Category Archives: Atlantic, Caribbean, and Gulf of Mexico

Atlantic TCs

Tropical Depression 19 Strengthens to Tropical Storm Rina

Tropical Depression Nineteen strengthened into Tropical Storm Rina on Monday night.  At 10:00 p.m. EST on Monday the center of Tropical Storm Rina was located at latitude 30.4°N and longitude 49.9°W which put it about 890 miles (1430 km) east of Bermuda.  Rina was moving toward the north at 7 m.p.h. (11 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 1010 mb.

Although an upper level low northwest of Tropical Depression Nineteen continued to produce westerly winds which caused moderate vertical wind shear, stronger thunderstorms developed east of the center of circulation.  Downdrafts in those storms were able to transport stronger winds to the surface and winds to tropical storm force were occurring at the surface.  The National Hurricane Center upgraded Tropical Depression Nineteen to Tropical Storm Rina on Monday night.

The circulation of Tropical Storm Rina is asymmetrical.  The stronger storms are occurring east of the center of circulation.  The winds to tropical storm force are occurring northeast of the center.  Winds to tropical storm force extend out about 60 miles to the northeast of the center of circulation.  The bands west of the center consist primarily of lower clouds and showers.  The upper level westerly winds are tilting the circulation toward the east with height.

The moderate vertical wind shear will continue to inhibit the intensification of Tropical Storm Rina.  Rina will move over water where the Sea Surface Temperature is near 25°C.  Although the water is cooler than it is in the tropical, colder air in the upper levels will make the atmosphere unstable enough to allow thunderstorms to continue to develop.  The vertical wind shear could decrease during the next 24 to 36 hours and some intensification is possible.  When Tropical Storm Rina moves farther north, it will move over colder water.

The upper level low to the northwest of Tropical Storm Rina and a ridge to the east of Rina are steering the tropical storm toward the north.  A general motion is expected to continue for another day or two.  On its anticipated track Tropical Storm Rina will pass between Labrador and the Azores.

Tropical Depression Nineteen Forms East of Bermuda

Tropical Depression Nineteen formed east of Bermuda on Monday.  At 10:00 a.m. EST on Monday the center of Tropical Depression Nineteen was located at latitude 29.5°N and longitude 50.4°W which put it about 875 miles east of Bermuda.  It was moving toward the north-northeast at 3 m.p.h. (5 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 1013 mb.

A small low pressure system has been meandering over the Atlantic Ocean between Bermuda and the Azores.  More showers and thunderstorms formed near the center of the the low and the circulation became more circular.  Because the low pressure system developed the characteristics of a tropical cyclone, the National Hurricane Center designated the system as Tropical Depression Nineteen on Monday morning.

The circulation of Tropical Depression Nineteen is being affected by vertical wind shear.  An upper level low located to the northwest of the system is producing easterly winds which are blowing across the top of the depression.  Those winds are producing moderate vertical wind shear shear which is tilting the upper portion of the circulation to the east.  The surface center of circulation was exposed on visible satellite images.  Most of the showers and thunderstorms were occurring to the east of the center.

Tropical Depression Nineteen is forecast to intensify into a tropical storm.  The depression will move over water where the Sea Surface Temperature is near 25.5°C, which is marginally warm enough to support intensification.  The upper level low will continue to produce vertical wind shear which will inhibit intensification during the next 12 to 24 hours.  The shear is forecast to decrease on Tuesday and Tropical Depression Nineteen could strengthen into a tropical storm before it moves over colder water.

Tropical Depression Nineteen is currently in an area where the steering currents are weak.  The circulation around the upper level low to the northwest of the Tropical Depression is being deflected around an upper level ridge to the east of the depression.  Some of the flow is turning northward and the rest of the flow is turning toward the south.  The orientation of the upper low and ridge is forecast to change and the two systems are forecast to steer the depression toward the northeast later this week.  However, if the wind shear stays strong enough to prevent the circulation of the depression from growing vertically, then the winds in the lower level could steer the depression more toward the west.

