Tag Archives: Tropical Depression Nine

Hurricane Fiona Blows Past Bermuda

Hurricane Fiona blew past Bermuda on Thursday night. At 8:00 a.m. EDT on Friday the center of Hurricane Fiona was located at latitude 34.1°N and longitude 64.9°W which put it about 125 miles (200 km) north of Bermuda. Fiona was moving toward the north-northeast at 25 m.p.h. (40 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 936 mb.

A Tropical Storm Warning was in effect for Bermuda. A Hurricane Warning was in effect for the portion of the coast from Hubbards to Brule, Nova Scotia. Hurricane Warnings were in effect for Prince Edward Islands and Isle de la Madeline. A Hurricane Warning was in effect for the portion of the coast from Parson’s Pond to Francois, Newfoundland. A Tropical Storm Warning was in effect for St. Andrews, New Brunswick to Hubbards, Nova Scotia. A Tropical Storm Warning was in effect for the portion of the coast from Brule, Nova Scotia to Cap Madeline, Quebec. Tropical Storm Warnings were in effect for Anticosti Island and for the portion of the coast from Sheldrake, Quebec to Parson’s Pond, Newfoundland. A Tropical Storm Warning was in effect for the portion of the coast from Boat Harbor to Hare Bay, Newfoundland. A Tropical Storm Warning was in effect for the portion of the coast from Francois to St. Lawrence, Newfoundland. A Tropical Storm Watch was in effect for the portion of the coast from Boat Harbor, Newfoundland to West Bay, Labrador.

The center of Hurricane Fiona passed west of Bermuda on Thursday night. The L. F. Wade International Airport in Bermuda reported a sustained wind speed of 64 m.p.h. (103 km/h) and a wind gust of 83 m.p.h. (134 km/h). There were reports of stronger wind speeds measured by automated stations in higher locations in Bermuda.

Hurricane Fiona continued to be a large, well organized hurricane. A circular eye with a diameter of 35 miles (55 km) was at the center of Fiona’s circulation. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms revolved around the core of Hurricane Fiona. Storms near the core generated strong upper level divergence that pumped mass away from the hurricane.

Hurricane Fiona grew into a large hurricane as it moved farther north on Thursday night. Winds to hurricane force extended out 90 miles (145 km) from the center of Fiona. Winds to tropical storm force extended out 345 miles (555 km) from the center of circulation. The Hurricane Intensity Index (HII) was 23.6. The Hurricane Size Index (HSI) was 32.70 and the Hurricane Wind Intensity Size Index (HWISI) was 56.3. Hurricane Fiona was larger than Hurricane Jeanne was in 2004.

Hurricane Fiona will move through an environment that will become less favorable for a major hurricane during the next 24 hours. Fiona will move over water where the Sea Surface Temperatures colder than 26˚C. An upper level trough near the East Coast of the U.S. will produce southwesterly winds that will blow toward the top of Fiona’s circulation. Those winds will cause the vertical wind shear to increase. Hurricane Fiona will start to weaken gradually when the wind shear increase. A combination of colder Sea Surface Temperatures and moderate vertical wind shear will cause Hurricane Fiona to make a transition to a very strong extratropical cyclone.

The upper level trough near the East Coast of the U.S. will steer Fiona toward the north-northeast during the next 24 hours. On its anticipated track, Hurricane Fiona will move away from Bermuda on Friday. Hurricane Fiona will approach the Canadian Maritimes on Friday night. Fiona will bring strong, destructive winds to the Canadian Maritimes. Heavy rain could cause floods in some locations.

Elsewhere over the Atlantic Ocean, Tropical Storm Gaston was bringing wind and rain to the Azores and Tropical Depression Nine formed over the southeastern Caribbean Sea. Tropical Storm Warnings were in effect for Corvo, Flores, Faial, Pico, Sao Jorge, Graciosa, and Terceira. At 8:00 a.m. EDT on Friday the center of Tropical Storm Gaston was located at latitude 40.5°N and longitude 29.2°W which put it about 135 miles (215 km) north-northwest of the Faial. Gaston was moving toward the east-southeast at 7 m.p.h. (11 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 999 mb.

At 5:00 a.m. EDT on Friday the center of Tropical Depression Nine was located at latitude 13.9°N and longitude 68.6°W which put it about 615 miles (985 km) east-southeast of Kingston, Jamaica. The tropical depression was moving toward the west-northwest at 13 m.p.h. (20 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 1006 mb. Tropical Depression Nine is forecast to intensify to a hurricane over the northwestern Caribbean Sea during the weekend. It could move over the southeastern Gulf of Mexico early next week.

Tropical Depression Nine Forms over Northwest Caribbean

Tropical Depression Nine formed over the northwestern Caribbean Sea on Thursday morning. At 11:00 a.m. EDT on Thursday the center of Tropical Depression Nine was located at latitude 16.9°N and longitude 79.2°W which put it about 210 miles (340 km) southeast of Grand Cayman. The tropical depression was moving toward the northwest at 13 m.p.h. (20 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 1005 mb.

