(ABOVE) The latest 5 Day Forecast Track from the National Weather Service
Hawaii County Civil Defense message (Aug. 7 at 6:44 a.m.)
HILO, Hawaii – Hurricane Iselle is a little bit weaker this morning. Maximum sustained winds are near 80 miles per hour, with higher gusts. The National Weather Service says some weakening is forecast during the next 48 hours, but Iselle is expected to be near hurricane strength as it makes landfall on the Big Island tonight.
Although the satellite presentation of Iselle has degraded slightly over the past couple of hours… A persistent eye feature continues to be observed… And Iselle remains a hurricane. Data from an air force reconnaissance aircraft corroborate the slight weakening trend observed by satellite… As maximum flight level winds in the northeast quadrant diminished from 100 kt to 85 kt overnight… And maximum sfmr winds have lowered to near 60 kt. Based on a blend of the aircraft data and satellite intensity estimates between 4.0/65 kt and 4.5/77 kt…The initial intensity of Iselle is being lowered to 70 kt for this advisory. National Weather Service t 5 a.m. HST
Hurricane force winds extend outward up to 35 miles from the center of the storm, which is currently 305 miles east southeast of Hilo. Hawaii Island is therfore under a Hurricane Warning. Tropical storm force winds extend outward up to 140 miles.
The updated forecast track remains consistent with the last several forecasts in the short term… And remains in good agreement with the multi-model consensus…Which has been consistent in depicting landfall along windward Big Island this evening. In 36 to 48 hours iselle is expected to reach the western periphery of the ridge as a weak cut off low digs southward along the forecast track… Resulting in a slowing of the forward motion through 72 hours. As the low moves south and Iselle weakens… A new ridge aloft is forecast to build north of the weakening Iselle… And the forward motion will increase once again. The updated forecast track only offers minor changes to the previous… And closely follows the well-performing consensus tvcn. National Weather Service t 5 a.m. HST
Hawaii Island is prepared to bear the brunt of the storm on Thursday. The County of Hawaii plans to make it a half day with only essential personnel staying on the job after noon. County Parks will be closed. Absentee walk-in voting will continue at four sites in Hawai‘i County from 8 a.m. to 1 p.m. Thursday. Those voting sites are Aupuni Center in Hilo, the West Hawai‘i Civic Center, Waimea Community Center and Pahala Community Center. All Hele-On buses are scheduled to operate as normal.
The intensity forecast calls for only slight weakening before landfall tonight… Despite the forecast of moderate northwesterly shear by ships guidance. Iselle remains south of a ridge aloft centered west of the main Hawaiian Islands and a ridge centered over the Baja Peninsula. A col… Or weakness… Between these two ridges provides a lighter shear environment in which Iselle would be able to maintain the current intensity before landfall… Whereas if Iselle were to move west of the col and closer to the ridge centered to the west… The shear profile would be more debilitating. The intensity forecast problem is that global models are offering different solutions as to the interaction between Iselle and the flow aloft in the short term…With some solutions tracking Iselle and the col westward in tandem… While others move Iselle west of the col and into an area of stronger shear. Interaction with the terrain of the Big Island is expected to weaken Iselle tonight… While a southward-moving cut off low developing northwest of the Hawaiian Islands on days 2 and 3 will bring stronger shear. Interaction with this low is expected to lead to the demise of Iselle… With remnant low status forecast by day 5…Closely following the trends offered by the ships guidance. National Weather Service t 5 a.m. HST