Category Archives: Atlantic, Caribbean, and Gulf of Mexico

Atlantic TCs

Tropical Depression Eight Forms East of the Bahamas

Tropical Depression Eight formed east of the Bahamas on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Tropical Depression Eight was located at latitude 25.3°N and longitude 70.3°W which put it about 470 miles (755 km) east of Nassau, Bahamas.  It was moving toward the north-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 gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1011 mb.

Data from satellites and NOAA buoy 41046 indicated that a low level center of circulation formed within former Invest 99L.  Based on those data the National Hurricane Center classified the system as Tropical Depression Eight.  Bands of showers and thunderstorms began to develop in Invest 99L on Saturday afternoon.  There were more bands in the eastern half of the circulation than there were in the western half.  Thunderstorms in the bands began to generate upper level divergence which was pumping away mass.  The circulation took on a more circular appearance and they system exhibited the characteristics of a tropical depression.

Tropical Depression Eight will move through an environment favorable for intensification during the next 36 to 48 hours.  It will move over water where the Sea Surface Temperature is near 30°C.  An upper low that was inhibiting the development of Invest 99L dissipated on Saturday.  When the upper low dissipated, the upper level winds weakened.  Tropical Depression Eight will move through an area where there is little vertical wind shear.  It will likely strengthen into Tropical Storm Gert on Sunday.  It could eventually intensify into a hurricane.

Tropical Depression Eight is moving around the western end of the subtropical high over the Atlantic Ocean.  The high is steering the depression toward the north-northwest and it is forecast to move primarily toward the north during the next 24 to 48 hours.  Tropical Depression Eight will eventually reach the westerly winds in the middle latitudes and it will turn toward the northeast when that happens.  On its anticipated track Tropical Depression Eight will remain east of the Bahamas.

Hurricane Franklin Brings Wind and Heavy Rain to Mexico

Hurricane Franklin brought gusty winds and heavy rain to parts of Mexico when it made landfall on Wednesday night.  The center of Hurricane Franklin made landfall between Veracruz and Nautla near the town of Lechuguillas, Mexico.  The maximum sustained wind speed was 85 m.p.h. (140 km) at the time of landfall, which made Franklin a Category 1 hurricane on the Saffir-Simpson Scale.  Franklin weakened to a tropical storm as it moved inland during the night.

At 8:00 a.m. EDT on Thursday the center of Tropical Storm Franklin was located at latitude 19.8°N and longitude 98.3°W which put it about 60 miles (95 km) east-northeast of the Mexico City, Mexico.  Franklin was moving toward the west at 15 m.p.h. (24 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 997 mb.

A Tropical Storm Warning remains in effect for the portion of the coast from Cabo Rojo to Boca Partido, Mexico.

Franklin brought hurricane force winds to the portion of the coast north of Veracruz, Mexico.  Those winds pushed water toward the shore and created a storm surge along the coast.  The highest surge may have reached 6 to 9 feet (2 to 3 meters) near and just to the north of where the center made landfall.  Winds blowing up the slopes of mountains produced very heavy rain and flooding could be occurring in some locations.  The heavy rain will continue as Tropical Storm Franklin moves west across central Mexico.

Tropical Storm Franklin will continue to weaken as it moves across Mexico.  Heavy rain will continue to fall over portions of central Mexico and the potential for additional flooding exists.  The mountains are likely to disrupt the low level circulation.  However, the middle and upper portions of the circulation could remain intact.  Some models are forecasting that Franklin, or its remnants, could redevelop when it reaches the Eastern North Pacific Ocean.

Franklin Strengthens Into a Hurricane Northeast of Veracruz

Formerly Tropical Storm Franklin strengthened into a hurricane northeast of Veracruz on Friday afternoon.  Franklin is the first hurricane to form over the Atlantic basin in 2017.  At 5:00 p.m. EDT the center of Hurricane Franklin was located at latitude 20.1°N and longitude 94.9°W which put it about 105 miles (170 km) northeast of Veracruz, Mexico.  Franklin was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 984 mb.

A Hurricane Warning is in effect for the portion of the coast from Puerto de Veracruz to Cabo Rojo, Mexico.  A Hurricane Watch is in effect for the portion of the coast from Cabo Rojo to Rio Panuco.  A Tropical Storm Warning is in effect for the portion of the coast from Puerto Dos Bocas to Puerto de Veracruz and from Tuxpan to Barra del Tordo.

