Tag Archives: 96L

Low Pressure System Approaches Southeast U.S.

A surface low pressure system that developed under the eastern side of an upper level low was approaching the southeastern U.S. on Monday morning. At 8:00 a.m. EDT on Monday the center of the low pressure system which was designated as Invest 96L was located at latitude 31.6°N and longitude 77.6°W which put it about 140 miles (220 km) southeast of Charleston, South Carolina. The low pressure system was moving toward the west-northwest at 17 m.p.h. (28 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 surface low pressure system formed over the Atlantic Ocean near the southeastern U.S. under the eastern side of an upper level low on Sunday. The surface low pressure system was clearly evident in visible satellite imagery on Monday morning. Bands of showers and lower clouds were revolving around the center of the surface low. Thunderstorms were occurring in bands on the far western side of the circulation around the surface low. The upper low was centered over northern Florida on Monday morning. It was producing easterly winds that were blowing across the top of the surface low. The easterly winds were causing moderate vertical wind shear and the wind shear was blowing the tops off clouds in many of the bands closer to the center of the surface low.

The surface low will move south of a high pressure system over the western Atlantic Ocean during the next 24 hours. The high will steer the surface low toward the west-northwest. On its anticipated track the center of the surface low will reach the coast near the border between Georgia and South Carolina on Monday evening. The low pressure system could bring gusty winds and locally heavy rain to the areas around Savannah, Georgia and Hilton Head Island, South Carolina.

If thunderstorms develop near the center of the surface low, the National Hurricane Center could designate the system as a tropical depression or a tropical storm. If the low pressure system strengthens, then a Tropical Storm Watch or Tropical Storm Warning could be issued for a portion of the coast. A reconnaissance plane is tentatively scheduled to investigate the low pressure system on Monday afternoon, if necessary.

Low Pressure System Forms Over Southwest Gulf of Mexico

A surface low pressure system formed over the southwestern Gulf of Mexico on Wednesday.  At 8:00 p.m. EDT on Wednesday the center of the low pressure system was located at latitude 20.8°N and longitude 95.4°W which put it about 70 miles (110 km) east-southeast of Nautla, Mexico.  The low was moving toward the north 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 1009 mb.

The northern end of a trough of low pressure moved over the Bay of Campeche on Wednesday and a surface low formed when the trough moved over the southwestern Gulf of Mexico.  More thunderstorms developed near the center of the low pressure system.  Divergence from a surface high pressure system over the U.S. was converging with the northern periphery of the circulation around the surface low and a band of showers and thunderstorms was occurring over the west central Gulf of Mexico.  Storms near the center of the low were starting to generate some upper level divergence.

The low pressure system will move through an environment that will be favorable for intensification during the next 24 to 36 hours.  The low will move over water where the Sea Surface Temperature is near 29°C.  It will move under an upper level ridge where the winds are weak and divergent.  The low could intensify slowly if it gets better organized on Thursday.  The National Hurricane Center is indicating that there is a 60% probability of formation of either a tropical or subtropical storm.  A reconnaissance plane has been tentatively tasked to investigate the low pressure system on Thursday afternoon.

The upper level ridge over the surface low pressure system will steer the low toward the northeast during the next several days.  On its anticipated track the low could approach the northeastern coast of the Gulf of Mexico on Friday.  The low will bring gusty winds and locally heavy rain.  The winds will generate higher waves and there could be a storm surge of 3 to 6 feet (1 to 2 meters).

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.