely to make landfall near Tecolutla.  Although the small size of Katia’s circulation will limit the wind damage, the hurricane will cause a significant storm surge along the portion of the coast where the center makes landfall.  Katia will also produce heavy rain and a chance for flash floods as it moves inland and dissipates.

Powerful Hurricane Irma Approaches Bahamas, Watches Issued for Florida

Powerful Hurricane Irma move north of the Dominican Republic on its approach to the Bahamas on Thursday morning.  Hurricane Watches were issued for south Florida because of the potential impact of Hurricane Irma.  At 11:00 a.m. EDT on Thursday the center of Hurricane Irma was located at latitude 20.4°N and longitude 69.7°W which put it about 120 miles (190 km) southeast of Grand Turk Island and about 785 miles (1265 km) east-southeast of Miami, Florida.  The maximum sustained wind speed was 175 m.p.h. (280 km/h) and there were wind gusts to 200 m.p.h. (320 km/h).  The minimum surface pressure was 921 mb.

Hurricane Warnings were in effect for the portion of the coast from Cabo Engano, Dominican Republic to Le Mole St. Nicholas, Haiti, the Turks and Caicos, the southeastern Bahamas including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana and the Ragged Islands, the central Bahamas including Cat Island, the Exumas, Long Island, Rum Cay and San Salvador, the northwestern Bahamas including the Abacos, Andros Island, Berry Island, Bimini, Eleuthera, Grand Bahama Island and New Providence.

A Hurricane Watch was in effect for the portion of the coast from Jupiter Inlet to Bonita Beach, Florida including the Florida Keys and Lake Okeechobee and from Matanzas province to Guantanamo province in Cuba.

A Tropical Storm Warning is in effect for the portion of the coast from Cabo Engano, Dominican Republic to the southern border with Haiti, from Le Mole St. Nicholas to Port Au Prince, Haiti and for the Cuban provinces of Guantanamo, Holguin and Las Tunas.

Hurricane Irma remains a large and dangerous hurricane.  Irma weakened slightly on Thursday morning, but it still was a Category 5 hurricane on the Saffir-Simpson Scale.  Irma has a large 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.  Winds to hurricane force extend out about 60 miles (95 km) from the center.  Winds to tropical storm force extend out about 185 miles (305 km) from the center.

The Hurricane Intensity Index (HII) for Hurricane Irma is 40.4.  The Hurricane Size Index (HSI) is 19.2 and the Hurricane Wind Intensity Size Index (HWISI) is 59.6.  Those indices indicate that Hurricane Irma is capable of causing widespread catastrophic damage.

Hurricane Irma will remain in a favorable environment for the next several days.  Irma will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds will be weak and there will be little vertical wind shear during the next 24 to 36 hours.  When Irma gets farther north it will be near the southern end of a large upper level trough over the eastern U.S.  The trough will produce southeasterly winds which will increase the shear somewhat.  Hurricane Irma will remain a large dangerous hurricane.

Hurricane Irma is moving around the western end of a subtropical high over the Atlantic Ocean.  The high is steering Irma toward the west-northwest and that general motion is expected to continue for another 36 to 48 hours.  The effects of the upper level trough are expected to turn Irma toward the north during the weekend.  On its anticipated track Hurricane Irma will reach the Turks and Caicos on Thursday night.  Irma will move across the southeastern Bahamas on Friday and it could be north of Cuba by Saturday morning.  Hurricane Irma could reach southern Florida by Sunday morning.

Hurricane Irma is capable of causing widespread catastrophic damage.  Irma will generate storm surges as high as 19 feet (6 meters) when it passes over the Bahamas.  Irma will cause widespread wind damage and locally heavy rain could cause flash floods.

The destructive core of Hurricane Irma moved over Barbuda, St. Barthelemy and St. Martin.  There are reports of widespread damage on those islands.  Other nearby islands my have also suffered significant damage.

Hurricane Jose is following in the wake of Hurricane Irma and Watches have been issued for some of the northern Leeward Islands.  At 11:00 a.m. EDT on Thursday the center of Hurricane Jose was located at latitude 14.9°N and longitude 50.6°W which put it about 715 miles (1155 km) east of the Leeward Islands.  Jose was moving toward the west-northwest at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 90 m.p.h. (150 km/h) and there were wind gusts to 105 m.p.h. (170 km/h).  The minimum surface pressure was 986 mb.

Hurricane Watches have been issued for Antigua and Barbuda.  Tropical Storm Watches have been issued for Anguilla, Montserrat, St. Kitts and Nevis.

