Hurricane John (1994) - Forecasting Difficulties

Forecasting Difficulties

During John's time in Western North Pacific, the Joint Typhoon Warning Center (JTWC) had particular difficulty in forecasting and even estimating the strength of John. John weakened considerably after entering the Western North Pacific, and, before estimates were later revised, four consecutive advisories were issued that declared John a tropical depression. Each of these advisories called for imminent dissipation. As John persisted and did not dissipate as the JTWC had predicted, it was upgraded to a minimal tropical storm in the next advisory. At the same time, however, two separate ship reports indicated that John had sustained winds of at least 55 knots (100 km/h, 65 mph), far stronger than the advisory strength of 35 knots (65 km/h, 40 mph). John would go on to restrengthen into a strong Category 1 hurricane after reentering the Central North Pacific, defying all JTWC predictions. After later reanalysis, the JTWC raised the estimated wind speeds of John for every advisory from 1200 UTC September 1 to its final advisory exactly a week later by at least 5 knots (9 km/h, 6 mph) and as much as 25 knots (46 km/h, 29 mph).