000 WTPA41 PHFO 231500 TCDCP1 Tropical Storm Hone Discussion Number 5 NWS Central Pacific Hurricane Center Honolulu HI CP012024 500 AM HST Fri Aug 23 2024 The satellite appearance of Hone has changed little since the previous advisory package, with only limited deep convection near the low level circulation center. The latest subjective Dvorak intensity estimates came in at 2.5 for PHFO and 2.0 for SAB and JTWC. The objective intensity estimates ADT/AiDT from UW-CIMSS came in at 35 knots and 38 knots respectively. Considering that the ASCAT MetOp-B pass last evening sampled a large swath of 35 to 40 knot winds in the eastern semicircle of Hone, the initial intensity will be held at 40 knots for this advisory. A U.S. Air Force Hurricane Hunter Aircraft is on it's way to sample Hone, and will give us valuable information on the intensity, structure, and size of the tropical cyclone later this morning. The initial motion for this advisory is set at 280/14 knots. This general motion is expected to continue during the next couple of days as Hone is steered by a large subtropical ridge to the north. A decrease in forward speed and a slight turn towards the west-northwest is expected early next week as a weakness develops in the subtropical ridge north of the system. By the middle of next week, Hone will likely get increasingly shallow as vertical wind shear increases, allowing the system to turn back toward the west as it becomes steered by the low level trade wind flow. The official forecast track is nearly identical to the track from the previous advisory, and closely follows the tightly clustered consensus guidance. Environmental conditions will change little during the next couple of days. Hone will remain in an environment characterized by low to moderate vertical wind shear, marginal sea surface temperatures around 26-27C, and marginally sufficient deep layer moisture. As a result, only slow and gradual strengthening of the system is forecast during the next couple of days as it moves steadily west to west-northwestward. It appears that there remains a window for further intensification Sunday and Monday as the system tracks south of the Hawaiian Islands. Hone will be moving into an area with slightly warmer sea surface temperatures around 27C and higher ocean heat content, while the westerly vertical wind shear remains at light to moderate levels. This could allow Hone to reach Hurricane strength and the current official forecast continues to reflect this. Beyond day 3, westerly vertical wind shear increases sharply to 30 to 40 knots, and some drier mid-level air appears to begin entraining into the system. This should result in steady weakening for days 4 and 5. The intensity forecast is close to the intensity consensus during the next couple days, and is roughly a blend of the consensus and dynamical intensity guidance from days 3 through 5. KEY MESSAGES: 1. There is the potential for excessive rainfall and flash flooding on portions of the Big Island starting later Saturday, continuing through Sunday and lingering into Monday as a large area of moisture associated with Hone. The heaviest rainfall will likely occur over windward and southeast facing slopes. 2. Tropical storm conditions are possible on the Big Island later Saturday into Sunday. Winds are expected to be strongest where they blow downslope from higher terrain, over headlands, and through passes. 3. Swell generated by Hone is expected to reach the Hawaiian islands Saturday night into Sunday. This swell could cause life-threatening surf and rip currents. Listen for later advisories and possible warnings from the National Weather Service. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 16.4N 146.3W 40 KT 45 MPH 12H 24/0000Z 16.6N 148.3W 40 KT 45 MPH 24H 24/1200Z 17.0N 151.2W 45 KT 50 MPH 36H 25/0000Z 17.4N 153.8W 50 KT 60 MPH 48H 25/1200Z 17.8N 156.1W 55 KT 65 MPH 60H 26/0000Z 18.3N 158.1W 60 KT 70 MPH 72H 26/1200Z 18.9N 160.0W 65 KT 75 MPH 96H 27/1200Z 20.0N 163.5W 55 KT 65 MPH 120H 28/1200Z 20.1N 166.5W 40 KT 45 MPH $$ Forecaster Jelsema