Soon after, upper-level shear weakened greatly, and Irene rapidly intensified, first to a hurricane, then to its peak strength as a 105 mph (170 km/h) Category 2 hurricane on the afternoon of August 16, while located 350 miles (560 km) northeast of Bermuda; at the same time it also attained minimum pressure of 970 mbar.
The Hurricane Weather Research and Forecasting model (HWRF) showed the storm attaining a minimum pressure below 900 mbar (hPa; 26.58 inHg), an intensity not attained by any Eastern Pacific hurricane on record.
0000 UTC (8 00 p.m. EDT October 27) - Tropical Storm Grace strengthened into a Category 1 hurricane.. 0000 UTC (8 00 p.m. EDT October 28) - Hurricane Grace attained its attains its minimum pressure of 980 mbar (hPa; 28.94 inHg) while just south of Bermuda.
On June 12, the storm attained a minimum pressure of 975 mbar while continuing westward.
By November 12, the system attained a minimum pressure of 992 mbar (hPa; 29.29 inHg) along with winds of 65 mph (100 km/h).
Based on measurements from nearby stations, it is estimated that the system attained a minimum pressure of 988 mb (hPa; 29.18 inHg) just as it moved ashore.
Subsequently it turned northeastward, and on October 27 attained a minimum pressure of 984 mbar, the lowest of its duration while tropical or subtropical.
The strongest typhoon of the season originated in July and attained a minimum pressure of 927 mbar, as reported by a ship northeast of the Philippines.
The cyclone was ranked as the strongest in the Arabian Sea for six years until it was surpassed by Gonu in 2007, which attained a minimum pressure of 920 mbar (hPa).
Tracking generally southwestward, the system slowly deepened, attaining a minimum pressure of 997 mbar (hPa; 29.44 inHg) early on January 27 before the FMS discontinued advisories on the storm.
Since the JMA kept reliable records in 1951, Roy became the ninth known typhoon to develop during the month of January as well as the second most intense during the month, attaining a minimum pressure of 940 mbar (hPa; 27.76 inHg).
