Tag Archives: Cape Verde Islands

Tropical Storm Karl Develops over the Eastern Atlantic

More thunderstorms developed near the center of Tropical Depression 12 and the National Hurricane Center named it Tropical Storm Karl on Thursday night.  Karl is the third tropical storm to form over the Atlantic Ocean this week.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Karl was located at latitude 17.9°N and longitude 32.5°W which put it about 1930 miles (3150 km) east of the Leeward Islands.  Karl was moving toward the west at 14 m.p.h.  The maximum sustained wind speed was 45 m.p.h. (70 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1005 mb.

The circulation of Tropical Storm Karl is asymmetrical.  Karl does have a large circular low level wind fields.  However the thunderstorms are northeast of the center of circulation, although some thunderstorms have developed closer to the northeast side of the center in recent hours.  Southwesterly winds in the upper levels are generating moderate vertical wind shear, which has contributed to the asymmetrical distribution of thunderstorms.  In addition, the upper level winds are inhibiting upper level divergence to the west of Tropical Storm Karl.

Tropical Storm Karl is moving through an environment that is not very favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 27°C.  There is moderate vertical wind shear, which will make it hard for thunderstorms to persist near the center of the tropical storm.  Karl could move into an area where the upper level winds are not as strong in a day or two.  The environment could be more favorable for intensification at that time.

A subtropical ridge north of Karl is steering the tropical storm toward the west.  The ridge is expected to get stronger and it should steer Tropical Storm Karl toward the west or west-southwest during the next few days.

Tropical Storm Gaston Forms Southwest of the Cape Verde Islands

A center of circulation quickly organized within a tropical wave on Monday night and the National Hurricane Center designated the system as Tropical Storm Gaston.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Gaston was located at latitude 12.6°N and longitude 30.7°W which put it about 450 miles (725 km) west-southwest of the Cape Verde Islands.  Gaston was moving toward the west-northwest at 18 m.p.h. (30 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 1005 mb.

The circulation consolidated rapidly around the center of Tropical Storm Gaston on Monday.  Several spiral bands of thunderstorms formed close to the center and additional bands formed farther from the center.  The thunderstorms near the center began to generate upper level divergence, which pumped mass away from the center.

Tropical Storm Gaston is moving through an environment that is favorable for intensification.  It is over water where the Sea Surface Temperature is near 28°C.  The upper level winds are light and there is little vertical wind shear.  Gaston is likely continue to intensify steadily during the next several days and it is expected to become a hurricane.  Once a tightly organized core consolidates completely, Gaston could undergo a period of more rapid intensification.

A subtropical ridge is steering Tropical Storm Gaston toward the west-northwest and that general motion is expected to continue for a day or so.  The ridge is expected to weaken northwest of Gaston, and the tropical storm is expected to turn more toward the north during the middle of the week.  Gaston could be moving out into the Central Atlantic Ocean by the end of the week.

Tropical Depression Six Forms Over Eastern Atlantic

A center of circulation developed within a tropical wave designated as Invest 98L on Tuesday and the National Hurricane Center classified the system as Tropical Depression Six.  At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Six was located at latitude 12.6°N and longitude 34.1°W which put it about 1800 miles (2900 km) east of the Leeward Islands.  The depression was moving toward the northwest at 14 m.p.h. (22 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.

The circulation of Tropical Depression Six is still organizing.  A center of circulation exists near the surface and thunderstorms are developing near the center.  Several partial spiral bands are beginning to form.  The thunderstorms near the center are generating a small region of upper level divergence, but the divergence is occurring mainly to the southwest of the depression.

Tropical Depression Six is moving through an environment that favors intensification.  It is moving over water where the Sea Surface Temperature is near 27°C.  An upper level ridge to the north is causing northeasterly winds to blow across the top of the depression.  There is some vertical wind shear, but the shear will only slow the rate of intensification.  The shear is not strong enough to prevent intensification and Tropical Depression Six is expected to become a tropical storm during the next day or two.

The subtropical ridge over Africa and the Atlantic Ocean is splitting into two parts and Tropical Depression Six is moving toward the northwest into the split that is developing.  The depression is expected to continue to move toward the northwest in the short term.  The longer term motion will depend on how strong Tropical Depression Six becomes.  If it intensifies more and develops a taller circulation, then the depression will be steered by the winds higher in the atmosphere.  The winds at those levels are more likely to carry it into the central Atlantic Ocean.  However, if vertical wind shear weakens the depression and the circulation is shallower, then the winds in the lower levels of the atmosphere could carry the depression farther to the west.  In either case Tropical Depression Six is no immediate threat to any land area.

Tropical Storm Grace Forms Southwest of Cape Verde

Enough organization developed in the center of an area of low pressure that moved off the coast of Africa several days ago for the National Hurricane Center to classify it as Tropical Storm Grace.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Grace was located at latitude 12.6°N and longitude 26.4°W which put it about 285 miles (460 km) southwest of the Cape Verde Islands.  Grace was moving toward the west at 14 m.p.h. (22 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 1007 mb.

