Tuesday, September 28, 2010

Tropical Storm Nicole (2010)

Storm Active: September 28-29
During the final week of September, Tropical Storm Matthew dissipated over Mexico. However, the huge amount of moisture left over from this system was accompanying a broad area of low pressure over Central America and the western Caribbean. Disorganized showers and thunderstorms began to appear in this area during the day of September 26, and pressures dropped over the area over the coming days. On September 28, a closed center formed, and the system was upgraded to Tropical Depression Sixteen. The depression's center was broad, with the only area of convection to the southeast of the circulation, but a band formed to the northeast of the center later that day, as well as the center itself becoming slightly more defined, and these factors resulted in the pressure dropping slightly as the system moved northnortheast, but not a promotion to tropical storm status. The depression made landfall in Cuba, but as it was a very asymmetrical and broad cyclone, it was very difficult to classify one way or the other. However, the presence of tropical storm force winds near the center was enough to push the cyclone to Tropical Storm Nicole during the morning of September 29, while still over Cuba.

The system emerged over water but the huge circulation lost the little tropical characteristics that it had, and was declared dissipated later that day, shortly after reaching its peak intensity of 40 mph winds and a pressure of 996 mb. However, the rainfall was by no means over. The remnant moisture of Nicole combined with an extratropical low off of North Carolina and a stationary front over the northeast to bring torrential rainfall to the region from Maine to Florida, with local amounts exceeding fifteen inches. This storm activity finally ceased by October 1. This cyclone caused 13 fatalities and $151.9 million in damage, but this does not include additional damage wreaked by the combined system that impacted the northeast U.S.

Nicole as an odd-looking tropical storm near Cuba.

Track of Nicole.

Friday, September 24, 2010

Tropical Storm Matthew (2010)

Storm Active: September 23-26
On September 19, a trough of low pressure formed in the south central Atlantic. It slowly organized organization and a low pressure center appeared on September 21. The system gained convection, and the convection showed signs of a organized circulation by September 23, meriting the promotion of the low to Tropical Depression Fifteen. The tropical depression's center was fairly open until later that day, when a band circumnavigated the center for the first time, and the system was named Tropical Storm Matthew.

Matthew moved quickly westward through the southern Caribbean, and strengthened slowly over the next day. However, Matthew only reached an intensity of 50 mph winds and a pressure of 998 mb, before making landfall in northern Nicaragua during the afternoon of September 24. It maintained an intensity of 50 mph over land, and briefly emerged over the Gulf of Honduras on September 25, before beginning to weaken over Belize later that day.

The system quickly weakened to a tropical depression, and was a remnant low by early on September 26. However, the large area of moisture associated with the large circulation of Matthew caused continual heavy rain and flooding through the next few days. Matthew was the direct cause of several mudslides in Central America, causing 109 fatalities.

Matthew at its peak intensity before making landfall in Mexico.

Track of Matthew.

Tuesday, September 21, 2010

Hurricane Lisa (2010)

Storm Active: September 20-26
The tropical wave that became Lisa emerged off of Africa on September 16. The cloud cover associated with the wave remained disorganized for a day, but a broad low pressure center formed on September 17. The low took a turn northwest before slowing its motion and drifting to the north over the next few days. This uncertain motion was caused by a weakness in the usual Azores high that pushes cyclones to the west, a weakness that was enlarged by Hurricane Julia a few days earlier. Meanwhile, the system became more organized, and was declared a tropical depression late on September 20. The depression soon strengthened into Tropical Storm Lisa.

The cyclone meandered northeast, then east, then south, and then east again through the next day, with no change in intensity. Some convection was lost during the day of September 21, and the system weakened to a tropical depression, still maintaining a slow east motion. By September 23, convection had organized enough for Lisa to become a tropical storm again, and the system was nearly stationary during that day. However, Lisa adopted a northward motion during the day of September 24, and continued strengthening.

By late on September 24, Lisa had quickly intensified to a hurricane, reaching its peak intensity of 80 mph winds and a pressure of 987 mb just before midnight. An eye feature even made a brief appearance. However, Lisa began quickly weakening the next day, as it moved into cooler waters. The system was a remnant low by the afternoon of September 26. Lisa moved north and quickly dissipated. The cyclone affected no land masses.

Lisa as a hurricane. It is obviously a very small storm.

Track of Lisa.

Tuesday, September 14, 2010

Hurricane Karl (2010)

Storm Active: September 14-18
Late on September 9, a low pressure system formed to the east of the northeastern coast of South America. The low stalled near the Windward Islands, and crossed into the Caribbean on September 10. The low produced a lot of disorganized shower and thunderstorm activity which brought stormy conditions to much of the Caribbean over the next few days as it moved west, but little of this convection showed evidence of any circulation. However, on September 14, a closed circulation became evident from an aircraft reconnaissance mission sent to investigate the system, and a small pocket of tropical storm force winds allowed the low to skip depression status and become Tropical Storm Karl.

