500 AM HST Thu Aug 23 2018 ...LANE CREEPING CLOSER TO HAWAII... ...TORRENTIAL RAIN SOAKING THE BIG ISLAND... SUMMARY OF 500 AM HST...1500 UTC...INFORMATION ---------------------------------------------- LOCATION...16.9N 157.4W ABOUT 210 MI...335 KM SSW OF KAILUA-KONA HAWAII ABOUT 305 MI...490 KM S OF HONOLULU HAWAII MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H PRESENT MOVEMENT...NW OR 320 DEGREES AT 7 MPH
500 AM HST (1500 UTC), the center of Hurricane Lane was located near latitude 16.9 North, longitude 157.4 West. Lane is moving toward the northwest near 7 mph (11 km/h). A turn toward the north-northwest and little change in forward speed is expected today. A turn toward the north is anticipated tonight and Friday, as Lane's forward motion slows. A turn toward the west is expected on Saturday and Sunday, with an increase in forward speed. On the forecast track, the center of Lane will move very close to or over the portions of the main Hawaiian islands later today through Friday. Maximum sustained winds are near 130 mph (215 km/h) with higher gusts. Lane is a powerful category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Steady weakening is forecast during the next couple of days. Lane is expected to remain a hurricane as it draws closer to the islands. Hurricane-force winds extend outward up to 35 miles (55 km) from the center and tropical-storm-force winds extend outward up to 140 miles (220 km). NOAA buoy 51002 located about 250 miles southwest of the Big Island recently reported sustained winds of 50 mph (80 km/h) and a gust of 64 mph DISCUSSION
500 AM HST Thu Aug 23 2018 Lane's satellite appearance has degraded somewhat since the previous advisory as southwesterly shear impacts the vertical integrity of the cyclone. However, the eye is still evident in traditional infrared imagery and remains surrounded by a solid ring of cold cloud tops. Water vapor imagery shows Lane's circulation becoming elongated, with outflow severely restricted in the southwest semicircle. The subjective Dvorak current intensity estimates from GTW/TAFB/HFO/SAB ranged from 6.0/115 kt to 6.5/127 kt for this advisory, while data-T numbers were as low as 5.5/105 kt. Using a blend, the initial intensity for this advisory is set at 115 kt. Lane is currently moving toward the northwest into an increasingly hostile environment between a deep-layer ridge to the east, and a trough aloft to the northwest. The initial motion for this advisory is 320/6 kt, with southwesterly shear estimated to be around 25 kt by UW-CIMSS. The track and intensity forecast are extremely dependent on one another in the current forecast scenario, with Lane expected to move generally toward the north while it remains a hurricane, and generally toward the west once it weakens. Confidence in the forecast is reduced because it is uncertain how Lane's core will be impacted by its potential interaction with island terrain, and the subsequent rate of weakening. Regardless of whether Lane's center moves over one of the Hawaiian Islands, an increasing amount of southwesterly shear along the forecast track will lead to significant weakening. If Lane's core were to move over one of the islands as has been consistently depicted by GFS/HWRF, then the cyclone would weaken even more rapidly. EMX2 is on the left side of the guidance and indicates less interaction with island terrain, and therefore a slightly slower rate of weakening. Based on a preponderance of evidence presented by the guidance, the updated forecast indicates a faster rate of weakening than indicated earlier, especially on days 2 and 3. The expectation is that Lane will weaken due to the combined and cumulative effects of debilitating shear and the interruption of the circulation due to proximity to the high mountains of Maui and the Big Island. The official intensity forecast now closely follows IVCN, SHIPS and the ECMWF-based SHIPS. The track forecast anticipates this weakening, with Lane turning sharply toward the west on day 3. Until then, the forecast track is shifted slightly to the right of the previous forecast through Friday, bringing Lane northward and very close to the Big Island and Maui County. This is similar to the multi-model consensus HCCA, which includes GFS and HWRF as weighted members. A slow forward speed is expected as this occurs, with Lane then moving more quickly toward west as it becomes shallow and carried by the low-level trade wind flow. NOAA Buoy 51002 to the southwest of the islands is in the path of Lane, and recently reported a wind gust to 56 kt and significant wave heights near 23 ft. Associated data were used to refine wind and seas radii in the northwest quadrant. KEY MESSAGES: 1. Lane will pass dangerously close to the main Hawaiian Islands as a hurricane today and Friday, and is expected to bring damaging winds. These winds can be accelerated over and downslope from elevated terrain, and will be higher in high rise buildings. 2. The slow movement of Lane also greatly increases the threat for prolonged heavy rainfall and extreme rainfall totals. This is expected to lead to life-threatening flash flooding and landslides over all Hawaiian Islands. 3. Large and damaging surf can be expected along exposed shorelines, especially along south and west facing coasts, with localized storm surge exacerbating the impacts of a prolonged period of damaging surf. 4. Do not focus on the exact forecast track or intensity of Lane, and be prepared for adjustments to the forecast. Although the official forecast does not explicitly indicate Lane's center making landfall over any of the islands, this could still occur. Even if the center of Lane remains offshore, severe impacts could still be realized as they extend well away from the center.