Category Archives: Atlantic, Caribbean, and Gulf of Mexico

Atlantic TCs

TD 16 Becomes Tropical Storm Otto

The National Hurricane Center named former Tropical Depression 16 as Tropical Storm Otto on Monday afternoon based on data from satellites.  At 4:00 p.m. EST the center of Tropical Storm Otto was located at latitude 11.3°N and longitude 79.2°W which put it about 315 miles (505 km) east of Bluefields, Nicaragua.  Otto was stationary.  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.

The structure of Tropical Storm Otto has not changed appreciably during today.  Most of the thunderstorms are occurring in bands north and west of the center of circulation.  There are fewer thunderstorms in the southeastern quadrant of the circulation.  Otto is a small tropical storm.  Winds to tropical storm force only extend out about 35 miles (55 km) from the center.  Thunderstorms are generating upper level divergence which is pumping mass out north and west of the tropical storm.

Tropical Storm Otto will move through an environment that will be favorable for intensification.  It will move over water where the Sea Surface Temperature will be near 29°C unless Otto moves so slowly that its own circulation mixes cooler water to the surface.  Southerly winds in the upper levels are generating moderate vertical wind shear, but those winds are expected to weaken.  When the vertical shear diminishes, Tropical Storm Otto will be likely to intensify and it could become a hurricane.

Tropical Storm Otto is currently in a region where the steering currents are weak.  However, a ridge of high pressure is forecast to build north of Otto, and the ridge is likely to steer the tropical storm toward the west.  On its anticipated track Tropical Storm Otto could approach the coast of Nicaragua and Costa Rica in 48 to 72 hours.

Tropical Storm Otto could be a hurricane by the time it reaches the coast of Nicaragua and Costa Rica.  Otto will be capable of bringing gusty winds and heavy rain to portions of Nicaragua, Costa Rica, northern Panama, Honduras, El Salvador and southern Guatemala.  The locally heavy rain could produce flash floods and mudslides in areas of steep terrain.

Tropical Depression 16 Develops Over Southwest Caribbean Sea

The National Hurricane Center upgraded Invest 96L to Tropical Depression 16 on Monday morning.  At 10:00 a.m. EST on Monday the center of Tropical Depression 16 was located at latitude 11.5°N and longitude 79.3°W which put it about 305 miles (495 km) east of Bluefields, Nicaragua.  Tropical Depression 16 was stationary.  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).  The minimum surface pressure was 1002 mb.

An Air Force Reserve Hurricane Hunter aircraft investigated the area of low pressure over the southwestern Caribbean Sea on Sunday afternoon and it found a distinct surface center with a lower pressure.  When more thunderstorms formed near the center of circulation early on Monday, the National Hurricane Center designated the system as Tropical Depression 16.

The circulation of Tropical Depression 16 is fairly well organized.  It has a tight core and several bands of thunderstorms.  Most of the bands are occurring north and west of the center of circulation.  There are fewer thunderstorms in the southeastern quadrant of the circulation.  The thunderstorms north of the center are generating upper level upper level divergence.  Southerly winds appear to be inhibiting upper level divergence to the south of the tropical depression.

Tropical Depression 16 is in an environment that is slightly favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 29°C.  However, the depression and its precursor have been over the same area for almost a week.  So, the winds in Tropical Depression 16 are gradually mixing cooler water to the surface.  An upper level ridge to the east and an upper level trough to the west are generating southerly winds which are blowing across the top of the depression.  The southerly winds are generating moderate vertical wind shear and they are inhibiting upper level divergence to the south.  The mixed environmental factors will limit intensification in the short term.  The upper level winds are forecast to weaken in a day or two and more intensification could occur when that happens.  Tropical Depression 16 is likely to intensify into a tropical storm and it could become a hurricane later this week.

The steering currents are weak around Tropical Depression 16 and it may move little during the next 24 to 36 hours.  A ridge of high pressure is forecast to build north of the depression and the ridge is forecast to steer it slowly toward the west later this week.  Tropical Depression 16 could approach the coast of Nicaragua in about three days.  It could be a hurricane at the time.

