Category Archives: Atlantic, Caribbean, and Gulf of Mexico

Atlantic TCs

Tropical Depression Seventeen Develops over Western Gulf of Mexico

Tropical Depression Seventeen developed over the western Gulf of Mexico on Friday.  At 11:00 a.m. EDT on Friday morning the center of Tropical Depression Seventeen was located at latitude 25.6°N and longitude 94.4°W which put it about 320 miles (515 km) south-southwest of Lake Charles, Louisiana.  It was moving toward the north at 16 m.p.h. (26 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.

More thunderstorms developed near the center of a low pressure system over the western Gulf of Mexico on Friday morning and the National Hurricane Center designated the system as Tropical Depression Seventeen.  Bands of showers and thunderstorms were also developing around the depression.  The strongest rainbands were in the eastern half of the circulation.  Bands in the western half of the circulation consisted of more showers and lower clouds.  Storms near the center were generating upper level divergence which was pumping mass away to the northeast of the depression.

Tropical Depression Seventeen is likely to strengthen during the next 12 to 18 hours.  The depression will move over water where the Sea Surface Temperature is near 28°C.  An upper level trough over the south central U.S. and Mexico will produce southwesterly winds which will blow toward the top of the depression.  Those winds will produce moderate vertical wind shear, which will inhibit intensification.  However, the shear will not be strong enough to prevent intensification while the depression is over the Gulf of Mexico.  The wind shear will cause the depression to start a transition to an extratropical cyclone.  A cold front will move toward the depression from the northwest and the depression could merge with the front during the next 24 hours.

The upper level trough will steer the depression toward the north during the next several days.  On its anticipated track the depression will make landfall on the coast of Louisiana during Friday night.  The depression could be a tropical storm when it makes landfall.  It will bring gusty winds to coastal Louisiana.  The depression is likely to drop heavy rain over parts of Louisiana, Mississippi, and eastern Arkansas.  The rain could cause floods in some locations.

Tropical Storm Nestor Causes Severe Weather in Florida

Tropical Storm Nestor caused severe weather in Florida.  At 2:00 p.m. EDT on Saturday the center of Tropical Storm Nestor was located at latitude 29.7°N and longitude 85.1°W which put it about 5 miles (10 km) west of Apalachicola, Florida.  Nestor was moving toward the east-northeast at 23 m.p.h. (38 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 999 mb.

A Tropical Storm Watch was in effect for the portion of the coast from Ochlockonee River to Suwanee River, Florida.

Tropical Storm Nestor began a transition to an extratropical cyclone as it approached the coast of Florida.  Strong westerly winds in the middle latitudes created significant vertical wind shear.  In addition, the circulation around Nestor pulled cooler, drier air into the western and southern parts of the tropical storm.  The effects of the upper level westerly winds and cooler, drier air caused the strongest rising motion to occur in bands well to the east of the center of circulation.  The strongest thunderstorms occurred in bands southeast of the low level center.

The vertical wind shear was strong enough that rotation developed in some of the thunderstorms over the Florida Peninsula.  Several tornado warnings were issued on Friday night because radar indicated likely rotation.  There were reports of property damage due to possible tornadoes in Cape Coral in Lee County, near Winston in Polk County, in Plant City in Hillsborough County and in Seminole in Pinellas County.

The center of Tropical Storm Nestor officially made landfall on St. Vincent Island west of Apalachicola on Saturday afternoon.  Many of the stronger thunderstorms had moved east of Florida by Saturday afternoon.  There were still bands of showers and thunderstorms moving over the Florida Peninsula.  Flow diverging from a surface high pressure system centered over the northeastern U.S. was converging with the flow around the northern part of Tropical Storm Nestor.  The convergence was generating a large area of rising motion.  Showers and thunderstorms were occurring over northern Florida, southeastern Alabama, southern Georgia and parts of South Carolina.

Tropical Storm Nestor will move toward the northeast as an extratropical cyclone during the next several days.  On its anticipated track the center of Nestor will move across southern Georgia and near the coast of South Carolina and North Carolina.  The low pressure system will continue to drop rain over those areas.  There has been below normal rainfall over the southeastern U.S. in recent weeks.  So, the rain is unlikely to cause flooding in most places.