An elliptical eye formed at the center of Hurricane Franklin and a reconnaissance plane detected surface winds in excess of 74 m.p.h. (119 km/h).  Based on data from the plane and an improved appearance on satellite imagery, the National Hurricane Center upgrade Franklin to hurricane status in its 5:00 p.m. EDT advisory.

The structure of Hurricane Franklin improved on Friday.  An elliptical eye oriented north to south formed at the center of circulation.  A ring of thunderstorms completely surrounded the eye.  The strongest winds were occurring in the northeastern part of the ring of storms.  Storms in the core of the circulation were generating upper level divergence which was pumping out mass and allowing the surface pressure to decrease.  A primary band of showers and thunderstorms coiled inward toward the core of Hurricane Franklin,  Additional bands of showers and thunderstorms were revolving around the core of Franklin.  Winds to hurricane force extended out about 35 miles (55 km) northeast of the center of circulation.  Winds to tropical storm force extended out about 140 miles (225 km) on the northern side of Franklin and about 100 miles (160 km) on the southern side of the hurricane).

Hurricane Franklin could intensify further before it makes landfall.  It is moving over water where the Sea Surface Temperature is near 30°C.  An upper level ridge over northern Mexico is generating northerly winds which are blowing toward the top of the circulation.  However, those winds are not very strong and the vertical wind shear is minor and it did not prevent Franklin from becoming a hurricane.  Hurricane Franklin has about another 6 to 12 hours to strengthen.  Once Franklin makes landfall and moves into the mountains, the surface circulation will weaken quickly.

A subtropical ridge is steering Hurricane Franklin toward the west and that general motion is expected to continue.  Hurricanes often turn slightly south of west when the approach the coast of the southwestern Bay of Campeche.  On its anticipated track the center Hurricane Franklin could make landfall on the coast of Mexico north of Veracruz in less than 12 hours.  The most likely landfall would be between Veracruz and Nautla.

Hurricane Franklin will bring strong gusty winds, a storm surge and heavy rain at the coast.  The storm surge could reach 6 to 9 feet (2 to 3 meters) near and just to the north of where the center makes landfall.  Franklin could produce very heavy rain when it reaches the mountains and flash flooding is a serious risk.

Tropical Storm Franklin Moves Over Bay of Campeche and Strengthens

Tropical Storm Franklin moved off the Yucatan peninsula over the Bay of Campeche and began to strengthen on Tuesday night.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Franklin was located at latitude 20.3°N and longitude 91.3°W which put it about 325 miles (525 km) east-northeast of Veracruz, Mexico.  Franklin was moving toward the west-northwest at 10 m.p.h. (16 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 996 mb.

A Hurricane Warning was in effect for the portion of the coast from Puerto de Veracruz to Tuxpan, Mexico.  A Hurricane Watch was in effect for the portion of the coast from Tuxpan to Rio Panuco.  A Tropical Storm Waring was in effect for the portion of the coast from Celestun to Puerto de Veracruz and from Tuxpan to Rio Panuco.

Although Tropical Storm Franklin weakened as it moved across the Yucatan peninsula on Tuesday, its circulation maintained its structural integrity.  In fact, a tighter inner core developed at the center of the circulation while the tropical storm moved over land.  New thunderstorms began to form near the center of Tropical Storm Franklin as soon as the center moved back over water.  A primary band of thunderstorms began to wrap tightly around the eastern and northern sides of the center.  Additional bands of showers and thunderstorms began to form over the Bay of Campeche.  Thunderstorms in the core were generating upper level divergence which is pumping away mass.

Tropical Storm Franklin will move over an environment very favorable for intensification on Wednesday.  Franklin will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is little vertical wind shear.  An upper level trough over the Bahamas may enhance the upper divergence by creating an outflow channel to the east of Franklin.  Tropical Storm Franklin will intensify on Wednesday and there could be a period of rapid intensification.  Franklin is likely to become a hurricane.

Tropical Storm Franklin is being steered to the west by a subtropical high to its northeast.  A general westerly motion is expected to continue for another day or two.  On its anticipated track Tropical Storm Franklin will approach the coast of Mexico north of Veracruz on Wednesday night.  Franklin will bring gusty winds, heavy rain and a storm surge at the coast.  When Franklin moves inland the mountains will enhance the rising motion and very heavy rain could fall.  The heavy rain could cause flash floods.

