Tropical Depression Eight (2009)

Storm Active: September 25-26

A tropical wave moved off of Africa on August 23, and began to develop disorganized showers and thunderstorms as it moved to the west-north-west at about 15 mph. On September 24, the Cape Verde Islands received scattered showers and thunderstorms as it passed to the south of the region. On September 25, the wave began to organize west of the Cape Verde Islands, despite being in an area only marginally favorable for tropical cyclone formation and started to develop a center of circulation. The system was declared Tropical Depression Eight at 5 p.m. on September 25 already at its peak intensity of 35 mph winds and a pressure of 1008 millibars. Over the next day, the depression moved northwest into cooler waters and became less organized. Then, exactly a day after formation, Eight lost its center of circulation and dissipated. The tropical wave continued to produce shower activity as it moved northwest and was monitored for regeneration, but no new low formed, and the possibility for reformation was gone by September 27.



The tropical wave destined to become Tropical Depression Eight organizing in the East Atlantic.



Track of Eight

Hurricane Fred (2009)

Storm Active: September 7-12

On September 6, a strong, organized, tropical wave associated with an area of low pressure moved off of Africa and quickly developed into Tropical Depression Seven the next day. The depression passed south of the Cape Verde Islands and intensified into Tropical Storm Fred on September 7. Fred's center became well-defined, and the system strengthened through the next day, becoming Hurricane Fred on September 8 with 75 mph winds and a pressure of 987 millibars. Hurricane Fred jumped to Category 3 intensity in just 12 hours and reached its peak intensity of 120 mph winds and a pressure of 958 millibars on September 9. At his time, Fred had a distinct eye feature, and it became the most southeasterly major hurricane ever to form in the Atlantic Ocean. Fred curved to the north, due to a ridge to its west, and its southeast side weakened. As a result, strong wind sheer ripped at the system from that direction, causing Fred to weaken, becoming a tropical storm on September 11. Convection began to separate from the center to the north, and Fred became nearly stationary, drifting east, then south, and weakening all the time and making a tight loop in the Eastern Atlantic. By mid-afternoon on September 12, Fred was a minimal tropical storm, with almost no convection. It was then downgraded to a remnant low that night, and moved west. The low continued to produce shower activity, but dissipated on September 16. However, a new low formed in association with Fred's remnants 500 miles south of Bermuda and the area was monitored once again. The low continued to drift west, and finally dissipated, becoming part of a frontal boundary, on September 20.



Hurricane Fred at Category 3 intensity in the far east Atlantic.



Track of Fred. Note that the triangles signifying Fred's remnant low continued much farther west before dissipating.

Tropical Storm Erika (2009)

Storm Active: September 1-3

On August 26, a tropical wave moving off of Africa became associated with a broad area of low pressure south of the Cape Verde Islands, producing shower and thunderstorm activity. However, the cloud cover and organization diminished over the next few days as the system moved west. By August 31, though, the low had regenerated into an organized ball of convection. The system was organized enough to be a tropical storm and had tropical storm force winds, but i still wasn't classified. This was because it lacked a center of circulation. The low was an elongated oval, widest north to south, and a center could have formed anywhere along the oval. During the afternoon of September 1, a center began to for, evident on visible imagery as a point just east of the cloud cover associated with with the system. Therefore, like the previous storm Danny, the system skipped tropical depression status and was upgraded directly to Tropical Storm Erika, with 50 mph winds and a pressure of 1007 millibars. Later that night, the pressure dropped to 1004 millibars and the winds increased to 60 mph, but Erika took a southerly turn and weakened the next morning. By mid-morning, Erika began to interact with the northern Leeward islands of the Caribbean Sea, causing wind and rain. Later on September 2, Erika entered the Caribbean, still maintaining minimal tropical storm winds of 40 mph. Erika struggled westward, its center well west of the convection, similar to Tropical Storm Danny's appearance several days earlier. Erika meandered through the Caribbean for another day, before weakening to a tropical depression south of Puerto Rico on September 3. Overnight, Erika weakened into a remnant low. The next day, the low dissipated. Damage was minimal and no fatalities resulted from Erika.



Erika near peak intensity. Even then, Erika was very disorganized.



Track of Erika.

Tropical Storm Danny (2009)

