Tag Archives: Cuba

Michael Strengthens Into a Hurricane, Watches Issued for Gulf Coast

Former Tropical Storm Michael strengthened into a hurricane on Monday morning and Watches were issued for portions of the Gulf Coast.  At 11:00 a.m. EDT on Monday the center of Hurricane Michael was located at latitude 21.2°N and longitude 84.9°W which put it about 50 miles (80 km) south of the western end of Cuba.  Michael was moving toward the north at 7 m.p.h. (11 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 982 mb.

A Hurricane Watch was in effect for the portion of the coast from the Alabama-Florida border to Suwanee River, Florida.  Tropical Storm Watches were in effect for the portions of the coast from the Alabama-Florida border to the Alabama-Mississippi border and from Suwanee River to Anna Maria Island, Florida.  A Hurricane Warning was in effect for the Cuban province of Pinar del Rio.  Tropical Storm Warnings were in effect for the Cuban province of Isle of Youth and for the portion of the coast from Tulum to Cabo Catoche, Mexico.

Hurricane Michael continued to organize quickly.  A circular eye with a diameter of about 30 miles (50 km) was forming at the center of Michael.  A ring of strong thunderstorms was wrapping around the eye and the strongest winds were occurring in the ring of storms.  Several bands of showers and thunderstorms were wrapping around the core of Hurricane Michael.  Storms near the core were generating upper level divergence which was pumping mass away from the hurricane.

Winds to hurricane force extended out about 30 miles (50 km) primarily to the northeast of the center of Hurricane Michael.  Winds to tropical storm force extended out about 175 miles (280 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Michael was 10.4.  The Hurricane Size Index (HSI) was 6.8 and the Hurricane Wind Intensity Size Index (HWISI) was 17.2.

Hurricane Michael will move into an environment that will become increasingly favorable for intensification.  Michael will move over water where the Sea Surface Temperature is near 30°C.  An upper level trough over the Gulf of Mexico was producing westerly winds which were blowing toward the top of the circulation.  Those winds were causing some vertical wind shear.  However, the upper level trough will move westward away from Hurricane Michael and the wind shear will decrease.  Hurricane Michael will continue to strengthen when it moves over the Gulf of Mexico and it could intensify rapidly once the eye and eyewall are fully formed.  Hurricane Michael is likely to strengthen into a major hurricane.

Hurricane Michael will move around the western end of a subtropical high pressure system centered over the western Atlantic Ocean.  The high will steer Michael in a northerly direction during the next several days.  It will get bigger and stronger during the next 48 hours.  On its anticipated track Hurricane Michael will approach the northeast coast of the Gulf of Mexico on Wednesday.  It is likely to be a major hurricane at that time.  Hurricane Michael has the potential to cause a storm surge of 10 to 15 feet (3 to 5 meters) at the coast.  It will bring strong winds which could cause regional major damage and result in significant power outages.  Locally heavy rain could cause flooding in some locations.

Tropical Storm Michael Strengthens East of Yucatan

Tropical Storm Michael strengthened east of the Yucatan peninsula on Sunday.  At 8:00 p.m. EDT on Sunday the center of Tropical Storm Michael was located at latitude 19.9°N and longitude 85.4°W which put it about 105 miles (170 km) east-southeast of Cozumel, Mexico.  Michael was moving toward the north at 5 m.p.h. (8 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 997 mb.

A Tropical Storm Warning was in effect for the Cuban provinces of Pinar del Rio and the Isle of Youth.  A Tropical Storm Warning is also in effect for the portion of the coast from Tulum to Cabo Catoche, Mexico.

