Tag Archives: HWISI

Tropical Cyclone Dumazile Drops Heavy Rain on La Reunion

Tropical Cyclone Dumazile dropped heavy rain on La Reunion on Monday.  At 4:00 p.m. EST on Monday the center of Tropical Cyclone Dumazile was located at latitude 23.3°S and longitude 52.5°E which put it about 260 miles (420 km) southwest of St. Denis, La Reunion.  Dumazile was moving toward the south-southeast at 11 m.p.h. (17 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 949 mb.

Tropical Cyclone Dumazile strengthened into the equivalent of a major hurricane on Monday.  It was a large, powerful tropical cyclone.  There was a small circular eye at the center of the circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several rainbands were revolving around the core of the circulation.  The storms around the core were generating strong upper level divergence which was pumping mass away from the tropical cyclone.  Winds to hurricane/typhoon force extended out about 90 miles (145 km) from the center of circulation.  Winds to tropical storm force extended out about 250 miles (400 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Dumazile was 20.6.  The Hurricane Size Index (HSI) was 30.3 and the Hurricane Wind Intensity Size Index (HWISI) was 50.9.  Those indices indicate that Tropical Cyclone Dumazile would be capable of causing extensive major damage if it made landfall.

Although the core of Tropical Cyclone Dumazile passed between Madagascar and La Reunion, the circulation was so large that rainbands on the eastern side of Dumazile passed over La Reunion.  Those rainbands dropped locally heavy rain and there were unconfirmed reports of flooding in parts of La Reunion.

Tropical Cyclone Dumazile has likely reached its peak intensity.  Dumazile is currently moving over water where the Sea Surface Temperature is near 28°C, but the tropical cyclone will move over colder water when it moves farther south.  An upper level trough near southern Africa is producing northwesterly winds which are blowing toward the top of the circulation.  Those winds are generating vertical wind shear and the shear is forecast to increase during the next several days.  The colder water and increased wind shear are forecast to weaken Tropical Cyclone Dumazile during the next few days.

Tropical Cyclone Dumazile has rounded the western end of a subtropical ridge and it is now moving toward the south-southeast.  A general southeastward motion is forecast for the next two or three days.  On its anticipated track Tropical Cyclone Dumazile should move away from Madagascar and La Reunion.

Powerful Tropical Cyclone Gita Hits Tonga, Threatens Southern Fiji

Powerful Tropical Cyclone Gita hit the most populated islands in Tonga on Monday and moved west to threaten the southernmost islands of Fiji.  Gita brought strong winds and very heavy rain to Tongapatu and Eau on Monday and there were reports of damage from Tonga.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Gita was located at latitude 21.1°S and longitude 178.9°W which put it about 300 miles (480 km) southeast of Suva, Fiji.  Gita was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (270 km/h).  The minimum surface pressure was 935 mb.  Tropical Cyclone Gita was the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.

Gita remains a powerful tropical cyclone.  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.  A rainband has wrapped most of the way around the core of Tropical Cyclone Gita and there are indications that a second, concentric eyewall is forming.  Other rainbands are revolving around the core of the circulation.  Storms in the core are producing strong upper level divergence which is pumping away mass and is allowing the tropical cyclone to remain very strong.  Winds to hurricane/typhoon force extend out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extend out about 200 miles (320 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Gita is 28.3.  The Hurricane Size Index (HSI) is 20.5 and the Hurricane Wind Intensity Size Index (HWISI) is 48.8.  Those indices indicate that Tropical Cyclone Gita is capable of causing significant damage.

Tropical Cyclone Gita will remain in an environment favorable for strong tropical cyclones for another 24 to 36 hours.  Gita will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is not much vertical wind shear.  If a second concentric eyewall forms, then an eyewall replacement cycle could produce a fluctuation in intensity.  Gita could weaken when the inner eyewall dissipates.  The circulation could strengthen again if the outer eyewall remains intact and starts to contract around the center of circulation.

Tropical Cyclone Gita is moving north of a subtropical ridge which is steering the tropical cyclone toward the west.  A general motion toward the west is expected to continue for another 48 to 72 hours.  On its anticipated track Tropical Cyclone Gita could move over the southernmost islands of Fiji on Tuesday.  The strongest part of Gita could affect Vatoa, Ono-i-lau, Tuvana-i-colo and Tuvana-i-ra.  Gita could bring destructive winds, locally heavy rain and storm surges to the southernmost parts of Fiji.  Tropical Cyclone Gita could approach southern Vanuatu and New Caledonia in about three days.

Powerful Tropical Cyclone Gita Threatens Tonga

Powerful Tropical Cyclone Gita posed an increasing threat to Tonga on Sunday night.  At 10:00 p.m. EST the center of Tropical Cyclone Gita was located at latitude 21.7°S and longitude 173.2°W which put it about 120 miles (195 km) east of Nuku’Alofa, Tonga.  Gita was moving toward the west 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 155 m.p.h. (205 km/h).  The minimum surface pressure was 944 mb.  Tropical Cyclone Gita was the equivalent of a major hurricane.

The circulation of Tropical Cyclone Gita is very well organized.  There is a circular eye at the center of circulation.  A ring of strong thunderstorms surrounds the eye and the strongest winds are occurring in that eye.  Bands of showers and thunderstorms are revolving around the core of Tropical Cyclone Gita.  Storms in the core are generating strong upper level divergence which is pumping mass away in all directions.  Winds to hurricane/typhoon force extend out about 50 miles (80 km) from the center of circulation.  Winds to tropical storm force extend out about 165 miles (270 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Gita is 23.6.  The Hurricane Size Index (HSI) is 16.0 and the Hurricane Wind Intensity Size Index (HWISI) is 39.6.  Those indices indicate that Gita will be capable of causing major damage when it moves over Tonga on Monday.