Tropical Storm Nestor Speeds Toward Northwest Florida

Tropical Storm Nestor sped toward northwest Florida on Friday afternoon.  The National Hurricane Center designated a strong low pressure system over the Gulf of Mexico as Tropical Storm Nestor on Friday afternoon.  At 2:00 p.m. EDT on Friday the center of Tropical Storm Nestor was located at latitude 26.3°N and longitude 89.5°W which put it about 355 miles (570 km) southwest of Panama City, Florida.  Nestor was moving toward the northeast at 22 m.p.h. (35 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 1001 mb.

Tropical Storm Warnings were in effect for the portions of the coast from Grand Isle, Louisiana to the mouth of the Pearl River, Mississippi and from the Mississippi/Alabama border to Yankeetown, Florida.  A Storm Surge Warning was in effect for the portion of the coast from Indian Pass to Clearwater Beach, Florida.

Tropical Storm Nestor exhibited an asymmetrical structure that is commonly seen in late season tropical storms over the Gulf of Mexico.  The strongest thunderstorms were occurring in bands in the eastern side of Nestor.  Bands in the western half of the circulation consisted primarily of showers and lower clouds.  The tropical storm force winds were occurring in the eastern half of Tropical Storm Nestor.  Winds to tropical storm force extended out 175 miles (280 km) in the eastern side of the circulation.  The winds in the western half of Nestor were mostly less than tropical storm force.

Drier air was being pulled around the western side of Tropical Storm Nestor.  In addition, an upper level trough over the western Gulf of Mexico was producing southwesterly winds which were blowing toward the top of the circulation.  Those winds were causing moderate vertical wind shear.  The combination of the drier air and the vertical wind shear was responsible for the asymmetrical distribution of thunderstorms and strong winds in the eastern half of the circulation.

Tropical Storm Nestor will move through an environment only marginally favorable for further intensification during the next 12 hours.  Nestor will move over water where the Sea Surface Temperature is near 29°C.  So, there is plenty of energy in the upper part of the Gulf of Mexico to support intensification.  However, the drier air and wind shear will inhibit intensification.  Tropical Storm Nestor will start a transition to an extratropical cyclone on Saturday.  Nestor could strengthen somewhat during the extratropical transition, but it could be over land before that occurs.

The upper level trough over the Western Gulf of Mexico will steer Nestor quickly toward the northeast during the next 48 hours.  On its anticipated track Tropical Storm Nestor could make landfall on the coast of northwest Florida between Panama City and Apalachicola.  Nestor will bring gusty winds to northern Florida on Saturday.  Strong southerly winds on the eastern side of Tropical Storm Nestor will push water toward the coast and a storm surge of 3 to 6 feet (1 to 2 meters) will occur around the northeastern Gulf of Mexico.  Nestor could drop locally heavy rain over parts of northern Florida, southeast Alabama, southern Georgia and South Carolina.  Tropical Storm Nestor will make landfall near where Hurricane Michael did so much damage in 2018.  Recovery efforts have been slow in that area and Nestor could set back the ongoing recovery from Hurricane Michael.

Low Pressure System Forms Over Southwest Gulf of Mexico

A surface low pressure system formed over the southwestern Gulf of Mexico on Wednesday.  At 8:00 p.m. EDT on Wednesday the center of the low pressure system was located at latitude 20.8°N and longitude 95.4°W which put it about 70 miles (110 km) east-southeast of Nautla, Mexico.  The low was moving toward the north at 9 m.p.h. (15 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.

The northern end of a trough of low pressure moved over the Bay of Campeche on Wednesday and a surface low formed when the trough moved over the southwestern Gulf of Mexico.  More thunderstorms developed near the center of the low pressure system.  Divergence from a surface high pressure system over the U.S. was converging with the northern periphery of the circulation around the surface low and a band of showers and thunderstorms was occurring over the west central Gulf of Mexico.  Storms near the center of the low were starting to generate some upper level divergence.

The low pressure system will move through an environment that will be favorable for intensification during the next 24 to 36 hours.  The low will move over water where the Sea Surface Temperature is near 29°C.  It will move under an upper level ridge where the winds are weak and divergent.  The low could intensify slowly if it gets better organized on Thursday.  The National Hurricane Center is indicating that there is a 60% probability of formation of either a tropical or subtropical storm.  A reconnaissance plane has been tentatively tasked to investigate the low pressure system on Thursday afternoon.

