Area Forecast Discussion
Issued by NWS Pago Pago
Issued by NWS Pago Pago
990 FXZS60 NSTU 260103 AFDPPG Area Forecast Discussion National Weather Service Pago Pago AS 203 PM SST Sat May 25 2024 .DISCUSSION... The latest satellite imageries shows a trough to the south of the area, oriented northwest to southeast, crossing over the Fiji Islands. This trough is expected to remain stationary as a ridge to the north and east holds it in place through at least midweek. The upper air data from this afternoon (26/00Z) shows instability lingering in the area with the potential thunderstorms embedded. Model data is showing a high pressure system to the southeast continuing to transport a gentle to moderate easterly flow with embedded showers over the territory for tonight through Wednesday night. A much broader and stronger high pressure system to the southwest will migrate eastward as it pushes a boundary layer closer to the territory. Easterlies will turn southeast and become fresh breeze by Thursday. These trade winds are expected to gradually increase and possibly reach wind advisory criteria by the end of the long term forecast period. With the trade winds increasing, an increased potential for numerous showers is also expected for this time frame. Therefore, expect isolated to scattered showers with a gentle to moderate east breeze for tonight through at least midweek. Winds will turn southeast at moderate breeze with scattered to numerous showers with embedded thunderstorms on Thursday through the end of the new week. && .Marine... Calm and smooth seas remains across the American Samoa coastal waters. Model data show these favorable conditions remaining through at least Monday night, with seas in the 4 to 6 feet range tonight through Monday, gradually building to advisory thresholds by Monday night. Model data has been consistent in also showing a large south swell reaching shores by Tuesday. This south swell is expected to peak at 15 feet with the possibility of reaching the lower end of the high surf warning criteria (>15 feet) by this time frame. This is due to the aforementioned broad high pressure system to the south-southwest, generating a far fetch wave series from the south. Wave periods that are 15 or more seconds long is indicative of enhanced surfs and strong rip currents. Winds will remain at a gentle easterly breeze for tonight through at least midweek, then increase to fresh breeze by the end of the forecast period. Will continue to monitor the latest model runs for the latest information. && .PPG WATCHES/WARNINGS/ADVISORIES... NONE && $$ JTAllen