Tag Archives: 06L

Potential Tropical Cyclone Seven Causes Tropical Storm Watch for U.S. Gulf Coast

Potential Tropical Cyclone Seven caused the National Hurricane Center to issue a Tropical Storm Watch for a portion of the U.S. Gulf Coast on Sunday afternoon.  A Tropical Storm Watch was in effect for the portion of the coast from the Alabama-Florida border to Morgan City, Louisiana including Lake Pontchartrain.  At 5:00 p.m. EDT on Sunday the center of Potential Tropical Cyclone Seven was located at latitude 22.7°N and longitude 77.3°W which put it about 275 miles (445 km) east-southeast of Marathon, Florida.  It was moving toward the west-northwest at 15 m.p.h (24 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 1012 mb.

Bands of showers and thunderstorms began to form in a tropical wave over the Bahamas and the National Hurricane Center designated the system as Potential Tropical Cyclone Seven in order to be able to issue the Tropical Storm Watch for the north coast of the Gulf of Mexico.  The circulation of Potential Tropical Cyclone Seven was still organizing.  A distinct low level center of circulation had not formed.  Bands of showers and thunderstorms were developing and the bands were starting to revolve around the inner part of the weather system.  Thunderstorms were beginning to generate some upper level divergence.

Potential Tropical Cyclone Seven will be moving into an environment favorable for intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge is forecast to develop over Potential Tropical Cyclone Seven.  If that occurs, then the upper level winds would be weak and there would be little vertical wind shear.  Potential Tropical Cyclone Seven is forecast to intensify into Tropical Storm Gordon.  If the system moves slowly enough, there is a chance it could strengthen into a hurricane before it reaches the Gulf Coast.

Potential Tropical Cyclone Seven will move around the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Potential Tropical Cyclone Seven in a general west-northwesterly direction.  On its anticipated track the system will move over the Florida Keys on Monday.  It will be over the eastern Gulf of Mexico on Tuesday and the system could reach the northern Gulf Coast late on Tuesday or early on Wednesday.

Elsewhere over the tropical Atlantic, Tropical Storm Florence was moving quickly away from the Cabo Verde Islands.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Florence was located at latitude 17.4°N and longitude 34.6°W which put it about 700 miles (1125 km) west of the Cabo Verde Islands.  Florence was moving toward the west-northwest at 15 m.p.h. (24 km/h).  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.

Tropical Storm Florence Develops West of Cabo Verde Islands

Tropical Storm Florence developed west of the Cabo Verde Islands on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Florence was located at latitude 15.6°N and longitude 29.0°W which put it about 310 miles (500 km) west of the Cabo Verde Islands.  Florence was moving toward the west-northwest at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1002 mb.

The circulation of former Tropical Depression Six became better organized on Saturday and the National Hurricane Center designated the system as Tropical Storm Florence.  The center of circulation became more well defined and more thunderstorms developed closer to the center.  Numerous bands of showers and thunderstorms began to form.  The forming rainbands were revolving around the center of circulation.  Storms near the center started to generate upper level divergence.

Tropical Storm Florence will be moving through an environment somewhat favorable for intensification during the next day or two.  Florence will move over water where the Sea Surface Temperature is near 26°C.  It will move through a region where the upper level winds will be weak and there will be little vertical wind shear.  Tropical Storm Florence is likely to intensify during the next 24 to 48 hours.

Tropical Storm Florence will be moving south of a subtropical ridge over the eastern Atlantic Ocean.  The ridge will steer Florence in a general west-northwesterly motion during the next two or three days.  On its anticipated track the center of Tropical Storm Florence will move farther away from the Cabo Verde Islands.

Potential Tropical Cyclone Six Causes Warning for Cabo Verde Islands

The potential strengthening of Potential Tropical Cyclone Six caused the government of the Cabo Verde Islands to issue Tropical Storm Warnings for some of the southern islands on Thursday.  Tropical Storm Warnings were issued to Santiago, Fogo and Brava.  At 5:00 p.m. EDT on Thursday the center of Potential Tropical Cyclone Six was located at latitude 12.9°N and longitude 19.4°W which put it about 360 miles (580 km) east-southeast of the Cabo Verde Islands.  It was moving toward the west 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 1007 mb.

The circulation of of Potential Tropical Cyclone Six was still organizing.  There was a broad area of low pressure, but there was not a well defined center of circulation.  Numerous bands of showers and thunderstorms were revolving around the circulation of the broad low.  Many of the stronger thunderstorms were in the outer part of the circulation.  Since there were few thunderstorm in the inner portion of the circulation, it had not started to generate upper level divergence.

Potential Tropical Cyclone Six will be moving through an area favorable for intensification.  It will move over water where the Sea Surface Temperature is near 28°C.  It will move through a region where there will be little vertical wind shear.  Potential Tropical Cyclone Six is forecast to become a tropical depression during the next 12 hours.  It could strengthen into a tropical storm on Friday and it could intensify into a hurricane during the weekend.

Potential Tropical Cyclone Six will move south of a subtropical ridge over the eastern Atlantic Ocean during the next few days.  The ridge will steer the system toward the west-northwest.  On its anticipated track Potential Tropical Cyclone Six will pass near the southern Cabo Verde Islands on Friday, which is why the Tropical Storm Warning was issued.