Storm Active: August 26-29

On August 20, a tropical wave moved off Africa. It showed little signs of organization, but it was monitored for development. The cloud cover diminished on August 22, but flared up again on August 23, as the wave interacted with an upper-level low to its northwest. The low, sheered the system, but it also fueled increasing convection around the wave over the next two days. As the tropical wave passed under the low on August 25, sheer lessened, and more organization was evident. The wave ad strong enough winds to be considered a tropical storm, but still lacked a specific center of circulation. However, this appeared on the morning of August 26, and the wave-low interaction was upgraded directly to Tropical Storm Danny. Danny had most cloud activity to the northeast of the center, and wasn't that organized. Despite this, stronger winds were found in the system and Danny strengthened, reaching its peak intensity of 60 mph winds and a pressure of 1006 millibars that night. Danny was heading generally northwest, but meandered north of the Bahamas, sometimes going west, north, even south. As Danny slowly made its way towards the U.S. east coast on August 27, it encountered less favorable conditions and began to weaken as its convection became increasingly displaced to the east of its center. By August 28, Danny was a minimal tropical storm, and was steered more northerly by a ridge of high pressure of the southeastern United States. Early on August 29, Danny was downgraded to a tropical depression off the Outer Banks of North Carolina. The last advisory was issued at 5 a.m. Eastern Standard Time that morning as Danny merged with a frontal low pressure system in the Northeast. Danny helped to enhance the moisture in the region even more, causing 2-4 inches of rain over various areas of New England. The merged low and accompanying frontal boundary continued northeast, eventually causing heavy rain in the Canadian Maritime on August 30. Danny, having never made landfall as a tropical system, caused little damage, and one fatality resulted from rip currents on the coast of North Carolina.



Visible satellite image of Danny while maintaining its peak. The center is highly evident as a swirl of clouds well outside the cloud cover, which is all east of the center.



Track of Danny.

Tropical Storm Claudette (2009)

Storm Active: August 16-17

On August 11, a scattered area of showers and thunderstorms became associated with a tropical wave over the Bahamas. The wave showed little to no organization over the next few days as it moved westward, and tracked south of Florida. On August 15, upon entering the Gulf of Mexico, the wave became significantly better organized, and on August 16, was classified Tropical Depression Four, with 35 mph winds and a central pressure of 1011 millibars. Later that same day, Tropical Depression Four became Tropical Storm Claudette. The system quickly reached its peak intensity of 50 mph winds that evening. Overnight, technically very early on August 17, Eastern Standard Time, Claudette made landfall in the panhandle of Florida. The system's central pressure briefly decreased after landfall, but then Claudette became a remnant low late on August 17. For a few more hours, the remnants of Claudette continued northwest, before it dissipated on August 18. Two fatalities occurred as a result of this system, and damages totaled around $1.2 million.



Claudette near peak intensity in the Gulf of Mexico.



Track of Claudette.

Hurrricane Bill (2009)

Storm Active; August 15-24

On August 11, a strong tropical wave moved off Africa. It took a few days to organize, but on August 15, it became Tropical Depression Three, with 35 mph winds and a pressure of 1006 millibars. A few hours later, Three became Tropical Storm Bill. Unlike the previous storm Ana, Bill quickly stregthened and became the first hurricane of the 2009 season on August 17 with 75 mph winds and a pressure of 987 millibars. It took a west-north-west track, which allowed for more favorable conditions. Inside the well-organized circulation, eyewall and eye structures quickly formed. A large area of high pressure kept Bill on this track, as it continued to gain strength. By August 18, it was a Category 2, with 100 mph winds and a pressure of 967 millibars. Then, overnight, Bill rapidly intensified into a Category 4 hurricane, with winds of 135 mph and a pressure of 948 millibars. Later that same day, Bill made its closest approach to the northeasternmost islands of the Caribbean, causing high surf but no other effects. On August 20, the ridge of high pressure keeping Bill to the south weakened, allowing Bill to take a northward turn. Bill slowly weakened, and on August 21, began to batter Bermuda with tropical storm force winds as a Category 2. Bill continued north, accelerating over time, and brushed Cape Cod with its outer bands causing huge surf and rip currents. On August 23, Bill's center paralleled the coast of Nova Scotia, staying barely offshore. At this time, Bill was turning east and was a minimal Category 1 hurricane. Late that night Bill made a landfall in Newfoundland and had passed by a mere six hours later. Early on August 24, Bill was a tropical storm, and, going east at 43 mph, Bill finally became extratropical. It continued eastward, and its extratropical remnants eventually brought wind and rain to Great Britain and surrounding areas. Bill caused two fatalities, both as a result of high surf on the east coast of the U.S.

Sorry, but an image of Hurricane Bill is not currently available on this website. To see one, click here.



Track of Bill.

Tropical Storm Ana (2009)

Storm Active: August 11-17

On August 8, a strong tropical wave emerged off Africa. It showed a lot of organization, and therefore was classified a tropical depression on August 11. Tropical Depression Two had 30 mph winds and an internal pressure of 1006 millibars on its first advisory, but it showed signs of strengthening. It also had minor effects on the southern Cape Verde Islands. Tropical Depression Two became more organized on August 12, when convection became more defined and covered the center of circulation. However, the system was still a tropical depression with 35 mph winds and a pressure of 1006 millibars. That night, however, the depression lost its cloud cover due to wind sheer, and weakened back to 30 mph winds on August 13. Despite some regeneration of the convection later that day, it was downgraded to a remnant low. However, cloud cover came back to the system slowly and on August 15, it became Tropical Depression Two once again. Then, six hours later, it became the first named storm of the 2009 season with its peak intensity of 40 mph winds and a pressure 1005 millibars. The newly named Tropical Storm Ana continued westward and interacted with the easternmost islands of the Caribbean, causing little damage. Only rain and some tropical storm force winds resulted. As it plowed deeply into wind sheer, the system weakened and became Tropical Depression Ana south of Puerto Rico. It brought periods of showers and winds to the island, before becoming a remnant low on August 17. The low continued west-north-west over the next few days, and dissipated near Florida on August 19. Damage from Ana was minimal and no fatalities resulted from this system.