Karl lost most of its convection during the night, but still strengthened slightly, before a burst of convection near the center caused the cyclone to intensify to 65 mph winds early on September 15 just before landfall in the southeast Yucatan Peninsula. Since Karl made landfall near the Mexican border, portions of both Mexico and Belize were struck by tropical storm force conditions. Karl weakened over land to a minimal tropical storm, but reemerged over the Bay of Campache by early on September 16. Karl immediately began a strengthening trend over water, and the system quickly intensified into a hurricane later on September 16. An eye feature developed over the next day, and Karl rapidly intensified into a major hurricane, reaching its major hurricane peak intensity if 120 mph winds and a pressure of 956 mb on early on September 17, before weakening slightly just before landfall in Veracruz, Mexico with maximum winds of 115 mph.

Karl quickly began to weaken over land, losing its major hurricane status quickly later on September 17. Karl was ripped apart by the mountainous regions of central Mexico as it moved southwest inland, but these same mountainous regions caused a large amount of flooding over the affected area. 22 fatalities and $3.9 billion in damage are direct effects of the cyclone.

Hurricane Karl before striking the Mexican coast.

Track of Karl.

Sunday, September 12, 2010

Hurricane Julia (2010)

Storm Active: September 12-20
Early in the second week of September, a strong tropical wave was already very evident over Africa, and it was monitored for development even before leaving the coast. By the time it did emerge over the Atlantic Ocean on September 11, it was very organized and was already showing tropical characteristics. As a result, the system was declared Tropical Depression Twelve on September 12. As the depression turned westnorthwest, it intensified into Tropical Storm Julia late on September 12.

Early on September 13, the southernmost Cape Verde islands experienced tropical storm conditions, as Julia passed just to the southwest. Julia took a more northward track than the cyclones before it, but it still intensified over the next day, as the predecessor of an eyewall formed near Julia's center, signifying a very healthy cyclone. The storm continued this strengthening trend, and became a Category 1 hurricane early on September 14.

It continued to strengthen through the morning as a structure that was almost an eye appeared, but Julia stabilized later in the afternoon after strengthening rapidly to its peak intensity as a Category 4 hurricane with 135 mph winds and a pressure of 950 mb early on September 15.

The cyclone turned farther to the north and began a general northwest motion. It began to encounter less favorable conditions as it approached cooler water and shear associated with the outflow of Igor. However, during its time as a Category 4, Julia set the record for strongest Atlantic cyclone east of 35ºW, surpassing the record set by Hurricane Fred just a year earlier. Julia continued to weaken over the next day, but wind shear died down slightly later on September 16, as Julia took a more westward turn. Julia maintained its Category 1 intensity over the next day, despite entering the outflow of the much larger and powerful Igor.

Julia continued weakening, and the center became separated from the convection on September 17. As a result, Julia soon became a tropical storm. Julia continued weakening into September 19, as it turned north and then northeast, accelerating over the open ocean. The system became extratropical on September 20, and started to be absorbed over the next day as a frontal boundary associated with Igor engulfed it. Julia caused only minimal damage while passing the Cape Verde islands, and was only notable for being a major hurricane very far east.

Julia near peak intensity.

Track of Julia.

Wednesday, September 8, 2010

Hurricane Igor (2010)

Storm Active: September 8-21
On September 6, a strong tropical wave emerged off of Africa. A low became associated with the system on September 7, and the system continued to organize, despite significant shear. On September 8, the system was organized enough to skip the tropical depression stage and intensify directly into Tropical Storm Igor.

The convection and circulation of Igor were at a very high level of organization, even with two low pressure systems in the vicinity. These three lows shared a low pressure trough extending from just off Africa to a few hundred miles north and west, but Igor began to strengthen later on September 8, and asserted its dominance. Igor meandered slowly to the west, before taking a turn north and then northwest on September 9. As it moved into greater shear, it weakened, becoming a tropical depression later that day, as the center became exposed from the east side. Despite this, the circulation deepened, the convection became more organized, and the system regained tropical storm status the next day. The shear had abated once again and Igor began to strengthen. During the morning of September 11, Igor developed an interesting eye feature on the north side of the system, and the storm approached hurricane strength. However, convection decreased during the afternoon before a burst of convection during the evening caused Igor to become a hurricane.