Tropical Storm Philippe Brings Wind, Rain to Cuba and South Florida

Tropical Storm Philippe brought wind and rain to parts of Cuba and south Florida on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Philippe was located at latitude 24.8°N and longitude 82.1°W which put it about 25 miles (40 km) northwest of Key West, Florida.  Philippe was moving toward the north-northeast at 24 m.p.h. (39 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 1003 mb.

Tropical Storm Warnings were in effect for the Cuban provinces of Isla de la Juventud, La Habana, Ciudad de la Habana, Matanzas, Cienfuegos and Villa Clara.  Tropical Storm Warnings were in effect for the northwestern Bahamas including the Abacos, Andros Island, Berry Island, Bimini, Eleuthera, Grand Bahama Island and New Providence.  Tropical Storm Watches were in effect for the portion of the coast from Craig Key to Golden Beach, Florida.  Tropical Storm Watches were also in effect for the Central Bahamas including Cat Island, the Exumas, Long Island, Rum Cay and San Salvador.

The circulation is of Tropical Storm Philippe is not well organized.  The appear to be multiple smaller centers of counterclockwise rotation moving around inside the broader circulation.  One center of circulation is in northwest of Key West.  Showers and thunderstorms were primarily northeast of that center of rotation.  There were low clouds west of that center.  Another center of rotation was just north of the coast of Cuba.  A primary band of showers and thunderstorms wrapped around the eastern side of this second center.  The middle and upper level circulation of Tropical Storm Philippe appeared to be associated with the center near Cuba.

Tropical Storm Philippe will move through an environment that will be somewhat favorable for intensification.  Philippe will move over water where the Sea Surface Temperature is near 29°C.  An upper level trough approaching Tropical Storm Philippe from the west is producing strong southwesterly winds which are causing significant vertical wind shear.  The shear is inhibiting the organization of the circulation.  Tropical Storm Philippe could intensify on Sunday if the center of circulation near Cuba becomes the dominant center, since it has a more complete vertical structure.

The upper level trough will continue to steer Tropical Storm Philippe quickly toward the northeast on Sunday.  On its anticipated track Tropical Storm Philippe will move through the Upper Florida Keys and over the Northwestern Bahamas on Sunday.   It will bring gusty winds and locally heavy rains to those areas.

Potential Tropical Cyclone Eighteen Prompts Warnings for Cuba and Bahamas

Potential Tropical Cyclone Eighteen prompted the governments of Cuba and the Bahamas to issue Tropical Storm Warnings and Watches for portions of those countries on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Potential Tropical Cyclone Eighteen was located at latitude 17.5°N and longitude 84.5°W which put it about 415 miles (670 km) south-southwest of Havana, Cuba.  It was moving toward the north-northwest at 6 m.p.h. (10 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.

Tropical Storm Warnings were issued for the Cuban provinces of Isla de la Juventud, La Habana, Ciudad de la Habana, Matanzas, Cienfuegos, and Villa Clara.  Tropical Storm Warnings were also issued for the northwestern Bahamas including the Abacos, Andros Island, Berry Island, Bimini, Eleuthera, Grand Bahama Island and New Providence.  Tropical Storm Watches were issued for the Central Bahamas including Cat Island, the Exumas, Long Island, Rum Cay and San Salvador.

An Air Force Reserve Hurricane Hunter reconnaissance plane investigated the system formerly known as Invest 93L on Friday afternoon.  The plane found sustained winds to tropical storm force.  The plane also found a broad circulation center with several smaller centers of circulation revolving around inside the broader center.  Based on the observations from the plane, the National Hurricane Center (NHC) chose not to upgrade the system to Tropical Storm Philippe in its 5:00 p.m. EDT advisory.  However, NHC did change the designation of the system from Invest 93L to Potential Tropical Cyclone Eighteen.  If a more well defined center of circulation develops, then NHC could still change designation of the system to Tropical Storm Philippe.

The circulation of Potential Tropical Cyclone Eighteen is still organizing.  As mentioned above, there is a broad center of counterclockwise rotation.  There are also several smaller counterclockwise swirls within the broader center.  More showers and thunderstorms developed closer to the center of circulation on Friday afternoon.  The storms closer to the center of circulation were generating some upper level divergence which was pumping away mass to the northeast of the system.  Some bands of showers and thunderstorms were developing in the outer portions of the circulation.

