Friday, September 13, 2013

Hurricane Ingrid (2013)

Storm Active: September 12-17

On September 10, a disturbance located just east of the Yucatan Peninsula began to show signs of development. Like several systems before it, the disturbance did not organize further until it passed over the peninsula and entered the Bay of Campeche. This occurred early on September 12, at which time thunderstorm activity began to concentrate near a low-pressure center. Organization continued to increase during the afternoon, and advisories were initiated on Tropical Depression Ten early that evening.

Any significant forward speed that Ten initially had toward the west evaporated overnight, as light steering currents caused the cyclone to become nearly stationary over the extreme southwestern Bay of Campeche. On September 13, the system gained some organization as its central pressure decreased, and it was upgraded to Tropical Storm Ingrid. A ridge to Ingrid's north continued to keep it nearly stationary that day, though the cyclone drifted slightly to the west, coming very close to the coast of Mexico that afternoon. Meanwhile, a tropical system formed in the Pacific Ocean just off of southwestern Mexico in the center of a large area of disturbed weather. Though this system caused some wind shear on Ingrid, its main effect was to produce an extremely vast area of showers and thunderstorms stretching from the Bay of Campeche, over Mexico, and into the Pacific Ocean. This phenomenon, coupled with Ingrid being nearly stationary, caused immense amounts of rainfall across much of southern Mexico.

During that evening, Ingrid began to reverse direction and move roughly north-northeast as the ridge lifted out of Texas. Meanwhile, a Central Dense Overcast (CDO) appeared in association with Ingrid and banding improved, suggesting that the storm was strengthening rapidly. Thus a special advisory was issued by the National Hurricane Center bringing the cyclone's intensity to 60 mph winds. Gradual intensification continued through September 14, and with the hint of an eye appearing on visual satellite imagery that afternoon, Ingrid was upgraded to a category 1 hurricane. Though moderate shear associated with Tropical Storm Manuel in the East Pacific continued to cause shear, Ingrid remained resilient: the eye disappeared, but an eyewall of very strong convection that appeared overnight indicated that the hurricane had continued to strengthen into September 15. The cyclone had begun to turn northwest that morning as well, due to the influence of a forming ridge to its northeast.

Upper-level winds still affected the system, however, and later that day they displaced the most powerful thunderstorms to the eastern hemisphere of the circulation, leaving the center nearly exposed on the western side. Due to this loss of organization, Ingrid weakened slightly, but was still a minimal hurricane, producing some hurricane force winds east of the center. This status quo remained unchanged as the cyclone approached the coast of Mexico overnight and during the morning of September 16. Later that morning, Ingrid made landfall in Mexico and, at about the same time, weakened to a tropical storm. Over the next day, though the system continued to produce deep convection and heavy rain, the circulation itself was ripped apart by the mountainous terrain. By early on September 17, Ingrid had dissipated.

Ingrid did not have the appearance of a traditional hurricane, even near peak intensity, as above: the cyclone still appears lopsided and the convection was often displaced to the east of the center.

Ingrid was a meandering and slow-moving storm. As a result, its main effect was prolonged heavy rainfall over some areas of Mexico, which caused severe flooding.