TYPHOON CHAN-HOM PUBLIC ADVISORY NUMBER 27
WIKI-HURRICANES FORECASTING CENTER
12:00 AM JST TUE JUL 07 2015
SUMMARY OF 12:00 PM JST...15:00 UTC...INFORMATION
CENTER POSITION CONFIDENCE: HIGH
ABOUT 340 MI...544 KM WNW OF SAIPAN, MARIANA ISLANDS
MAXIMUM SUSTAINED WINDS...70 KT...80 MPH...120 KM/H
MINIMUM BAROMETRIC PRESSURE...975 MB...28.86 INCHES
PRESENT MOVEMENT...WNW AT 10 KT...12 MPH...19 KM/H
DISCUSSION AND 48-HOUR OUTLOOK
At 12:00 am JST, the center of Typhoon Chan-hom was situated near 17.5N 138.9E, about 335 miles (540 km) west-northwest of Saipan, Mariana Islands. Maximum sustained winds were 70 knots (80 mph, 125 km/h), with higher gusts. The minimum barometric pressure was 975 millibars (hPa; 29.86 inHg), and the cyclone was tracking west-northwest at 10 knots (12 mph, 19 km/h). Environmental conditions are expected to favor steady to rapid intensification over the next 48 hours, and Chan-hom is likely to become a powerful cyclone over the West Pacific.
Next complete advisory at 6:00 am JST.
TYPHOON CHAN-HOM DISCUSSION NUMBER 27
WIKI-HURRICANES FORECASTING CENTER
12:00 PM JST MON JUL 06 2015
Chan-Hom was becoming better organized until a few hours ago, when the organization rate slowed. Cloud tops have cooled, though dry air is still not fully out of harms way and has caused the rainbands to not only diminish, some may have gotten into the core, and as a result, the core of the storm. With that said, the storm in general looks much better than it did 24 hours ago. CI values from JTWc are at T4.0/65 knts, although objective estimates from CIMSS, JTWC, and JMA are a bit lower at T3.5, T3.6, and T3.9. Given the ASCAT showed a wide area of 60+ knt barbs, this is likely still a typhoon and if not is stronger. Hence, the intensity is increased to 70 knts, but this could be conservative.
A 12z AMSU pass showed that 70% of an eye is present on microwave. Since then, if I had to guess, the eye has become even more open due to the above dry slot. However, I expected it to start closing off the eyewalll by morning, and rapid deepening will likely start this afternoon. 10 knts of intensification is shown in 12 hours. Given the cold cloud tops present, this storm should have no issues reaching major hurricane intensity, and the WHFC shows it happening in 24 hours. Thereafter, the eye will likely approach zero and start to clear out, and thus Category 4 status is likely at or slightly before 36 hours. After that time, since extended periods of RI are rare, some leveling off is shown at the 48 hour forceast point. The intensity forecast remains largely unchanged after 48 hours.
Once again, Chan-hom continues to track steadily west-northwest under the influence of a potent mid-level ridge to the cyclone's north. This steering mechanism is expected to dominate the forecast period, and very little change in trajectory is expected. On the forecast path, Chan-hom is expected to pass closest to the southern Japanese Islands by day 4 before tracking directly into mainland China by day 5. All indications are that Chan-hom will pose an extreme threat to the China mainland by the end of the week.
Residents both in the southern Japanese Islands and China should very closely monitor the progress of what is expected to be a large and powerful cyclone and should not focus on the exact forecast point, especially in the long-range due to its size and high margin of error.
INIT 06/1500Z 17.5N 138.9E 70 KT 80 MPH
12H 06/0000Z 18.1N 137.6E 80 KT 90 MPH
24H 07/1200Z 19.0N 136.0E 100 KT 115 MPH
36H 07/0000Z 20.1N 134.2E 115 KT 130 MPH
48H 08/1200Z 21.2N 132.5E 125 KT 145 MPH
72H 09/1200Z 23.8N 127.8E 140 KT 160 MPH
96H 10/1200Z 26.3N 124.5E 140 KT 160 MPH
120H 11/1200Z 29.6N 120.6E 55 KT 65 MPH...INLAND