Potential Tropical Cyclone Eighteen will move through an environment somewhat favorable for intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  The system is embedded in a flow over warm moist air.  However there is a stationary front northwest of the system and there is cooler, drier air north of the stationary front.  The system is currently under the western side of an upper level ridge.  The upper level winds are weak and there is not much vertical wind shear.  Potential Tropical Cyclone Eighteen could slowly intensify during the next 24 hours as the circulation becomes more well organized.

The ridge east of Potential Tropical Cyclone Eighteen is steering the system toward the north-northwest.  That general motion should continue for another six to twelve hours.  An upper level trough will approach the system from the west on Saturday and the trough will start to steer it more toward the northeast.  On its anticipated track Potential Tropical Cyclone Eighteen will approach Cuba on Saturday afternoon.  The center of the system will move south of the Florida Keys on Saturday night and it could move across the northwestern Bahamas on Sunday.

The system will bring gusty winds and locally heavy rain to those locations.  The locally heavy rain could cause flooding.  There could be a storm surge of several feet (one to two meters) on parts of the south coast of Cuba, where the wind blows the water toward the coast.  There could also be some storm surge along the coasts of the Florida Keys.

Low Pressure Forms Near Northwest Caribbean Sea

An area of low pressure formed near the northwestern Caribbean Sea on Monday and the system has been designated as Invest 93L.  At 8:00 p.m. EDT on Monday the center of Invest 93L was located at latitude 14.0°N and longitude 83.0°W which put it about 75 miles (120 km) south-southeast of Cabo Gracias a Dios.  It was moving toward the north at 6 m.p.h. (9 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.

An area of low pressure formed in the southern portion of an area of showers and thunderstorms that has persisted over the western Caribbean Sea for several days.  The circulation of Invest 93L is not well organized.  There is no well organized center of circulation nor are there well organized rainbands.  Most of the showers and thunderstorms are occurring in the northern portion of the circulation.  There are not many showers or thunderstorms in the southern half of the circulation.  Much of the western half of the circulation is over Nicaragua and Honduras.

Invest 93L will move through an environment mostly favorable for the development of a tropical cyclone during the next few days.  It will move over water where the Sea Surface Temperature is near 30°C.  Invest 93L is near the axis of an upper level ridge.  So, the upper level winds are weak over the system.  There are stronger winds farther north over the northern Caribbean Sea.  Invest 93L will be slow to develop as long as almost half of the circulation is over land.  Development will be more likely when the center moves farther away from land.

Invest 93L is just west of the axis of the ridge, which is steering the system slowly toward the north.  That general motion is forecast to continue for several more days.  On its anticipated track Invest 93L will move over the northwestern Caribbean Sea later this week.  Invest 93L will drop locally heavy rain over Nicaragua and Honduras and it could cause flash floods in some areas.

Former Hurricane Ophelia Brings Strong Winds to Ireland

Former Hurricane Ophelia brought strong winds to Ireland and parts of the United Kingdom on Monday.  Although former Hurricane Ophelia had made a transition to an extratropical cyclone before it reached Ireland, it was still a very powerful storm when it moved across that region.  There were reports of several fatalities, damage and power outages across Ireland.  Met Eireann (the Irish meteorological agency) reported the following wind gusts during the passage of former Hurricane Ophelia.

At the Fastnet Lighthouse (anemometer at 200 feet [61 meters] ) there was a gust of 191 km/h (118 m.p.h.).  Sherkin Island reported a wind gust of 135 km/h (84 m.p.h.) before the power went out.  Cork airport reported a wind gust of 126 km/h (78 m.p.h.) before the power went out. Shannon airport reported a wind gust of 122 km/h (76 m.p.h.).  Roches Point reported a wind gust of 156 km/h (97 m.p.h.).  The Kinsale Platform reported a wind gust of 141 km/h (87 m.p.h.) and the Dublin airport reported a wind gust of 104 km/h (65 km/h).