Tropical Storm Franklin Makes Landfall on Yucatan

The center of Tropical Storm Franklin made landfall on the southeast coast of the Yucatan peninsula on Monday night.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Franklin was located at latitude 19.1°N and longitude 87.3°W which put it about 75 miles (120 km) east-northeast of Chetumal, Mexico.  Franklin was moving toward the west-northwest at 14 m.p.h. (22 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 995 mb.

A Hurricane Watch is in effect for the portion of the coast from Puerto de Veracruz to Rio Panuco, Mexico.  A Tropical Storm Warning is in effect for the portion of the coast from Chetumal to Sabancuy, Mexico and from Belize City northward to the Belize/Mexico border.  A Tropical Storm Watch is in effect for the portion of the coast from Sabancuy to Puerto de Veracruz, Mexico.

The circulation of Tropical Storm Franklin became better organized on Monday, but thunderstorms were unable to consolidate around the core of the circulation.  A ring of showers and weaker thunderstorms surrounds the center of circulation.  A band of stronger thunderstorms curls around the eastern side of the circulation.  The are weaker bands of showers and thunderstorms in the western half of the circulation.  The thunderstorms in the eastern side of Franklin were generating upper level divergence which was pumping mass away to the east of the tropical storm.

Tropical Storm Franklin will weaken as it moves over the Yucatan peninsula.  Franklin will spend approximately 18 hours over land and it will be a weaker tropical storm or tropical depression by the time it reaches the southern Gulf of Mexico.  The Sea Surface Temperature of the southern Gulf of Mexico is near 30°C.  The upper level winds should be weak and there is likely to be little vertical wind shear when Franklin moves over the southern Gulf.  Franklin is likely to intensify when it moves over the Gulf of Mexico and it could strengthen into a hurricane.

A subtropical high pressure system is steering Tropical Storm Franklin toward the west-northwest and that general motion is expected to continue for another day or two.  On its anticipated track Franklin will move across the Yucatan peninsula on Tuesday.  Franklin will produce gusty winds and locally heavy rainfall.  Floods could occur in some locations.

Tropical Storm Franklin Develops Over Northwest Caribbean Sea

A center of circulation developed in a system previously designated as Potential Tropical Cyclone Seven and the National Hurricane Center named the system Tropical Storm Franklin on Sunday night.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Franklin was located at latitude 16.4°N and longitude 83.0°W which put it about 380 miles (610 km) east-southeast of Chetumal, Mexico.  Franklin was moving toward the west-northwest at 13 m.p.h. (20 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.

A Tropical Storm Warning is in effect for the portion of the coast from Chetumal to Campeche, Mexico.  A Tropical Storm Watch is in effect for the portion of the coast from Belize City, Belize northward to the Belize/Mexico border.

Visible satellite images just before sunset suggested that a center of circulation had formed in the tropical wave previously designated Potential Tropical Cyclone Seven and the National Hurricane Center named it Tropical Storm Franklin.  The circulation of Tropical Storm Franklin is still not well organized.  The apparent center is located near the western edge of an area of thunderstorms.  Most of the thunderstorms are still forming east of the system, which indicates that vertical wind shear is probably still affecting the circulation.  The thunderstorms are producing some upper level divergence which is pumping mass away to the east of the tropical storm.

The environment ahead of Tropical Storm Franklin will become more favorable for intensification.  Franklin will move over water where the Sea Surface Temperature is near 30°C.  An upper level trough west of Franklin is producing westerly winds which are causing the vertical wind shear.  The trough is expected to weaken on Monday and when that happens the shear will diminish.  Warm water and less shear should allow Tropical Storm Franklin to strengthen before it reaches the Yucatan peninsula.  Franklin will weaken when it moves over land, but it is likely to re-intensify when it moves over the southern Gulf of Mexico.

Tropical Storm Franklin is being steered toward the west-northwest by a subtropical high centered over the Atlantic Ocean.  A general west-northwesterly motion is expected to continue.  On its anticipated track Tropical Storm Franklin could approach the Yucatan peninsula in about 24 hours.  Franklin will bring gusty winds and locally heavy rain to that area.  The heavy rain could cause flooding in some locations.