The upper level ridge over the surface low pressure system will steer the low toward the northeast during the next several days.  On its anticipated track the low could approach the northeastern coast of the Gulf of Mexico on Friday.  The low will bring gusty winds and locally heavy rain.  The winds will generate higher waves and there could be a storm surge of 3 to 6 feet (1 to 2 meters).

Tropical Depression Fifteen Forms Southeast of Cabo Verde Islands

Tropical Depression Fifteen formed southeast of the Cabo Verde Islands on Monday.  At 5:00 p.m. EDT on Monday the center of Tropical Depression Fifteen was located at latitude 13.2°N and longitude 20.2°W which put it about 320 miles (515 km) southeast of the Cabo Verde Islands.  The depression was moving toward the northwest at 8 m.p.h. (13 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.

A large, well developed low pressure system embedded in the northern end of a tropical wave moved over the Atlantic Ocean west of North Africa on Monday.  Bands of showers and thunderstorms began to strengthen when the low moved over water and the National Hurricane Center designated the system as Tropical Depression Fifteen.  Bands of showers and thunderstorms were revolving around the center of the depression.  Storms closer to the center were generating upper level divergence which was pumping mass away from Tropical Depression Fifteen.  The circulation around the depression was quite large.  The diameter of the low level circulation was about 500 miles (800 km).

Tropical Depression Fifteen will move through an environment favorable for intensification during the next 24 to 48 hours.  The depression will move over water where the Sea Surface Temperature is near 28°C.  It will move under the western end of an upper level ridge centered over North Africa.  The upper level winds will be weak and there will be little vertical wind shear during the next day or two.  Tropical Depression Fifteen is likely to strengthen into Tropical Storm Nestor.

The ridge over North Africa will steer Tropical Depression Fifteen toward the northwest during the next several days.  On its anticipated track the center of the depression could reach the Cabo Verde Islands within 24 hours.  Since the depression is forecast to strengthen into a tropical storm watches and/or warnings could be issued.

Elsewhere over the Atlantic Ocean, Tropical Storm Melissa completed a transition to an extratropical cyclone on Monday.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Melissa was located at latitude 41.0°N and longitude 51.4°W which put it about 405 miles (650 km) south-southeast of Cape Race, Newfoundland.  Melissa was moving toward the east at 23 m.p.h. (37 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 1004 mb.

Subtropical Storm Melissa Develops off Northeast U.S. Coast

Subtropical Storm Melissa developed off the northeast coast of the U.S. on Friday.  At 11:00 a.m. EDT on Friday the center of Subtropical Storm Melissa was located at latitude 38.5°N and longitude 69.6°W which put it about 190 miles (300 km) south of Nantucket, Massachusetts.  Melissa was moving toward the south-southwest at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 995 mb.

More thunderstorms developed near the center of a large low pressure system off the northeast coast of the U.S. on Friday morning and the National Hurricane Center designated the system as Subtropical Storm Melissa.  Melissa initially began as an extratropical cyclone along a slow moving cold front off the east coast of the U.S earlier this week.  The cold front moved east of the surface low pressure system and the surface low stalled underneath an upper level trough.  More showers and thunderstorms began to develop in bands and the low pressure system started to look more subtropical.

The circulation around Melissa was characteristic of a subtropical storm.  There was a well defined center of circulation visible on satellite images.  However, many of the stronger thunderstorms were occurring in a band that wrapped around the northern portion of the circulation.  Bands in the other parts of the circulation consisted primarily of showers and lower clouds.  The circulation was drawing cooler, drier air into the western and southern parts of the subtropical storm.  The wind field around Subtropical Storm Melissa was large and asymmetrical.  Winds to tropical storm force extended out 350 miles (565 km) from the center in the northeastern part of Melissa.  Tropical storm force winds only extended out 100 miles (160 km) to the southeast of the center of circulation.

The intensity of Subtropical Storm Melissa may not change much during the next 12 to 24 hours.  Melissa will remain under the middle of the upper level trough during the rest of Friday.  The winds are weak in the middle of the trough and there will not be much vertical wind shear.  Subtropical Storm Melissa will be over water where the Sea Surface Temperature is near 24°C.  So, there will not be a lot of energy in the upper ocean to support intensification.  The upper level trough will move eastward on Saturday and westerly winds will blow toward the top of Melissa.  The westerly winds will cause significant vertical wind shear, which will start to weaken Subtropical Storm Melissa.