Tropical Depression Two before dissipating and regenerating into Tropical Storm Ana.



Track of Ana.

Lack of Hurricane Activity in the Atlantic Basin in 2009

In the first two months of the hurricane season, i.e. up to the end of July, typically only one tropical cyclone has occurred in the north Atlantic Basin, but in the last decade, an average of three named storms have already occurred by this point. Also in the last decade, there has been about a fifty percent chance of a hurricane forming before July 31.

Tropical Depression One has been the only storm of the season, and it formed before the season started, in May, making it a preseason storm. Since then, hardly any activity has occurred and no cyclones have formed. The very opposite of this has happened in the East Pacific Basin, where, after a late start, five tropical cyclones, four of them named, and two of them hurricanes formed before July 31.

Some potential for tropical cyclone formation was present in June, and a fair amount of tropical waves came and dissipated during that time. However, an El Nino event (see here) that had been building for months reached strength in early July, stopping anything from forming. The current prediction is for a near average hurricane season with 11 named storms. However, the current trend may end in a below average season, the first since 2006, and before that, 1997. Both of these seasons' source of inactivity was an El Nino as well.

Despite this, there are exceptions. In 2004, no storms formed until August 1, which is a very late start. However, the 2004 season went on to have 15 named storms, with 9 hurricanes and 6 major hurricanes, along with over 3,100 fatalities, making it one of the most damaging seasons ever.

Hurricane activity is very unpredictable, and a lot may happen between the end of July, and the end of November which marks the end of the hurricane season.

Sources: National Hurricane Center, and wikipedia (which got its information from the National Hurricane Center)

El Nino and La Nina

El Nino and La Nina are two phenomena that concern pressure differences over the Pacific Ocean and have effects all over the world, most specifically on North and South America. El Nino and La Nina conditions are defined by the pressure of the air above the northeastern Pacific Ocean. During an El Nino, a low pressure system is situated over this region, and during a La Nina, a high pressure is situated over this region. Although low and high pressure systems come and go, some areas of the world generally have a low pressure or high pressure over them. One example of this is the Bermuda high, which is a high pressure over the Bermuda area during the summer months. When this high pressure is weaker, it allows tropical cyclones to curve off the east coast of the United States and not impact land, but when it is strong, it acts as a barrier, and tropical cyclones are pushed into making landfall along the Atlantic coast.



An example of a weak Bermuda high. Tropical cyclones are able to curve eastward without affecting land



An example of a strong Bermuda high. Tropical cyclones are pushed into the U.S. This condition was present during the 2004 and 2005 seasons, and these were some of the worst and most active in history.

Minor El Nino and La Nina conditions are common and usually only last a few months. But a long term event, or episode, occurs every five to seven years. An El Nino has the effect of letting a stronger Jet Stream enter the United States, which causes wet weather in the Midwest and South, and cool weather in the north. During a La Nina, the high pressure system in the Pacific severely weakens the Jet Stream and prevents moisture from reaching the Midwest and South. Therefore, there is dry weather in this region. El Nino and La Nina conditions also affect tropical cyclone formation. The strong Jet Stream during an El Nino causes a strong west to east wind along the tropics, causing intense wind shear (for the effects of a strong Jet Stream, see The Dagger of Death) which rips tropical cyclones apart. During a La Nina event, the lack of wind shear allows more tropical cyclones to form. A recent example of tropical cyclone formation hindered by an El Nino was 2006, when only 10 storms formed. Also, due to the effect of the Jet Stream on the Bermuda High, the only strong hurricanes of this season didn't affect land.



The effects of El Nino and La Nina.

El Nino and La Nina also affect water temperature, and therefore fish migrations. The fish migrations, in turn, affect the fishing business and therefore the economy. Although the results of El Nino and La Nina seem minor, they start many chains of events that change things in many different topics in many different parts of the world.

Sources: http://svs.gsfc.nasa.gov/vis/a010000/a010000/a010069/index.html (images), wikipedia (some information and image)

Tropical Depression One (2009)

Storm Active: May 28-29

A low pressure system formed on May 27 off the coast of North Carolina. Drifting northeast, the low showed no signs of development until, on May 28, it rapidly strengthened into Tropical Depression One with 35 mph winds and a pressure of 1007 millibars. The convection associated with the system was tight, and therefore didn't affect any landmass. The depression continued east-north-east into May 29, when, at its peak intensity of 35 mph winds and a pressure of 1006 millibars, the circulation began to separate from the clouds associated with it. Soon after it became extratropical and was absorbed by a frontal boundary. Tropical Depression One was a preseason storm, and therefore the 2009 season is the third consecutive season with a storm forming before June 1. No land was affected by this system.



Tropical Depression One in the Northwest Atlantic.



Track of One.