The circulation around Tropical Storm Michael is still organizing and the distribution of thunderstorms is asymmetrical.  Most of the thunderstorms are occurring in bands in the eastern half of the circulation.  A new center of circulation formed on Sunday afternoon near those thunderstorms.  Many of the rainbands in the western half of Tropical Storm Michael contain primarily showers and lower clouds.  One outer rainband in the southwestern periphery of the circulation does contain numerous thunderstorms.  The strongest winds are occurring in the rainbands on the eastern side of Tropical Storm Michael.  The winds are weaker on the western side of the circulation.  Storms on the eastern side of Michael are generating some upper level divergence which was pumping mass away from the tropical storm and was allowing the surface pressure to decrease.

An upper level trough over the Gulf of Mexico is producing westerly winds which are blowing across the top of Tropical Storm Michael.  Those winds are causing moderate vertical wind shear which was slowing the rate of intensification, but the shear is not strong enough to prevent Michael from strengthening.  The wind shear is probably the reason for the asymmetrical distribution of thunderstorms.  The upper level trough will move westward during the next few days and the upper level winds will weaken.  Michael will move over water where the Sea Surface Temperature is warmer than 30°C.  Tropical Storm Michael will strengthen slowly during the next 24 hours.  However, it will intensify more rapidly on Tuesday when the upper level winds weaken.  Michael will strengthen into a hurricane when it moves over the Gulf of Mexico and it could intensify into a major hurricane.

Tropical Storm Michael has been moving slowly while the circulation organizes and the center reforms.  Michael will move around the southwestern part of the subtropical high pressure system over the western North Atlantic Ocean.  The high will steer Michael in a northward direction during the next two or three days.  On its anticipated track the center of Tropical Storm Michael will pass between the western end of Cuba and the Yucatan peninsula on Monday.  Michael could approach northern Florida by Wednesday.  It will be a hurricane at that time and it could be a major hurricane.  Michael could produce strong winds, a significant storm surge and drop heavy rain when it reaches the coast.

Possible Tropical Development Near Yucatan Peninsula

A tropical cyclone could develop near the Yucatan peninsula during the next few days.  At 2:00 p.m. EDT on Friday the center of Invest 91L was located at latitude 16.0°N and longitude 84.3°W which put it about 400 miles (640 km) southeast of Cancun, Mexico.  It was moving toward the northwest at 6 m.p.h. (10 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 1007 mb.

A broad area of low pressure is over the western Caribbean Sea, Central America and the adjacent waters of the Eastern North Pacific Ocean.  Several smaller, mesoscale centers of rotation appear to be revolving around the larger low pressure system.  One of the mesoscale centers is over the Eastern North Pacific Ocean just west of the coast of Central America.  One or two other mesoscale centers appear to be over the western Caribbean Sea near Honduras.  The low level circulation is not currently well organized.  It is broad and diffuse.  Thunderstorms are clustered around the mesoscale centers, but large scale rainbands have not formed.

Westerly winds in the upper levels are are blowing over the top of the system.  Those winds are creating moderate vertical wind shear which is inhibiting the development of the low pressure system.  The upper level winds are forecast to weaken during the next few days and the wind shear will diminish.  The Sea Surface Temperature of the water in the northwestern Caribbean Sea and Gulf of Mexico is near 30°C.  The broad low pressure system could slowly organize during the next two to three days.  The National Hurricane Center is indicating that there is a 70% probability of formation of a tropical cyclone near the Yucatan peninsula or over the southern Gulf of Mexico during the next five days.  A reconnaissance plane is scheduled to investigate the low pressure system on Sunday, if necessary.

The broad low is southwest of a subtropical high pressure system over the Atlantic Ocean.  The high is expected to steer the low toward the northwest during the weekend.  On its anticipated track the low will move over the northwestern Caribbean Sea during the next several days.  it could move into the Gulf of Mexico on Monday.

Elsewhere over the Atlantic Ocean, Tropical Storm Leslie continued to meander northeast of Bermuda.  At 11:00 a.m. EDT on Friday the center of Tropical Storm Leslie was located at latitude 36.2°N and longitude 58.4°W which put it about 455 miles (730 km) northeast of Bermuda.  Leslie was moving toward the north-northwest at 9 m.p.h. (15 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 986 mb.