Hurricane Jose is moving through a favorable environment of warm Sea Surface Temperatures and little vertical wind shear.  Hurricane Jose is forecast to intensify into a major hurricane.  The same subtropical high steering Hurricane Irma is also steering Hurricane Jose.  On its anticipated track Hurricane Jose could reach the northern Leeward Islands on Saturday.  It could be a major hurricane at that time.  If Hurricane Jose moves over some of the same places hit by Hurricane Irma it will serious impede efforts to recover from Irma.

Hurricane Katia is threatening parts of Mexico.  At 11:00 a.m. EDT on Thursday the center of Hurricane Katia was located at latitude 21.6°N and longitude 94.6°W which put it about 215 miles (345 km) east of Tampico, Mexico.  Katia was stationary.  the maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155km/h)  The minimum surface pressure was 980 mb.

A Hurricane Warning is in effect for the portion of the coast from Cabo Rojo to Laguna Verde, Mexico.

 

Cat. 5 Hurricane Irma Moving Over Northern Leeward Islands

Category 5 Hurricane Irma moved over the northern Leeward Islands on Wednesday morning.  At 5:00 a.m. EDT on Wednesday the center of Hurricane Irma was located at latitude 17.9°N and longitude 62.6°W which put it about 35 miles (55 km) east-southeast of St. Martin.  Irma was moving toward the west-northwest at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 185 m.p.h. (295 km/h) and there were wind gusts to 210 m.p.h. (340 km/h).  The minimum surface pressure was 912 mb.

The core of Hurricane Irma moved across Antigua, Barbuda, St. Barthelemy and St. Martin in recent hours.  It will reach Anguilla later this morning.

Hurricane Watches were in effect for Antigua, Anguilla, Barbuda, Montserrat, St. Kitts, Nevis, Saba, St. Eustatius, Sint Maarten, St. Martin, St. Barthelemy, the British Virgin Islands, the U.S. Virgin Islands, Puerto Rico, Vieques, Culebra, Guadeloupe, the southeastern Bahamas including the Acklins, Cooked Islands, Long Cay, the Iguanas, Mayaguane, the Ragged Islands, the Turks and Caicos, and the portion of the coast of Cabo Engano, Dominican Republic to the northern border with Haiti.  Hurricane Watches are in effect for the central Bahamas, the portion of the coast from Le Mole St. Nicholas to the northern border with Haiti and from Matanzas province to Guantanamo province in Cuba.  A Tropical Storm Warning is in effect for the portion of the coast from Cabo Engano, Dominican Republic to the southern border with Haiti.  A Tropical Storm Watch is in effect for the portion of the coast from Le Mole St. Nicolas, Haiti to Port Au Prince.

Hurricane Irma maintained its intensity during the northern overnight hours.  It has a circular eye with a diameter of 30 miles (48 km).  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring of storms.  Winds to hurricane force extend out about 60 miles (95 km) from the center.  Winds to tropical storm force extend out about 160 miles (260 km) from the center.

The Hurricane Intensity Index (HII) is 44.1.  The Hurricane Size Index (HSI) is 19.8 and the Hurricane Wind Intensity Size Index (HWISI) is 63.9.  Those indices indicate that Hurricane Irma is capable of causing widespread catastrophic wind damage.

Hurricane Irma will continue to move over an environment very favorable for hurricanes.  Irma will stay over water where the Sea Surface Temperature is near 30°C.  The upper level winds will remain weak for several more days and there will be little wind shear.  An upper level trough over the eastern U.S. will produce strong winds when Irma gets closer to Florida.  The wind shear will increase at that time.  Hurricane Irma could go through eyewall replacement cycles which would cause fluctuations in intensity.

Hurricane Irma is moving near the western end of a subtropical high pressure system over the Atlantic Ocean which is steering Irma toward the west-northwest.  The west-northwesterly motion is expected to continue for several more days.  Eventually, the upper level trough over the eastern U.S. is forecast to turn Hurricane Irma toward the north when it approaches Florida.  On its anticipated track the center of Hurricane Irma is forecast to pass north of Puerto Rico and Hispaniola.

Elsewhere, Tropical Storm Jose is trailing behind Hurricane Irma and Tropical Storm Katia has developed over the southern Gulf of Mexico.  At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Jose was located at latitude 12.5°N and longitude 42.8°W which put it about 1255 miles east of the Leeward Islands.  Jose was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 1002 mb.

At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Katia was located at latitude 22.1°N and longitude 96.3°W which put it about 105 miles (165 km) east of Tampico, Mexico.  Katia was moving toward the east at 2 m.p.h. (3 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 1006 mb.