Hurricane Pablo (2019)

Storm Active: October 25-28

On October 23, a non-tropical low centered several hundred miles west of the Azores began to deepen and produced strong winds and scattered rains over a large area of the northeast Atlantic. The low moved generally east-southeastward over the following days. On October 25, a small pocket of deep convection formed about the center of circulation. That afternoon, the system became Tropical Storm Pablo, a very small tropical storm in the middle of what appeared on a larger scale as an extratropical cyclone. Pablo was named at the same time as Tropical Storm Olga in the Gulf of Mexico, a new record for the latest in a season that two storms were named simultaneously. Though ocean temperatures were below the ordinary threshold for tropical cyclone development, a cool upper atmosphere gave the system enough instability to support tropical development.

Upon formation, the tiny Pablo had an even tinier eye feature on satellite imagery. Gale force winds associated with the tropical cyclone extended only a few dozen miles from the center, even though the parent extratropical system still was generating comparable winds in its much bigger northwest quadrant. On October 26, Pablo turned east and then northeast, strengthening a bit as it did so. Early that evening, the center passed close to the easternmost Azores islands, bringing additional rain, strong winds, and high waves. Defying expectations, the cyclone intensified further as the eye became better defined. During the morning on October 27, Pablo achieved hurricane status. At 42.8° N, 18.3° W, this was the furthest northeast any hurricane had ever formed on record. Pablo reached its peak intensity of 80 mph winds and a central pressure of 977 mb a few hours later. Meanwhile, the storm turned back toward the north and slowed down somewhat.

Soon after, even colder waters along Pablo's track at last caused convection to degrade. The small system suffered a rapid demise overnight, weakening to a low-end tropical storm and then becoming post-tropical early on October 28 when it degenerated into a swirl of low clouds. The remnant low drifted slowly northwest before it was absorbed by another low pressure system.

The above image shows Pablo near hurricane strength on October 27.

Pablo became a hurricane farther to the northeast than any previous cyclone on record.

Tropical Storm Olga (2019)

Storm Active: October 25

During the latter part of October, a tropical wave moved across the Caribbean and toward central America. As it passed near Belize around October 22, it began to exhibit disorganized thunderstorm activity. The system moved west-northwestward over the following days but did not develop further until emerging into the Bay of Campeche. On October 24, a circulation began to spin up in earnest over water west of the Yucatan Peninsula and convection increased markedly. Already, a autumn cold front approaching from the northwest was beginning to interact with the developing low. Nevertheless, it managed to become Tropical Depression Seventeen during the morning of October 25.

A few hours later it strengthened into Tropical Storm Olga. The front accelerated the newly formed Olga north-northeast that afternoon and its circulation elongated. Aircraft data collected during the evening suggested that the center had become embedded within the frontal boundary, and that a clear temperature gradient existed across the two sides of the circulation separated by the front axis. Thus, Olga was deemed post-tropical, only 12 hours after initially becoming a tropical cyclone. That night, ex-Olga made landfall in Louisiana. The combined system brought very heavy rain and widespread wind gusts to gale force, with some reaching 70 mph. Olga's tropical moisture drove up rain totals with the storm for the next few days as it pushed eastward.

The above image shows Tropical Storm Olga on October 25 interacting with the front.

Just like Nestor before it, Olga was a short-lived tropical cyclone in the Gulf of Mexico whose primary impacts occurred after merging with a front.

Tropical Storm Nestor (2019)

Storm Active: October 18-19

Around October 12, a large low pressure area formed over the southwestern Caribbean sea. The system moved slowly northwest over the following days but land interaction with central America stifled any chance at development initially. It emerged into the Bay of Campeche on October 16 and began a gradual turn toward the northeast. The disturbance deepened over water, but it also began to interact with a trough of low pressure to its northeast across the northern Gulf of Mexico. This interaction spawned a cyclone with some tropical characteristics, but which was also highly asymmetrical. The pull of the front also caused the system to accelerate northeastward. Finally, during the afternoon of October 18, the cyclone began sufficiently tropical to be classified Tropical Storm Nestor.

Though rather disorganized and not resembling a classical tropical cyclone, Nestor gained a boost in strength from the nearby trough, pushing it to its peak intensity of 60 mph winds and a pressure of 996 mb late that evening. By this time, the storm was approaching the panhandle of Florida, already bringing rain and gale force wind gusts. Nestor lost its tropical characteristics the morning of October 19 as convection retreated well to the east of the circulation and became post-tropical. The post-tropical storm made landfall a few hours later. Soon after, it crossed the U.S. southeast and exited toward the open Atlantic waters.

The above shows the disorganized Nestor shortly after classification as a tropical cyclone.

Nestor's remnants spawned a few tornadoes over the U.S. southeast as the system passed through.

Tropical Depression Fifteen (2019)

Storm Active: October 14-16

On October 13, a large tropical wave emerged into the Atlantic, exiting western Africa. Ordinarily, tropical waves do not organize so far east by mid-October, but unusually warm waters and low wind shear allowed the disturbance to consolidate. During the afternoon of October 14, the wave developed into Tropical Depression Fifteen. The formation took place southeast of the Cabo Verde islands, making the depression one of the easternmost forming tropical cyclone ever observed so late in the year. It tracked northwest over the following day but changed little in organization. Having a very broad circulation, Fifteen struggled to develop deep convection. However, this did not prevent the cyclone from bringing locally heavy rains and gusty winds to the Cabo Verde islands on the 15th. The system's circulation became elongated soon after as atmospheric conditions began to deteriorate. Fifteen dissipated during the morning of October 16.

The above image shows Tropical Depression Fifteen near the coastline of West Africa.

Though very short-lived, Fifteen was notable for forming so close to Africa exceptionally late in the calendar year.

Tropical Storm Melissa (2019)

Storm Active: October 11-14

On October 8, a non-tropical low pressure center formed along the western edge of a dissipating frontal boundary situated west-southwest to east-northeast across the western Atlantic ocean. When the low formed, it was located a few hundred miles off the North Carolina coastline. It moved north-northeastward over the next few days, deepened some, and absorbed another disturbance approaching from the south. Steering currents collapsed on October 10 and the system became almost stationary east of the mid-Atlantic coastline. Even as a non-tropical system, it brought dangerous ocean conditions and strong winds to the coastline, especially southern New England. There was not much in the way of rainfall associated with the low at first, but convection increased in a curved band north of the center early on October 11. Shortly afterward, the disturbance was classified Subtropical Storm Melissa, already with maximum winds of 65 mph and a central pressure of 995 mb.

That day, the cyclone drifted slowly southward, but soon westerly flow steered Melissa east and caused it to accelerate some away from the U.S. coastline. The structure changed some by October 12, with convection moving closer to the center of circulation. The structural change necessitated a reclassification of Melissa as a tropical storm. As the cyclone moved east, it encountered more hostile atmospheric conditions, which stripped away most of the thunderstorm activity. Melissa weakened into October 13. These trends continued until the cyclone became extratropical on October 14.

The above image shows Melissa after transitioning to a tropical storm on October 12. During this transition, the windfield contracted significantly, leaving a small area of central convection

Melissa formed near the east coast but moved away without affecting land.