The tornado covered 38 miles (61 km) during its 85-minute existence, destroying thousands of homes, killing 36 people (plus an additional five indirectly), and leaving US$1 billion (1999 USD) in damage,[7] ranking it as the fifth-costliest on record not accounting for inflation.

The tornado first touched down at 6:23 p.m. Central Daylight Time (CDT) in Grady County, roughly two miles (3.2 km) south-southwest of the town of Amber.

It quickly intensified into a violent F4, and gradually reached F5 status after traveling 6.5 miles (10.5 km), at which time it struck the town of Bridge Creek.

The most prolific tornadic activity associated with the May 3 outbreak – and the multi-day outbreak as a whole – occurred in Oklahoma; 14 of the 66 tornadoes that occurred within the state that afternoon and evening produced damage consistent with the Fujita scale's "strong" (F2–F3) and "violent" (F4–F5) categories, which, in addition to the areas struck by the Bridge Creek–Moore tornado family, affected towns such as Mulhall, Cimarron City, Dover, Choctaw and Stroud.

[9] On the morning of May 3, in its Day 1 Convective Outlook for the United States, the Storm Prediction Center (SPC) – based in Norman, approximately 10 miles (16 km) south of the tornado's eventual damage path – issued a slight risk of severe thunderstorms from southern Nebraska to central Texas.

SPC analysis had detected the presence of a dry line that stretched from western Kansas into western Texas that was approaching a warm, humid air-mass over the Central Plains; the condition ahead of the dry line and a connecting trough positioned over northeastern Colorado appeared to favor the development of thunderstorms later that day that would contain large hail, damaging straight-line winds, and isolated tornadoes.

Around 4:00 a.m. CDT that morning, Doppler radar and wind profile data indicated a 90-knot (100 mph; 170 km/h) streak of elevated jet stream winds along the California−Nevada border, though weather balloon soundings sent up the previous evening by National Weather Service (NWS) offices in the western U.S. and numerical computer model data failed to detect the fast-moving air current as it moved ashore from the Pacific Ocean.

[12] Despite conflicting model data on the specified area where thunderstorms would develop, the newly available information that denoted a more favorable severe thunderstorm setup in that part of the state prompted the SPC to upgrade the forecasted threat of severe weather to a moderate risk for south-central Kansas, much of the western two-thirds of Oklahoma, and the northwestern and north-central portions of Texas at 11:15 a.m. CDT that morning, which now indicated that the atmospheric conditions present would "provide sufficient shear for a few strong or violent tornadic supercells given the abundant low level moisture and the high instability."

The increasing threat of a severe weather/tornado outbreak for late that afternoon into the evening was reemphasized by NWS Norman forecasters in a Thunderstorm Outlook issued by the office at 12:30 p.m.

[11][13] By the early afternoon hours, forecasters at both the SPC and NWS Norman (both of which shared an office complex near Max Westheimer Airport at the time), realized that a major event was likely to take place based solely on observational data from radar and weather satellite imagery and balloon soundings, as the computer models remained uncooperative in helping meteorologists determine where the greatest threat of severe storms would occur.

[10] At 3:49 p.m. CDT, the SPC − having gathered enough data to surmise that there was a credible threat of a significant severe weather outbreak occurring within the next few hours − amended its Day 1 Convective Outlook to place the western nine-tenths of the main body of Oklahoma, central and south-central Kansas and the northern two-thirds of Texas under a high severe weather risk, denoting a higher than normal probability of strong (F2+) tornadoes within the risk area.

Five more tornadoes developed as the storm continued northeast; a sixth one, which would be given an F3 rating, formed a short time later and caused substantial damage in central Grady County, including some to the Chickasha Municipal Airport, where roofs were torn off of two hangars.

[18] The tornado rapidly intensified and grew in size as it crossed Oklahoma State Highway 92, attaining F4 strength about 4 miles (6.4 km) east-northeast of Amber.