Since the winds are weak in the middle of the upper level trough, Subtropical Storm Melissa is unlikely to move much during the rest of Friday.  Stronger westerly winds will steer Melissa to the east during the weekend.  On its anticipated track Subtropical Storm Melissa is forecast to move away from the U.S. during the weekend.  The large circulation around Melissa will generate large waves which will affect the south coast of New England and the Mid-Atlantic states.  Coastal flooding could occur in some locations.

Hurricane Lorenzo Brings Wind and Rain to the Azores

Hurricane Lorenzo brought wind and rain to the Azores on Tuesday night.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Lorenzo was located at latitude 39.1°N and longitude 32.7°W which put it about 85 miles (135 km) west-southwest of Flores Island, Azores.  Lorenzo was moving toward the northeast at 40 m.p.h. (65 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 960 mb.

Hurricane Warnings were in effect for the western and central Azores including Flores, Corvo, Faial, Pico, Sao Jorge, Graciosa and Terceira. Tropical Storm Warnings were in effect for the eastern Azores including Sao Miguel and Santa Maria.

Although Hurricane Lorenzo moved into a more extratropical environment, it remained a large and powerful hurricane.  Winds to hurricane force extended out 150 miles (240 km) from the center of circulation.  Winds to tropical storm force extended out 390 miles (630 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Lorenzo was 16.5.  The Hurricane Size Index (HSI) was 50.2 and the Hurricane Wind Intensity Size Index (HWISI) was 66.7.  The radius of hurricane force winds was larger in Hurricane Lorenzo than it was in Hurricane Sandy in 2012.  The overall size of Hurricane Lorenzo was similar to the size of Hurricane Sandy.

Hurricane Lorenzo will move into an extratropical environment during the next several days.  Lorenzo will move over water where the Sea Surface Temperature is colder than 24°C.  An upper level trough over the north Atlantic Ocean will produce southwesterly winds which will blow toward the top of the circulation.  Those winds will cause strong vertical wind shear.  The colder water and strong shear will cause Hurricane Lorenzo to weaken gradually.  The cooler, more strongly sheared environment will also cause Hurricane Lorenzo to make a transition into a strong extratropical cyclone during the next 48 hours.

The upper level trough will steer Hurricane Lorenzo rapidly toward the northeast during the next 24 to 36 hours.  Lorenzo will turn more toward the east later on Thursday.  On its anticipated track Hurricane Lorenzo will bring strong winds, large waves and heavy rain to the Azores on Wednesday.  Lorenzo will be capable of causing extensive serious damage.  The extratropically transitioned Hurricane Lorenzo could approach Ireland and the United Kingdom on Thursday night and Friday.

Hurricane Lorenzo Prompts Watches for the Azores

The risk posed by Hurricane Lorenzo prompted the issuance of watches for the Azores.  At 11:00 p.m. EDT on Sunday the center of Hurricane Lorenzo was located at latitude 27.6°N and longitude 43.5°W which put it about 1195 miles (1920 km) west-southwest of the Azores.  Lorenzo was moving toward the north-northeast at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 952 mb.

Hurricane Watches were issued for the western and central Azores including Flores, Corvo, Faial, Pico, Sao Jorge, Graciosa, Terceira.  Tropical Storm Watches were issued for the eastern Azores including Sao Miguel and Santa Maria.

Hurricane Lorenzo weakened on Sunday when it moved into a less favorable environment.  Lorenzo moved over water where the Sea Surface Temperature was a little cooler.  In addition, an upper level trough west of Hurricane Lorenzo was producing southwesterly winds which were blowing toward the top of the circulation.  Those upper level winds were causing more vertical wind shear.  The combination of cooler water and more shear was responsible for weakening Hurricane Lorenzo.

Even though Hurricane Lorenzo weakened on Sunday it remained a large and powerful hurricane.  Winds to hurricane 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 Hurricane Lorenzo was 19.2.  The Hurricane Size Index (HSI) 32.6 was and the Hurricane Wind Intensity Size Index (HWISI) was 51.8.  Hurricane Lorenzo was capable of causing widespread serious damage.

Hurricane Lorenzo is likely to continue to weaken slowly during the next several days because of the less favorable environment consisting of cooler water and more vertical wind shear.  Since the circulation around Lorenzo is so large, the hurricane will weaken slowly.