Tropical Storm Warning Issued for Mexico Due to Potential Tropical Cyclone Seven

The National Hurricane Center changed the designation of Invest 90L to Potential Tropical Cyclone Seven because of the need to issue a Tropical Storm Warning for portions of Mexico.  At 5: 00 p.m. EDT on Sunday the center of Potential Tropical Cyclone Seven was located at latitude 15.6°N and longitude 82.0°W which put it about 90 miles (145 km) east-northeast of Cabo Gracias a Dios.  It was moving toward the west-northwest at 12 m.p.h. (19 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 1008 mb.

A Tropical Storm Warning has been issued for the portion of the coast from Chetumal to Campeche, Mexico.  A Tropical Storm Watch has been issued for the portion of the coast from Belize City to the Belize/Mexico border.

A broad area of low pressure formed in a strong tropical wave over the northwestern Caribbean Sea.  There is not a well defined center of circulation within the broad area of low pressure.  Most of the thunderstorms are developing in the eastern half of the circulation.  There are few thunderstorms in the western half of the system.  The thunderstorms in the eastern half of the low are generating some upper level divergence which is pumping out mass to the east of the low.

Potential Tropical Cyclone Seven will move through a relatively favorable environment over the northwestern Caribbean Sea.  It will move over water where the Sea Surface Temperature is 30°C.  A small upper level trough to the west of the low is producing westerly winds which are causing moderate vertical wind shear.  The wind shear is probably the reason why most of the thunderstorms are in the eastern side of the circulation.  The upper trough is forecast to weaken and the shear is expected to diminish.  Potential Tropical Cyclone Seven could become a tropical storm over the northwestern Caribbean Sea, which is why the Tropical Storm Warning was issued.

Potential Tropical Cyclone Seven is being steered to the west-northwest by a subtropical high pressure system centered over the Atlantic Ocean.  That general motion is expected to continue for the next several days.  On its anticipated track Potential Tropical Cyclone Seven could reach the Yucatan Peninsula within 36 hours.  It could bring gusty winds and heavy rain when it moves over the Yucatan.  The system could restrengthen when it moves over the southern Gulf of Mexico.

NHC Monitoring Two Areas for Tropical Development

The National Hurricane Center (NHC) was monitoring two areas for possible tropical development on Thursday afternoon.  A strong tropical wave was moving through the southeastern Caribbean Sea and the wave was designated as Invest 90L.  At 2:00 p.m. EDT on Thursday the center of Invest 90L was located at latitude 12.2°N and longitude 65.8°W which put it about 160 miles (260 km) east of Bonaire.  The tropical wave was moving toward the west at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 35 m.p.h. (55km/h) and there were gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1011 mb.

Another tropical wave moved off the coast of West Africa on Thursday and NHC designated that wave as Invest 99L.  At 2:00 p.m. EDT on Thursday the center of Invest 99L was located at latitude 10.2°N and longitude 20.9°W which put it about 370 miles (595 km) south-southeast of the Cabo Verde Islands.  The tropical wave was moving toward the west at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1010 mb.

The tropical wave over the southeastern Caribbean Sea will have the most immediate impact to land.  The wave could bring gusty winds to Aruba, Bonaire and Curacao within 24 hours.  The circulation of Invest 90L is elongated in an east-west direction and that is probably because of strong easterly winds blowing in the lower atmosphere.  There are some indications of a counterclockwise rotation on loops of visible satellite imagery, but it is not clear if the rotation extends all the way down to the surface.  The tropical wave is generating winds to near tropical storm force in the northern portion of the wave.  There are numerous thunderstorms developing along the axis of the wave.

Invest 90L is moving under the western end of an upper level ridge.  The ridge is producing southerly winds which are blowing over the top of the tropical wave and those winds are contributing to moderate vertical wind shear.  The strong easterly winds in the lower levels are also contributing to the shear.  Invest 90L could develop into a tropical cyclone when it moves farther west.  The shear could diminish and the Sea Surface Temperatures in the western Caribbean Sea and Bay of Campeche are very warm.  NHC is indicating that there is a 20% probability Invest 90L will become a tropical cyclone during the next five days.

The tropical wave over the far eastern Atlantic has a better chance of developing into a tropical cyclone.  Invest 99L is moving over water where the Sea Surface Temperature is near 28°C.  It is moving under the eastern end of an upper level ridge.  The ridge is causing northeasterly winds which are blowing toward the top of the tropical wave.  Those winds are producing moderate vertical wind shear.  When the wave moves farther west, it will move under weaker winds and the wind shear will decrease.  NHC is indicating that there is a 70% probability that Invest 99L will become a tropical cyclone during the next five days.