Invest 90L Organizing North of Panama

The structure of the low pressure system designated as Invest 90L became better organized on Saturday over the southwestern Caribbean Sea north of Panama.  At 7:00 p.m. EDT on Saturday the center of Invest 90L was located at latitude 10.8°N and longitude 80.9°W which put it about 220 miles (355 km) east-southeast of Bluefields, Nicaragua.  Invest 90L was moving toward the east 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. (70 km/h).  The minimum surface pressure was 1006 mb.

More thunderstorms developed closer to the center of circulation on Saturday.  A band of stronger thunderstorms formed south of the center and a second band of storms developed northeast of the center.  Other rainbands appeared to be forming in other areas of the circulation.  Storms in the band northeast of the center began to produce upper level divergence that was pumping mass away.  An improved convective structure could be a indication that Invest 90L is developing into tropical depression.

The atmospheric environment became more favorable for tropical development on Saturday.  Upper level southwesterly winds which were blowing across the top of the low pressure system weakened on Saturday  and the vertical wind shear lessened.  Less shear allowed more thunderstorms to develop and persist.  Since Invest 90L has meandered over the same part of the southwestern Caribbean Sea for several days, it has mixed slightly cooler water to the surface.  However, the water in that part of the Caribbean Sea is very warm and Invest 90L is moving over water where the Sea Surface Temperature is still near 29°C.  The environment is favorable for development of a tropical cyclone and Invest 90L could become a tropical depression or a tropical storm at any time.

Invest 90L is located underneath an upper level ridge and the steering currents are weak.  The low pressure system drifted toward the east on Saturday and some models are suggesting that Invest 90L could make a slow counterclockwise loop over the southwestern Caribbean Sea during the next few days.

Invest 90L Meandering Over Southwest Caribbean Sea

An area of low pressure designated as Invest 90L has meandered over the southwestern Caribbean Sea during the past several days.  At 7:00 p.m. EST on Thursday the center of Invest 90L was located at latitude 12.3°N and longitude 81.3°W which put it about 170 miles (275 km) east of Bluefields, Nicaragua.  Invest 90L was moving toward the west at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 25 m.p.h. (40 km/h) and there were wind gusts to 35 m.p.h. (55 km/h).  The minimum surface pressure was 1006 mb.

Invest 90L consists of a broad area of low pressure over the southwestern Caribbean Sea.  There is a definite area of counterclockwise rotation, but the is no well defined core at the center of the low.  There is a swirl of low clouds and showers at the center of Invest 90L, but there are no thunderstorms near the center.  Thunderstorms form and dissipate in bands around the periphery of the circulation.

The environment around the southwestern Caribbean Sea is not as favorable for the development of a tropical cyclone as it was earlier this week.  Invest 90L is moving over water where the Sea Surface Temperature is near 29°C.  However, northerly winds blowing across the Gulf of Mexico have transported drier air over the northwestern Caribbean Sea.  The drier air has not reached Invest 90L, but the drier air is just to the northwest of the low pressure system.  An upper level trough over the Gulf of Mexico is producing southwesterly winds which are blowing over the top of Invest 90L.  Those winds are generating moderate vertical wind shear which is inhibiting the organization of the low pressure system.  Even with the inhibiting factors the National Hurricane Center is indicating that the probability of the formation of a tropical cyclone during the next five days is 70%.

The fact that there is only a low level circulation means that Invest 90L is being steering by winds closer to the surface.  The winds in the lower levels have been pushing the low pressure system very slowly toward the west.  Guidance from numerical models suggests that Invest 90L could meander over the southwestern Caribbean Sea for several more days.