Potential Tropical Cyclone Seven Causes Tropical Storm Watch for U.S. Gulf Coast

Potential Tropical Cyclone Seven caused the National Hurricane Center to issue a Tropical Storm Watch for a portion of the U.S. Gulf Coast on Sunday afternoon.  A Tropical Storm Watch was in effect for the portion of the coast from the Alabama-Florida border to Morgan City, Louisiana including Lake Pontchartrain.  At 5:00 p.m. EDT on Sunday the center of Potential Tropical Cyclone Seven was located at latitude 22.7°N and longitude 77.3°W which put it about 275 miles (445 km) east-southeast of Marathon, Florida.  It was moving toward the west-northwest at 15 m.p.h (24 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 1012 mb.

Bands of showers and thunderstorms began to form in a tropical wave over the Bahamas and the National Hurricane Center designated the system as Potential Tropical Cyclone Seven in order to be able to issue the Tropical Storm Watch for the north coast of the Gulf of Mexico.  The circulation of Potential Tropical Cyclone Seven was still organizing.  A distinct low level center of circulation had not formed.  Bands of showers and thunderstorms were developing and the bands were starting to revolve around the inner part of the weather system.  Thunderstorms were beginning to generate some upper level divergence.

Potential Tropical Cyclone Seven will be moving into an environment favorable for intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge is forecast to develop over Potential Tropical Cyclone Seven.  If that occurs, then the upper level winds would be weak and there would be little vertical wind shear.  Potential Tropical Cyclone Seven is forecast to intensify into Tropical Storm Gordon.  If the system moves slowly enough, there is a chance it could strengthen into a hurricane before it reaches the Gulf Coast.

Potential Tropical Cyclone Seven will move around the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Potential Tropical Cyclone Seven in a general west-northwesterly direction.  On its anticipated track the system will move over the Florida Keys on Monday.  It will be over the eastern Gulf of Mexico on Tuesday and the system could reach the northern Gulf Coast late on Tuesday or early on Wednesday.

Elsewhere over the tropical Atlantic, Tropical Storm Florence was moving quickly away from the Cabo Verde Islands.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Florence was located at latitude 17.4°N and longitude 34.6°W which put it about 700 miles (1125 km) west of the Cabo Verde Islands.  Florence was moving toward the west-northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1000 mb.

Tropical Storm Chris Develops South of Cape Hatteras, Beryl Nears Lesser Antilles

Tropical Storm Chris developed south of Cape Hatteras on Sunday morning, while Tropical Storm Beryl neared the Lesser Antilles.  At 11:00 a.m. EDT on Sunday the center of Tropical Storm Chris was located at latitude 32.9°N and longitude 75.0°W which put it about 160 miles (260 km) south of Cape Hatteras, North Carolina.  Chris was nearly stationary.  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 1006 mb.

Thunderstorms developed closer to the center of circulation on Sunday morning and the National Hurricane Center designated former Tropical Depression Three as Tropical Storm Chris.  The circulation of Chris was organizing quickly.  A band of showers and thunderstorms was wrapping around the center of circulation.  Several other rainbands were revolving around the core of the tropical storm.  The bands northwest of the center were weaker because there was drier air in that part of Chris.  The storms near the center of circulation were beginning to generate upper level divergence.

Tropical Storm Chris will remain in an environment favorable for intensification for the next two or three days.  The water in the upper portion of the Atlantic Ocean east of the Carolinas is warmer than normal.  Tropical Storm Chris will be over water where the Sea Surface Temperature is near 28°C.  Chris will be southeast of an upper level trough over the northeastern quarter of the U.S. and it will be under a small upper level ridge.  The upper level winds will be weak and there will be little vertical wind shear.  Tropical Storm Chris will continue to intensify and it could strengthen to a hurricane in the next day or two.