Tropical Storm Warnings were issued for the Cayman Islands. Tropical Storm Warnings were also issued for the Cuban provinces of Matanzas, Mayabeque, Havana, Artemise, Pinar del Rio and the Isle of Youth.

Satellite images indicated the development of a circulation within a tropical wave over the northwestern Caribbean Sea on Thursday morning and the National Hurricane Center designated the system as Tropical Depression Nine. The circulation around Tropical Depression Nine was still organizing. Bands of showers and thunderstorms were starting to form. The strongest thunderstorms were occurring in bands forming on the eastern side of the tropical depression. An upper level low near Florida was producing south-southwesterly winds that were blowing across the western side of Tropical Depression Nine. Those winds were causing moderate vertical wind shear and they were contributing to the asymmetrical distribution of thunderstorms.

Tropical Depression Nine will move around the southwestern part of a subtropical high pressure system during the next several days. The high will steer the depression toward the northwest. On its anticipated track Tropical Depression Nine will move over the Cayman Islands on Thursday night. It could be near western Cuba on Friday evening. The system will move over the Gulf of Mexico during the weekend. It could approach the center coast of the Gulf of Mexico on Sunday.

Tropical Depression Nine will move into an environment that will become more favorable for intensification during the next three days. The upper low near Florida will move off to the northwest and it will weaken. When the upper low weakens, they vertical wind shear will decrease. The tropical depression will move over water where the Sea Surface Temperatures are near 30°C. Tropical Depression Nine could strengthen to a tropical storm later today. It could strengthen to a hurricane during the next 36 hours. An upper level ridge will be over the Gulf of Mexico during the weekend. The upper level winds will be weak and there will be little vertical wind shear. A period of rapid intensification could occur when the system moves toward the central Gulf Coast. It could rapidly intensify to a major hurricane.

Tropical Depression Nine Develops Near the Bahamas

Tropical Depression Nine developed near the Bahamas on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Tropical Depression Nine was located at latitude 25.6°N and longitude 75.0°W which put it about 140 miles (225 km) east-southeast of Great Abaco, Bahamas.  It was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1009 mb.

Tropical Storm Warnings were in effect for the Abacos, the Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.  A Tropical Storm Watch was in effect for the portion of the Florida coast from Jupiter Inlet to the Volusia/Brevard County Line.

An Air Force Reserve Hurricane Hunter plane was able to identify a low level center of circulation in a tropical disturbance near the Bahamas on Friday afternoon and the National Hurricane Center designated the system as Tropical Depression Nine.  The center of circulation developed on the southwestern side of a cluster of thunderstorms just east of the Bahamas.  The circulation around the depression was still in the early stages of organization.  Most of the stronger thunderstorms were occurring in the eastern half of the tropical depression.  Bands in the western half of the circulation consisted primarily of showers and lower clouds.

Tropical Depression Nine will move through an environment somewhat favorable for intensification during the next few days.  The tropical depression will move over water where the Sea Surface Temperature is near 29°C.  A large upper level low over the Gulf of Mexico will produce southerly winds which will blow toward the top of the depression.  Those winds will cause moderate vertical wind shear and they will inhibit intensification.  The upper low is forecast to move westward away from the  tropical depression and the wind shear could decrease during the weekend.  Tropical Depression Nine is forecast to slowly become more organized and it could strengthen into a tropical storm.

The upper low over the Gulf of Mexico will help to steer Tropical Depression Nine toward the northwest during the next day or two.  A strong upper level trough over the Great Lakes will start to turn the depression toward the east later in the weekend.  On its anticipated track the center of the depression could move near the Northwestern Bahamas.  If Tropical Depression Nine brings wind and rain to that region, it will hinder efforts to recover from Hurricane Dorian.

Tropical Depression Nine Causes Hurricane Watch for Part of Florida

Although Tropical Depression Nine did not strengthen on Tuesday afternoon, guidance from numerical models suggested it could be stronger when it eventually reaches the coast of Florida.  As a result, the National Hurricane Center at 5:00 p.m. EDT issued a Hurricane Watch for the portion of the Florida coast from Anclote River to Indian Pass.  A Tropical Storm Watch was issued for the portion of the coast from Indian Pass to the Walton County/Bay County line.

At 5:00 p.m. EDT on Tuesday the center of Tropical Depression Nine was located at latitude 24.4°N and longitude 87.3°W which put it about 345 miles (555 km) west of Key West, Florida.  It was moving toward the northwest 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. (70 km/h).  The minimum surface pressure was 1004 mb.

The circulation of Tropical Depression Nine is not currently well organized.  The surface center is located northwest of an apparent mid-level center.  Upper level divergence is not well developed.  The development of thunderstorms has been cyclical during the past several days.  Clusters of thunderstorms developed south and east of the center and then they weaken.  A few hours later more thunderstorms would develop, persist for a few hours and weaken again.  It appears that new thunderstorms are developing northeast and southwest of the surface center which would be a change from the previous pattern.