An eye became evident within this convection early on September 12, and Igor underwent explosive strengthening, ballooning from a minimal hurricane to a amazing Category 4 by that afternoon as a result of a drop of 50 mb in 12 hours. Igor's forward motion slowed and the system moved due west throughout that same day. Igor continued to strengthen, reaching an intensity of 150 mph late on September 12, and this remarkable intensity was maintained throughout the day of September 13, as a beautiful symmetric eye dominated the system. By that evening, surf began to increase in the Northern Leeward Islands as Igor approached from the west. Igor made a slight westnorthwest turn that night, and an eye replacement cycle destabilized the system, weakening it. However, it remained a Category 4 through the day of September 14, before organizing further and strengthening once again during the evening. Igor reached a peak intensity of 155 mph and a pressure of 925 mb later that night before the eye clouded over and a weakening trend commenced.

However, Igor organized once again, and the fluctuations in intensity continued as Igor became a powerful Category 4 once more with 145 mph winds. The convection became slightly asymmetrical, with the bulk of the cloud cover on the north side on September 16, but the moisture evened out during the evening as a a pronounced rain band formed south of the center. Also, during the day of September 16, Igor's tropical storm wind field broadened to 506 miles in diameter, making it the third-largest Atlantic hurricane on record. Igor began weakening, however, and finally lost it's Category 4 status during the late afternoon of September 16, after maintaining it for four days. The system continued to weaken over the next day. By the afternoon of September 18, Igor was a Category 2, but the windfield was still broadening, and squally weather was already sweeping over Bermuda. By later that night, Igor's tropical storm force windfield engulfed Bermuda, and the winds increased throughout the day, despite the fact that Igor weakened to a Category 1.

The center of Igor passed just to the west of Bermuda late on September 19, and the island saw sustained winds near hurricane-force as a result. Igor accelerated northeastward, and maintained a minimal hurricane status while the extratropical transition began on September 20. However, this transition wasn't completed by the time Igor passed Newfoundland, and the center passed just to the east of the island, causing sustained winds near hurricane force and dumping over 9 inches of rain in some areas, causing flooding. Igor finally became extratropical on September 21. Igor caused 3 fatalities and about $100 million in damage. The cyclone was also notable for being the largest Atlantic hurricane ever recorded, with a tropical storm force wind diameter of 920 miles, until it was surpassed by Hurricane Sandy of 2012.

Igor near peak intensity.

Track of Igor.

Monday, September 6, 2010

Tropical Storm Hermine (2010)

Storm Active: September 5-7
On September 3, a low pressure system formed in the eastern Pacific and quickly became Tropical Depression Eleven-E. However, the system made landfall in Mexico the next day without becoming a tropical storm. The remnant low of the system moved into the Bay of Campeche on September 5 and began to organize again. The low was associated with a very large area of showers and thunderstorms covering a significant portion of the western Gulf of Mexico. Late on September 5, the system was organized enough to be upgraded to Tropical Depression Ten. Ten quickly strengthened, and became Tropical Storm Hermine early on September 6.

Hermine quickly organized, and began rapidly strengthened as it moved generally to the north. Hermine reached its peak intensity of 65 mph winds and a minimum pressure of 991 before making landfall in extreme north Mexico late on September 6. Hermine crossed the U.S.-Mexico border inland a few hours later, as it steadily weakened. Hermine maintained minimal tropical storm status for a fairly long time inland, but finally weakened to a tropical depression by the evening of September 7. By later that night, it was no longer monitored by the national hurricane center, but it still maintained tropical depression status, as it tracked northward through the central U.S. The depression merged with a frontal boundary on September 9. The remnant moisture combined with the frontal system caused heavy rain from the midwest to the northeast over the next couple of days, before moving off the coast on September 12.

Hermine inland over Texas, still maintaining tropical storm strength and a healthy outflow.

Track of Hermine.

Thursday, September 2, 2010

Tropical Storm Gaston (2010)

Storm Active: September 1-2
A tropical wave emerged off of Africa on August 29, and immediately began to organize, developing a low pressure center rapidly. By the beginning of September, a defined center had formed, and the system became Tropical Depression Nine early on September 1. The depression quickly crossed the border to tropical storm strength and was named Tropical Storm Gaston.

However, some Saharan dry air was still embedded in the system, preventing deep convection in the center. Meanwhile, the cyclone was tracking only very slowly westward, due to the presence of a trough to its north. The dry air present in the system weakened Gaston to a tropical depression and then a remnant low by the afternoon of September 2. However, early on September 3, convection associated with the remnant increased, and organization continued to increase over the next few days. Despite this, the low lost its good circulation, and, although convection persisted, the chance of development was significantly decreased by September 7 as it passed through the Caribbean. On September 8, the low dissipated. Gaston affected no landmasses and therefore had no impact.

Note: It is believed that the remnants of Gaston may have briefly attained tropical depression status again on September 4, but post-season analysis will confirm this after the conclusion of 2010.

Gaston on September 4, possibly a tropical depression.

The track of Gaston, with appropriate changes made from post-storm analysis.