Tracking westward across the Atlantic with little development, it passed over Central America and into the eastern Pacific Ocean on July 18, where favorable environmental conditions promoted steady organization.

Upon approach, Flossie threatened to become the first tropical storm to make a direct hit on Hawaii in two decades; however, the system weakened prior to doing so.

[1] Early on July 21, a broad low-pressure area formed in association with the wave, and the National Hurricane Center (NHC) began monitoring the disturbance for slow development into a tropical cyclone accordingly.

[2] Shower and thunderstorm activity coalesced over the subsequent days, prompting the NHC to increase its chances for development to the high category;[3] despite this, satellite data from early on July 24 did not reveal a well-defined circulation necessary for classification.

By that evening, a combination of visible and microwave satellite imagery depicted an improvement of the vortex, and the system was upgraded to a tropical depression at 00:00 UTC on July 25, while situated 980 miles (1,575 km) west-southwest of the southern tip of the Baja California peninsula.

At 1200 UTC, the system attained its peak intensity with maximum sustained winds of 70 mph (110 km/h) and a minimum barometric pressure of 994 mb (hPa; 29.35 inHg).

[6] The low-level vortex became exposed to view and progressively ill-defined as outflow boundaries in association with a previous convective burst impeded on the low.

[7][8] At 00:00 UTC on July 30, Flossie was downgraded to a tropical depression; after the circulation became indistinguishable on satellite imagery twelve hours later, the system was declared a remnant area of low pressure.

[1] Upon entering the central Pacific Ocean, Flossie prompted the issuance of a tropical storm watch for Hawaii and Maui counties on July 27.

[10] Due to the threat of heavy rain, forecast to reach 15 inches (380 mm) in localized areas, a flash flood watch was issued for all of Hawaii, valid between July 29 and 30.