Tag Archives: Tropical Depression Four

Tropical Storm Bret Nears Barbados

Tropical Storm Bret moved near Barbados on Thursday afternoon. At 2:00 p.m. EDT on Thursday the center of Tropical Storm Bret was located at latitude 13.4°N and longitude 58.9°W which put it about 45 miles (75 km) east-northeast of Barbados. Bret was moving toward the west at 14 m.p.h. (22 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 1002 mb.

Tropical Storm Warnings were in effect for Barbados, St. Lucia, Martinique, Dominica and St. Vincent and the Grenadines. A Hurricane Watch was also in effect for St. Lucia.

The intensity of Tropical Storm Bret appeared to peak on Thursday morning. A U.S. Air Force Reserve Hurricane Hunter aircraft found that Bret was close to hurricane intensity on Thursday morning. A microwave satellite image showed an eyelike feature in the middle levels of Tropical Storm Bret. After its intensity peaked in the morning, the portion of Bret’s circulation in the lower levels appeared to race out ahead (to the west) of the parts of the circulation in the middle and upper troposphere during Thursday. The rapid movement of the circulation near the surface was creating strong vertical wind shear. The lower level circulation consisted primarily of showers and lower clouds. Thunderstorms were occurring in bands the eastern part of Tropical Storm Brett. Those thunderstorms were occurring near the circulation center in the middle levels.

The distribution of wind around Tropical Storm Bret remained asymmetrical. Winds to tropical storm force extended out 115 miles (185 km) in the northern side of Bret’s circulation. Winds to tropical storm force extended out 45 miles (75 km) in the southern part of Tropical Storm Bret.

Tropical Storm Bret will move through an environment unfavorable for intensification during the next 24 hours. Bret will move over water where the Sea Surface Temperatures are near 28˚C. It will move under the western end of an upper level ridge over the tropical Atlantic Ocean. The ridge will produce southerly winds that will blow toward the top of Bret’s circulation. Bret will move around the southern side of a subtropical high pressure system over the Atlantic Ocean. The subtropical high will produce strong easterly winds in the lower levels of the atmosphere. The strong easterly winds in in the lower levels will cause strong vertical wind shear. The strong wind shear will cause Tropical Storm Bret to weaken during the next 24 hours.

Tropical Storm Bret will move south of a subtropical high pressure system over the Atlantic Ocean. The subtropical high will steer Bret toward the west during the next 24 hours. On its anticipated track, Tropical Storm Bret will bring gusty winds and locally heavy rain to Barbados on Thursday afternoon. The center of Bret could pass close to St. Lucia on Thursday night. Tropical Storm Bret will bring strong winds and locally heavy rain to St. Lucia. Bands in the northern part of Bret’s circulation will also bring strong winds and locally heavy rain to Martinique and Dominica. Tropical Storm Bret could produce gusty winds and heavy rain over St. Vincent and the Grenadines. Locally heavy rain could cause flash floods in some locations.

Elsewhere over the Atlantic Ocean, Tropical Depression Four formed halfway between Africa and the Lesser Antilles. At 11:00 a.m. EDT on Thursday the center of Tropical Depression Four was located at latitude 11.3°N and longitude 42.9°W which put it about 1270 miles (2040 km) east of the Lesser Antilles. Tropical Depression Four was moving toward the west-northwest at 15 m.p.h. (24 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 1007 mb.

Tropical Depression Four Forms, Tropical Storm Warning for South Carolina

Tropical Depression Four formed on Monday morning and the National Hurricane Center issued a Tropical Storm Warning for a portion of the coast of South Carolina. At 11:00 a.m. EDT on Monday the center of Tropical Depression Four was located at latitude 31.9°N and longitude 78.3°W which put it about 110 miles (175 km) east-southeast of Charleston, South Carolina. Tropical Depression Four was moving toward the west-northwest at 16 m.p.h. (26 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 Tropical Storm Warning was issued for the portion of the coast from Edisto Beach to South Santee River, South Carolina. The Tropical Storm Warning included Charleston.

The National Hurricane Center designated a low pressure system off the coast of South Carolina as Tropical Depression Four on Monday morning. Bands of showers and lower clouds were revolving around the center of Tropical Depression Four. Thunderstorms were occurring in bands on the far western side of the circulation around the depression. An upper low was centered over northern Florida on Monday morning. The upper low was producing easterly winds that were blowing across the top of the tropical depression. 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 depression

Tropical Depression Four will move through an environment that is only slightly favorable for intensification during the next 12 hours. The depression will move over water where the Sea Surface Temperatures are near 27°C. The upper level low will continue to cause vertical wind shear that will inhibit the formation of thunderstorms near the center of Tropical Depression Four. If the wind shear decreases, then there is a chance Tropical Depression Four could strengthen to a tropical storm later on Monday.

Tropical Depression Four will move south of a high pressure system over the western Atlantic Ocean during the next 24 hours. The high will steer the depression toward the west-northwest. On its anticipated track the center of Tropical Depression Four could make landfall near Edisto Beach, South Carolina on Monday night. The depression will produce gusty winds along the coast of South Carolina. It could also drop locally heavy rain over parts of southern South Carolina and extreme eastern Georgia.

Tropical Depression Four Develops East of the Lesser Antilles

Tropical Depression Four developed east of the Lesser Antilles on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Four was located at latitude 12.8°N and longitude 38.4°W which put it about 1545 (2485 km) east of the Lesser Antilles.  The depression was moving toward the west-northwest at 14 m.p.h. (22 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.

A larger area of thunderstorms formed and persisted on the western side of a tropical disturbance formerly designated as Invest 94L on Wednesday and the National Hurricane Center classified the system as Tropical Depression Four.  The distribution of thunderstorms is still asymmetrical.  Most of the stronger storms are developing in the western half of the circulation.  The thunderstorms in the western part of the circulation were beginning to generate upper level divergence.  There were few thunderstorms in the eastern half of the depression and the vertical structure of the circulation could be tilted to the west with height.

Tropical Depression Four will be moving through an environment that contains both positive and negative factors for intensification.  The depression will move over water where the Sea Surface Temperature is near 27°C.  So, there is sufficient energy in the upper ocean to support intensification.  An upper level ridge is producing easterly winds which are blowing toward the top of the circulation.  Those winds could be causing the circulation to tilt toward the west with height.  Moderate vertical wind shear could inhibit intensification.  Drier air is north of the tropical depression.  If the depression remains south of the drier air and if the vertical wind shear does not become too strong, then the depression could strengthen.  Alternatively, if the depression pulls in drier air and/or the vertical shear increases, then the depression could weaken back to a tropical wave.

The subtropical ridge over the Atlantic Ocean is steering Tropical Depression Four toward the west-northwest.  A general west-northwesterly motion is expected for the next several days.  The actual track will also have a significant effect on the future intensity of Tropical Depression Four. If the depression moves on a more southerly track, it will stay south of the drier air and it would have a greater opportunity to intensify.  If the depression moves farther to the north, it will move into the drier air and will be more likely to weaken,