Tag Archives: 97L

Invest 97L Poses Risk for Caribbean Sea

A tropical disturbance designated as Invest 97L poses a potential risk for locations around the Caribbean Sea.  At 8:00 p.m. EDT on Tuesday the center of Invest 97L was located at latitude 13.1°N and longitude 55.3°W which put it about 285 miles (460 km) east of Barbados.  Invest 97L was moving toward the west at 19 m.p.h. (31 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 1008 mb.

A U.S. Air Force Reserve Hurricane Hunter aircraft flew a reconnaissance mission into Invest 97L on Tuesday afternoon.  The plane found the there were winds to near tropical storm force, but it could not identify a closed circulation.  The winds on the western side were weaker and the plane was unable to find a surface center.  There does seem to be cyclonic rotation above the surface at least on infrared satellite imagery.

The circulation in Invest 97L is still organizing.  Many of the stronger thunderstorms are forming north and east of the apparent center on satellite imagery.  Rainbands are also forming north and east of the center.  Recent satellite images suggest that some thunderstorms could be developing closer to the center of cyclonic rotation.  The current thunderstorms are generating upper level divergence which is pumping out mass to the north and east of the system.

Invest 97L is moving through an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 29°C.  The upper level winds over the majority of the circulation are relatively weak.  An upper level trough over the Caribbean Sea is generating vertical wind shear over the northern fringe of the circulation.  Invest 97L could become a tropical storm at any time.

A subtropical high pressure system to the north of Invest 97L is steering it toward the west and that general motion is expected to continue for another day or two.  On its anticipated track Invest 97L will move through the Windward Islands near Barbados, St. Lucia, Martinique, and Dominica on Wednesday.  It could bring gusty winds and locally heavy rain to those locations.

Possible Tropical Development

The National Hurricane Center (NHC) is monitoring two tropical disturbances which are designated Invest 96L and Invest 97L for possible development into tropical cyclones.

At 8:00 p.m. EDT on Thursday the center of Invest 97L was located at latitude 13.4°N and longitude 37.0°W which put it about 1525 miles (2460 km) east-southeast of the Leeward Islands.  Invest 97L was moving toward the west at 21 m.p.h. (34 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 1011 mb.

At 8:00 p.m. EDT on Thursday the center of Invest 96L was located at latitude 11.2°N and longitude 20.9°W which put it about 320 miles (515 km) south-southeast of the Cape Verde Islands.  Invest 96L was moving toward the west-northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1010 mb.

Invest 97L consists of a fast moving tropical wave over the central Atlantic Ocean.  The circulation of Invest 97L is not well organized.  A few thunderstorms are occurring near the northern part of the axis of the tropical wave, but convection is scattered.  The rapid forward motion of the wave is preventing the thunderstorms from consolidating around a center of circulation.

If the forward speed of Invest 97L slows, then it may move into an environment that is more favorable for the development of a tropical cyclone.  It is over water where the Sea Surface Temperature (SST) is near 27°C and it will move over warmer water as it gets closer to the Caribbean Sea.  There is not much vertical wind shear except for the low level shear created by the rapid forward motion of the wave.  There is drier air to the north of Invest 97L, but it is embedded in the moister air closer to the Equator.  NHC has a 30% probability that Invest 97L will develop into a tropical cyclone during the next five days.  As a result, NHC has tentatively tasked a plane to fly reconnaissance into Invest 97L on Saturday if it shows signs of developing as it approaches the Caribbean Sea.

Invest 96L also consists of a tropical wave, but it is more well organized than Invest 97L  There are numerous thunderstorms west of the center of circulation and some rainbands are developing south of the center of circulation.  The thunderstorms west of the center are starting to generate some upper level divergence to the west of Invest 96L.  There are some indications that a low level center of circulation may be forming.

Invest 96L is currently in an environment that is mostly favorable for further development.  It is moving over water where the SSTs are near 28°C.  An upper level ridge north of Invest 96L is causing easterly winds to blow over the top of it.  The vertical wind shear is moderate and shear is the primary factor slowing the organization of the Invest 96L.  NHC has a 40% probability that Invest 96L will develop into a tropical cyclone during the next five days.

Because it is more well organized and it is moving more slowly, Invest 96L has a better chance for developing into a tropical cyclone during the next two days.  However, Invest 96L could move into a less favorable environment after that time.  Invest 97L will be moving into a more favorable environment during the weekend.  If Invest 97L holds together until its forward speed slows, then it could have a better chance of developing in several days.  If Invest 97L becomes a tropical cyclone it could threaten portions of the Caribbean Sea.