The vertical structure of Tropical Depression Nine has been out of sync.  As mentioned above, the surface center was northwest of the mid-level center.  Both the surface and mid-level centers have been located on the western edge of a larger upper level high.  Clockwise flow around the upper high has been creating vertical wind shear, which has prevented the development of a vertically coherent structure in the depression.  Despite the effect of the wind shear and the lack of a coherent vertical structure, the surface center has managed to persist and become a little more organized each day.

Tropical Depression Nine is moving through an environment that is currently marginal for intensification.  It is moving over water where the Sea Surface Temperature is near 31°C.  So, there is plenty of energy in the upper ocean.  The vertical wind shear mentioned previously is the primary factor inhibiting intensification.  However, as Tropical Depression Nine moves north, if is forecast to move into an area where the upper level winds are not as strong.  If that happens, then the depression will strengthen.  As the depression becomes more organized, the rate of intensification could increase and the depression could become a hurricane over the northeastern Gulf of Mexico.

An upper level ridge over the southeastern U.S. has been blocking the northward movement of Tropical Depression Nine.  An upper level trough approaching from the west is expected to weaken the ridge.  As the ridge weakens, The depression will be able to move north.  Eventually in a couple of days, the upper level trough is expected to steer the depression more toward the northeast.  On its anticipated track the depression could be approaching the northeastern Gulf Coast by Thursday afternoon.

The northeastern Gulf Coast is very susceptible to storm surges and a surge is the greatest risk.  Locally heavy rain could cause some flooding, and there could be some minor wind damage.

Tropical Depressions Form South of Key West & Southeast of Cape Hatteras

Two tropical depressions formed near the U.S. on Sunday.  Tropical Depression Nine formed south of Key West, Florida and Tropical Depression Eight formed southeast of Cape Hatteras, North Carolina.  Both depressions could have an impact on the U.S., but Tropical Depression Nine could pose a greater risk to the southeastern U.S.

At 5:00 p.m. EDT on Sunday the center of Tropical Depression Nine was located at latitude 23.7°N and longitude 81.7°W which put it about 60 miles (95 km) south of Key West, Florida.  It was moving toward the west at 9 m.p.h. (15 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. (70 km/h).  The minimum surface pressure was 1009 mb.

At 5:00 p.m. EDT on Sunday the center of Tropical Depression Eight was located at latitude 31.8°N and longitude 70.9°W which put it about 355 miles (570 km) southeast of Cape Hatteras, North Carolina.  It was moving toward the west at 9 m.p.h. (15 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. (70 km/h).  The minimum surface pressure was 1010 mb.

The circulation of Tropical Depression Nine is still organizing.  A NOAA plane found a distinct center of circulation, but most of the stronger thunderstorms are south and east of the center.  There is a broader counterclockwise rotation with numerous showers and thunderstorms indicated by the National Weather Service radar in Key West.  An upper level low east of Florida is contributing to easterly winds that are blowing across the northern side of the depression.  The vertical wind shear is inhibiting the development of thunderstorms north and west of the center.

The circulation of Tropical Depression Eight was more well organized earlier today.  Strong easterly winds from the same upper level low that is affecting Tropical Depression Nine are creating significant vertical wind shear.  Those winds and the shear they caused blew the upper portion of the depression’s circulation west of the low level center of circulation.  The low level circulation is presently exposed as seen on visible satellite imagery and by an Air Force Reserve Hurricane Hunter aircraft.

The intensity forecast for Tropical Depression Nine is challenging because it is moving through a complex environment.  The depression is moving over water where the Sea Surface Temperature is near 31°C.  So, there is plenty of energy in the upper ocean.  However, as mentioned above, an upper low is causing vertical wind shear which will inhibit intensification.  Tropical Depression Nine could move into a region where there is less shear when it moves over the Gulf of Mexico.  Tropical Depression Nine has a good chance to intensify into a tropical storm, but it is unclear if it could become a hurricane before it reaches the coast.

There is also significant uncertainty in the track forecast for Tropical Depression Nine.  A ridge over the southeastern U.S. is steering the depression toward the west and that general motion should continue for several more days.  The ridge is forecast to weaken during the middle of the week and that should allow Tropical Depression Nine to turn toward the north.  The timing of that turn and how sharp it will be are still uncertain.

The upper low is expected to continue to generate wind shear over Tropical Depression Eight.  If the upper levels winds remain as strong as they are now, the depression will slowly weaken.  If the upper level winds weaken, then Tropical Depression Eight could strengthen into a minimal tropical storm.  The upper level low is steering the depression west and that general motion is expected to continue in the short term.  The depression could stall just off the coast of North Carolina.

Tropical Depression Nine could intensify and bring wind and rain to the Gulf Coast later this week.  The Gulf Coast is also vulnerable to storm surges.  Given the uncertainty in both the track and intensity, interests along the coast should monitor official sources of information for updates on Tropical Depression Nine.  The primary effects of Tropical Depression Eight are likely to be higher than normal surf, rip currents and some beach erosion along the North Carolina coast.  People along the Mid-Atlantic coast should pay attention to the depression in case the forecast changes.