Ophelia Strengthens to Major Hurricane South of the Azores

Hurricane Ophelia strengthened into a Category 3 hurricane on the Saffir-Simpson Scale on Saturday morning as it moved south of the Azores.  That made Ophelia a major hurricane.  At 11:00 a.m. EDT on Saturday the center of Hurricane Ophelia was located at latitude 34.8°N and longitude 26.6°W which put it about 220 miles (355 km) south of the Azores.  Ophelia was moving toward the northeast at 25 m.p.h. (40 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 135 m.p.h. (220 km/h).  The minimum surface pressure was 960 mb.

It is very unusual to have such a strong hurricane near the Azores, but Ophelia contains all of the elements of a major hurricane.  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 of storms.  Well formed rainbands exists in the outer portions of the circulation.  Storms in the core of Ophelia are generating upper level divergence which is pumping mass away to the northeast of the hurricane.  Winds to hurricane force extend out about 40 miles (65 km) from the center of circulation.  Winds to tropical storm force extend out about 125 miles (205 km) from the center.

Hurricane Ophelia is moving over water where the Sea Surface Temperature is near 25°C.  Normally, water at that temperature would be considered to be too cool to support the development of a major hurricane.  However, the temperature of the air in the upper troposphere is also cool and so the atmosphere is unstable enough to allow for the development of deep convection.  An upper level trough west of Ophelia is producing southwesterly winds which are blowing toward the top of the circulation.  There are also southwesterly winds in the lower and middle levels of the atmosphere and so the vertical wind shear is not strong enough to inhibit intensification

Hurricane Ophelia will be moving over cooler water and it is likely to weaken gradually during the next several days.  When Ophelia moves over the cooler water it will make a transition to an extratropical cyclone.  The size of the circulation will increase during the transition.  Hurricane Ophelia will evolve into a large very powerful extratropical cyclone during the next several days.

The trough west of Ophelia is steering the hurricane toward the northeast.  Hurricane Ophelia is expected to turn more toward the north during the next two or three days.  On its anticipated track Hurricane Ophelia will pass east of the Azores later today.  The strong extratropical cyclone that Ophelia will transition into could approach Ireland and the United Kingdom by Monday morning.  That cyclone will bring very strong winds and heavy rain to that region.

Hurricane Ophelia Moves Closer to the Azores

Hurricane Ophelia moved closer to the Azores on Friday.  At 5:00 p.m. EDT on Friday the center of Hurricane Ophelia was located at latitude 32.3°N and longitude 31.8°W which put it about 480 miles (770 km) southwest of the Azores.  Ophelia was moving toward the east-northeast at 13 m.p.h. (20 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 971 mb.

Despite moving over slightly cooler water, Hurricane Ophelia maintained its structure and intensity on Friday.  There was a small circular eye at the center of circulation, although there appeared to be a break on the northwest side of the ring of thunderstorms around the eye.  Thunderstorms in the core of Ophelia were generating upper level divergence which was pumping away mass.  Bands of showers and thunderstorms were revolving around the core of Hurricane Ophelia.  The stronger rainbands were in the eastern half of the circulation.  Winds to hurricane force extended out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out about 100 miles (160 km) from the center.

Hurricane Ophelia will move through an environment that is capable of supporting a strong cyclone.  Ophelia will move over water where the Sea Surface Temperature is near 25°C.  Normally, that water would be too cool to support a strong hurricane.  However, the temperature in the upper levels of the atmosphere is also cool and that is keeping the atmosphere unstable enough to allow for thunderstorms to develop.  The speed of the winds in Hurricane Ophelia is likely to decrease gradually during the next several days.

When Hurricane Ophelia moves farther north, it will move into a cooler environment with stronger westerly winds in the upper levels.  A cooler environment with more vertical wind shear will cause the structure of Hurricane Ophelia change into the structure of an extratropical cyclone.  The area of stronger winds will expand and the cyclone will become much larger.

