17W is located 619 km west-northwest of Chichi Jima, and has moved northward at 30 km/h (16 knots) over the past 6 hours.
Environmental conditions remain marginally favorable as characterized by warm sea surface temperatures (28-29°C) and strong poleward outflow induced by an upper-level jet, which remains laid across the Sea of Japan.
17W will move along the western edge of a deep-layer subtropical ridge. 17W will begin rounding the ridge axis in 12 to 24 hours and increase in track speed and only increase intensity to a peak of 65 km/h (35 knots) as an approaching upper-level trough moves in from the west, while wind shear increases over mainland Honshu.
17W is expected to make landfall near the city of Tahara, Aichi Prefecture, Japan in 24 to 36 hours. 17W will continue on a northeast track encountering the rugged terrain of the Japanese Alps, whereby beginning the dissipation process, completely dissipating in 3 days over water.
Model guidance remains in tight agreement, with only a 67 km spread up to 24 hours. Thereafter, the model guidance only widens to 181 km once the system makes landfall, excluding JGSM, which never shows landfall for the system.
The overall JTWC track guidance confidence is high for the first 24 hours, and low thereafter, as the circulation weakens rapidly overland due to shear and terrain interaction. Therefore, the JTWC official track forecast is placed with medium confidence.
The JTWC initial intensity confidence is medium up to 24 hours, but decreases to low once landfall occurs due to the land interaction.
Maximum significant wave height is 4.3 meters (ca. 14 feet).
Environmental conditions remain marginally favorable as characterized by warm sea surface temperatures (28-29°C) and strong poleward outflow induced by an upper-level jet, which remains laid across the Sea of Japan.
17W will move along the western edge of a deep-layer subtropical ridge. 17W will begin rounding the ridge axis in 12 to 24 hours and increase in track speed and only increase intensity to a peak of 65 km/h (35 knots) as an approaching upper-level trough moves in from the west, while wind shear increases over mainland Honshu.
17W is expected to make landfall near the city of Tahara, Aichi Prefecture, Japan in 24 to 36 hours. 17W will continue on a northeast track encountering the rugged terrain of the Japanese Alps, whereby beginning the dissipation process, completely dissipating in 3 days over water.
Model guidance remains in tight agreement, with only a 67 km spread up to 24 hours. Thereafter, the model guidance only widens to 181 km once the system makes landfall, excluding JGSM, which never shows landfall for the system.
The overall JTWC track guidance confidence is high for the first 24 hours, and low thereafter, as the circulation weakens rapidly overland due to shear and terrain interaction. Therefore, the JTWC official track forecast is placed with medium confidence.
The JTWC initial intensity confidence is medium up to 24 hours, but decreases to low once landfall occurs due to the land interaction.
Maximum significant wave height is 4.3 meters (ca. 14 feet).
TROPICAL DEPRESSION #17W
9.22.20 21 UTC
LOCATED 30.0°N 134.68°E
MOVING 20 mph (ca. 32 km/h)
WINDS 35 mph (ca. 56 km/h)
PRESSURE 1000 hPa
