Forming east of the
Mariana Islands while Typhoon Tasha struck China and Typhoon Keoni was moving over open water, Vernon originated from an area of deep
convection embedded within the
monsoon trough north of
Pohnpei that was first observed by the
Joint Typhoon Warning Center (JTWC) on the morning of August 18. At 17:00 UTC on August 20, following an increase in the system's convection, the JTWC issued a
Tropical Cyclone Formation Alert.[1][3] Midday on August 21, the
Japan Meteorological Agency (JMA) upgraded the system into a tropical depression.[4][nb 3][nb 4] Following an increase in organization and a
Dvorak intensity estimate of T1.5/50 km/h (30 mph), the JTWC followed suit and declared the system a tropical depression at the same time. Early the next morning, a Dvorak estimate of T2.5/65 km/h (40 mph) resulted in the JTWC upgrading the depression into Tropical Storm Vernon.[1] At 06:00 UTC on August 22, the JMA upgraded Vernon into a tropical storm.[7]
After tracking north-northwest for 18 hours, Vernon briefly turned west on August 22 as it gradually intensified.[8] The JMA upgraded Vernon into a
severe tropical storm at noon on August 23.[4] Following a Dvorak intensity estimate of T4.0/75 mph (120 km/h), the JTWC upgraded Vernon into a typhoon at 00:00 UTC on August 24,[1] although the JMA did not follow suit until 30 hours later.[4] Continuing to intensify, Vernon tracked west-northwest. Late on August 24, the JTWC estimated that Vernon obtained its peak intensity of 145 km/h (90 mph). At noon the next day, the JMA estimated that the typhoon reached its peak wind speed of 130 km/h (80 mph) and a minimum
barometric pressure of 965 mbar (28.5 inHg).[7] Tracking northwest,[8] the storm, according to the JMA, maintained its peak intensity for 15 hours before starting to weaken and undergo extratropical transition.[1][4] Vernon began to recurve the north-northwest, passing east of Toyko and skirting Honshu on August 27.[1][8] Both the JTWC and JMA reported that Vernon weakened below typhoon intensity that day.[7] At 00:00 UTC on August 28, the JTWC declared Vernon an
extratropical cyclone. At the time, the system was located in the
Sea of Okhotsk.[1] Three hours later, the JMA followed suit, although they continued to track the storm until the evening of August 30.[4]
Impact
The cyclone dropped heavy rainfall across northern portions of the Japanese archipelago.[9] A total of 340 mm (13 in) occurred on
Mount Zaō, most of which fell within a 24 hour period.[10] A peak hourly rainfall total of 64 mm (2.5 in) was observed in
Toyko.[11] Meanwhile, a peak wind gust of 76 km/h (47 mph) was recorded in
Miyake-jima.[12]
^Wind estimates from the JMA and most other basins throughout the world are
sustained over 10 minutes, while estimates from the United States-based Joint Typhoon Warning Center are sustained over 1 minute. 10‑minute wind speeds are about 1.14 times the amount of 1‑minute wind speeds.[6]
References
^
abcdefJoint Typhoon Warning Center; Naval Pacific Meteorology and Oceanography Center (1994).
Annual Tropical Cyclone Report: 1993(
PDF) (Report). United States Navy, United States Air Force. p. 56. Retrieved May 11, 2020.
^
abcKenneth R. Knapp; Michael C. Kruk; David H. Levinson; Howard J. Diamond; Charles J. Neumann (2010).
1993 Typhoon VERNON (1993229N10159). The International Best Track Archive for Climate Stewardship (IBTrACS): Unifying tropical cyclone best track data (Report). Bulletin of the American Meteorological Society. Retrieved May 11, 2020.