000 WTPA42 PHFO 252059 TCDCP2 Hurricane Douglas Discussion Number 22 NWS Central Pacific Hurricane Center Honolulu HI EP082020 1100 AM HST Sat Jul 25 2020 The satellite presentation of Douglas is degrading somewhat, likely due to restricted outflow to the south and 26C SSTs. The U.S. Air Force 53rd Weather Reconnaissance Squadron sampled the hurricane this morning, and a blend of SFMR, flight level winds, and dropsonde data from two passes supports decreasing the intensity to 80 kt with a central pressure of 984 mb. Douglas continues to move toward the west-northwest (290 deg) at 16 kt. Douglas is being steered by a low- to mid-level ridge to the northeast and is nearing a weakness in the mid-level ridge. A continued motion toward the west-northwest and a slight decrease in forward motion will bring Douglas over or very near portions of the main Hawaiian Islands on Sunday. On Monday, a mid-level ridge is forecast to build to the north of Douglas, potentially inducing a turn toward the west, with some increase in forward speed. The updated forecast track is very close to the previous forecast and lies close to the ECMWF toward the southern end of a rather tightly clustered guidance envelope. Weakening is expected through the forecast. Douglas will remain over an area of 26C SST today, which is expected to continue the gradual weakening trend. SSTs along the forecast track increase tonight, at the same time that Douglas will move into an area of increased vertical wind shear. This is expected to maintain a weakening trend, although at a fairly slow rate. 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. Based on the latest forecast, a Hurricane Warning has been issued for Oahu. Tropical Storm Warnings remain in effect for Hawaii County and Maui County. A Hurricane Watch remains in effect for Hawaii County and Maui County, and a Tropical Storm Watch is in effect for Kauai County. Key Messages: 1. Douglas continues to approach the main Hawaiian Islands, potentially passing dangerously close to, or over, the islands late tonight 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. 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. Hurricane force wind gusts are possible even within the tropical storm warning area. Winds will also be stronger at the upper floors of high rise buildings. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 19.5N 150.1W 80 KT 90 MPH 12H 26/0600Z 20.1N 152.1W 75 KT 85 MPH 24H 26/1800Z 21.0N 154.9W 70 KT 80 MPH 36H 27/0600Z 21.8N 157.7W 65 KT 75 MPH 48H 27/1800Z 22.5N 160.4W 60 KT 70 MPH 60H 28/0600Z 23.1N 163.5W 55 KT 65 MPH 72H 28/1800Z 23.7N 167.0W 50 KT 60 MPH 96H 29/1800Z 24.5N 173.7W 45 KT 50 MPH 120H 30/1800Z 25.8N 180.0E 35 KT 40 MPH $$ Forecaster Wroe