Meteorological history of Hurricane Guillermo
| Category 5 major hurricane (SSHWS/NWS) | |
 Hurricane Guillermo near peak intensity on August 5 | |
| Formed | July 30, 1997 |
|---|---|
| Dissipated | August 24, 1997 (extratropical after August 15) |
| Highest winds | 1-minute sustained: 160 mph (260 km/h) |
| Lowest pressure | 919 mbar (hPa); 27.14 inHg |
| Fatalities | 3 direct |
| Areas affected | Pacific coast of Mexico, California, Hawaii |
| Part of the 1997 Pacific hurricane season | |
Hurricane Guillermo was the seventh storm of the active 1997 Pacific hurricane season. It formed as a wave on July 16 off the African coast and entered the Eastern Pacific eleven days later. Guillermo was absorbed by an extratropical low on August 24, over 1 month after forming in the Atlantic. Guillermo did not affect land except for some swells and heavy surf along California. Three people were killed directly by Guillermo.
Guillermo became one of 12 storms to reach Category 5 status in the Eastern Pacific basin. Its peak intensity of 919 millibars was the second strongest on record at the time (behind Hurricane Ava of 1973), but Hurricane Linda later that year and Hurricane Kenna in the 2002 season surpassed it.
Formation
Tropical storm (39–73 mph, 63–118 km/h)
Category 1 (74–95 mph, 119–153 km/h)
Category 2 (96–110 mph, 154–177 km/h)
Category 3 (111–129 mph, 178–208 km/h)
Category 4 (130–156 mph, 209–251 km/h)
Category 5 (≥157 mph, ≥252 km/h)
Unknown
Extratropical cyclone, remnant low, tropical disturbance, or monsoon depressionA Tropical wave moved off Central America July 27. The wave showed sings rather quick and becoming a tropical cyclone rather quick and became one on on June 30
Upon becoming a tropical cyclone, convection increased in amount and the wave strengthened into Tropical Depression Ten-E on July 30, 345 miles (555 km) south of Salina Cruz, Mexico. The depression strengthened quickly in the Pacific Ocean, become Tropical Storm Guillermo the very next day.[1] A cloud circulation had appeared over Guillermo and the storm continued to strengthen, becoming a hurricane on August 1 near Acapulco, Mexico.[1] After upper-level outflow became well established, an eye started to appear in Guillermo, which strengthened into a Category 2-hurricane at 1200 UTC August 2. Guillermo strengthened into a 120 mph (190 km/h) Category 3-storm within six hours and became a Category 4-storm a further six hours later.[1]
Peak intensity
Guillermo soon fluctuated in strength. 0600 13.5 109.1 935 125 1200 13.6 110.2 925 135 1800 13.7 111.4 927 130 04/0000 13.9 112.6 929 130 0600 14.0 113.9 928 130 1200 14.1 115.2 925 135 1800 14.2 116.6 921 140 05/0000 14.3 118.0 919 140 0600 14.3 119.5 920 140 1200 14.4 120.9 921 140 1800 14.6 122.4 925 135 06/0000 14.8 123.8 930 130 0600 15.2 125.2 938 125