Possible Tropical Development Over the Southwest Caribbean Sea

A weak trough of low pressure over the Southwestern Caribbean Sea has the potential to develop into a tropical cyclone during the next few days.  The National Hurricane Center is stating that there is a 70% probability of the formation of a tropical cyclone during the next five days.  A broad trough of low pressure stretches from near Panama to east of Nicaragua.  There is not a well defined center of low pressure within the broader trough.  There were more thunderstorms earlier today, but many of them weakened on Monday evening.  A few more thunderstorms developed north of Panama during the past several hours.

The environment over the southwestern Caribbean Sea is favorable for intensification.  The Sea Surface Temperature of water in that part of the Caribbean Sea is around 29°C.  There is an upper level ridge over the area.  The winds are weaker in the center of the ridge and there is little vertical wind shear in that part of the atmosphere.  The ridge providing a source of upper level divergence which is allowing the surface pressure to decrease slowly.

Several numerical models are suggesting that a tropical cyclone could develop during the next few days.  The models do differ on exactly when and where the tropical cyclone could form.  The probability of development will be higher if the area of lower pressure remains over the water.  However, if the trough of low pressure drifts closer to the coast of Nicaragua, then the interaction of the circulation with land could inhibit the formation of a tropical cyclone.  Even if a tropical cyclone does not form, the trough could produce locally heavy rain over parts of Panama, Nicaragua and Honduras.

Hurricane Nicole Bringing Strong Winds and Heavy Rain to Bermuda

Hurricane Nicole is bringing strong winds and heavy rain to Bermuda on Thursday morning.  At 11:00 a.m. EDT on Thursday the center of Hurricane Nicole was located at latitude 32.3°N and longitude 64.6°W which put it about 10 miles (15 km) east of Bermuda.  Nicole was moving toward the northeast at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 961 mb.  A Hurricane Warning remains in effect for Bermuda.

Nicole is a large powerful hurricane.  Winds to hurricane force extend out about 65 miles (105 km) from the center of circulation.  Winds to tropical storm force extend out about 180 miles (290 km) from the center.  The diameter of the eye is approximately 35 miles (55 km).

A weather station on Pearl Island reported sustained winds to 87 m.p.h. (141 km/h) with wind gusts to 119 m.p.h. (191 km/h).  An elevated weather station at Commissioner’s Point reported sustained winds to 92 m.p.h. (148 km/h) and wind gusts to 122 m.p.h. (196 km/h).

Hurricane Nicole is moving toward the northeast at 16 m.p.h. (26 km/h).  So, it will take approximately two hours for the eye of Hurricane Nicole to move across Bermuda.  After the eye passes, hurricane force winds in the southern half of Nicole will affect Bermuda.  The winds should gradually diminish later today when Hurricane Nicole moves northeast of Bermuda.

Powerful Major Hurricane Nicole Nearing Bermuda

Hurricane Nicole intensified into a powerful major hurricane late on Thursday as it moved closer to Bermuda.  At 11:00 p.m. EDT on Thursday the center of Hurricane Nicole was located at latitude 30.1°N and longitude 66.4°W which put it about 180 miles (290 km) south-southwest of Bermuda.  Nicole was moving toward the north-northeast at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 950 mb.  Nicole is a Category 4 hurricane on the Saffir-Simpson Scale.  A Hurricane Warning is in effect for Bermuda.

Hurricane Nicole intensified very rapidly during the past 12 hours.  The maximum sustained wind speed increased from 100 m.p.h. (160 km/h) to 130 m.p.h. (215 km/h) during that time period.  The minimum surface pressure decreased from 970 mb to 950 mb at the same time.  Hurricane Nicole now has a large circular eye with a diameter of 35 m.p.h. (55 km).  Hurricane Nicole also increased in size as it intensified.  Winds to hurricane force now extend out 65 miles (105 km) from the center of circulation.  Wind to tropical storm force extend out 160 miles (260 km) from the center.

Nicole is a large powerful hurricane. The Hurricane Intensity Index (HII) is 25.1.  The Hurricane Size Index (HSI) is 20.6 and the Hurricane Wind Intensity Size Index (HWISI) is 45.7.  The indices indicate that Hurricane Nicole is capable of causing widespread significant wind damage.