Hurricane Ophelia is being steered toward the east-northeast by westerly winds in the middle levels.  A trough will approach Hurricane Ophelia from the west.  Southwesterly winds ahead of the trough will carry Ophelia more toward the north in about 36 hours.  On its anticipated track the center of Hurricane Ophelia will move south of the Azores on Saturday.  Ophelia could bring gusty winds and rain to the Azores when it moves by those islands.  The strong extratropical cyclone that evolves from Hurricane Ophelia could approach Ireland and the United Kingdom on Monday.  That cyclone could bring very strong winds and heavy rain to that region.

Ophelia Strengthens Into a Hurricane Southwest of the Azores

Tropical Storm Ophelia strengthened into a hurricane southwest of the Azores on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Ophelia was located at latitude 30.0°N and longitude 35.7°W which put it about 745 miles (1195 km) southwest of the Azores.  Ophelia was moving toward the northeast at 3 m.p.h.  The maximum sustained wind speed was 85 m.p.h. (140 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 986 mb.

The circulation of Hurricane Ophelia became more circular and symmetrical on Wednesday.  A circular eye developed at the center of circulation.  Thunderstorms in the ring around the eye became taller.  Additional bands of showers and thunderstorms were revolving around the core of Hurricane Ophelia.  Thunderstorms in the core were producing upper level divergence which was pumping mass away to the east of the hurricane.  Winds to hurricane force extended out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out about 70 miles (110 km) from the center.

Hurricane Ophelia will be moving through an environment that could support further intensification on Thursday.  Ophelia will move over water where the Sea Surface Temperature is near 26.5°C.  Ophelia is in an area of weaker upper level winds.  It is north of the subtropical jet stream and it is south of the stronger westerly winds in the middle latitudes.  As a result the vertical wind shear is minimal.  The combination of warm water and little shear allowed Ophelia to intensify into a hurricane and it could strengthen further on Thursday.

Hurricane Ophelia is in an area of weak westerly winds which are steering the hurricane slowly toward the east.  An upper level trough will approach Ophelia from the west and the trough will start to pull the hurricane toward the northeast more quickly later this week.  On its anticipated track Hurricane Ophelia could approach the Azores in two or three days.

Tropical Storm Ophelia Forms Over Eastern Atlantic

The busy 2017 Atlantic hurricane season continued when Tropical Storm Ophelia formed over the eastern Atlantic Ocean on Monday.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Ophelia was located at latitude 31.5°N and longitude 39.6°W which put it about 845 miles (1355 km) west-southwest of the Azores.  Ophelia was moving toward the northeast at 3 m.p.h. (5 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 1005 mb.

Thunderstorms formed on Monday near the center of a low pressure system which had been lingering over the eastern Atlantic Ocean and the National Hurricane Center designated the system as Tropical Storm Ophelia.  The thunderstorms formed near the eastern side of the center and several bands of showers and thunderstorms formed in the rest of the eastern half of the circulation.  There were fewer thunderstorms in the western half of Ophelia.  The thunderstorms near the center of circulation were generating upper level divergence which was pumping mass away to the east of the tropical storm.

Tropical Storm Ophelia is an environment that is somewhat favorable to intensification.  Ophelia is moving over water where the Sea Surface Temperature (SST) is near 27°C.  It is near the axis of an upper level trough which is oriented east to west over the Atlantic Ocean.  The trough is producing westerly winds which are blowing toward the top of the circulation and those winds are causing some vertical wind shear.  However, since Ophelia is over water where the SST is 27°C, the clouds are not rising as far into the atmosphere as they would if the water was warmer and some of the upper level winds are blowing completely over the top of the circulation of the tropical storm.  So, the vertical wind shear is not as significant as it could be if the top of Ophelia was higher in the atmosphere.  Tropical Storm Ophelia is likely to strengthen during the next several days and it could eventually become a hurricane.

Since Tropical Storm Ophelia is near the axis of the upper level trough, the steering winds are weaker.  The westerly flow is pushing Ophelia slowly toward the northeast.  The orientation of the trough is forecast to change during the next day or two and Ophelia is expected to move more toward the east-southeast.  On its anticipated track Tropical Storm Ophelia is expected to meander over the eastern Atlantic Ocean for several more days.