On the morning of August 20, the NHC began to feature the remnants of Harvey on their Tropical Weather Outlooks, assessing it with a medium chance of redevelopment over the next five days.
However, this was increased to high just hours later after showers and thunderstorms associated with the system increased in coverage.
The system regained winds of tropical storm-force later on August 20, yet a closed circulation still could not be found.
Harvey's remnant trough continued to move steadily westwards to west-northwestwards towards Belize and the Yucatán Peninsula through August 21, passing over the latter on August 22.
As the low-pressure area associated with ex-Harvey moved over land, its circulation became better defined, and the NHC noted that tropical cyclone development was almost a certainty over the next few days as the system entered the Bay of Campeche.
At this time, the NHC also mentioned the possibility of hurricane-force winds affecting the coast of Texas.
The NHC's forecasts came to fruition at 12:00 UTC on August 23 as Harvey regenerated into a tropical depression 175 mi (280 km) west of Progreso, Mexico, after the presence of a closed circulation was finally confirmed.

Over the next few hours, Harvey continued to consolidate, with the radius of maximum winds decreasing to 70 mi (110 km) early on August 24.
Moving slowly northwestwards to north-northwestwards in response to a weak ridge to the northeast, Harvey intensified to a tropical storm at 04:00 UTC.
By that time, Harvey was located 440 mi (705 km) southeast of Port O'Connor, Texas.
Further strengthening was anticipated, as wind shear over Harvey decreased with the weakening of an upper-level low over the northwestern Gulf of Mexico.
In fact, the NHC assessed that the probability of rapid intensification—sustained winds increasing by 35 mph (55 km/h) in 24 hours—increased to 45 percent just five hours after Harvey had been declared a tropical storm.
This forecast materialized shortly afterwards as Harvey began rapidly strengthening, with reconnaissance aircraft monitoring the storm at around 14:00 UTC reporting the structure had "markedly improved": a 15–20 nmi (17–23 mi; 28–37 km) eye had developed and the central pressure had fallen to 982 mbar (hPa; 28.99 inHg).
This resulted in a substantial increase in the intensity forecast, with the cyclone expected to be a powerful hurricane by the time it reached the Texas coastline.
Less than two hours later, at 18:00 UTC, Harvey was upgraded to a mid-range Category 1 hurricane on the Saffir–Simpson scale based on additional aircraft data.

Afterwards, the intensification process stalled somewhat and the eye lost some definition, despite a steady decrease in the central pressure.
This was attributed to likely dry air entrainment.
Early on August 25, however, strengthening resumed again, with Harvey attaining Category 2 intensity at roughly 05:00 UTC that day.
During this time, the satellite presentation improved significantly with the appearance of an intermittent eye feature embedded in a central dense overcast (CDO), as well as improving outflow.
However, shortly afterwards, concentric eyewalls were reported within Harvey—signifying an eyewall replacement cycle—which prevented the sustained winds from increasing beyond 110 mph (175 km/h) for a while despite an unusually low pressure of 947 mbar (hPa; 27.97 inHg), which is typical of a stronger storm.
Despite this, Harvey managed to quickly strengthen into a major hurricane—a storm with winds of 111 mph (179 km/h) or greater—at 19:00 UTC that day.
Rapid strengthening eventually culminated with Harvey reaching peak sustained winds of 130 mph (215 km/h)—a Category 4 hurricane on the Saffir–Simpson scale—at 23:00 UTC, as a well-defined eye formed within the hurricane.
The pressure bottomed out at 937 mbar (hPa; 27.67 inHg) hours later at 03:00 UTC on August 26, just as it was making landfall on San José Island.
On the morning of August 20, the NHC began to feature the remnants of Harvey on their Tropical Weather Outlooks, assessing it with a medium chance of redevelopment over the next five days. However, this was increased to high just hours later after showers and thunderstorms associated with the system increased in coverage. The system regained winds of tropical storm-force later on August 20, yet a closed circulation still could not be found. Harvey's remnant trough continued to move steadily westwards to west-northwestwards towards Belize and the Yucatán Peninsula through August 21, passing over the latter on August 22. As the low-pressure area associated with ex-Harvey moved over land, its circulation became better defined, and the NHC noted that tropical cyclone development was almost a certainty over the next few days as the system entered the Bay of Campeche. At this time, the NHC also mentioned the possibility of hurricane-force winds affecting the coast of Texas. The NHC's forecasts came to fruition at 12:00 UTC on August 23 as Harvey regenerated into a tropical depression 175 mi (280 km) west of Progreso, Mexico, after the presence of a closed circulation was finally confirmed.
Over the next few hours, Harvey continued to consolidate, with the radius of maximum winds decreasing to 70 mi (110 km) early on August 24. Moving slowly northwestwards to north-northwestwards in response to a weak ridge to the northeast, Harvey intensified to a tropical storm at 04:00 UTC. By that time, Harvey was located 440 mi (705 km) southeast of Port O'Connor, Texas. Further strengthening was anticipated, as wind shear over Harvey decreased with the weakening of an upper-level low over the northwestern Gulf of Mexico. In fact, the NHC assessed that the probability of rapid intensification—sustained winds increasing by 35 mph (55 km/h) in 24 hours—increased to 45 percent just five hours after Harvey had been declared a tropical storm. This forecast materialized shortly afterwards as Harvey began rapidly strengthening, with reconnaissance aircraft monitoring the storm at around 14:00 UTC reporting the structure had "markedly improved": a 15–20 nmi (17–23 mi; 28–37 km) eye had developed and the central pressure had fallen to 982 mbar (hPa; 28.99 inHg). This resulted in a substantial increase in the intensity forecast, with the cyclone expected to be a powerful hurricane by the time it reached the Texas coastline. Less than two hours later, at 18:00 UTC, Harvey was upgraded to a mid-range Category 1 hurricane on the Saffir–Simpson scale based on additional aircraft data.
Afterwards, the intensification process stalled somewhat and the eye lost some definition, despite a steady decrease in the central pressure. This was attributed to likely dry air entrainment. Early on August 25, however, strengthening resumed again, with Harvey attaining Category 2 intensity at roughly 05:00 UTC that day. During this time, the satellite presentation improved significantly with the appearance of an intermittent eye feature embedded in a central dense overcast (CDO), as well as improving outflow. However, shortly afterwards, concentric eyewalls were reported within Harvey—signifying an eyewall replacement cycle—which prevented the sustained winds from increasing beyond 110 mph (175 km/h) for a while despite an unusually low pressure of 947 mbar (hPa; 27.97 inHg), which is typical of a stronger storm. Despite this, Harvey managed to quickly strengthen into a major hurricane—a storm with winds of 111 mph (179 km/h) or greater—at 19:00 UTC that day. Rapid strengthening eventually culminated with Harvey reaching peak sustained winds of 130 mph (215 km/h)—a Category 4 hurricane on the Saffir–Simpson scale—at 23:00 UTC, as a well-defined eye formed within the hurricane. The pressure bottomed out at 937 mbar (hPa; 27.67 inHg) hours later at 03:00 UTC on August 26, just as it was making landfall on San José Island.
Meteorological history of Hurricane Harvey