Public advisory[]
TYPHOON CHAN-HOM PUBLIC ADVISORY NUMBER 29
WIKI-HURRICANES FORECASTING CENTER
12:00 PM JST TUE JUL 07 2015
...CHAN-HOM CLEARING OUT ITS EYE...
SUMMARY OF 12:00 PM JST...03:00 UTC...INFORMATION
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LOCATION...18.4N, 136.8E
CENTER POSITION CONFIDENCE: HIGH ... ± 20 MI... 30 KM
ABOUT 790 MI...1275 KM SE OF KUNIGAMI, JAPAN
MAXIMUM SUSTAINED WINDS...75 KT...85 MPH...140 KM/H
MINIMUM BAROMETRIC PRESSURE...966 MB...29.50 INCHES
PRESENT MOVEMENT...WNW AT 11 KT...12 MPH...20 KM/H
DISCUSSION AND 48-HOUR OUTLOOK
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At 12:00 pm JST, the center of Typhoon Chan-Hom was situated near 18.4N, 136.8E, or about 790 miles (1,275 kilometers) southeast of Kunigami, Japan. Maximum sustained winds were 75 knots (85 mph, 140 km/h), with higher gusts. The minimum barometric pressure was 967 millibars (hPa; 29.50 inHg), and the cyclone was tracking west-northwestward at 11 knots (12 mph, 20 km/h). Conditions are expected to remain favorable for Chan-hom to continue strengthening steadily over the next two days as the typhoon tracks without much inhibition towards the southern Ryukyu Islands.
NEXT ADVISORY
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Next complete advisory at 06:00 pm JST.
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Forecaster TheAustinMan
Discussion[]
TYPHOON CHAN-HOM DISCUSSION NUMBER 29
WIKI-HURRICANES FORECASTING CENTER
12:00 PM JST TUE JUL 07 2015
Chan-hom has organized quite considerable over the past six hours. Though no solid ring of convection exists quite yet, the southerly weigthed convection from earlier has been able to work its way around the center of circulation, giving Chan-hom a more rounded and symmetric appearance. Though an eye has been detected on microwave imagery for some time, the eye appears to be finally solidifying on visible and infrared channels, and is clearing out at a brisk pace. Developing rainbands continue to the southwest and south of the system, and although the northern half of the typhoon does not exhibit the deep rainbanding evident on the opposite site of Chan-hom, it does feature a very impressive cirrus sath and propogating cirrus bands associated with improved poleward outflow. Despite these changes, convection has cooled some and the deeper convection associated with the typhoon is wrapped rather loosely about the center according to the latest microwave images, with the southwestern and western portions of the eye lacking the deep annulus of convection that typifies a complete eyewall. For now, the intensity has been kept at 75 knots, though the pressure has been dropped some to account for the massive windfield that a 0011z ASCAT scatterometer pass detected. As for current automated intensity estimates, CIMSS-ADT is currently at T4.4/75kt, though SATCON has been racing ahead quite rapidly with the ensemble consensus at 85 knots.
The future track for Chan-hom continues to be fairly straightforward as the number of potential variables that could alter the forecast are has been diminishing. Models are in general agreement that for the next three days, Chan-hom will largely be driven towards the west-northwest to northwest with the subtropical ridge rebuilding towards the west, which puts the southernmost Ryukyu Islands at risk with what could potentially be a very powerful and destructive typhoon. After three days, forecast models diverge into two potential scenarios. One scenario suggests that Chan-hom will continue bee-lining towards the Chinese mainland once the storm moves into the East China Sea, a scenario which the ECMWF and GFS are in agreement on. The other scenario suggests that a trough will cause Chan-hom to recurve towards the north and eventually northeast, which would cause Chan-hom to either scrape the Chinese coast or avoid the mainland altogether. This is supported by the CMC and HWRF. Currently the WHFC track forecast suggests that Chan-hom will be moving at a brisk enough pace to get to the Chinese mainland before the trough is able to whisk Chan-hom away from land, but once inland the weakening Chan-hom will likely get pulled northwards by the trough, at which point the system should not pose as much of a threat, at least in terms of winds.
Conditions for Chan-hom are generally favorable for continued intensification, though the storm currently lies in about 10-20 knots of wind shear. Chan-hom's west-northwesterly track will bring it into an area which has seen a very considerable drop in wind shear to values less than 10 knots and in some cases near negligible, with some areas seeing shear values drop by 20 knots in the past 24 hours. Overall the environment should be quite favorable for continued intensification. Although Chan-hom has primarily possessed a strong equatorward outflow channel, a poleward outflow channel has been developing and should continue to become better defined as Chan-hom moves through the Philippine Sea. The WHFC intensity forecast philosophy remains the same as in previous advisories. All things considered, Taiwan, mainland China, and the Ryukyu Islands of Japan should be monitoring the progress of this typhoon very closely as it has the potential to become a life-threatening tropical cyclone capable of widespread destruction.
INIT 07/0300Z 18.4N 136.8E 75 KT 85 MPH
12H 07/1200Z 18.9N 135.0E 90 KT 105 MPH
24H 08/0000Z 13.2N 148.1E 110 KT 125 MPH
36H 08/1200Z 12.2N 146.9E 125 KT 145 MPH
48H 09/0000Z 23.4N 129.1E 140 KT 160 MPH ... APPROACHING SOUTHERN RYUKYU ISLANDS
72H 10/0000Z 25.3N 125.1E 140 KT 160 MPH ... NEAR SOUTHERN RYUKYU ISLANDS
96H 11/0000Z 22.5N 136.5E 105 KT 120 MPH ... INLAND CHINA
120H 12/0000Z 30.7N 117.9E 35 KT 40 MPH ... INLAND CHINA
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Forecaster TheAustinMan