Damage surveyors noted that the remaining structural debris from some of the homes in this area was finely granulated into small fragments, and that trees and shrubs were completely debarked.

Extensive ground scouring occurred, and vehicles were thrown hundreds of yards from where they originated, including a mangled pickup truck that was found wrapped around a telephone pole.

[23][25] Continuing northeastward, the tornado briefly weakened to F4 status before re-strengthening to F5 intensity as it neared the Grady-McClain County line, where a car was thrown roughly 0.25 mi (0.40 km) in the air, and a well-built home with anchor bolts was reduced to a bare slab.

David Andra, a meteorologist at the NWS Norman office, said that, in drafting the enhanced warning, he wanted to "paint the picture [to residents] that a rare and deadly tornado was imminent in the metro area."

A man who helped the mother and son up the overpass suffered severe injuries to his leg, which was partially sliced by a highway sign thrown by the winds.

Then, the powerful tornado struck the densely populated Greenbriar Eastlake Estates at F5 intensity, killing three people and reducing entire rows of homes to rubble.

[9] As the tornado entered Cleveland County, NWS Norman activated emergency procedures, preparing to evacuate staff and others present at the facility in the event that the supercell should turn right, placing areas surrounding the Norman campus in the tornado's path (under NOAA protocol in situations posing a danger to personnel at local Weather Forecast Offices and related guidance centers, responsibility over the issuance of warnings and statements on the unfolding outbreak would have been transferred to the nearest NWS Forecast Office, based in Tulsa, while the SPC's forecasting responsibilities would be turned over to the 557th Weather Wing at Offutt Air Force Base).

Flights were grounded at Will Rogers World Airport as the northern edge of the supercell (containing hail up to 1.25 inches (3.2 cm), straight-line wind gusts up to 70 mph (110 km/h), and moderate to heavy rain) approached the area; the tornado turned right, away from southwestern parts of the city proper located within Oklahoma County, shortly before airport officials began evacuating employees and visitors at the terminals.

Traffic on I-35 in southern Oklahoma City and northern Moore became backed up for several miles, as drivers evacuated from their vehicles to seek shelter under overpass overlooking South Shields Boulevard.

Ultimately, Westmoore High sustained heavy damage and dozens of cars that were in the school's parking lot were tossed around, some of which were completely destroyed or thrown into nearby homes.

[citation needed] NWS researchers estimated that the death toll from the storm would likely have exceeded 600 had it not been for the advanced warning through local television and radio stations and proper safety precautions being exercised by area residents.

In a press statement by the Federal Emergency Management Agency (FEMA), then-director James Lee Witt stated that, "The President is deeply concerned about the tragic loss of life and destruction caused by these devastating storms.

[42] That day, FEMA also declared that seven counties − Canadian, Craig, Grady, Lincoln, Logan, Noble and Oklahoma − were eligible for federal financial assistance.

[50] On June 21, an educational road show made by FEMA visited the hardest hit areas in Oklahoma to urge residents to build storm cellars.

Two of these were from the F5 Bridge Creek–Moore tornado while the third was from a comparatively less intense F2, which struck a rural area in Payne County, north-northeast of Oklahoma City; many other serious to life-threatening injuries also occurred at these locations.

[32] The FEMA corroborated with Doswell and Marshall's findings in its Building Performance Assessment Team Report on the May 3 outbreak, noting that much of the structural damage resulted from strong winds generated by the tornado and associated windborne debris that often "produced forces on buildings not designed to withstand such forces" and in some cases, were due to improper construction techniques and "poor selection" of materials used in their construction.

The report acknowledged that federal construction code requirements needed to be revised above the then-current minimum standards to allow newer buildings to better withstand higher wind speeds consistent with tornadoes of lesser intensity than the one that devastated Bridge Creek and Moore, thereby lessening the degree of damage, fatalities and injuries that are probable in buildings of typically less reinforced construction.