Tropical Storm Emily Makes Landfall on West Coast of Florida

Tropical Storm Emily made landfall on the west coast of Florida at Anna Maria Island late Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Emily was located at latitude 27.5°N and longitude 82.7°W which put it about 10 miles (15 km) northwest of Bradenton, Florida.  Emily was moving toward the east at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1005 mb.  A Tropical Storm Warning was in effect for the portion of the coast from Anclote River to Bonita Beach, Florida.

Thunderstorms developed near the center of the non-tropical low pressure system over the eastern Gulf of Mexico.  Latent energy released higher in the atmosphere by condensation in those storms created a warm core and the low pressure system made a transition to Tropical Storm Emily.  Thunderstorms near the core of Emily were generating a small area of upper level divergence.  Thunderstorms near the core, a warm core and upper level divergence are part of the typical structure of a tropical cyclone, which is why the National Hurricane Center classified the system as Tropical Storm Emily.  Emily has a well developed circulation, but most of the bands of showers and thunderstorms are in the eastern half of the tropical storm.  Drier air northwest of Emily and vertical wind shear are the probable causes of the asymmetrical distribution of precipitation.

Tropical Storm Emily is bringing gusty winds and heavy rain to parts of Central Florida.  A surface weather station in Sarasota (KSRQ) reported a sustained wind of 39 m.p.h. (63 km/h) and a wind gust of 49 m.p.h. (80 km/h).  The Skyway Bridge over Tampa Bay was closed due to strong winds.

Tropical Storm Emily is likely to weaken as it moves eastward across Central Florida.  When Emily moves over the Atlantic Ocean, it will move over water where the Sea Surface Temperature is near 29°C.  Emily could strengthen back into a tropical storm at that time.

Emily is being steered toward the east by a high pressure system north of the tropical storm.  An upper level trough over the Midwestern U.S. is forecast to move southeastward.  When Emily reaches the Atlantic Ocean southwesterly winds ahead of the trough will turn the tropical storm toward the northeast.

Tropical Depression Six-E Forms West of Mexico

The Eastern North Pacific basin continues to be active tropically.  Tropical Depression Six-E formed west of Mexico on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Six-E was located at latitude 12.2°N and longitude 109.9°W which put it about 740 miles (1190 km) south of the southern tip of Baja California.  It was moving toward the west at 12 m.p.h. (19 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.

A center of circulation consolidated within a large area of thunderstorms south of Baja California on Tuesday.  A primary band of showers and thunderstorms wrapped around the western and southern sides of the center of circulation.  Additional bands of showers and thunderstorms were beginning to form north and west of the center.  There were not many showers and storms in the eastern half of the circulation.  The thunderstorms near the core of the circulation were beginning generate upper level divergence which was pumping away from depression.

Tropical Depression Six-E will move through an environment that will be favorable for intensification.  It will move over water where the Sea Surface Temperature (SST) is near 29°C.  Tropical Depression Six-E is near the western end of an upper level ridge and the upper level winds are relatively weak.  Warm SSTs and little vertical wind shear should allow the depression to strengthen during the next several days.  Tropical Depression Six-E is likely to become a tropical storm on Wednesday and it could become a hurricane later this week.

Tropical Depression Six-E is moving south of a subtropical ridge which is steering the depression toward the west.  The subtropical ridge is expected to continue to steer the depression toward the west during the next few days.  On its anticipated track the depression is expected to move away from the coast of Mexico.

Tropical Depression Six Intensifies Into Tropical Storm Fiona

Tropical Depression Six intensified on Wednesday and the National Hurricane Center named it Tropical Storm Fiona.  At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Fiona was located at latitude 15.1°N and longitude 37.8°W which put it about 1545 miles (2490 km) east of the Leeward Islands.  Fiona was moving toward the northwest at 16 m.p.h. (26 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 1006 mb.

Tropical Storm Fiona has a small circulation and winds to tropical storm force only extend out about 25 miles (40 km) from the center circulation.  Most of the thunderstorms are occurring close to the center of circulation.  Those thunderstorms are generating some upper level divergence, but it does not extend very far from the core of Tropical Storm Fiona.  There are bands of lower clouds and showers rotating around the core of Fiona.

Tropical Storm Fiona is moving through an environment that is mostly favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 27°C.  An upper level ridge north of Fiona is generating northeasterly winds which are blowing across the top of the tropical storm.  Those winds are causing some vertical wind shear, but it should only inhibit, but not stop, intensification.  There is drier air northwest of Fiona and that is the main negative factor in the environment.  If the drier air gets pulled into the core of Tropical Storm Fiona, it will reduce the supply of energy and weaken Fiona.  Since the core of Fiona is so small, the tropical storm could intensify or weaken very quickly as the environmental conditions change.

The subtropical high that extends from Africa across the Atlantic Ocean is splitting into an eastern ridge and a western ridge.  Tropical Storm Fiona is moving toward the weakness where the split is occurring.  This is producing a motion toward the northwest and that general motion is expected to continue during the next several days.  On its anticipated track Tropical Storm Fiona could be northeast of the Leeward Islands in a few days.

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.

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.