Since Tropical Storm Chris is under the small upper level ridge, the steering winds are weak.  Chris may not move much during the next 24 to 48 hours.  Tropical Storm Chris is forecast to linger of the coast of the Carolinas for several days.  Eventually an upper level trough will approach from the west and start to push Chris toward the northeast.

Elsewhere, Tropical Storm Beryl was nearing the Lesser Antilles on Sunday morning.  At 11:00 a.m. EDT on Sunday the center of Tropical Storm Beryl was located at latitude 14.4°N and longitude 57.9°W which put it about 210 miles (335 km) east of Martinique.  Beryl was moving toward the west-northwest at 23 m.p.h. (37 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 1007 mb.

Tropical Storm Warnings were in effect for Dominica and Guadeloupe.  Tropical Storm Watches were in effect for Saba, St. Eustatius, St. Maarten, St. Martin, Martinique, St. Lucia, and St. Barthelemy.

Thunderstorms continued to develop near the center of Tropical Storm Beryl on Sunday morning and the weakening trend halted at least temporarily.  Beryl remained a small tropical storm.  Winds to tropical storm force only extended out about 45 miles (75 km) from the center of circulation.  There were several bands of showers and thunderstorms in the eastern half of Tropical Storm Beryl.  The bands in the western half of the circulation consisted primarily of showers and low clouds.

Tropical Storm Beryl is forecast to into a region where the easterly winds in the lower levels are stronger.  That would increase the vertical wind shear and make it difficult for the circulation to stay vertically coherent.  Beryl will move over water where the Sea Surface Temperature is near 27°C.  So, there will be enough energy in the upper ocean to support a tropical storm if the wind shear is not too strong.  Tropical Storm Beryl is forecast to weaken when it moves over the eastern Caribbean Sea, but that will depend on how strong the vertical shear gets.

Tropical Storm Beryl is moving south of the subtropical high over the Atlantic Ocean which is steering Beryl toward the west-northwest.  A general motion toward the west-northwest is forecast to continue for several more days.  On its anticipated track Tropical Storm Beryl will bring gusty winds and locally heavy rain to St. Lucia, Martinique, Dominica and Guadeloupe during the next few hours,

Subtropical Storm Alberto Forms Over Northwest Caribbean Sea

Subtropical Storm Alberto formed over the northwestern Caribbean Sea on Friday morning.  The National Hurricane Center (NHC) designated an area of low pressure as Subtropical Storm Alberto on Friday morning based on data from buoys and ship reports.  At 5:00 p.m. EDT on Friday the center of Subtropical Storm Alberto was located at latitude 19.4°N and longitude 86.3°W which put it about 85 miles (135 km) south-southeast of Cozumel, Mexico.  Alberto was moving toward the east at 2 m.p.h. (3 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1005 mb.

A Tropical Storm Watch has been issued for the portion of the U.S. coast from Indian Pass, Florida to Grand Isle, Louisiana including New Orleans.  The government of Mexico issued a Tropical Storm Watch for the portion of the coast from Tulum to Cabo Catoche.  The government of Cuba issued a Tropical Storm Watch for the province of Pinar del Rio.

The circulation around Subtropical Storm Alberto was asymmetrical.  The low level center of circulation was located just to east of the Yucatan Peninsula.  The strongest thunderstorms were occurring in a band located about 100 miles (160 km) east and north of the center.  Flow around an upper level trough over the Gulf of Mexico was producing westerly winds which were blowing toward the top of the circulation.  Those winds were causing strong vertical wind shear which was the reason why the thunderstorms were occurring well to the east of the center of circulation.

Subtropical Storm Alberto will move through an environment marginally favorable for intensification during the next 24 to 36 hours.  Alberto will move over water where  the Sea Surface Temperature is near 28°C.  So, there is sufficient energy in the upper ocean to support intensification.  However, the upper level trough will continue to cause moderate to strong vertical wind shear during the next day or so.  The wind shear will inhibit intensification.  Some gradual strengthening is possible.  The winds are weaker near the axis of the upper level trough.  If Alberto moves under the axis of the trough when it reaches the northern Gulf of Mexico, then the wind shear will decrease.  Alberto could strengthen more quickly if that happens.  There is a chance that Alberto could reach hurricane intensity.  If more thunderstorms form closer to the center of circulation, then NHC could change the designation of Alberto to a tropical storm.

