000 WTPA42 PHFO 250902 TCDCP2 Hurricane Douglas Discussion Number 20 NWS Central Pacific Hurricane Center Honolulu HI EP082020 1100 PM HST Fri Jul 24 2020 Douglas remains a powerful hurricane this evening as confirmed by the U.S. Air Force 53rd Weather Reconnaissance Squadron. The Hurricane Hunters found maximum flight level winds of 108 knots (97 knots with appropriate wind reduction factor to the surface from the 700 mb flight level) and SFMR winds of 93 knots. Based on these data and recent trends showing a degraded satellite presentation, the initial intensity for this advisory will be lowered to 95 knots. Douglas continues to move rapidly to the west- northwest, with an initial motion set at 295/16 knots. Despite relatively low vertical wind shear values forecast to affect the tropical cyclone during the next day or so, SSTs will remain below 26C. As a result, the official intensity forecast calls for slow but steady weakening during the next couple days as Douglas nears Hawaii, with the cyclone expected to be a minimal category 1 hurricane or strong tropical storm approaching the eastern end of the state late Saturday night or Sunday. Continued weakening is then forecast as Douglas tracks westward over or near the other main Hawaiian islands and west of the state early next week. The official intensity forecast has changed very little from the previous advisory, and generally follows a blend of the corrected consensus and statistical model guidance. Douglas is forecast to move rapidly off to the west-northwest during the next couple days toward a weakness in the sub-tropical ridge north of the Hawaiian islands. The subtropical ridge is forecast to strengthen north of the state over the weekend, and this should steer the tropical cyclone westward over or very near the Hawaiian Islands late Saturday night through Sunday night, before exiting to the west of the state early next week. The official track forecast is virtually identical to the previous advisory, and continues to hug the southern end of the guidance envelope. This track is roughly in between the corrected consensus guidance HCCA and the ECMWF and GFS ensemble mean tracks. Based on the latest intensity and track forecast, Tropical Storm Warnings have been issued for Hawaii County and Maui County. A Hurricane Watch remains in effect for Hawaii County, Maui County and Oahu. A Hurricane or Tropical Storm Warning may be required for Oahu on Saturday. A Hurricane or Tropical Storm Watch may be required for Kauai County on Saturday. Key Messages 1. Douglas continues to approach the main Hawaiian Islands, potentially passing dangerously close to, or over, the islands Saturday night through Sunday night. The close passage of Douglas brings a triple threat of hazards, including but not limited to damaging winds, flooding rainfall, and dangerously high surf, especially along east facing shores. 2. It is vital that you do not focus on the exact forecast track or intensity of Douglas, and remain prepared for changes to the forecast. Due to Douglas' angle of approach to the islands, any small changes in the track could lead to significant differences in where the worst weather occurs. Even if the center remains offshore, severe impacts could still be realized over the islands, as they extend well away from the center. 3. Terrain effects can cause strong localized acceleration of the wind through gaps and where winds blow downslope. These acceleration areas will shift with time as Douglas passes near the islands. Winds will also be stronger at the upper floors of high rise buildings. FORECAST POSITIONS AND MAX WINDS INIT 25/0900Z 18.5N 146.7W 95 KT 110 MPH 12H 25/1800Z 19.3N 149.0W 85 KT 100 MPH 24H 26/0600Z 20.3N 151.9W 75 KT 85 MPH 36H 26/1800Z 21.1N 154.8W 70 KT 80 MPH 48H 27/0600Z 21.8N 157.7W 65 KT 75 MPH 60H 27/1800Z 22.4N 160.8W 60 KT 70 MPH 72H 28/0600Z 22.9N 164.1W 55 KT 65 MPH 96H 29/0600Z 24.0N 171.0W 45 KT 50 MPH 120H 30/0600Z 25.0N 177.5W 35 KT 40 MPH $$ Forecaster Jelsema