Tropical Storm Emily Makes Landfall on West Coast of Florida

Tropical Storm Emily made landfall on the west coast of Florida at Anna Maria Island late Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Emily was located at latitude 27.5°N and longitude 82.7°W which put it about 10 miles (15 km) northwest of Bradenton, Florida.  Emily was moving toward the east at 9 m.p.h. (15 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.  A Tropical Storm Warning was in effect for the portion of the coast from Anclote River to Bonita Beach, Florida.

Thunderstorms developed near the center of the non-tropical low pressure system over the eastern Gulf of Mexico.  Latent energy released higher in the atmosphere by condensation in those storms created a warm core and the low pressure system made a transition to Tropical Storm Emily.  Thunderstorms near the core of Emily were generating a small area of upper level divergence.  Thunderstorms near the core, a warm core and upper level divergence are part of the typical structure of a tropical cyclone, which is why the National Hurricane Center classified the system as Tropical Storm Emily.  Emily has a well developed circulation, but most of the bands of showers and thunderstorms are in the eastern half of the tropical storm.  Drier air northwest of Emily and vertical wind shear are the probable causes of the asymmetrical distribution of precipitation.

Tropical Storm Emily is bringing gusty winds and heavy rain to parts of Central Florida.  A surface weather station in Sarasota (KSRQ) reported a sustained wind of 39 m.p.h. (63 km/h) and a wind gust of 49 m.p.h. (80 km/h).  The Skyway Bridge over Tampa Bay was closed due to strong winds.

Tropical Storm Emily is likely to weaken as it moves eastward across Central Florida.  When Emily moves over the Atlantic Ocean, it will move over water where the Sea Surface Temperature is near 29°C.  Emily could strengthen back into a tropical storm at that time.

Emily is being steered toward the east by a high pressure system north of the tropical storm.  An upper level trough over the Midwestern U.S. is forecast to move southeastward.  When Emily reaches the Atlantic Ocean southwesterly winds ahead of the trough will turn the tropical storm toward the northeast.

Non-Tropical Low Forms Over Northeast Gulf of Mexico

A non-tropical low pressure system formed over the northeastern Gulf of Mexico on Sunday.  The low pressure system is currently designated as Invest 98L.  At 2:00 p.m. EDT on Sunday the center of Invest 98L was located at latitude 28.4°N and longitude 85.5°W which put it about 100 miles (160 km) south-southwest of Apalachicola, Florida.  It was moving toward the east 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 1009 mb.

The low pressure system formed along a frontal boundary that stalled over the northeastern Gulf of Mexico.  It is not usual for low pressure systems to form along stationary fronts.  A source of positive vorticity to provide counterclockwise rotation and upper level divergence to pump away mass and allow the surface pressure to decrease will generate a surface low.  The low pressure system does not have a warm core in the middle and upper levels and it is still associated with a frontal system.  So, it is classified as a non-tropical low pressure system.

The low pressure system will be moving through an environment that will be only marginally favorable for a transition to a tropical or subtropical cyclone.  The Sea Surface Temperature in the northeastern Gulf of Mexico is near 30°C.  So, there is plenty of energy to support the formation of a tropical cyclone.  However, an upper level ridge over the central U.S. and a trough over the northeastern U.S. are combining to produce northerly winds of 40 m.p.h. (65 km/h) over the northeastern Gulf of Mexico.  Those winds are generating significant vertical wind shear.  The shear has limited the development of thunderstorms in the northern half of the low and it may be tilting the vertical structure of the low toward the south.  The strong upper level winds will also inhibit divergence on the northern side of the low and they could make it difficult for a warm core to develop in the middle and upper levels.  The air north of the frontal boundary is drier continental air, which is another a negative factor for transition to a tropical cyclone.  Based on all of the environmental factors the National Hurricane Center is indicating that there is a 30% chance the low could make a transition to a tropical or subtropical cyclone.

The low pressure system is moving a little to the south of due east.  A strong surface high pressure system over the eastern U.S. is now pushing the front toward the south as a cold front.  The low is moving slowly eastward along the front.  Combination of the southward motion of the front and eastward motion of the low produces a forecast motion of a little south of due east.  On its anticipated track the low pressure system could reach the west coast of Florida in 24 to 36 hours.  So, the low has about a day, if it is going to transition to a tropical cyclone over the Gulf of Mexico.