ZCZC HFOTCDCP2 ALL TTAA00 PHFO DDHHMM Hurricane Lane Discussion Number 28 NWS Central Pacific Hurricane Center Honolulu HI EP142018 1100 AM HST Tue Aug 21 2018 Lane remains a powerful hurricane this morning, with a well- developed warm eye completely surrounded by persistent cold cloud tops. Morning visible satellite imagery also depicts a well-defined eye. The Hurricane Hunter aircraft from the 53rd Weather Reconnaissance Squadron is flying through Lane again this morning, and confirms that the hurricane has intensified further since their previous visit on Monday evening. The central pressure has dropped around 10 mb during the past 12 hours, with the most recent dropsonde in the eye finding 941 mb. Peak SFMR winds measured so far have been 134 kt, and max flight level winds are 143 kt. Subjective Dvorak current intensity estimates range from 6.5/127 kt to 7.0/140 kt, with the latest ADT current intensity at 6.4/125 kt. Based primarily on the aircraft data, the intial intensity for this advisory is increased to 135 kt, which makes Lane a high-end Category 4 hurricane. Lane is moving a bit slower this morning and appears to have wobbled slightly to the WNW during the last few hours, and the initial motion for this advisory is 280/8 kt. Lane has been moving westward to the south of a mid-level ridge during the past several days. However, this will be changing soon, as Lane begins to round the western periphery of this ridge and moves into an area of relatively light steering flow. This is expected to allow the cyclone to gain latitude as its forward speed diminishes. The hurricane is forecast to turn gradually to the west-northwest through tonight, then to the northwest Wednesday through Thursday, as it moves between the mid-level ridge to the east and a developing upper-level trough to the northwest of Hawaii. After this point, the track and intensity forecasts remain highly uncertain, as the majority of the reliable model guidance brings Lane very close to the islands with potential interaction between Lane and the mountainous terrain of the islands. This interaction combined with increasing vertical wind shear leads to a weakened Lane being steered to the west by the low-level trade wind flow. The new track forecast has been nudged slightly to the north or closer to the islands from 36 through 72 hours, into better agreement with the multi-model consensus HCCA. Water temperatures along the forecast track will be sufficiently warm to support a major hurricane, and thus any significant weakening before Lane draws closer to the Hawaiian Islands will likely be due to increasing wind shear. In the short-term through the next 24 hours or so, shear is expected to remain light, and expect only slow weakening as the cyclone moves over slightly cooler SSTs and may be impacted by eyewall replacement cycles. At 72 hours and beyond, the forecast anticipates a sharp increase in shear as Lane moves closer to the large upper trough to the northwest of the main Hawaiian Islands. The new intensity forecast is close to the previous forecast, and although it remains on the high end of the guidance envelope, it generally follows the trends presented by the multi-model consensus IVCN and HCCA. In addition to continued storm penetrations by the Hurricane Hunters of the 53rd Weather Reconnaissance Squadron, the NOAA G-IV will once again be sampling the larger scale environment today to help with initialization of the forecast models. KEY MESSAGES: 1. Lane is forecast to move dangerously close to the main Hawaiian Islands as a hurricane later this week, potentially bringing damaging winds and life-threatening flash flooding from heavy rainfall. As Lane is expected to be slow-moving as it nears the islands, it will produce large and damaging surf. A Hurricane Watch remains in effect for Hawaii and Maui counties, and additional Tropical Storm or Hurricane Watches may be required this afternoon or tonight. 2. It is much too early to confidently determine which, if any, of the main Hawaiian Islands will be directly impacted by Lane. Even if the center of Lane were to remain offshore, it is important to remember that impacts from a hurricane can extend well away from the center. Interests throughout Hawaii are urged to closely monitor the progress of Lane during the next few days. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 14.3N 153.2W 135 KT 155 MPH 12H 22/0600Z 14.7N 154.2W 130 KT 150 MPH 24H 22/1800Z 15.6N 155.3W 120 KT 140 MPH 36H 23/0600Z 16.6N 156.2W 110 KT 125 MPH 48H 23/1800Z 17.9N 156.9W 100 KT 115 MPH 72H 24/1800Z 20.6N 158.2W 80 KT 90 MPH 96H 25/1800Z 21.7N 160.5W 55 KT 65 MPH 120H 26/1800Z 21.5N 164.0W 40 KT 45 MPH $$ Forecaster Jacobson NNNN