Tropical Storm Adrian was a very rare preseason eastern pacific tropical cyclone, and even took the record for the earliest tropical cyclone in the region.
On May 6, an area of low pressure formed in association with the Pacific monsoonal trough, and began to move slowly towards the north-northwest, before being given a low potential for development by the National Hurricane Center the following day. By the end of the following day, this had been raised to the medium category, before being raised to the high category around 1600 UTC.
It is estimated, however, that Tropical Depression One-E developed around 1800 UTC after a series of banding features began to merge into the still developing low level circulation. By around midnight UTC on May 10, it is estimated that Tropical Storm Adrian developed, and the NHC also upgraded the system at 0300 UTC. However, following an increase in shear from the southeast, the mid and upper level circulations began to detach from the weakening low level circulation, completely detaching by 0300 UTC on May 11, which is when it is estimated that Adrian weakened to a remnant low.
Over the rest of the day, the low level remnants weakened, before convection began to intermittently fire over the exposed circulation, though too weak to keep the systems remains as a tropical cyclone. Around this time, the mid to upper level circulations of Adrian made landfall in Mexico, dropping heavy rainfall in the process, before moving southeast and weakening, dissipating by the end of the day.
| SSHWS category | 1-min winds | Pressure | Location | Date and time | ACE generated |
|---|---|---|---|---|---|
| Tropical Depression | 35 mph | 1006 mbar | 9.3N, 91.3W | 09/05/2017 2100 UTC | N/A |
| Tropical Storm | 40 mph | 1005 mbar | 9.5N, 92.3W | 10/05/2017 0300 UTC | 0.1225 |
| Tropical Storm | 45 mph | 1004 mbar | 10.0N, 92.7W | 10/05/2017 0900 UTC | 0.1600 |
| Tropical Storm | 40 mph | 1005 mbar | 10.4N, 92.7W | 10/05/2017 1500 UTC | 0.1225 |
| Tropical Storm | 40 mph | 1006 mbar | 10.5N, 92.7W | 10/05/2017 2100 UTC | 0.1225 |
| Tropical Depression | 35 mph | 1007 mbar | 10.5N, 93.1W | 11/05/2017 0300 UTC | N/A |
| Total ACE | 0.5275 |