Southwesterly winds on the eastern side of a upper level trough will steer Hurricane Nicole toward the northeast.  When Nicole moves further north, westerly winds will steer it more toward the northeast.  On its anticipated track the core of Hurricane Nicole will reach Bermuda on Thursday morning.  Nicole has the potential to be a very destructive hurricane.

Nicole Strengthens Into a Hurricane, Warning for Bermuda

Tropical Storm Nicole intensified into a hurricane on Tuesday afternoon and a Hurricane Warning was issued for Bermuda.  At 5:00 p.m. EDT on Tuesday the center of Hurricane Nicole was located at latitude 27.4°N and longitude 66.4°W which put it about 350 miles (565 km) south-southwest of Bermuda.  Nicole was moving toward the northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 980 mb.

The organization of the circulation of Hurricane Nicole improved rapidly on Tuesday afternoon.  The primary rainband wrapped around the center of circulation and an eye developed.  The eye currently has a diameter of about 30 miles (48 km).  A ring of strong thunderstorms surrounds the eye.  Those thunderstorms are producing well developed upper level divergence which is pumping out mass in all directions.  Additional rainbands are developing in the rest of the circulation.  Nicole is a relatively small hurricane.  Hurricane force winds only extend out about 35 miles (55 km) from the center and tropical storm force winds on extend out about 120 miles (195 km) from the center.

The environment around Hurricane Nicole became much more favorable on Tuesday afternoon.  The winds in the upper level weakened and the vertical wind shear diminished.  The weaker upper level winds also allowed the upper level divergence to pump out more mass and the pressure decreased 10 mb in six hours on Tuesday afternoon.  Less vertical wind shear allowed Hurricane Nicole to extract energy more efficiently from the ocean.  Hurricane Nicole is moving over water where the Sea Surface Temperature is near 28.5°C.  Nicole is likely to intensify for another 36 to 48 hours.  So, Hurricane Nicole will continue to intensify and it could intensify rapidly.  Nicole could be a major hurricane by the time it nears Bermuda.

Nicole is moving around the western end of a subtropical high pressure system which is steering the hurricane toward the northwest.  When Hurricane Nicole reaches the western end of the high, it will turn more toward the north.  As Hurricane Nicole moves farther north, the westerly winds in the middle latitudes will turn it toward the northeast.  On its anticipated track, Hurricane Nicole could approach Bermuda on Thursday morning.  It could be a major hurricane at that time.

Tropical Storm Nicole Prompts Hurricane Watch for Bermuda

While water rescues continued in parts of North Carolina and recovery efforts accelerated after the passage of Hurricane Matthew, Tropical Storm Nicole prompted the issuance of a Hurricane Watch for Bermuda.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Nicole was located at latitude 26.3°N and longitude 65.4°W which put it about 415 miles (670 km) south of Bermuda.  Nicole was moving toward the north at 6 m.p.h. (10 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 992 mb.

After becoming a hurricane last Thursday Nicole weakened back to a tropical storm during the weekend.  A combination of intermittent vertical wind shear and drier air caused the structure of Tropical Storm Nicole to deteriorate.  The eye disappeared and the thunderstorms in the rainbands weakened.  There appears to be a remnant of the eyewall, but it only consists of lower clouds and showers.  Several rainbands exist around the circulation, although they are not as strong as they were a few days ago.  Thunderstorms southeast of the center of circulation seem to have increased on Monday afternoon.  The new thunderstorms are generating some upper level divergence but it is not currently well developed.

Tropical Storm Nicole is an environment that is marginal for intensification.  An upper level trough north of Nicole is generating some vertical wind shear.  In addition cooler, drier air has moved close to the western part of the circulation of Tropical Storm Nicole.  On the other hand, Tropical Storm Nicole is moving over water where the Sea Surface Temperature is near 29°C.  So, there is plenty of energy in the upper ocean.  The vertical wind shear and drier air could prevent Tropical Storm Nicole from intensifying much on Tuesday.  The upper level trough will move off to the east and the vertical wind shear could decrease during the middle of the week.  If the shear diminishes and not much drier air gets pulled into the circulation, then Tropical Storm Nicole has a chance to intensify into a hurricane.

