1-minute GOES-18 imagery to monitor convection across American Samoa
1-minute GOES-18 Infrared images with an overlay of Total Precipitable Water and GLM Flash Points, from 2301 UTC on 07 May to 2100 UTC on 08 May [click to play MP4 animation]
A plot of rawinsonde data from Pago Pago at 0000 UTC (below) displayed a Total Precipitable Water (PW) value of 2.35″ — and a GOES-18 derived Total Precipitable Water value near Tutuila around that time was somewhat higher at 2.52″ (GOES-18 derived Total Precipitable Water values in the vicinity of the island were as high as 2.61″ at 0451 UTC).
Plot of rawinsonde data from Pago Pago at 0000 UTC on 08 May [click to enlarge]
Sentinel-3B altimeter Significant Wave Height at 0931 UTC on 08 May
East-southeast surface winds at Pago Pago during this time period were gusting as high as 36 kts or 41 mph (METAR list | Decoded surface reports) — and these winds were creating Significant Wave Heights of 15-16 feet just east and southeast of the island of Tutuila at 0931 UTC (above). Widespread moderate southeasterly winds across the Samoan Islands region were caused by the pressure gradient between a trough of low pressure just north of the islands (along which the more pronounced convective activity was focused) and high pressure to the south (mean sea level analyses: 0000 UTC | 0300 UTC | 0600 UTC | 1230 UTC | 1500 UTC | 1800 UTC | 2100 UTC) — and the broad areal coverage of these winds was depicted in OSCAT-3 scatterometer data at 1158 UTC (below).
OSCAT-3 scatterometer winds at 1158 UTC on 08 May
The combination of these winds and periodic heavy rainfall was responsible for some flooding and wind damage across parts of Tutuila (Local Storm Reports).