The area of low pressure that became Tropical Storm Grace had a large area of thunderstorms when it moved off the coast of West Africa.  A few thunderstorms developed closer to the center of circulation and there are signs that a couple of spiral bands could be forming near the core of Grace.  The strongest thunderstorms are occurring in the southwestern quadrant of the circulation.  Some of the thunderstorms appear to be getting taller, but the core of the circulation is still organizing.

Tropical Storm Grace is moving over water where the Sea Surface Temperature is near 29°C.  Although there are stronger upper level westerly winds north of the tropical storm, the vertical wind shear over Tropical Storm Grace is relatively modest.  It has a day or two for the core of the circulation to organize and to intensify.  When Grace moves farther west it could move into a region where there is drier air.  An upper level trough could produce more vertical wind shear when the tropical storm gets closer to the Caribbean Sea.

A subtropical ridge is steering Grace toward the west and that steering pattern is expected to continue for the next few days.  If Grace gets stronger and the convection taller, it would take a track a little farther to the north.  If it remains weaker and shallower, lower level winds will steer it more to the west.  On its anticipated track, Grace could approach the Lesser Antilles in five or six days.

Hurricane Fred Bringing Wind and Rain to Cape Verde Islands

Hurricane Fred brought strong winds and heavy rain to many places in the Cape Verde Islands on Monday.  At 5:00 p.m. EDT on Monday the center of Hurricane Fred was located at latitude 17.2°N and longitude 24.6°W which put it about 20 miles (30 km) east of Santo Antao in the Cape Verde Islands.  Fred was moving toward the northwest at 12 m.p.h. (19km/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 989 mb.  A Hurricane Warning was in effect for the Cape Verde Islands.  It is unusual for a tropical cyclone of with sustained winds to hurricane force to move through the Cape Verde Islands.

Hurricane Fred has probably already gotten as strong as it is going to get.  It is moving over water where the Sea Surface Temperature (SST) is around 27°C.  However, an upper level trough located northwest of Fred is generating southwesterly winds that are blowing across the top of the hurricane.  The resulting vertical wind shear is beginning to affect the circulation in Fred and the eyewall is not as intact as it was earlier today.  As Fred moves farther north, the SSTs will decrease and the vertical wind shear will increase.  Those negative environmental factors should caused a steady weakening of Fred.

Hurricane Fred is moving toward a weaker portion of the subtropical ridge.  The ridge is expected to strengthen this week.  In addition, as the hurricane gets weaker, its circulation will become shallower.  That will mean it will be steered by winds lower in the atmosphere.  Those winds are likely to turn Fred toward the west in a day or two.

Fred will continue to bring wind and heavy rain to the Cape Verde Islands on Monday night, but conditions should start to improve on Tuesday when the hurricane moves farther west and weakens.

Rapidly Intensifying Tropical Storm Fred Threatens Cape Verde Islands

An area of low pressure organized quickly after it moved off the coast of West Africa and the National Hurricane Center designated it as Tropical Storm Fred.  At 2:00 p.m. EDT on Sunday the center of Tropical Storm Fred was located at latitude 14.1°N and longitude 20.7°W which put it about 195 miles (315 km) east-southeast of Praia in the Cape Verde Islands.  Fred was moving toward the northwest at 16 m.p.h. (26 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 1000 mb.  A Hurricane Warning has been issued for the Cape Verde Islands.

Tropical Storm Fred was a well organized low pressure system when it moved over the eastern Atlantic Ocean from West Africa.  The input of energy from the ocean enhanced the existing thunderstorms and the low pressure system quickly reached the intensity necessary to be classified as a tropical storm.  The circulation continued to organize further on Sunday.  A primary rainband has wrapped almost entirely around the center of circulation.  A small eye and an eyewall may be forming and other spiral bands of thunderstorms are developing.  The thunderstorms are generating upper level divergence which is pumping out mass.  Fred is moving over water where the Sea Surface Temperatures (SSTs) are near 27°C to 28°C.  The winds in the upper levels are relatively light and there is not much vertical wind shear.  The favorable environmental conditions are allowing Fred to intensify rapidly and it could become a hurricane tonight.  As Fred moves farther toward the northwest, it will start to move over cooler SSTs and into a region where there is more vertical wind shear.  As a result, Fred is likely to weaken back to tropical storm intensity later this week.

There is a weaker area in the subtropical ridge over the Atlantic Ocean and Fred is moving northwest toward that area.  The ridge is expected to strengthen during the week and as it strengthens it will cause Fred to move more toward the west.  On its anticipated track Fred will reach the Cape Verde Islands in about 12 hours.  It could bring strong winds and heavy rain when it move across those islands.