Subtropical Storm Alberto is moving around the western end of a large high pressure system over the Atlantic Ocean.  The high is steering Alberto slowly toward the north-northeast.  A general motion toward the north is forecast during the next day or so.  When Alberto gets farther north, the upper level trough could steer it more toward the north-northwest.  There is a chance that the steering currents could weaken when Alberto nears the Gulf Coast.  Thus, there is much more uncertainty about the track forecast after that time.

The greatest risk with Subtropical Storm Alberto will be locally heavy rain and the potential for flooding.  Most of the heavy rain is likely to fall north and east of the center.  Much less rain is likely to fall from the western side of Alberto.  The coast of the Gulf of Mexico is very susceptible to storm surges.  The water level will rise along the eastern and northern coasts of the Gulf of Mexico where the winds blow the water toward the shoreline.

Cyclone Likely to Form Over Gulf of Mexico

A cyclone is likely to form over the Gulf of Mexico during the upcoming weekend.  A broad area of low pressure at the surface is currently centered over the Yucatan Peninsula.  The area of low pressure is currently designated as Invest 90L.  The circulation around the low pressure system is not well organized at the current time.  The center of the surface low is over the Yucatan Peninsula.  Showers and lower clouds are occurring near the center of the low.  Stronger thunderstorms are occurring on the eastern side of the low over the northwestern Caribbean Sea.  Sustained winds of 20 m.p.h. to 30 m.p.h. (30 km/h to 50 km/h) were blowing across the northwestern Caribbean Sea.  The winds were weaker over land near the center of circulation.

An upper level trough over the Gulf of Mexico was producing strong westerly winds which were blowing over the top of the surface low.  Those winds were causing strong vertical wind shear and the wind shear was one of the reasons why the stronger thunderstorms were occurring east of the center of circulation.  Sinking motion in the western portion of the upper level trough was bringing drier air to the surface and the drier air was inhibiting the formation of thunderstorms in the western side of the surface low.

The National Hurricane Center (NHC) indicated in a Special Tropical Weather Outlook at 2:00 p.m. EDT on Thursday that there is a 70% probability of the formation of a subtropical or tropical depression during the next 48 hours.  NHC has tentatively tasked a reconnaissance aircraft to investigate the low pressure system on Friday afternoon if necessary.

The wind speeds are slower near the axis of the upper level trough.  If the surface low pressure system moves under the axis of the upper level trough, then there would be less vertical wind shear and a cyclone could form.  If thunderstorms develop near the center of circulation after the center moves over the northwestern Caribbean Sea or southeastern Gulf of Mexico, then NHC would likely designate the system as a tropical depression.  If the thunderstorms develop farther away from the center of circulation and the circulation does not exhibit a tropical appearance, then NHC could classify the system as a subtropical depression.  NHC would issue advisories on the cyclone even if it is designated a subtropical depression.

There is a strong high pressure system over the Atlantic Ocean and the high is likely to steer the surface low toward the north.  The Sea Surface Temperature of the water in the southeastern Gulf of Mexico is near 27°C.  So, there is enough energy to support the formation of a tropical cyclone.  Most of the stronger thunderstorms are likely to continue to form in the eastern side of the circulation because of the vertical wind shear and drier air to the northwest of the surface low.  The low pressure system could slowly organize into a tropical storm during the weekend.

Heavy rain and the potential for flooding are the greatest risks with this low pressure system.  There will be some storm surge along the eastern and northern coasts of the Gulf of Mexico as counterclockwise rotation around the low blows water toward the shore.

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.