A high pressure system blocked the northward movement of Tropical Storm Nicole and the high even pushed Nicole toward the south at times during the weekend.  The high appears to be moving farther to the east, which is allowing Tropical Storm Nicole to move slowly toward the north.  As the high pressure system shifts to the east, it will start to steer Tropical Storm Nicole more toward the northwest.  When Nicole reaches the western end of the high, it will turn toward the northeast.  The westerly winds in the middle latitudes will accelerate Nicole toward the northeast later this week.  On its anticipated track the center of Tropical Storm Nicole could pass near Bermuda on Thursday.

Hurricane Matthew Causing Serious Flooding in the Carolinas

Hurricane Matthew produced heavy rainfall which led to serious flooding in South Carolina and North Carolina on Saturday.  The total rainfall in some locations exceeded 10 inches (25 cm) in numerous locations in those two states.  Heavy prolonged rain caused creeks and rivers to rapidly rise and flood.

The National Hurricane Center (NHC) still classified Hurricane Matthew as a hurricane in its 11:00 p.m. EDT advisory.  At 11:00 p.m. EDT on the center of Hurricane Matthew was located at latitude 34.1°N and longitude 76.5°W which put it about 35 miles (55 km) south of Cape Lookout, North Carolina.  Matthew was moving toward the east-northeast at 14 m.p.h. (22 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 Warning is in effect for the portion of the coast from Little River Inlet to Surf City, North Carolina.  A Hurricane Watch has been issued for the portion of the coast from Surf City to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Tropical Storm Warning is in effect for the portion of the coast from Surf City to Duck, North Carolina including Pamlico and Albemarle Sounds.

According to NHC the center of Hurricane Matthew made an official landfall near Cape Romain southeast of McClellanville, South Carolina at 11:00 a.m. EDT on Saturday.  Since that time the center of Hurricane Matthew has moved back out over the Atlantic Ocean.  New bands of showers are forming closer to the center south of the coast of North Carolina.  The winds to hurricane force are occurring over a small area on the southwestern side of Hurricane Matthew.

Easterly winds blowing around the north side of Hurricane Matthew converged with northerly winds blowing along a cold front to generate a broad area of rising motion.  The rising motion and the existing rainbands of the hurricane combined to produce very heavy rain over South Carolina and the southeastern half of North Carolina.  The area of heavy rain spread into southeastern Virginia around Norfolk on Saturday night.  The prolonged heavy rainfall caused the water in creeks and rivers to rise very quickly.  Serious flooding was occurring in parts of South Carolina and North Carolina.  Numerous roads were closed because of flooding in those two states.

Along the coast of North Carolina southeasterly winds were blowing water toward the coast and Hurricane Matthew was still generating storm surges.  When Matthew moves east of the Outer Banks of North Carolina, the wind will change direction and it will blow from the northwest.  Those northwesterly winds will push water in Pamlico and Albemarle Sounds onto the western sides of the Outer Banks.  Storms surges caused by Hurricane Matthew caused varying amounts of damage from Florida to North Carolina.  The most destructive storm surges appear to have been near Jacksonville Beach, Florida, around the barrier islands of Georgia and South Carolina.  However, a full damage assessment has not been made of those locations at this time.

Even though the center of Hurricane Matthew stayed over the Atlantic Ocean most of the time, gusty winds caused power outages from Florida to North Carolina.  As the heavy rain saturated the ground, gusts of winds toppled trees which fell onto power lines.  More power outages are likely in eastern North Carolina and southeastern Virginia as more trees are uprooted.

Hurricane Matthew will slowly move out to sea on Sunday.  Matthew appears to be making a transition to an extratropical cyclone.  During that transition the wind field is likely to expand.  So, conditions should improve slowly over North Carolina and Virginia on Sunday.