Tropical Cyclone Gita will be moving through an environment favorable for strong tropical cyclones during the next 24 to 48 hours.  Gita will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is little vertical wind shear.  The favorable environment could allow Tropical Cyclone Gita to intensify more before it reaches Tonga.

Tropical Cyclone Gita is moving north of a subtropical ridge which is steering the tropical cyclone toward the west.  A general motion toward the west is expected to continue for another two or three days.  On its anticipated track the center of Tropical Cyclone Gita could reach Tonga within 12 hours.  Tropical Cyclone Gita will be capable of causing major wind damage when it reaches Tonga.  Gita will also drop heavy rain and flooding is possible.  Winds blowing the wind toward the coast could also produce significant storm surges in some locations.

Tropical Cyclone Cebile Intensifies Rapidly Into Equivalent of Major Hurricane

Tropical Cyclone Cebile intensified rapidly on Sunday from a tropical storm to the equivalent of a major hurricane over the South Indian Ocean.  At 4:00 p.m. EST on Sunday the center of Tropical Cyclone Cebile was located at latitude 14.5°S and longitude 82.5°E which put it about 850 miles (1375 km) southeast of Diego Garcia.  Cebile was moving toward the southwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 945 mb.

Tropical Cyclone Cebile intensified very rapidly during the past 24 hours as it moved through a very favorable environment.  The maximum sustained wind speed increased from 50 m.p.h. (80 km/h) to 130 m.p.h. (215 km/h).  The circulation of Tropical Cyclone Cebile is very well organized.  There is a circular eye at the center of circulation.  The eye is surround by a ring of strong thunderstorms and the strongest winds are occurring in the ring of storms.  Rainbands are revolving around the core of the circulation.  Tropical Cyclone Cebile is generating strong upper level divergence which is pumping away mass and allowing the surface pressure to decrease rapidly.

The circulation of Tropical Cyclone Cebile is symmetrical.  Winds to hurricane/typhoon force extend out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extend out about 150 miles (240 km) from the center.  The Hurricane Intensity Index (HII) for Tropical Cyclone Cebile is 25.1.  The Hurricane Size Index (HSI) is 12.7 and the Hurricane Wind Intensity Size Index (HWISI) is 37.8.

Tropical Cyclone Cebile continues to move through an environment favorable for intensification.  Cebile is moving over water where the Sea Surface Temperature is near 28°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Cebile is likely to intensify further and it could become the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.

Cebile is moving near the western part of a subtropical ridge which is steering the tropical cyclone toward the southwest.  A general southwesterly motion is expected to continue for the next few days.  On its anticipated track Tropical Cyclone Cebile will remain well south of Diego Garcia.

Elsewhere in the tropics, Tropical Cyclone 08S was moving near the northern end of New Caledonia.  At 4:00 p.m. EST on Sunday the center of Tropical Cyclone 08S was located at latitude 18.8°S and longitude 162.1°E which put it about 370 miles (600 km) northwest of Noumea, New Caledonia.  It was moving toward the southeast at 11 m.p.h. (17 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 986 mb.

Strong Tropical Cyclone Ava Makes Landfall in Madagascar

Strong Tropical Cyclone Ava made landfall on the east coast of Madagascar near Toamasina on Friday.  At 10:00 a.m. EDT on Friday the center of Tropical Cyclone Ava was located near 18.0°S and longitude 49.2°E which put it near Toamasina.  Ava was moving toward the west-southwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 959 mb.  Tropical Cyclone Ava was the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.

Tropical Cyclone Ava intensified rapidly during the past 12 hours and it was still intensifying when it made landfall on the coast of Madagascar.  There was a well defined circular eye at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of the circulation.  Thunderstorms in the core of Tropical Cyclone Ava were generating strong upper level divergence which was pumping away mass and allowed the surface pressure to decrease rapidly.  Winds to hurricane/typhoon force extended out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extended out about 180 miles (290 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Ava was 17.8.  The Hurricane Size Index (HSI) was 17.6 and the Hurricane Wind Intensity Size Index (HWISI) was 35.4.  Those indices indicate that Tropical Cyclone Ava is capable of causing regional serious damage.  The core of Tropical Cyclone Ava passed over Toamasina and there is likely to be serious wind damage in that city.  Heavy rain was falling in parts of eastern Madagascar and floods could occur.  Tropical Cyclone Ava could produce a storm surge of 10 feet (3 meters) south of where the center made landfall, because the strong winds will be blowing the water toward the coast.

Tropical Cyclone Ava will weaken while the center moves over land in eastern Madagascar.  However, the rest of the environment is favorable for a tropical cyclone.  The Sea Surface Temperature off the east coast of Madagascar is near 28°C.  The upper level winds are weak and there is little vertical wind shear.  If the inner core of Tropical Cyclone Ava remains intact, then Ava could intensify again when the center moves back over the South Indian Ocean in a day or so.

Tropical Cyclone Ava is moving around the western end of a subtropical ridge which is steering the tropical cyclone toward the west-southwest.  Ava will start to move toward the south when it reaches the end of the ridge in a few hours.  On its anticipated track Tropical Cyclone Ava is forecast to move just inland of the east coast of Madagascar.  Ava is forecast to move back off the coast in 24 to 36 hours.  Tropical Cyclone Ava is capable of causing serious damage along the central east coast of Madagascar.

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.