The upper level trough will steer Hurricane Lorenzo toward the northeast during the next two or three days.  On its anticipated track Hurricane Lorenzo could reach the Azores by Tuesday night.  Lorenzo could be a large hurricane capable of causing widespread serious damage when it reaches the Azores.

Hurricane Lorenzo Strengthens to Cat. 5 Southwest of the Azores

Hurricane Lorenzo strengthened to Category 5 on the Saffir-Simpson Scale on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Hurricane Lorenzo was located at latitude 24.2°N and longitude 44.9°W which put it about 1420 miles (2285 km) southwest of the Azores.  Lorenzo was moving toward the north at 10 m.p.h. (16 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 Lorenzo strengthened to Category 5 farther east in the Atlantic Ocean than other hurricane on record.  Lorenzo appeared to complete an eyewall replacement cycle earlier on Saturday and then it start to strengthen quickly.  A circular eye with a diameter of 35 miles (55 km) became evident at the center of circulation.  A ring of very strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Hurricane Lorenzo.

The circulation around Hurricane Lorenzo was large.  Wins to hurricane force extended out about 50 miles (80 km) from the center of circulation.  Winds to tropical storm force extended out about 275 miles (445 km) from the center.  The Hurricane Intensity Index (HII) was 35.0.  The Hurricane Size Index (HSI) was 21.2 and the Hurricane Wind intensity Size Index (HWISI) was 56.2.

Hurricane Lorenzo will remain in a very favorable environment for another 12 to 24 hours.  It will move over water where the Sea Surface Temperature is near 28°C.  An upper level trough will approach Lorenzo from the west later on Sunday.  The trough will produce southwesterly winds which will create more wind shear.  Hurricane Lorenzo will start to weaken when the wind shear increases.  Lorenzo will also move over cooler water on Monday, which will cause more weakening.

The upper level trough will steer Hurricane Lorenzo toward the northeast during the next few days.  On its anticipated track Hurricane Lorenzo could approach the Azores on Tuesday night.  Lorenzo is likely to be a hurricane when it reaches the Azores.  Hurricane Lorenzo will eventually make a transition to a strong extratropical cyclone.  It could be near Ireland in four or five days.

Powerful Hurricane Lorenzo Churns Southwest of the Azores

Powerful Hurricane Lorenzo churned southwest of the Azores on Friday.  At 5:00 p.m. EDT on Friday the center of Hurricane Lorenzo was located at latitude 20.3°N and longitude 43.6°W which put it about 1575 miles (2535 km) southwest of the Azores.  Lorenzo was moving toward the north-northeast at 12 m.p.h. (19 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 948 mb.

Hurricane Lorenzo weakened slowly on Friday, but it remained a large and powerful hurricane.  Winds to hurricane force extended out 45 miles (75 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 Hurricane Lorenzo was 23.6.  The Hurricane Size Index (HSI) was 20.7 and the Hurricane Wind Intensity Size Index (HWISI) was 44.3.  Hurricane Lorenzo was capable of causing major damage.

Hurricane Lorenzo weakened on Friday because it moved into a less favorable environment.  Lorenzo continued to move over water where the Sea Surface Temperature was near 27°C.  However, an upper level trough west of Lorenzo was producing southwesterly winds which were causing moderate vertical wind shear.  in addition, Hurricane Lorenzo appeared to be drawing drier air into the western half of the circulation.  The effects of increased vertical wind shear and drier air caused Lorenzo to weaken.

Hurricane Lorenzo will continue to move through a less favorable environment and weaken.  Since Lorenzo is a large hurricane, it will weaken more slowly than a smaller hurricane would.  As a result, Lorenzo will likely remain a hurricane for several more days.

The upper level trough will steer Hurricane Lorenzo toward the northeast during the next few days.  On its anticipated track Hurricane Lorenzo will likely approach the Azores on Tuesday.  Lorenzo is likely to still be a hurricane at that time.

Elsewhere over the Atlantic Ocean, Tropical Depression Karen weakened to a trough southeast of Bermuda on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of former Tropical Depression Karen was located at latitude 29.3°N and longitude 58.5°W which put it about 425 miles (685 km) south-southeast of Bermuda.  Karen was moving toward the northeast at 6 m.p.h. (10 km/h).  The maximum sustained wind sped 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 1007 mb.